How to shape a dagger board?
 

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 Thu, 15 Sep 2005 22:11:16 GMT, "Toller" wrote:

snip
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.


Google for "naca airfoils"
Regards,

Bruce Nichol
Talon Computer Services
ALBURY NSW Australia

http://www.taloncs.com.au

If it ain't broke, fix it until it is....

I assume you have the old board to use for a pattern of the cross section.

I know that white oak would be difficult to shape by hand plane or any of
the power tools you mention.

For my 3" thick plywood rudder, I use a 4" disk grinder fitted with a
special wood carving wheel. This is a steel disk with chain saw teeth on
it's edge. Very aggressive cutting, so go slow and careful..

The PacNW wood carvers use these along with their regular chainsaw tip to
carve detailed statues.

Just rough out your board shape and finish with the plane or belt sander.


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions

"Toller" wrote in message
...
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.

I'd go for the power planer. A good one can take away 1.5mm (1/16") in one
stroke, which means you can take away half of the thinkness of your blank in
16 strokes.

Meindert

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.


Use your table saw as a shaper by sliding the blank sideways over
the blade. It will leave concavities, a hollow ground shape you can
refine more easily. A well made slide jig should provide a reagulare
shape and remove most of the unwanted material.

Don't be afraid to drill a few bolt holes in your saw top to hold
special jigs, or use eccentrics to hold in guide slides.

Cut strips to sit in grooves able to slide, lay ply on top, pin with
brads, screw together from other side. with saw, route grooves the
other way, make side slider jig. Screw on a fence to enable milling.
Terry K

You can make transverse saw cuts and take out the wood with a chisel. Then
clean up with a plane or whatever. Dont' go all the way in with the saw
because the wood will not cut out smoothly. Practice on scrap first.
If you can figure out some way to do it with a power saw it allows you to
set the depth of cut.
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"Toller" writes:

snip

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.

Question: Is this a massive plank or quarter-sawn strips glued together?
If it is a massive plank you should count on it warping.

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.

This is probably the wrong answer but I actually mean this:
Use the oak for something else. Buy some light wood like Western Red
Cedar and shape a board. Add unidirectional carbon for bending
stiffness and strenght. Sheat in glass-epoxy and paint.

A WRC blank should be light enough to handle on the table saw.
Cut grooves to a depth that just 'touches' the future profile.
Use a power plane to remove material almost down to the future
profile and then continue with a hand plane and long board sanding.

Have someone calculate how much carbon you need and then use a
router to cut out some material from the WRC board so you can add
the carbon without ruining your profile.

More on boards at:
http://hem.bredband.net/b262106/Boat/dagger.html

--
================================================== ======================
Martin Schöön

"Problems worthy of attack
prove their worth by hitting back"
Piet Hein
================================================== ======================

I'd go with Martin's recommendation of materials. A white oak board, while
maybe stable, will be too heavy to handle.
Google for a NACA foil design program.
For shaping it, I'd use a router as the shaping tool. Make a slotted
'bridge' which will guide a router over the victim. The bridge can run
either the long way or cross-ways. If the bridge runs the long way, it can
be straight but rest on curved templates at the ends of the board. If the
short way, the bridge must be curved, but it will run on straight guides at
the edge of the board. I'd favor the short curved bridge, which will flex
less.
"Schöön Martin" wrote in message
...
"Toller" writes:

snip

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.

Question: Is this a massive plank or quarter-sawn strips glued together?
If it is a massive plank you should count on it warping.

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.

This is probably the wrong answer but I actually mean this:
Use the oak for something else. Buy some light wood like Western Red
Cedar and shape a board. Add unidirectional carbon for bending
stiffness and strenght. Sheat in glass-epoxy and paint.

A WRC blank should be light enough to handle on the table saw.
Cut grooves to a depth that just 'touches' the future profile.
Use a power plane to remove material almost down to the future
profile and then continue with a hand plane and long board sanding.

Have someone calculate how much carbon you need and then use a
router to cut out some material from the WRC board so you can add
the carbon without ruining your profile.

More on boards at:
http://hem.bredband.net/b262106/Boat/dagger.html

--
================================================== ======================
Martin Schöön

"Problems worthy of attack
prove their worth by hitting back"
Piet Hein
================================================== ======================

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 Thu, 15 Sep 2005 22:11:16 GMT, "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.

I congratulate you on eliciting a wonderfully practical, innovative,
and helpful thread. Even the most radical contributions ("Don't use
oak!") were well-meant. Notice that suggestion of using a wood carve
blade in a circular saw? Wow! Wood propeller carvers use a router in
a kind of copier frame, profiling an existing fair copy of the blade.
I notice the respect given to mahogany on the traditional end, but
also the foam core glass or carbon approach at the leading edge end.

