NACA foil was approximated by carrying the taper of the foil shape down horizontally. I really doubt much lift is achieved this low in the board. The main goal is to reduce energy robbing eddys (turbulence) from forming due to sharp edges. That is the reason for the rounded off trailing edge and rounded of foot.
Unfortunately, I am out of Interlux two part epoxy fairing compound. I will fair and sand until very smooth. Then I will use e-glass 6 oz cloth and encapsulate with epoxy. Next I will use the yellow cloth you see in the picture which is Kevlar and sheath the surface that might drag in shallow water. This will protect the wooden board from intrusion by water. Finally I will fair over the entire surface blending the margins of the glass. Kevlar cannot be sanded so it has to be faired up to the protruding margins much as I did with the centerboard on Belle. When finished I will coat with 2-3 applications of Interlux Interprotect 3000/3001. The final coat will be Awlgrip off white above the waterline (because I have a can of it and antifouling below the waterline. I haven't yet decided on a color for the antifouling. Meanwhile I await an order from Jamestown Distributors.
Update: I found the cans of Interlux two part epoxy fairing compound.
Tuesday, July 24, 2012
So my cure is a small block of teak about one inch by one-half inch square placed at the top of the luff groove as a stopper. I hollowed out the back to match the radius of the mast. A carefully drilled hole in the lower third of the block was drilled with deep taper to accommodate a one-inch flat head stainless #8 screw. I contemplated using cyanoacrylate glue to secure but decided a nice tight screw would hold fine as I found my drill sinking through the solid block inset to the mast tube. If the piece should crack and fail, I would want a lot of grief removing it. A strap eye was bent from flat to clevis shape to serve as a fairlead. The fairlead was bolted through a carefully drilled transverse hole drilled through the upper third. A transition rounding was filed in the pass-through section of the wood. This arrangement should stop the sail luff at the top and re-route the pull to an angle just outside the luff groove. The fairlead will keep the line from falling to the side and becoming fouled as the sail reaches the top of the mast. Click on the picture for a more detailed look.
I have decided while in the process of re-shaping the rudder to core-drill and put some lead shot in each hole. The idea is to reduce neutral buoyancy so I will have some steerage when leaving from a beach. Once in deeper water the rudder is cleated in the down position with a break-away cleat. I need just a little rudder into the water to maintain steerage when the rudder is not fully down. A few ounces of lead should help.
Monday, July 23, 2012
We are waiting for the cyanoacrylate glue to repair the mast track on Tridarka. We are in search of some lead shot to place in the bottom of the rudder as well.
Sunday, July 22, 2012
Monday, July 16, 2012
The weather was lovely. And yes, I am at the controls. My pendant controller is running the autopilot.
We traveled all the way to Browns bridge. Then we noticed a very threatening cloud with lightening.
On the way back we found to our horror two inches of water in the cabin. De-Javu all over again to coin an oft used phrase. Here is what we found when we removed the centerboard trunk case.
Well, there you have it. Too much water pressure for the RTV silicone. I believe 3m 5200 will do the job.
We were just pulling onto the trailer when the squall hit. 30 knot winds and driving rain. Glad I took heed and headed back when I did.
Sunday, July 15, 2012
Monday, July 9, 2012
We polished off the rest of the job in less than an hour.