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!