Building the 6'6" Gang Buster. Roy Stuarts Parallel Profile construction method.

I'd be wary of anything that can't seal end grain with 100% confidence. You'd probably have to oil it after every use at a minimum and you won't be able to tell if there is a problem until it's too late.

 

Hi Charles yes I don't see why not we use linseed oil on paipos and it seals ok.

Are you still planning to do a tunnel fin? If so were you thinking of a larger single tunnel? I think that the best way to do larger tunnels is a glass or paper and resin layup as it is stronger than wood. The big single tunnels need to be stronger as they can take a beating, the smaller ones are inherently stronger and are protected by the front and/or side fins.

 

I think real Tung oil would be a superior choice.

 

Looking good, the rocker looks fine, and will suit a tunnel, or just about any fin setup.

 

You could do a big wooden one if it is glassed for strength. The Baron tunnel is made of paper and tinted resin, just cover your mould with masking tape (I put it with the sticky side out ) then layer paper with resin in between (use a brush) until it's about 1/4" to 3/8" thick (lots of layers. 40 plus from memory, and the best paper is absorbent e.g. art paper for water colours) then hold it in place with masking tape around the edges. They can be foiled inside and out or just on the outside, which is easier to do. Both ways work well. I use more than half a cylinder, about an inch extra, so the tunnel is a bit taller than the radius, with a bit extra when laying it up so that it has some tabs to set into the board. They only need to be set in about 1/4" as the structure is so stable. Resin can be tinted with powdered watercolour paint.

A ten inch tunnel should do the trick, make it about 3 inches long fore and aft, you'll be able to slide it out sideways when surfing in a controlled way if it is pushed hard, which is fun and pretty functional, some small side bites can be added if you want more hold.

 

Foiling wise when using a single in front of the tunnel I use a laminar flow foil, with the thickest part of the chord back at about 45% aft, like the top foiling the picture below, but for a tunnel on its own bring the thickest part of the fin forward to about 30% aft like the bottom picture. The reason for is that with a fin in front of the tunnel the angle of attack of the tunnel is controlled, so a lower drag laminar flow foil can be used, with the tunnel alone it needs the foil proportion more forward as that enables the fin to handle greater angles of attack. I also make a stand alone tunnel a tad thicker for the same reason.

http://www.boatdesign.net/forums/attachments/sailboats/46081d1280865411-best-foil-shape-rn-250-000-750-000-e836vsn63a010vsn0012_shape.jpg

 

The tunnel for the 'Rampant has two layers of 3mm wood with a glass layer in between. because the glass layer is on the neutral axis it doesn't add much strength, it's really there to give some structure to the thinned out trailing edge. Glassing on the outside is best done after foiling. Glassing the inside is tricky to do because the cloth can't be pulled tight, but it can be done.

The black/metallic fins are coated with epoxy resin mixed with graphite powder. this makes a very fast and abrasion resistant surface and the graphite powder is cheap, only $5 per half a litre or so, WEST system sell it I think. the graphite coated fins are marine ply ( some of them glassed with kevlar ) or glass/epoxy also there is a tri fin tunnel setup which is paulownia covered with resin, graphite and white pigment to make a metallic grey.

If you can't find plumbing pipe a mould can be made with two semi circular end pieces covered with thin ply bent around it.

A two layer wooden tunnel glassed both sides would be fine, easier to glass the inside if you don't foil the inside, but I'd go for a paper and resin layup, tinted or covered with graphite, it's up to you though. If doing a big wooden tunnel making it thicker will help with strength, also harder wood makes them stronger, though heavier. paper and resin is heavier than cedar of course but because it can be made thinner it winds up fairly light.

 

Always interesting to see another builders perspectives on a build, especially when well thought out. I'm getting some good ideas from this thread for the next one. I'm really interested in seeing this tunnel go together! Keep us posted with as many Pics as you care to take!

 

Now that all the hazing and the my d!ck is better than your d!ck banter is behind us, I've gotta say I'm enjoying y'alls discussion on how to build these boards. Very informative and interesting. Thanks

 

Looking good, be careful not to break it while foiling. Glassed it will be ultra strong as the shape is naturally very strong.

 

Monologues