Iobserve in passing that the center board on the SouthCoast 22 I am
preparing, is a hefty chunk of iron - its weight so low down is of
course desirable - but that has a wind up hoist.

Brian Whatcott Altus OK

You can make transverse saw cuts and take out the wood with a chisel. Then
clean up with a plane or whatever.

That's an interesting idea that none of the woodworker I spoke to thought
of.
I will try it out on some scrap.

Question: Is this a massive plank or quarter-sawn strips glued together?
If it is a massive plank you should count on it warping.

It is two pieces (both 2" thick) glued together. I don't need it until next
spring. I can get it close, leave it for a few months, and then finish it.
Would that help?

This is probably the wrong answer but I actually mean this:
Use the oak for something else. Buy some light wood like Western Red
Cedar and shape a board. Add unidirectional carbon for bending
stiffness and strenght. Sheat in glass-epoxy and paint.

Oak is about 50% heavier than mahogany, but I actually want the weight, so
that is not a problem. Besides, it is free and the cedar would be about
$50.

Toller wrote:

Oak is about 50% heavier than mahogany, but I actually want the weight, so
that is not a problem. Besides, it is free and the cedar would be about
$50.


What you are describing is a disaster guarenteed to happen.

As someone suggested, use the oak for something else.

Might even barter it for some good foam, but these days, good white oak,
even 8/4 is cheap compared to foam, even Divinycell.

Cover the foam with some 17 oz double bias and epoxy.

SFWIW, the above describes how my rudder will be built.

Lew

What you are describing is a disaster guarenteed to happen.

Why?
The mahogany board weighs 15 pounds. The oak board should weight about 23.
Even if I hadn't just lost 7 pounds, what severe problems will the 8 pounds
cause?

I am not being argumentative; I concede I don't know anything about boat
building, and little more about sailing. But I have sailed this with my 95
pound son in it, and it is fine (if a little sluggish); why would 8 pounds
of board matter?

Toller wrote:
What you are describing is a disaster guarenteed to happen.


Why?
The mahogany board weighs 15 pounds. The oak board should weight about 23.
Even if I hadn't just lost 7 pounds, what severe problems will the 8 pounds
cause?

I am not being argumentative; I concede I don't know anything about boat
building, and little more about sailing. But I have sailed this with my 95
pound son in it, and it is fine (if a little sluggish); why would 8 pounds
of board matter?




It is not the added 8 lbs although rudders are designed to be as light
as possible.

It is that this is not a good application for white oak.

Now if you quarter saw that 8/4 stock, you can make some very nifty trim
for tha boat.


Lew

"Toller" wrote in message
...
What you are describing is a disaster guarenteed to happen.

Why?
The mahogany board weighs 15 pounds. The oak board should weight about
23.
Even if I hadn't just lost 7 pounds, what severe problems will the 8
pounds cause?

I am not being argumentative; I concede I don't know anything about boat
building, and little more about sailing. But I have sailed this with my
95 pound son in it, and it is fine (if a little sluggish); why would 8
pounds of board matter?

Without looking at the board and reading the grain, it is near impossible to
tell what it will do. Not knowing how old it is and how it was dried
muddles things further. I don't think the weight is a concern. I would
think warping, bending, settling, etc. of the board is the potential (big
word there) cause for concern. A guaranteed disaster? I hardly think so.
A likely disaster? Nah. It is yours, the board is free. The penalty will
be to redo it. Go for it, it might just work!

Ed

"Toller" writes:

Question: Is this a massive plank or quarter-sawn strips glued together?
If it is a massive plank you should count on it warping.

It is two pieces (both 2" thick) glued together. I don't need it until next
spring. I can get it close, leave it for a few months, and then finish it.
Would that help?

Some but I think it will warp sooner or later anyway. A good
epoxy seal helps slow the process. But as someone else stated:
Without being able to see your blank and how the grain looks it
is very hard to be anything but rather vague about this.

This is probably the wrong answer but I actually mean this:
Use the oak for something else. Buy some light wood like Western Red
Cedar and shape a board. Add unidirectional carbon for bending
stiffness and strenght. Sheat in glass-epoxy and paint.

Oak is about 50% heavier than mahogany, but I actually want the weight, so
that is not a problem. Besides, it is free and the cedar would be about
$50.

