Open Source F16 design

Wikipedia


How come there is not an Open Source F16 design? ...
Based on the community knowledge and experience

http://www.freeship.org
FREE!ship is totally FREE and open-source.

You (or anybody) wants to start such a project ?

It can well be done.

Wouter

Not sure I understand what is being proposed, do you mean we get together and design an F16 and make the models, plans, calculations etc freely available to all.

Gareth

Yup that is what open source is all about. A group of people getting together building a design and making it better and better.

I love this idea and aproach.

I would love to start this, in fact I have already started
you can download the file here
www.qcm.co.il/files/f16.zip (AutoCAD)
I'm sure there will be many opinions about this design

I don't have autocat, can you export the picture to a jpg or gif format ?

Wouter

Look at the attachment in Erez's post..

http://www.catsailor.com/forums/download.php?Number=89089

I dont know much about hull design, so I'll refrain from comments.

autoCAT \ autoCAD
I make that mistake all the time
I wonder why ?

It came up as a solidworks drawing on my computer...I have an academic version of Solidworks so maybe it just recognized it and opened it up with that?

Regards,
Bob

Try this Free AutoCAD viewers

http://www.infograph.com/products/dwgviewer/DWGdownload1.asp

http://www.solidworks.com/pages/programs/edrawings/e2_downloadcheck.html

http://www.freedownloadscenter.com/Multimedia_and_Graphics/Animated_GIF_Editors/Free_DWG_Viewer.html

Search Google for "Free AutoCAD viewer"

I'm in the middle of designing a new hull to stick under my current rig and beams (modified mosquito). It will be able to support the F16 minimum weight with crew as opposed to the mosquito weight. If it goes well I'd be interested in supporting the open source F16 and provide a hullform with internal structure.

The best way to do this maybe in the form of a wiki dedicated to the process.

I'm not sure if it will be a worthwhile exercise though, there's not a lot to the design of an F16 without going to extreme analysis techniques or just good old fashioned on-water testing.

Sails - pretty much sussed and only on-water testing is likely to produce any improvements, unless you want to purchase/write some hefty software.
Rigs - stiff is fast.
Beams/Platforms - stiff is fast.
Hull Structure - Sooo many varieties that all work, some better than others, but all have there advantages.
Hull Form - only real area that development is possible, and that is mainly because of personal preferences, therefore let the owner of the boat decide.
Foils(Centreboard/Rudders) - a fair bit of freedom here...

Probably a better idea is to provide a set of resources that ppl can put into use in their own designs (general hull construction, tips and tricks, traps for beginners, photos, rig details, etc). Also, we could put our combined brain power to a list of improvements that can be made to current design/construction practices. This would make its way into the above mention resource of current best practices once it is proven on the water.

I can assure you that a lot of the information that will be generated will be based on heresay, rumour, misinformation, lack of understanding and just plain miscommunication. I have heard it all with regard to boat design! This needs to be carefully controlled with proper, unbiased discussion and not heated argument(which will only ruin the idea).

Another part to this could be a set of spreadsheets/software that can be used to develop an F16 design. Just simple stuff like basic hydrostatics for F16 weight with your specific crew weight, maybe some basic resistance calcs for a design (although this is very tricky)...

Really what I am counter proposing is just a collaboration of all the information we currently have spread all over the world into one source. There is already tons of it in this forum and even more of it in the minds of the current sailors, but it is difficult to find sometimes.

I hope I haven't come across as negative to the idea of an open source F16, I just think it needs a bit of fine tuning towards something that would be less frustrating, more inclusive of everyones ideas and more useful to everyone that is interested. I think encouragement of homebuilt F16's is a very good idea and this resource will be very valuable to the F16 homebuilder.

An example of what I'm talking about is
Lester Gilbert personal website with a good array of information for International One Metre model yachts. It is set out in relatively easy to browse categories.

Done Formula 16 Catamaran Design
There may be problems with adding an F16 design wiki to wikipedia, someone has objected to it being an "instruction manual". Might have to come up with another idea or just edit the article or title. Maybe place a wiki on the F16 website.

I would be willing to contribute to this open-source design, but I'm not going to "pull-the-car" on this project.

I think such a project has many advantages. It educates the sailors which I think to be very important. There is just too much misunderstanding about and the F16's need a skilled crew to really get it going. And I think it will be very helpful to sailors who are looking to adjust their boats to personal preferences. This in fact helps out our dealors and builders as it is very hard for them to deliver "perfect" boats for the inexpensive price we demand of them. Besides "perfect" is different for everybody else. It will be very attractive for the sailors to do their own part in this setup and an open sourse design that lists several alternatives for each aspect will be excellent here.

Additionally it will be a promotional dream. Already we attract many sailors from other classes who are looking to read about these things. An open source probject like this will only spread the name familiarity of F16 more and could really help in its international growth. Also it can show that proper lightweight designing can both be dependendable and simple.

And such a owners/volunteers driven open source project will be a gold mine for the professional designers and builders to see what people prefer and what alternatives may exist to their current way of doing things. They don't have to invest alot of their own time, and were are talking alot of time here, or large sums of money by having an employee research the matters. All this will only help the builders and our class as a whole. It will definately act as a continuing market research and customer feedback project.

Of course it will also be a lot of fun for the persons involved.

However like Ncik says, we need a small team of supervisors that are scientifically capable to run the show and seperate unfounded "stories" from scientifically founded fact. This will be a most important role and a hard one to forfil. I know because we went through such a setup when we first drafted the F16 rules. You got to have a very clear view and policy of what is scientifically founded and what is not. You can decide to have a seperate section to give wild idea's a chance but it needs to be set apart from the main project. Otherwise you are getting nowhere, believe me.

Also we should set up our own dedicated website and not use wikipedia for this. Again this is a job for a dedicated person.


If you guys are succesful in getting this up and running then I'm willing to contribute heavily to it in the way of designing.

