Wood CNC's..

If you are going to go to the trouble, why not machine a foil out of a block of laminated wood/composite. I don't remember anyone trying that.

Build your block out of wood or foam laminated with fiberglass, carbon, Kevlar, foam, aluminum... You could leave appropriate volumes hollow and except for your reference points, the finish could be sloppy.

Machine out the foil then machine out the skin(wood, carbon prepreg...) and glue them together

Or use a reinforced paper for the skin. Print it out on a large printer with little cutouts to make it lay flat. You could print whatever graphics you like. You could have a foil with your face on

I don't think this has been tried with a foil. I have heard of similar methods used for architectural pieces or high price furniture. You could be the first and lead the way if it shows promise.

Phil's foils...he's been machining wood core foils for some time. I think he's since merged operations with CCI.

http://fastcomposites.ca/publications/TankTalkPhilsFoils.pdf

http://www.fastcomposites.ca/site/marine/design-tips-fabrication-overview/care-of-wood-cored-foil/

Hey Jake >

I was just gonna say Phil's Foils or maybe mention Jim Bauman, from Recreational Composites. JB has done a few cat and tri foils as you know. He is about finished with restoring the C 24 and is willing to work for food

Bauman is great - I had him clean up a pair of Nacra 20 foils for me once and he became standard to clean up our foils from then on. There's nothing worse than 500 miles on a boat that speed warbles a song through the water all day and night. A little touch up from Jim and they are silent!

Karl with all this time you have spend the Weekend and Build yourself a DN.With all your carpentry skills you would have it built in no timeI am coming down this summer to Build some Planks with A few guys.

DN is on the short list.

Jim's retired from epoxy work. Too much exposure. Sad to see a master retire.

What I was thinking about is a little different from machining a wood core and then vacuum bagging or molding a skin over it.

The idea started years ago when I saw an exotic piece of furniture built like this. With this method the structure was built into the "block". First the skeleton was bonded to gather in a jig. Long, short, and little blocks of wood, composite and even steel was joined to form the structure. Then the outer wood that will be seen was bonded to the structure so that it formed a rough blocky equivilent to the final shape. Then the furniture was carved out and finished. The advantage was you could build "solid" wood in shapes that are not structurally possible with plain wood.

When I saw this, my first thought was you could build a hollow wood rudder by laminating strips of wood and composite for strength. You would not need the jigs and molds normally needed. Just build the rough shape around a hollow core and cut the outside to the final shape.

While this might not be as light as say a hollow core carbon, as long as you have access to a way of cutting out the final shape, the tools needed are simpler. Also since molds are not needed, it would be easier to build rudders with different foil profiles or even shapes.

I don't think this will revolutinize the world, but if you want to CNC a set of foils, its probably better and cheaper than starting with a block of aluminum.

For straight foils, you can get by with CNC cut foam cores (high density foam) and laminating carbon over them (lots of carbon). If people are interesting, I can cut 100 PSI foam on my CNC for reasonable prices.

The issue is when you go longer or curved; in these cases you need a CNC router machined core and a PVC based foam or wood core. Finding someone that will machine cores or molds for reasonable prices is not a trivial task, I have a few sources and may evaluate designing and building some curved A-Cat foils if the business case is justifiable.

As far as aluminum is concerned, built properly you can approach composites in weight and strength, but time wise it would take longer than the methods proposed above (unless you are THE metal guy). The corrosion issues posted above have never really been solved, take a look at any aluminum vessels (boats or seaplanes come to mind) after 10 years. Foils would not hold up very well to this abuse!

I believe you could have used him on your 18 at Tradewinds. According to the Vid, those things were pretty dang loud!

Jim is still in the foil business. He is finishing the C 24 as his final tribute to boatwork. He is hoping to mount the ama this week and begin installing the nets.

Once this boat project is complete he will be devoted to his windsurfing fin business, sailcraft foil design, fabrication, and repair.

There are many alloys available, some are very strong, some not some have excellent corrosion behaviour, some not, and so on. But fact is that the right alloy is resistent to salt water and strong (as proven by thounds of masts). It has similar strength to hand layed up glasfibre, but less than carbon. Best production process would be extruding (if you can live with a straight board), not machining. Topcats use extrude alu rudders since ever. They have decent quality and are unkaputtbar (undestructable). At all the whole rudder system is a nice one on the Topcats.
Not cheaper than some glass boards though. http://www.topcat.de/shop/index_e.htm . The rest of the boat is fairly outdated...
Alu rudders wouldn't be particular heavy, about the same or a bit more than glass fibre boards of the same strength and size and maintenance free by the way.

Cheers,

Klaus