All,

I am considering building an F16. I have been interested in the class for a while, 1 up spin sailing appeals to me and the ability to carry a friend for crew is a bonus. Boat building is something I have often considered, partly as a way to learn more about the technical details of the hull construction and rigging and partly for the bragging rights of racing something I built.

Right now I am in touch with Phill regarding the Razor. Planes are not available so I am working off of the information he has been more than kind enough to provide for me (taking time away from his Tri to do so). My current plan is to build the hulls using the stich and glue method Phill has devised, although the striped foam method looks equally feasible: http://lindahlcompositedesign.weebly.com/index.html

My largest concern is sourcing the rest of the required bits at reasonable prices. So far I am considering the following:

1) Bent H16 mast used for crossbeams (need to check cross section and wall thickness to ensure strength)
2) Old Tornado mast. Would need to be cut down, custom mast base constructed, proper spreaders rigged etc.

The rest I am planning on sourcing used if possible but likely buying new. Sails are expensive but new sails with custom r&d are a necessity if using the Tornado mast. Some of the other major bits are pretty expensive (spinnaker setup) and/or difficult to obtain (jib self-tacker, APS wants $900 for their F18 jib traveler, ouch!).

Some bits I would like opinions on:
1) Rudder hardware-go the used route (TheMightyHobie18 etc.) or new
2) Wing mast vs. non wing mast. I've been told the wing mast is a 2% performance increase over the non wing mast
3) Rudder and dagger board sizing. Current boat measurements would be nice, at least the surface areas of each. I plan on designing the foils and building them from foam and carbon, a starting point would be very useful.

While I am sourcing good used parts where I can, I fully realize that this is going to be an expensive and time consuming process. My current estimate puts the cost of the boat at $11,000 plus considerable labor on my part. I was wondering if their are some catamaran sailors in the Annapolis area that would be interested in building an F16? If so, the striped foam method makes a little bit more sense for multiple boats, or possibly getting CLC to cut kits.

-Sam

Sam,

Good luck with your project.
If you're looking for new pieces (jibtrack, ...) contact Matt.
Concerning the mast, a wing mast might in theory only add 2% performance increase, but you can trim the boat a lot better towards more or less wind, making the boat a lot easier to sail and in the end a lot faster. Not only wingmast or not, but the stiffness of the mast is important. I would reconsider this part.

Gill

Hi Sam,

I doubt about the 2% benefit of a wing mast. As long as your sail fits to the mast and the mast is light, strong (it will not break) and flexible (it can be trimmed over a wide wind range), everything is fine. In other words a cut Tornado section sounds reasonable. For example Landenberger gives you some advises how to measure the flexibility of the mast and he will cut you a sail to this mast, but I am sure other sailmaker offer you the same service.

Crossbeams: You can make your crossbeams form CFRP in your workshop as well, or you can buy standard alu extrusion 100mm diameter. I think a H16 mast is to flexible for a crossbeam.
Self-tacker: Buy a straight track, go to a smith with a machine to bend metal.

Rudders, boards: I can take a measure next Saturday, if you want. I can give you sections which I have developed for Tornado rudders as well, however they are thicker than standard section (yet have less drag), so you may need custom rudder heads. Rudders and boards shoud either have a high density core (as wood on Tornados) or spars to avoid core-crushing. If not you need significant skin thickness of CFRP. I think that the cheapest and yet light way to do is to have a wood core (CNC machined from a good carpenter shop) covered with glass fibre (you may add Aramid on the leading and tralning edge).

Good luck.

Cheers,

Klaus

Best of luck. I've always wanted to build a boat but it's too much work for me. I'd never finish.

$11K + a lot of man hours and no sailing, yuk!!! There is a relatively new Viper in OC, MD listed on CatSailor. Complete rig w/trailer and beach wheels, and not much more than your $11K. Also, a very new Falcon in SW Florida on CatSailor. Probably can get a good deal also.

There is nothing like building your own boat but it is a lot of blood, sweat, and tears.

Maybe build hulls at your leasure while racing a Viper or Falcon. You could use the same rig.

Good Luck.

That's an idea, just us the rig off another boat.

That's what Chris Amador did. He had an Alter cup Blade, built his current boat now, Trident, and then used the rig off of the Blade and put it on the Trident.