Wouter

A good start for this project would be to do a webwide search for scientifically well developped articles and websites like :

http://www.onemetre.net/

or the miss Nylex design article (C-class) that contains results of actual testing (but I can't seem to find now.

It will be most easy to discuss the scientific merit and dependability of these website as a group. This saves us all alot of time typing of lengthy pieces only to find out that it was disproven somewhere else.

This way we also build a common base of understanding of scientific principles and what has already been developped by skilled engineers using this principles. It will be far better the advance the open source project on this foundation then to shoot us in some direction. This point is key, I can't overstress is enough. Again there are alot of misconception around with respect to boat design.

Wouter

How difficult would it be to implement a wiki on the formula 16 website?

For those that don't know, a wiki is a web based reference tool that can be edited by anyone. The principle is very simple, if you don't agree with what is written, you can edit it. As time goes on, a very rich source of well developed, solid concepts are brought to life. They are very user friendly and would be perfect for this project.

I hope I'm not hijacking this idea of an open-source design (it's gone a bit quiet in here), the two concepts could work very well hand-in-hand. It is the beauty of the wiki, it is what we make it.

Not difficult but apparently the wikipedia boys don't want anything other then encyclopic articles on their website and an open source design project is not encyclopidic.

Would be a big hard going if they delete the stuff every 5 days as they are threatening to do now.

Maybe we could request a page nevertheless or ask for their website engine.

Wouter

And here another installment :

Landenberg Tuning guide

This one is helpful for designing the placings of the mast fittings etc.

Wouter

OK, I am also willing to participate, I can contribute engineering and design knowledge, not very good with any of the web stuff though.

Gareth

Would it be nice to follow some parallel pathways in the development of the Open Source F16 ?

Like one setup using rotomolded hulls and another using glass hulls. See what we can come up with ?

I'm sure Rolf will be in on the team as well. Probably mostly with sail design. That would be good as well.

Wouter

I am not an engineer,
I can help with the web stuff
If ther is a need for a web platform dedicated to document this project I can build it, host it and administrate it....

Technically, putting a wiki on the Formula 16 website is not too hard, but running the things is surprisingly difficult. I've had a lot of trouble with spammers on wikis that I've run in the past - they come and delete your content and insert links to their websites (the idea being to gain Google page rank). It's not hard to revert out their changes, but it gets boring very quickly.

It's probably not a huge issue at the moment: our website has a miserably low page rank, so is not very attractive to the spammers (I'll start a thread about that, as it's something we should address...)

The wiki software that wikipedia uses is mediawiki. I've not used mediawiki, but I've used several others and they all suck in their own little ways...

Paul

Would it be possible to run it in a closed area ? Were everybody can view it but only registered people can modify it ?

We could even use the software that this catsailor forum used and set the edit timeframe to indefinately. Everybody then has his own login account. We could even share a single userid and be done with it.

Quick and dirty.


Wouter

Are there any other ways to share the data.

Using a forum will be more painful than a wiki but I understand the problem with spammers in wikis.

I like the idea of registered users only, just so long as everyone who wants to contribute can do so.

I think the wiki (or whatever) should be placed on the existing F16 website.

Give me a day or two to come up with something

Registered users is pretty straightforward, provided that you can approve the users manual (or by email verification). Spammers have automated systems for registerding for and signing into most standard wiki software...

Paul

We must also have a very good backup storage system implemented. It will be a right loss to see months of work distroyed by some Viagra jerk or disk crash.

Wouter

email verification it will be



The server is backed up every day by the storege company, How ever I suggest sending a backup of the files and database to 3 responsible members ones a week or once a month and the administrators user name and password

We need a domain
Please make suggestions...

And owner for the domain
Maybe f16 class organization

Just use the website we have. If we start using other domains etc etc, we are going to confuse ourselves. Just like the One and Two up ratings.

Keep it simple folks.

It is an option

You can see what i did here:
http://www.hot-tub.co.il/osf16/index.php

It needs more tuning

It is a demo so you can play with it and do what ever you like

The platform is PHPNuke

If the decision will be to use this platform then i will put more hours in to it

Perhaps we can tie the access to this "registered" site to dues paying members of the various WW F16 organizations(USF16, europeF16, PacificF16, etc...).

A good reason to support the WW organization.

You've just openned yourself up to exploits from every script kiddie on the planet.

Its tiresome to run such a platform. I tried and gave up after a couple years of constantly being "hacked" by kids who think they're smart.

I have found a way to make this platform completely safe,
It would take an expert to hack it and he would have a hard time trying.



I know how you feel,



This platform is open source and I should make my knowledge Public, how ever once I do, it will not be safe anymore
so I don't

I would have been very very interested in just how you did that.

Good idea guys but being totally able to edit any bodies ideas and thoughts on line must really mean we go around and around in ever expanding circles of thought as we all have our own views on what a F16 should be.

The Unicorn class here in the UK must be one of the most sucessfull amatuer built cats with over 1200 built I think, and really because they had loose design rules much like our box rule, good basic ways of building boats within that box rule and a steering committee who didn't allow the design to deviate too much.


To speed up the build perhaps we should be thinking along the lines of building them using the Kelsall KSS method http://www.kelsall.com/KSS.htm, if you design to the building method you will acheive a far easier and quicker build time.


Go for it guys & girls but try not to get to distracted by the small and petty things and lets have a steering committe who overlooks the whole project and will bring it back onto track when we do get deviated from our task.

Best approach I found while designing (and I do a bit of that in different areas) is to first design the functionality you want, how things should be. And then try to implement that within the limits of reality, cutting corners where you have to. This means to get down on the overall shape first and only later as a seperate project try to design the building method. This will keep one design project relatively independent of another. And we don't want somebody to delete a whole though train because he feels that it can't be done in ply or what ever.

Remember that the Blade F16 project eventually came up with a building method that could build a hull shape that was thought to be impossible before that time. The driving force was that this hull shape had to be on the Blade and so the challenge was then to figure out how it could be done. I can name many other examples. In the West engineers thought that you couldn't weld aluminium to stainless steel. In Russia they just did it when they found out how to do it after a dew failed tries.