I would say your troubles with the white oak is more about
handling and working on it in your workshop than all-up weight
on your boat. You will spend a lot more time shaping your oak than
it takes to shape cedar.

Oh, I almost forgot. It is my experience that oak and epoxy coats
don't always work well together.

--
================================================== ======================
Martin Schöön

"Problems worthy of attack
prove their worth by hitting back"
Piet Hein
================================================== ======================

There is no need to worry about making a daggerboard, centreboard, or
rudder out of solid wood. Visit your nearest sailing facility and look at
all the centreboards, daggerboards, and rudders made of solid wood. The
fact that your board is glued up means it will not warp. You can look at
the end grain to see which way the two pieces are oriented. Put a couple
coats of polyurethane varnish on it and refinish it every few years.

I've never put epoxy resin on oak but peope who have say it's only
necessary to sand the surface of teh wood to roughen it up a bit. Oak
contains tannin, and acid, and acids dilute epoxy rdeucing its bonding
strength. One way to clean up epoxy resin that has not cured is to use
vinegar, lemon juice, or some other mild acid.


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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

On Thu, 15 Sep 2005 22:11:16 +0000, 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.

Several people have suggested finding NACA foil software. If you don't
want to do that, I would be happy to calculate the coordinates for you and
post them here. I would need to know the desired thickness of the foil
(at its thickest point), and the chord length (fore and aft extent of the
daggerboard).

I am assuming that the daggerboard is basically rectangular when viewed
from the side.

--Mac

"Mac" wrote in message ...
[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
... [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.
[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

On Thu, 22 Sep 2005 03:44:33 +0000, Mac wrote:

Several people have suggested finding NACA foil software. If you don't
want to do that, I would be happy to calculate the coordinates for you and
post them here. I would need to know the desired thickness of the foil
(at its thickest point), and the chord length (fore and aft extent of the
daggerboard).

Or go he http://www.ae.uiuc.edu/m-selig/ads.html for free section
coordinates.

/Martin

I bought a good 3.5" power planer and cut it down in 30 minutes. I used a
belt sander to smooth the lines out, and a router table to radius the front
and back.

Tomorrow I will see if it fits. (the boat is 30 miles away, with no
electricity) Since oak is 40% heavier than mahogany and the finished oak
board is only 20% heavier than the mahogany board, I must have made it
thinner than I intended; but since oak is also 50% stronger than mahogany,
that shouldn't matter.

It may not be a perfect mathematical airfoil, but it is pretty close to the
(unpracticed) eye.

.. I must have made it
thinner than I intended; but since oak is also 50% stronger than mahogany,
that shouldn't matter.

maybe, maybe not. if it's too thin for the slot it can vibrate while
sailing. you can always build it up with a fibreglass coating to make it
fit better. with wood you can always take more off, but you can't put it
back on. that's what fibreglass is for, although it makes the product heavier.

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"William R. Watt" wrote in message
...

with wood you can always take more off, but you can't put it
back on.

A carpenter is a whittler who knows when to quit.

Ed

"William R. Watt" wrote in message
...

.. I must have made it
thinner than I intended; but since oak is also 50% stronger than
mahogany,
that shouldn't matter.

maybe, maybe not. if it's too thin for the slot it can vibrate while
sailing. you can always build it up with a fibreglass coating to make it
fit better. with wood you can always take more off, but you can't put it
back on. that's what fibreglass is for, although it makes the product
heavier.

I was thinking that myself, but I am unsure about the technique. I have
done fiberglassing, but not on something like that.
Would it be reasonable to staple the glass in place, and then apply the
epoxy; while working on waxed paper?

In article ,
"Ed Edelenbos" wrote:

"William R. Watt" wrote in message
...

with wood you can always take more off, but you can't put it
back on.

A carpenter is a whittler who knows when to quit.

Ed

a "journeyman" is a guy who knows how to fix his fux ups.

if wood is going near water, it needs several coats of epoxy. read
directions about application and secondary bonding. fiberglass cloth is
imbedded in wet epoxy using paint brush and squeegee. see directions for
weight of cloth and radius of corners glassed over. second and third
coats of epoxy/filler yield smooth surface and built up(squared) corners.
good luck.

"mac" wrote in message
...
In article ,
"Ed Edelenbos" wrote:

"William R. Watt" wrote in message
...

with wood you can always take more off, but you can't put it
back on.

A carpenter is a whittler who knows when to quit.

Ed

a "journeyman" is a guy who knows how to fix his fux ups.

if wood is going near water, it needs several coats of epoxy. read
directions about application and secondary bonding. fiberglass cloth is
imbedded in wet epoxy using paint brush and squeegee. see directions for
weight of cloth and radius of corners glassed over. second and third
coats of epoxy/filler yield smooth surface and built up(squared) corners.
good luck.

