toller,

I have been watching this thread, but did not have time to write until
today. There seems to be a a multple of questions here and some
interesting thoughts among the responses.

First, If you glued the damaged board with epoxy and glassed also with
epoxy, there is no reason it will not last as long as the mohogan holds
out - that may be quite some time.

Mohogany is a relatively light wood, but not that light. You will pick
up probably 10-12 pounds. It was probably choosen for it's rot
resistance and the ease of working. It is a very dimensionally stable
wood which is why it is so valued by pattern makers.

By "cut the corners off" I am guessing that you mean the long edges. If
that is the case, we need to ask more questions here.
Are you going to make this cut the entire length of the blank?
If yes, just be sure you have pusher sticks handy and a friend to catch
the plank and trim as they come out of the saw. The second cut will be
much more exciting the than the first because of the small support area
left on the trailing edge.
If no, you still need the friend, but not the pusher sticks. Plus now
the operation has a new twist because sawblades only cant one way. In
one direction, you will have to start the cut as a pocket cut and saw
out of the blank, and the other you have to stop in the blank. There is
only one safe way to do this. Shut the saw down and then retract the
blade. You will have to finsh the cut by hand.

As to the actual section, yes, you can get there with the power plane
and belt sander (look up supergrit belts - effective prices). If the
boat is a class of any kind, the class site probably has the section
available. If not, you probably want a modified four digit. I own code
for this, but I do not know if it is available on the web - search.

Cutting guide reference slots is not a bad idea, you will have a lot of
wood to hack off before you get close to the sand-to-shape phase. You
might consider doing that before you even "cut the corners off" because
it will be easier to handle the blank then.

Thinking is the Cheap thing to do.

Matt Colie (I have been at this way too long)

Toller wrote:
My mahogany dagger board was damaged when I bought the boat used. I glued
it with epoxy and put some fiberglass around it and it has held up for a few
years, but I don't think it will last.

I bought some 8/4 white oak on ebay for almost nothing (100bf for $1.25),
and figured I will build a new daggerboard while I had something intact to
copy.

The blank is 44" long, 2" thick, and 15" wide. It weights 35 pounds.
I originally intended to cut the corners off on my table saw, but it is so
heavy that it doesn't seem particularly safe.
So, I have been going at it with my 3" belt sander and my 2" power planer.
Both would work, but they would take hours and hours of work.

Any suggestions for a good way to shape my blank into an airfoil shape?
I am thinking of buying a better planer, but hope someone here will be
resourceful.

On Sat, 17 Sep 2005 11:45:10 -0400, Matt Colie wrote:

snip
Cutting guide reference slots is not a bad idea, you will have a lot of
wood to hack off before you get close to the sand-to-shape phase. You
might consider doing that before you even "cut the corners off" because
it will be easier to handle the blank then.

Well put. This was what I intended to describe but your command of
the English language is clearly superior.

I recommend Western Red Cedar (or similar light wood) for two reasons:
1) Easier to handle both while building and on the boat.
2) Easier to work on than oak.

I have shaped plugs out of MDF-blanks this way. A plug for a rudder
1.8 m long and with a 30 cm cord took only one evening to shape.
Painting, wet sanding, rubbing and polishing took much longer.

Thinking is the Cheap thing to do.

Indeed :-)

Here are some more ideas on shaping foils if you don't want to
make molds.

* Strip planking using 6-8 mm thick WRC strips. Use external frames.
Glass+epoxy inside, join halves and don't forget that you need
a good structural member running down the middle of the foil.
The exterior will need some final shaping, then add carbon as
needed and wrap in glass and epoxy. Potentially lighter than
the massive board for big boards but more work and less robust.

* Central structural member made from WRC+carbon laminate. Foil
shaped from foam cut by hot wire. Cover in glass+epoxy laminate.
Note, this time the laminate is structural.
My current boards were build like this some ten years ago.
They are 2.5+ m long and has a 44 cm cord. New they weighed
12 kg each.

/Martin

On Sun, 18 Sep 2005 10:53:39 +0200, Martin Schöön wrote:

[snip]

* Central structural member made from WRC+carbon laminate. Foil
shaped from foam cut by hot wire.

If you go this route, consider having the core cut by the folks at
flyingfoam.com. They are in business to cut wings for RC gliders and
airplanes, but a core is a core.

Cover in glass+epoxy laminate.
Note, this time the laminate is structural.
My current boards were build like this some ten years ago.
They are 2.5+ m long and has a 44 cm cord. New they weighed
12 kg each.

/Martin


--Mac

"Mac" wrote in message news [snip]
If you go this route, consider having the core cut by the folks at
flyingfoam.com. They are in business to cut wings for RC gliders and
airplanes, but a core is a core.

--Mac


http://philsfoils.com/ is reported to do this sort of thing for dinghies and multihulls.
Probably cost-justified only if you're serious about racing.

On Thu, 22 Sep 2005 09:42:15 -0400, Jim Conlin wrote:


"Mac" wrote in message
news
If you go this route, consider having the core cut by the folks at
flyingfoam.com. They are in business to cut wings for RC gliders and
airplanes, but a core is a core.

--Mac


http://philsfoils.com/ is reported to do this sort of thing for dinghies
and multihulls. Probably cost-justified only if you're serious about
racing.
[snipped HTML]

Cool, I didn't know about philsfoils. But I don't think that flyingfoam is
very expensive.

I got a quote from them once, but I don't remember the details. Then
again, I don't have a lot of free time, so what seems reasonable to me
might seem expensive to others.

--Mac