So guys which subjects should we handle first ?

Wouter

Maybe we should clear up some of the debate about centreboards...canted, assymetrical, etc...

Okay Ncik,

make the first entry and the rest can respond to it.

Wouter

Ok, I've put something quick and dirty up there but it is unfinished and very simplified.

I don't understand the layout and process yet.

Who are the experts? How are they chosen?

The layout looks a little unintuitive.

I realise it is a preliminary arrangement for comments and suggestions.

If there is a dispute, it is possible to write a statement which covers both points of view...

"...there are two schools of thought with respect to blah, on one hand blah, however some ppl believe blah..."

I think ppl would be surprised at how willing others are to avoid conflict and cover all points of view, especially when evidence is provided for both of these, even if that evidence is common practice and documented experience.

Remember it is a document that gets developed, rather than a collection of time-stamped personal comments like those seen in forums.

I only see my own comments on there no beginnings of somebody starting the design yet.

I hope you guys all forgive me but I won't make the first steps and write up all I know. You guys start and I'll jump in later. The beginning is least interested for me personally as I covered the basics already several years ago. Alot is already to be found in my posts on this forum. So you guys start and work up a basic understanding of the principles so my comments will be picked up easier by you then.

Here you have a new website link :

http://www.geocities.com/kustzeilen/



look at subpages as :

http://www.geocities.com/kustzeilen/sailvectors.html

http://www.geocities.com/kustzeilen/heeling_pitchpole.html

http://www.geocities.com/kustzeilen/Skiff_cat_paradox.html


There is some basics about apparent winds etc there that we all need to understand. There are errors in some of the plots and conclusions but it will do for now. Hell, find the errors and fix them and then you be a long towards to more techy and interesting stuff.


Wouter

What kind of F16 are you looking to design, In order to expand on Wouters request for a spec.

Do you want to design to a budget?
Do you want to design to a weight target?
Are you designing a boat that can be homebuilt?
Do you want to optimize for certain conditions? i.e.
a certain crew weight, i.e. one up or two up
certain wind conditions i.e. a good high wind boat, or light wind boat.

Gareth

Now let's see....

I want a boat that's down to minimum weight, can be built incredibly cheaply and quickly at home. It needs to be incredibly fast in light winds as well as 20knots plus. Oh yes, it also needs to be the fastest fast thing ever in all the wind speeds in between.....<img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />




































I'll get me coat then?

For anyone who might be interested in my idea of an extreme F16, this is it:


Striker screen grab





I've christened it "Striker". Well, you've got to find something to do rather than work, haven't you?

Are those images at scale? What program is that? I think I can use that to design and create scaled graphics.

That's the Freeship program that Erez posted the link to earlier. Yes, they are to scale.

It looks like a "Striker" to me!
but it needs more volume up front
How long did it take you to do?

I did say it was extreme.... I have actually put quite a bit of volume up front, especially low down. I guess it took a bit over an hour to knock up.

"Striker"? Looks more like a "Sniper" to me <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
How would you build it?

How about canted hulls and daggerboards? I really do not know the proper terms, but try to visualize. The hulls canted outwords (away from the mast) and the dagger boards canted inwards (towards the mast). No extreme angles though. Something simple, maybe at 80 to 70 degrees from the mast.

I dunno im just throwing an idea out.

It'd have to be built in carbon/kevlar/epoxy because of all the compound curves. So that means building a plug, and a mould and a vacuum system so it's not a realistic home DIY project. Anyhow, it's only my idea of the ultimate, 'edgy' F16 hull shape. The hydrostatics actually look pretty good but I think it'd be really difficult to sail and the crew weight and position would be hyper-critical.

There is some software available to analyze hull performance. When toying around with ideas, it can be a fun exercise to run your hullshapes trough it. A hull canted outwards should be inferior when sailing the boat flat.

http://www.cyberiad.net/michlet.htm

Here is an example of how the software can be used:
http://personal.inet.fi/private/muu/torodrag.htm

The Stealth already has hulls canted at 4.5 degrees, I don't know that it makes a huge difference over vertically set hulls though.

Canting the boards has a lot of theoretical advantages and banana boards even more so. However, I don't think the F16 class want to be getting into the sorts of arguments that have taken place in the A Class......

Hmm, the way I would aproach that in a home build is install the board trunk close to the out edge on the deck and close to the inner edge on the hull.

The dagger boards to do not have to be curved. And to be make the hulls canted maybe create/build some beam cradles with an angle.

ill draw something up when I get home.

John,

there is always vertical foam stripping, strip plank or even cold moulding for one off projects. It gets more expensive the more high-tech you go, but not impossible for DIY.

From the DIY perspective. The hulls don't seem to me a big deal. Certainly there can and will be more development and refinement that will take place. Lots of folks have the time and skills to build Blade hulls or Mozzie hulls or take your pick hulls and that cost will not vary too much.

The superwing mast is the stumbling block. I sail/race an old boat on a limited budget. I only look at the F16 forum as I would drive past the Porsche dealership, very slowly and only looking.

What possibly can be done to take the "bite" out of the mast cost? Is it that much a contributor to speed? Can a different (more common) extrusion be developed along with accompanying sail.

Is this at all possible or just another dream?

I dont see why not. The question is, will it be as competitive as a wing masted F16? Depends on who is sailing the wingmasted boat vs the non wingmasted boat. So its a matter of who you will be sailing with. If it is just to ponder around a lake without any need for racing, then sure do it. But if you want to be competitive then the wingmast is the way to go.

Robi, I'd point out that the Stealth doen't use a wingmast and it's every bit as competitive as the Blade/Taipan....

I personally am competitive. My point is I've been able to race a well taken care of second hand boat, that still is at minimum weight with relatively new sails and have great fun competeing in the middle of the fleet. Would my (if I could) buying a new boat or sails every year or so move me up (probably not).

Can a percentage be put on super-wing versus non? Is it like a turbo vs. non-turbo or is it like a Porsche with a VW motor? Or does anyone really know?