He worked on the Trident mostly over the winter, so there wasn't a lot of sailing time lost there, but he still was building on it during the sailing season. So, he had the option to still go out on the days during the sailing season.


If I was building a boat, I would seriously use the rig on the F16's anyway. It's way too optimized for the boat as it is to try to do something different that might not be optimized.

You can't beat the Aluminum wing mast. It's plenty tough, but bendy enough to depower when needed.

Mike

I never found the exact source for this theory either. There was some discussion on it "a long time ago" and half qualified information but no proper testing. Discussion touched topics like attaching flow after stalling, separation bubble on windward side, the need to trim mastrotation more while sailing as the wing is not as forgiving etc etc.
I do know the common thinking now is that the wingmasts are about 2% faster even if I know of no proper testing done on beachcats in real life. Hopefully somebody did this testing both under controlled conditions and real sailing conditions.



Or if you have more time than money, build it in composites.



Very interested! DAG profile?
CNC shops willing to machine a mould, blanks or cores are not everywhere. Phils foils are well known but if you have other references, I am very interested.



PS:Buying used is a very good move! All my boatbuilding experience tells me so

Wow, lots of interest!

Klaus,

I'd be very interested in your foil measurements as well. I think you posted your modified NACA 0012 foils on this site at some point. Did you do inverse modelling in Xfoil for their generation or?

All,

Bending of metal can be done but needs the proper tools. I've got some links to some potentially lighter and relatively inexpensive rudder hardware (A-Cat builder).

Foils: My method of construction can be found here: http://www.single-handedskiffs.com/images/centerboard_construction_final.pdf
I may make some changes, probably reduce the layup schedule where appropriate, possibly go for a more finished route using mylars during the layup. I have the foam cutting equipment and vacuum bagging supplies needed to do this job, plus I've done it a dozen times with model airplane wings.

Cost: I've found some cheaper sources for bigger ticket items (mainsheet blocks for example). The Tornado mast sounds very viable, if the sail is cut to match. This would save ~$1.5k. If used competitive F16's were available for less than $10k, I think I would go that route and drop the home build. The Blade, while competitive, is an outdated hull design by Viper, Falcon and Razor standards, plus I feel it is lacking in volume (ok for lighter air sailing but I would be happier with more volume on a distance race for example). Another option may be acquire a F18 and build the F16 over the winter. At this point the project is in the planning stages, so may get derailed by life but I think it is pretty feasible.

Ok I try to not forget the ruler and take some pictures of the stock Bimare foils of my boat.

For the section design, I used indeed x-foil, but not in the inverse mode (I never managed to use it for symetric sections). I started from NACA for digit foils, modified the gemoetry based on my knowledge to achieve high maximum lift, higher cavitation speeds and less drag at a given lift ratio. I tried to avoid making "laminar-sensitive" sections as well. So I got some hundreds of new sections geometries, which I run through X-foil and put the customer for the difficult question which exact combination from lift, drag and cavitation he wanted. Basic outcome was, that you can have much thicker foils with more maximum lift and less cavitation for more or less the same drag as a conventional NACA 0012.
In my opinion those foils are better than most available sections, which are too thin or try to be laminar.

My friend used a similar construction method for his Tornado rudders as you. But after some sailing the rudder crushed the foam core at high speed, partly beacuse bad glueing (he didn't have vacuum equipment), but mainly because of to thin CFRP skins. Taking wood resolves the probem of core crushing and you still can stay with the thin CFRP skin (or glass as on the T's). I guess machining wood is more expensive though.

Rudder data are at home now, but maybe I will have some time and put them in a document, which I can share here.

Cheers,

Klaus

Klaus,

I agree with your analysis, laminar foil sections tend to make little sense for this application, the drag reduction is minimal to non-existent, any benefits are instantly lost if the surface finish isn't perfect and they stall at 5 degrees lower angle of attack. Plus the drag outside the bucket is significantly higher than in the bucket. I could see there use on dagger boards but on rudders that operate outside the bucket for >50% of the time, I don't see the point.

Out of curiosity, how are you modelling cavitation effects?

