Which naca profiles for sailingboats

[Nicholas Scheuer]

I used basically the sort of tool (Router + lateral guide track) to mill my foil leeboards, kenjamine. I needed two different track profiles to mill the assymetric foils. I had lead bricks in mine, too.

[SHClark]

A link to Mark Drela's "freehand" shaping techniques.
http://www.charlesriverrc.org/articl...oilshaping.pdf
This is specifically about shaping model airplane wings, but can be applied to centerboards and rudders.
I have used table saws and resaws to remove the big slabs of wood using more or less this protocol. You can also do tricky things with shims and thickness planers, but nothing quite beats a really sharp set of planes for making a mountain of shavings.
"Sailing Theory and Practice" by Tony Marchaj p276-284 has perhaps the most accessible and complete discussion of centerboards. After reading it, the conclusion is unambiguous
One should also consider slot gaskets to get rid of the open slot when the board is down. They tested the value of slot gaskets years ago at Southampton and I think the amount of drag reduction was truly impressive. Granted they were using the International Canoe "Wake" as the test boat, but I recall the reduction being something like 15%. I can't lay hands on the reference to confirm my recollection and 15% is huge. Most of us would trade our little sisters for a tenth of that. I can confirm that I can definitely tell the difference.
SHC

[kenjamin]

Here's a few more pictures of my NACA 0008-34 foil centerboard for my SCAMP build:

The results with the router machining operation – really rough but the basic shape is there waiting to be cleaned up with a grinder!



Here the two halves are glued together:



Here's the centerboard after cleaning up with the grinder:



Here it is after a bunch of sanding. It's not perfect but it will definitely be the slickest foil I've ever made:

[Chris Ostlind]

She's a beauty, Bubba. Nice craftsmanship and very sweet attention to the surface. While I'm not a big fan of laminates for this type of application, as you give away half of your longitudinal strength, it's still a well crafted board.

[kenjamin]

The tricky part was getting the lead pockets registered from one half to the other half. I used little holes through both halves using the drill press to mark the corners of the pockets for the lead and sealed the holes with thickened epoxy before the final gluing. Also rounded the tops of the lead bricks so they could find their way into the corresponding pockets in the other half during the glue up. Thanks for the compliment. Now Xena's gonna want better foils – that's the only problem with learning how to do it.