Thanks John, If I hang around long enough I may learn something! Makes sense that Stealth is very competitve priced.

You may continue and I'll window shop. <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

I think the issue of wingmast vs. teardrop shaped mast on beachcats still is undecided. The latest showdowns between Blades and Stealths at least seem to imply so. The wingmast do produce less drag and possibly higher lift, but getting it in the groove is the hard part.
I have heard that the A-class mast has become more wing shaped, but dont know how they compare to the Superwing.
This is one of the reasons why the Zandvoort event next august will be so much fun (Robi, start working on your better part to get funding)

John, if you want to go F-16. Get or even homebuild the hulls and foils, and put any comparable rig on it and get on the water! In the end, time spent well on the water is what is important (both in competition and recreational sailing).

And what is really good about this program, (besides the fact that it is specifically for long thin catamaran like hulls) is that freeship can output the data directly to it, so if John can post his hull file somehow, I am happy to run it through michlet for you.

But as Wouter said unless you have a spec, i.e. something to aim for the results won't mean much.

Gareth

Yes but the Stealth mast is carbon and probably its stiffness distributing is optimized in various spots. The top taper is up there as well.

If a plain alu mast keeps level with this then the alu mast is at least good. If it is better then it will ve very good indeed. The alu masts are extruded so you have less variables to play in order to get the best mast bending characteristics.

But it will never be a race winning secret wapon. The differences are too small for that.

Wouter

What boat are you sailing now flatlander ?

Wouter

A-cat mast profiles and superwing profile are very much the same with the superwing profile being scaled up a bit.

Wouter

One way of comparing this designs to other is to calculate where the 150 kg crew needs to sit in order to put the boat at its intended waterline in absolutely no wind. This is then easily compared to the other F16's out there. Just test sail your own boat and see how far you need to sit up front in extreme light winds for the same to happen. The relative distance between positions is a relatively good indication how the volume is distributed. Is the bow more or less resistant to pushing its bows in.

We can then all do this measurement on our own boats and produce an overview and make founded design choice. More or less volume or a different distribution.

Can the software calculate the total volume of the boat. You want it at to be above 500 kg's or it will be a total dud for sitting to deep in the water.

Wouter

I would assume the advantages would be when the hulls are lifted, no flat sailing.

But we dont have a rule that rules them out, so I dont see how this can be a disadvantage. Im thinking more like straight canted boards, not bannana shaped.
Good point, so there is a good way to keep cost down. It would interesting to know how much more or less the Stealth's rig cost compared to the Taipan's and Blade's superwing is. This is a good way of keeping the cost down.

Bump - to cant or not to cant.

Canted hulls with canted daggerboards?
Regular hulls with canted daggerboards?
Canted hulls with regular daggerboards?

You missed one Robi;

Regular hulls with regular daggerboards <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

True!

Looking at how well Matt/Gina did at the Alter Cup qualifier I say that uncanted/uncanted is probably a very good place to start our Open source project.

Wouter

OK so regular uncanted/uncanted - GOOD start!

Now to some hull dimensions. This is where I usually have the hardest time.

Just as a square, how tall and wide should the hulls be at the tallest and widest point? We know it will be 16'4" or 5.0meters long.

I am going to try to go one step at a time, starting by the hulls. I might even consider building this project after it looks good on paper.

I think my Taipan hull is 0.34 mtr wide at the widest point; shall we start at 0.35 mtr.

Again the hulls volume must at lead be 500 liters or it will sit to deep in the water. I think 550 liters is the total volume of the Taipan hull and that one is a bit to deep in the water when sailed by crews heavier then 145 kg. So lets start for our project with a total hull volume of at least 600 kg. That would be a good start also.

Can you tell that I've done this before ? <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Ohh, lets decide to ONLY use SI units like mtr. kg, liter, newtons and no US or imperial units. Till save alot of work and miscalculations.

For example under SI the displacement of a volume is simply the product of the volume in mtr^3 times 1000.

Wouter

I agree, we should use only one measuring system.

So far
Non canting
600kg total volume.
Hull width of .35m
Hull length of 5.0m

Hull height What would be a good starting point? Maybe .46m??

I'm not going to get overly involved in your project as its not my class (and there is an F18 kit boat on my "drawing board" at present). But can I recommend starting out with a discussion of LCG, LCF and prismatic coefficient. The rest of your hull design will follow.

Not taking anything away from Matt & Gina but aren't we forgetting that IF they were sailing a Cat with canted hulls etc they might have won and Qualified? A's have been a development class for years longer than F16's and nearly all the top designs are canted hulls. Lets not fall into the Tiger Trap. Tigers have won the F18 Worlds on nearly every occassion but IMO this is can be attributed mainly to Hobie buying the right crews and not necessarily designing the optimum F18.

Good points Mark,

I will further support my proposal. And it is just that, a proposal.

I propose uncanted hulls and uncanted daggerboards because ;

-1- No clear quantizied advantage of canted can be shown as of yet. I would elaborate but it will be much easier to ask to other side to provide actual data that canting is faster. I, for one, have over the last 5 years not been able to quantize its effect, either positive OR negative. I propose to not include complexity adding components to a design UNLESS their is a clear and quantizied advantage to doing so.

-2- Canted hulls are best implemented by making assymetrical hulls. Not something a homebuilder appreciates. You can't make both hulls from one mould or deck jib anymore. Therefor canting adds cost in building the boat. Same can be said, but too a lesser extend, with respect to canted boards.

-3- Canted hulls and boards appear to be a drawback in conditions where you can't luff your windward hull. Often this is the region where most people do poorly. I must rather trade in some "overpowered weather" performance for good "underpowered weather" performand then the other way around. Such compromises will have to be performed more often during the design. You can design the perfect craft for 10-15 knots and end up with a total dud in 0-10 and 15-25 knots. Lets not design the cats equivalent of a "single gear race car".