I can very easily cut foam to the proper shape for a rudder and daggerboard. By easily I mean all 4 foils can be done in one eight hour session with the hot wire bow. I don't think cutting wood to an airfoil section will take that little time. I can vacuum bagged the next day, paint on the third day-its a very quick process for me as I've done it a lot. Concerns of crushing the foam core are valid, I would use Dow High Load 100 as it is the highest density foam that I can relatively easily acquire and most importantly still cut with the bow-going to Rohacell IG 71 would double the crush resistance (231 PSI vs. 100 psi) , but drive the cost up and I would need CNC equipment to get the proper shape. My experience with the high load foams is it isn't too bad in dent resistance with 1 light layer of fiberglass. Considering I'm going to 4 layers of 5.7oz carbon minimum to handle the bending loads, I'm not too worried about it. If the core is getting crushed at high speeds, the number of skin layers is insufficient to handle the loads.

Granted, probably a different skill set at play here, but with a couple of sharp block planes, and carefully choosen material you could hammer out those out pretty quickly.

Agreed, the trick is to mark out cut depths with a carefully set circular saw first. I've seen professional builders knock up a set of 10' boards in a couple of days.

Draw knife.

Hand power planer....ever watch a good surfboard shaper or yacht builder use one...in a for profit environment block planes are too slow except for very minor tweaks.

I have even seen jigs set up where the hand planer rides on rails following a predetermined arc, kind of a poor man’s answer to CNC. If you do some research surfboard shaping you will probably find some pictures.

Scarecrows suggestions sounds like a good way to give you some good control lines to follow as well.

A power plane in the hands of a skilled craftsman should be able to knock out the wood core of two rudders and two straight dagger boards for an F16 in about the same amount of time.

The more powerful the tool the bigger the mistake. Don't ask...

I kinda agree with this. I don't own a hand held power plane, (I've used them, just never was good with one), but I do have a nice collection of block planes. I've got a bigger two handed model that when properly sharpened can really hog material off. When I say properly sharpened, I mean literally razor sharp, like you can pull the knife and shave with it.

A sharp block plane is a joy to use. And I'm not saying it can't be done other ways, I make a living making stuff outta wood, and it was the first thing that came to mind.

Man, this thread makes me want to carve up some wooden boards and blades just for fun. Making them hollow would be kind neat too.

Karl one thing I noticed after years using both is that if you really stay focused with the power plan it is more precise when taking off a lot of material...in that if the knives are sharp you can take off even amounts with every pass. Can you do it with a block plane? yes...will it take longer...also yes...

While it is not wood...a good surfboard shaper can take a very rough blank and give you a precision surboard with near perfect symmetry in 20 minutes. A shape that is larger and much more complex in form than a Rudder or Daggerboard. They take full advantage of the ability to remove equal amounts with each pass....every pass they make on one side it duplicated on the other. If you ever get the opportunity to go to the Surf Expo Trade show they usually have a few well known shapers shape boards in a glass fronted shaping booth...they are amazing to watch.

Pete, Thats why I said in the hands of a "skilled craftsman"
LOL. The right person could shape them with a 8" sander/polisher with a "Diskit" and 40 grit/80grit/120 grit paper. In the wrong hands the sander would trash the project in about 3 seconds.

http://www.waterputty.com/pages/repair.htm Ever used this stuff?

Hmm,

The wooden shape method I have evaluated. I am by far a better composites builder than a wood worker. One of the reasons I considered building the boat in composites was my lack of large scale wooden boat building compared with my hundreds of hours of composite manufacturing (and I am by no means an expert in this area).

I trust that in the hands of a skilled shaper, accurate foils can be built quickly. In my hands, nada. One must also evaluate the level of perfection needed when making high performance dagger boards and rudders. For reference, my high end glider wing cores are accurate to within 1/100 of an inch-I'm limited by the precision my inkjet printer can drop ink on paper. CNC hot-wired cores done by a professional are accurate to within 0.002". Airfoils tend to need this level of precision to function as designed-I'm sure the best shapers are accurate to within 1/1000, I've seen experienced metal workers hit those numbers by hand. My hands lack that precision on a large block of wood.

On another note, does anyone know of a good anodizer? I have a lead on inexpensive 6061 Aluminum beams, but they would need to be anodized or painted (heavy).

Absorbs water.