-4- Which way do you cant it ? In or out. For a time outward cant was popular in A-class now inward canting is. If you decide on inward canting the will stick out to the side and could become a very nice shin basher when you are trapezing in rought conditions. An uncanted board has the advantge that it is well out of the way there in the middle of the hull.



Now allow me to reply to the other statements.




True, however on this forum a few years ago, Jim Boyer himself wrote that the only difference they found with canting was that the boat steered a little better in the mid range winds, something that was found advantagious when wildthinging the boat. No noticeable speed advantage was reported beyond improved control that in turn allows to maintain top speed better. AHPC had just put out the mark 4 Boyer A-cat which was effectively a Mark 3 but with canted hulls. In F16's we don't do much of wildthing at all. Under spinnaker the way the boat behaves is different from a boat without that does the wildthing.

I'm argueing that this could be a case of where a thing that works in A-cats might well not work in F16's. And there are alot more of these things. I won't elaborate but A-cats and F16's are remarkably different craft. The A-cat designs operate under a very different set of balances and specification, often to such extend that data acquired there is not easily transferable to F16's.

I can also state here that I spoke to 3 different A-cat builders/designers about this and all said that they didn't think that canted hulls would help much at all on boats that carried a crew of two. I won't elaborate so you can dismiss this point I you want.





The Capricorn F18 is uncanted in both boards and hulls : 2006 world champions
The Cirrus F18 is uncanted in both boards and hulls : 2002 world champions

All other world championships ever held were won by the Hobie Tiger (uncanted/uncanted)

So no worlds was ever won by a canted/canted design.

Note how no new F18 has canted boards anymore, only a few have canted hulls. I think only the Nacra Infusion has canted hulls as one of the newer F18 designs. I think we can regard the F18 as a development class of long standing as well.

I refer back to my original point; unless it provides a clear and quantizeable advantage then I wouldn't propose making the design more complex then necessary.


However having said all this, I propose that is people are committed to canted hulls and daggerboards then lets open up a parallel design path where the alternative design has them. Then when both are done we can look at which is the most attractive when balancing performance potential to things like production considerations and cost.

Wouter

Canted boards are not legal under the F18 rule. The boards must be located on the centre plane of the hulls.

I already said that I'm not an engineer
So what ever I write is not based on calculations.
I'm very curious as for hull shapes
I have been looking at the hull shapes of every beach catamaran I could find trying to figure out it's concept
and what the designer was trying to achieve,
The more I looked I was able to see things I could not see in the beginning.
I'm very excited about this Open Source Project and I can't wait to find out all the things I don't know that I don't know.

As for the hull width I suggest 0.4m where the water line is,
and then play with the deck width to achieve total hull volume of at least 600 kg.

more volume = more weight
carbon = less weight
carbon = $$$
<img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />



We can design a part that will be placed between the hull and the beam and make the hull canted,
or not canted with a different part,
I am not talking about one part with two positions.

Erez I am trying to get a box measurements and then concentrate on where it should be wider, narrow, taller, shorter etc etc.

Volume - 600kg
Length - 5.0m
Width - .35m
Height - ????.45m .46m .44m????

After we get this box dimensions, we can play with placement of the values. For instance how far back will the tallest, widest thickest point be? Rocker placement, crossbeam positions and everything else.

wouter, displacement is volume multiplied by 1025 if in salt water...1000 if in fresh water.

well we want the boat to also float in fresh water so lets err on the right side and stick to 1000. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Robi,

Lets use 0.5 mtr height as a start of point. Later it can always be raised or lowered if that is needed.

You can also measure your own daggerboards and get a rough estimation of good starting point for height.

I as a Taipan sailor want more height above the water, my current design can flap the wave now and then when I doublehand. I seem to remember my hull is 0.45 mtr high at the daggerboard well.

Wouter

Can we define the "freeboard" instead of the "height". I hate to get antsy but the height you are talking about should really be called depth, which is the technical term for the distance between the top of the hull and the bottom of the hull. This is generally speaking the draft of the boat plus the freeboard. Draft is heavily determined by the displacement of the boat, which F16's have generally fixed at about 260-270kg, and the rocker of the keel of the boat, so most F16's would be within a fairly narrow range of these values. Freeboard is what is required to keep the beams and deck above the water and hence waves, hence lower drag. So really, you need a draft, rocker and freeboard, rather than a height.

My hull design has got a freeboard of about 350-400mm (from memory) at the fwd beam. Where I sail is quite choppy so I need lots of freeboard for the beams to clear the waves. Haven't designed to a specific rocker or draft (so don't know those values off the top of my head), have just fiddled with it to make sure the under water hull looks good when supporting 260kg.

So far

Volume - 600kg
Length - 5.0m
Width - .35m
Freeboard - .45m

Alright,

Good points Ncik. Freeboard it is. This bring us to the requirement of having a section that provides definitions. Are you willing to make that for us Ncik ?

To everybody :

It is time to start using our wiki at :

http://www.catsailor.com/forums/showthre...age=0#Post89232

I will start on the article dealing with beam design.

You guys take care of some of the other articles okay.

Robi, you are our graphics men ! Our diagrams and pics must be good looking indeed. You are good at that.

Rolf, are you up for some sail design c.q. building article.


Erez, is the wiki well protecten and back-upped regulary now ? In short is it dependable ? Is the hosting secure and can the wiki be ported quickly and succesfully to another hosting (like our F16 webpage) in case of emergency. Even from the back-up files ? I've learning in my time as a network administrator that this was always extremely important.


Wouter

For some reason I can't do Sh!t on our wiki !!!!

I have an account

Can somebody explain to me how to add, alter or start comments/articles ?

Wouter

I had the same problem, it gets approved before publishing. Plus it doesn't appear to be a true wiki, more of a forum.

The wikipedia F16 design wiki I setup will be canned shortly, I will investigate other options.

I will work on some definitions appropriate for F16 and post to wherever it needs to go.

Well after gathering what we have I went downtown on my graphics/vectorizing program. This program is a graphics design program that I can create images to scale. The good thing about using this type of software is, I can modify any line to any point in the design. For example, lets say you dont like where the bow starts once we agree on where the bow should start I can go ahead an input it into the software and it will show a preview on how it will look. The image is totally scalable and anything can be modified extremely easy.



Edit, this is a sideways view obviously. I still have to create the top view. That is comming soon.

The fall back angle of the bow is pretty much a direct result of the width of the deck. At the current steep angle the deck narrows very quickly towards the bow. I don't see the advantages of that. No reserved bouyancy at all and most waves will flow over the top splasing against the beam as the bow is not lifted much at all.

Anyway we should decide on the bouyancy distribution in the bow and then the corresponding fall back angle of the bow will simply appear.


Wouter

Not to sound defensive, but the addition of canted hulls, foils or any other "gee-whiz" gadgets being discussed here would have in no way affected the outcome of these past races for us.

You guys need to be having a few beers with this thread or maybe something more hallucinogenic. There is nothing revolutionary in what is being dicussed. As evidenced in the A class and F18s, it is the crew winning the events not the boats. Tigers are out-dated, yes, but still are capable of winning events, same with Marstrom A-cats.

1)Hull shapes are all trade-offs. The new trend in shape popularized with the Flyer is no faster than a well done older style design. They are easier to sail not necessarily faster.

2)Wing-masts, as pointed out earlier between the Taipans and Blades as compared to the Tear-drop Stealths, show no real performance advantage either. Theoretically, they provide better flow and more tune-ability in the rig, but they are much harder to tune correctly.

3) The Blade or Taipan would theoretically sail better with high aspect boards. With the low aspect boards they are put down when we leave the beach and never worried about again. For me, the less I have to do the more I can concentrate on the race..i.e. they're faster.

4) I have raced canted board and hulls and I don't know if they are any faster, but I do know that the boat is much more difficult to control on a start line. Mess up the start and they had better be faster by an order of magnitude to make a difference.

I do not mean to knock any discussion meant in fun, as this would be a cool home project, but a lot of people spend more time fussing over fine adjustments to something that has no effect on what they are trying to achieve.

Matt

Just to clarify, my opinion of the design project is that the aim is to provide a bare-bones, stock-standard, F16 that anyone can build. Something that future F16 sailors will be happy with, and in the right crews hands could be a winner.

A sort of aside project is to de-bunk a lot of the myths surrounding catamaran designs with some proven and well explained engineering...

Have I got it right?

ncik,

From anxiously awaiting on the sidelines Yes, please <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

As stated in one of your earlier posts


A one up or two up, 5 to 20 knots, smooth and choppy water boat. A consensus boat.

Matt M makes excellent points about all the gadgets. The cool thing about the class is all the possibilities and personalized gadgetry.

Let's get some basic boats on the water.

I fully agree with what Matt said. But try to make the boat easier to sail correctly all the time, that is, make the control lines easily adjustable, that will lead to more speed.

There have only been some small advances in hull speed, mostly from reducing overall weight by reducing weight in the hulls, masts and sail material.

Then there is sail shape, like the square top mains, self tacking jibs (may not actually add sail power but are faster to tack, allowing the crew to get out on the wire a second sooner, wich makes the boat a tiney bit faster). But you need only look at the Tornado to see that rig improvments have gained more speed than hull shapes in the past 20 years. A "fast" upwind hull may be slow downwind, so that is the trade off you have to make.

I think the "Next Big Thing" in terms of actual speed improvements will be development of foils. Look at the Moth class. If they can do it on a skinny mono, we should be able to figure a way to make it work on a cat. All you really have to do is take two Moths, remove the side wings and connect them with a couple 8 foot carbon beams, move the mast to the middle of the forward beam and voila, you have a foiling cat!

Or...maybe we can talk Matt into mounting a couple of daggerboard trunks at an angle beneath the forward and read beams of a couple of Blade hulls, slide in some longer boards (steal some Inter 20 boards) and see what happens! <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />

I volunteer to be the Test Pilot. (or crash test dummy)

From my understanding it takes about 10 - 12 knots of wind before the Moths can effectively fly the hull properly and over come the extra drag of the foil to enable a faster speed than a conventional hull. As my limits are about 15 - 18 knots with my Stealth then this seriously limits the number of days that I can go sailing if I have to wait until the wind gets up around 10 - 12 knots. Foils may have there place in the great scheme of things but for alround 2 - 20 knot wind sailing capabilities then I'm afraid it has got to be a conventional design.

One thing to think about in the design is that a " solid " trampoline would stiffen the boat up, would probably be lighter if " aircraft flooring " boards were to be used, would work out cheaper in the long run and would allow much smaller beams ( the loads are spread right along the hull rather than just at the attachment points ), if it were to be built into the design right from the start, just maybe it might be good idea ???????.

Speaking to a few of the guys at Grafham... They need 8 kts to get foiling, but only 7 kts to stay foiling. I wonder if we;ll ever get pumping protests "to get on the foil" (or not).

I dont think a solid trampoline to stiffen up the platform is viable. The loads on a cat are mostly from wracking and the rig, where one hull tries to move in a different direction than the other. Looking at the platform, this means that the mainbeam mostly see torsional loads while the aft beam is trying to bend into an S-shape. You would probably add much more weight (and cost) in the stiff deck than you could remove from the beams. The deck would have to be very thick to make it stiff enough to contribute to platform stiffness.
By "aircraft flooring" I think you mean paper honeycomb cored composite panels. This is the same stuff Marstrøm build boats from.




I'll be happy to upload some saildesigns for comments and discussion. This is one are where there is way too little discussion. Having correct sail trim is one of the major parts of boatspeed, spotting worn out sails is also an important skill. Being able to compare your own sails with the design shape (even if flying shape and design shape differ) is a good thing.
I think writing comprehensive tuning, sailtrim and sailing manuals would be more important for recruiting than an open-source design. If I was to choose a class to start in, having access to this information would be more important for me than having access to open information about how to build the boat.

Btw: I think I prefer to fall on my face/behind/knees on a relatively soft trampoline instead of crushing a solid and expensive panel <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

Not to mention the solid trampoline...

Paul

Plus moths have no minimum weight so are extremely light, 9kg for the bare hull! I think they are about 25-30kg rigged, 90-100kg with crew...which makes them lighter than an F16 boat alone! With F16's on the water at about 270kg, we would need approximately 3 times the area of foil if it was in a T-foil arrangement, even more if it was a dihedral foil arrangement.

It can be done, but I won't have a part of it. If I wanna foil, I'll get a moth.

I think the gentlemens rule in moths is to not protest about pumping. They've done it since the time when the boats started getting narrower just to keep them upright.

The other thing with the foliers is they are a PITA to launch. Need to swim them out into enough water to get them sailing with foils down.

I think the ride makes up for the launching. I hope to find out this Christmas at the aussie nationals, my mate has one!

It would be prudent for us to address the three general wind regimes with the open source design for sure. Light (0-7 knots), Medium (7-15 knots) and Heavy (15-25 knots).

It probably only affects the centreboards, rudders and hulls though, because the effectiveness of these items will change with the speed and heel of the boat, but the structures will have to withstand the highest loads anyway.

Are we designing for windward-leeward courses or other? A simple design aspect that will be affected by this decision will be the height of the bow. If shy/tight reaching much, I would want a fairly high and full bow to take the trimming moment from the sails, if doing windward leewards (hotdogs) we can get away with much less reserve volume in the bow. If designing for both, I would want to be on the conservative side of a full bow.

Speaking of bows, I have debated for a long time the effectiveness of wave piercing designs. With kite/spinnaker cats, the bow will rarely bury upwind, and will certainly not be succeptible to nose diving upwind. Downwind, the kite will lift the bows significantly. I think "wave piercers" are more effective at removing weight from the bow of the boat rather than actually piercing waves. Probably looking at a kilo or two on each hull, which is nothing to sneeze about all the way out at the end of the bow. Reducing weight at the extremities of the boat is an effective and proven way to improve boatspeed.

I'll admit that wave piercing may be effective on A-Class cats because they have such little hull depth and no kite to lift the bow downwind. But again, the weight reduction in the bow probably has more effect.

I doubt the reduced bow profile on the 'A's is a wave piercing issue but rather a move to reduce the volume forward to reduce windage and improve pointing. Valid for most cats, particularly if you have a spi pole and snuffer pulling the bows down.

ooh yeah, I forgot about windage...

We have set up a catamaran based wiki at f18.ca which you are very welcome to add content to.

Which site are we supposed to use for this F16 open design?

5 Options are:

1.

2.

3.

4.

5. Use all 4 platform, it is only a matter of copying and pasting the information that is Open Source in the first place


I prefer no 3

I've been trying option 3 but it just doesn't "work" for me. I find working with it too cumbersome.

Wouter

Same

I see the problem with no 3,

How ever you do not offer an alternative,

We can use this forum (catsailor)

Put a general sticky Thread with links to every subject of the project, that way it will be easy to find the information.

Simple!

???

Next question, which should've really been asked much earlier, one-up or two-up (cat or sloop rigged with one or two crew). This will affect the weight significantly.

I've been working away on a two-up design because that's how my boat will be sailed 99% of the time.

Surely the reason it wasn't asked is because it's irrelevant. The F16 class is not about optimising for solo or two-up. The whole point of the class is its flexibility in either mode. We need to look at the min weight rule really as it makes a distinction where there should be none. (Just my personal view)

This is a 14ft model. It could be stretched to fit the F-16 rules. The Center of Buoyancy and Beam @ Water line could be manipulated according to Crew weight and Rig Dimensions and centers. Feedback is welcome.

Ricky

Sail one-up with out jib and at 134 to 140 kg total crew weight two-up, with jib and stiff upper battens in the same main sail. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Since you asked, I want a boat for both conditions.

That is the original intention, right?

As I mentioned previously, I have no intension of contributing to this design process but because you seem to be stalling out and I’d like to see what you as a group will come up with, I’d like to suggest some refinements to the process you’re following. While its fun to play with hull shapes etc., at this stage it’s a waste of time. I recommended the following process.

1. Compile a list of all the equipment to go on the boat including its weight (if known).
2. Draw a layout (plan view) of the boat showing all the equipment etc. (at this stage you’ll need to discuss and decide on a first guess location of the beams and and settle on a “standard” system for halyards etc.)
3. Draw a preliminary sail plan.
4. Make the assumption that your hull isn’t contributing to lateral resistance and determine size and placement of foils. When doing this locate the foils for the 2up option. If you place the foils for the 1up option you’ll end up with lee helm if sailing 2 up, however, the extra weather helm from having no jib if foils are placed for 2up can be offset with rudder angle.
5. Generate a weight estimate including an LCG (longitudinal Centre of gravity) by combining your equipment list with the data from the drawings. You’ll need to decide here on ideal (2up) crew weight and where you would like the 2 crew to be located going up wind (also check where a single sailer will end up to keep the same overall LCG). For your first pass through the process assume that the hull’s centre of gravity is at midships (this will be refined later).
6. Having done all this, now you can start playing with hull shapes. Things to consider: Location of LCB (longitudinal centre of buoyancy)
Location of LCF (longitudinal centre of flotation) the point the hull pivots around when changing trim.
Prismatic coefficient (how much buoyancy is in the ends below water lines).
Desired transom height (above or below water etc)
How the LCB and trim move as you transition from two hulls to one

7. Design the hull structure.
8. Calculate hull weight.
9. Go back to 1. and replace best guesses with new data.
10. Repeat 1-9 until nothing changes each time you do a loop or you run out of time and have to start building.

At first glance, one of the hardest things about designing a good hull for the F16 is the massive difference in displacement that the hulls see in different sailing modes.

i.e. one up with both hulls in the water you need to optimise for 90kg, 105kg boat + 75kg crew =180kg/2= 90kg

Two up flying a hull you need to optimise for 300kg, 110kg boat + 190kg crew = 300kg

The optimised hulls for these two conditions are very different.

However a good compromise hull works surprisingly well when sailed at either 90kg or 300kg.

Here are two graphs that show the drag of three hulls when sailed at 90 kg and 300 kg.

Hull1 is optimised for 90kg, Hull3 for 300kg and Hull2 is my compromise hull.
300kg

90kg


The same graphs but zoomed in on what I consider to be the most important speed range 8-12 knots.

300kg

90kg


As you can see the compromise hull performs well across the displacement range required by the F16 class. I have more data I just need somewhere to put it.

Gareth

What these plots say to me is that it is very attractive to design a 300 kg hull (although I think 190 kg for the crew is a bit high). Because it appears that sailing a 300 kg hull light (180 kg) hardly increases the drag at all. Especially since the hull related drag at max makes up only 20 % of the total drag of a beach catamaran. So even if the 300 kg hull sailed light has 10 % more hull drag then it would only amount to 2% increase in drag over the whole drag of the boat. This is negligiable. Clearly sailing a light hull heavy is much more worse.

Thanks alot for the graphs Grob !




I'm willing to help you guys out in the way of beams etc, but as written earlier I'm not pulling this car and I'm not accepting any cumbersome publication methods.

I do think we got a great project going here, but some of you really do have to get that site up and running and one that is easily backupped and updated.

Why not just make a site with PDF files and have a download corner where the original Word documents are. A person can then download the word file, make the changes and submit the new Word file to be checked and converted to PDF. Simple, easily accessible and spam proof. I'm sure Paul Warren will make space on the formula16.org website. Now we only need someone to check and maintain this segment of the project. I'm already doing the picture and video gallery so count me out of this one. I'll be only a contributor nothing more.

Wouter

I have conducted a preliminary weight estimate based on a mosquito arrangement. This is where a displacement of 260-270kg has come from.(If you are pushing 180kg total soaking wet crew weight or above, you should probably consider an F18 or bigger!) I would share the weight estimate but it is too hard atm. If someone could do a weight estimate for a Blade or Taipan F16, that would be good. Don't forget that we have a rigged minimum weight to meet already, so that simplifies the weight estimate process drastically, it is the structure that can get fine tuned to bring the weight down below this, then add a bit of lead.

I agree with leaving the hull shape to later, it is really influenced by everything else, including crew weight. With a range of displacements from 180kg 1-up to 270kg 2-up, it makes it very difficult to design for all conditions. Just look at the extreme end of 1-up mode, Gary on Altered. It would not perform with 160kg of crew weight onboard, but is very good in a 1-up configuration.

As far as prismatic coefficients go, we would need data for other successful beach cat designs to have an idea of this. I don't believe that data exists in the public domain. If people have this data it could be very beneficial.

I'm looking into a new method of sharing and contributing to this Open Source F16. Bear with me, my skillz at web administration are newberish at best.

http://www.sailcut.com/

Hey these guys have been able to get the Wikipedia software to run their wiki !

http://wiki.sailcut.com/Main_Page

Wouter

I have no objection to (trying to) install MediaWiki as part of the F16 website, but I do not want to be responsible for dealing with any spam. I've found this to be a big problem with wikis in the past, and even installing those irritating "type in the word that's displayed in this image" things doesn't fully solve the problem.

That said, the F16 website's Google PageRank is pretty miserable at the moment, so we'll be very unattractive to spammers for the time being. On that subject, if you have your own webpage, please help to improve Google's opinion of us by linking to http://www.formula16.org

Paul

You are on!

http://www.formula16.org/wiki

Have fun.

Paul

Awesome.

Very cool, Paul.

Now, let's see people use it productively (and sensibly)!

What is worse is that when I google F-16 catamaran or Formula 16 catamaran, I only get the former site at geocities.com, and it is clear that site has not been updated since December of 2005, so it makes look like the class is extinct. <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" />

Can you put a forwarding message on that site, to send people to the new site? And eventually eliminate the old site? And can't you notify the Google people about the change?

Adding a forwarding message would certainly be a good move, and would help with the Page Rank of the new site. The Google people can't/won't do anything here.

If anyone who has links to the old Geocities address changes them to the new formula 16 site address, this will help promote the new site over the old site in Google's mind.

One such place is the welcome message in this forum - Wouter, could you edit that post?

Paul

Wouter is not able to edit the post. Rick or I will do it tomorrow.

All that would be needed is a re-direct in the old website.

I'll look into redirecting the visitors from the old page to the new.

Wouter

Mary,

Thanks for making the change to the website URL in that post. Could I trouble you to also change the contact address to formula16class@formula16.org ? Sorry for not spotting this the first time round...

And while I'm at it *bump*. Anyone brave enough to make the first move on the wiki? I've locked down the front page, so email me if you want stuff adding there, otherwise you're all free to sign-up and start editing.

This would be a really good place to create rigging and tuning guides for F16s. Next time I take the Blade somewhere, I'll photograph the process of rigging single-handed and do a write-up. But there's no need to wait for me...

Wouter - any chance you could take a look at the old Geocities site? I don't mind making the change if you want to just send me login details.

Paul

Old geocities site change shouldn't be a problem, it just slipped my mind sorry.

Wouter

I'm in the process of preparing some stuff for the wiki. Will hopefully post shortly.

Now we are getting somewhere <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

I think that for newbies like me most interesting part would be boat tuning, this could really speed up the learning. Of course this information is already buried here in forums and can be found, but it's not always clear if you have found something worth of trying. Having a F16 tuning faq might make this forum less active though, because there is no point of asking if your questions are already answered <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

Don't worry about that. In sailing there is no such thing as having all questions answered. Every answer leads to more questions. It goes on forever. And even the basics of tuning a specific boat might change tomorrow or be different depending on who is presenting them. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

This wiki works for me ....

So everybody try it out yourselfs and lets get stuck into it.

Wouter