Hmmm.... in a word... bullhockey. There is a chance that a bit less
maintainance will be needed but epoxy is hardly a necessity. Epoxy is no
guarantee of seaworthiness or durability.

Ed

In article ,
"Ed Edelenbos" wrote:

"mac" wrote in message
...
In article ,
"Ed Edelenbos" wrote:

"William R. Watt" wrote in message
...

with wood you can always take more off, but you can't put it
back on.

A carpenter is a whittler who knows when to quit.

Ed

a "journeyman" is a guy who knows how to fix his fux ups.

if wood is going near water, it needs several coats of epoxy. read
directions about application and secondary bonding. fiberglass cloth is
imbedded in wet epoxy using paint brush and squeegee. see directions for
weight of cloth and radius of corners glassed over. second and third
coats of epoxy/filler yield smooth surface and built up(squared) corners.
good luck.

Hmmm.... in a word... bullhockey. There is a chance that a bit less
maintainance will be needed but epoxy is hardly a necessity. Epoxy is no
guarantee of seaworthiness or durability.

Ed

well, give it a couple of coats of primer and then a coat of your
favorite anti-fouling. (personally, the only things I use wood for is
interior trim and of course, the fireplace. if I was building yet
another daggerboard, I'd use foam core and fiberglass/epoxy. different
tech. for different folks, huh?)

"mac" wrote in message
...
In article ,
"Ed Edelenbos" wrote:


Hmmm.... in a word... bullhockey. There is a chance that a bit less
maintainance will be needed but epoxy is hardly a necessity. Epoxy is no
guarantee of seaworthiness or durability.

Ed

well, give it a couple of coats of primer and then a coat of your
favorite anti-fouling. (personally, the only things I use wood for is
interior trim and of course, the fireplace. if I was building yet
another daggerboard, I'd use foam core and fiberglass/epoxy. different
tech. for different folks, huh?)

I guess I should have thrown in a smiley or a (grin).... Different
strokes, not only for different folks, but for different applications.

I had a Luders L-16 many years back. A 26' loa cold molded plywood boat.
It was made with mahogany and resourcinol glue which I used to match up the
repairs it needed when I got it. It seems to me that that would be the
"perfect" material (only sub'ing epoxy for the glue) for a larger boat. All
the best points of both wood and plastic.

For a simple daggerboard (and again, depending on the application) the
simple method described by the OP seems fine to me. The last dagger I made
was 1/2" plywood. I rough cut it with a bandsaw, sanded the profile with
various power and hand sanders, filled the voids with a glue sawdust mix and
it has about 12 coats of polyurethane on it. It works great and has lasted
(with no new coating) for about 3 years so far. It was for a Snark (the
styrofoam covered with plastic sheathing boat). As is, it was more work
than the boat is worth. But "worth" rarely fits in a discussion of boat
building or repair. If it were a boat I was racing (not likely, another
"not my bag") I'd have probably put more into it. (grin)

Ed

"Ed Edelenbos" ) writes:

... The last dagger I made
was 1/2" plywood. I rough cut it with a bandsaw, sanded the profile with
various power and hand sanders, filled the voids with a glue sawdust mix and
it has about 12 coats of polyurethane on it. It works great and has lasted
(with no new coating) for about 3 years so far.

I'm a great beliver in economy. I have one 1/2" plywood daggerboard which
serves all three of my home made sailboats. After all, a person can only
sail one boat at a time. It was rounded off on the leqding edge and
tapered on the trailing edge with a sanding disk on an electric drill. The
edges were then give a couple of coats of tinted polyester resin the the
whole thing was painted with exterior latex house paint from a garage
sale. The plywood was made of some sort of dark wood, salvaged from a
packing case, possibly some sort of mahogony. When it got wedged under one
of the boats in shallow water and cracked it was repaired by pumping PL
Premium into the crack and weighting it down with bricks over night. It's
been well used and looks beat up but is still functioning fine. Photos on
my website under "Boats".

Come to think of it the rudder on a 20 footer I once owned was also made
from plywood. I broke the cheeks on it surfing downwind under full sail in
a blow and had to replace them. The cheeks were plywood.


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In article ,
"Ed Edelenbos" wrote:

"mac" wrote in message
...
In article ,
"Ed Edelenbos" wrote:


Hmmm.... in a word... bullhockey. There is a chance that a bit less
maintainance will be needed but epoxy is hardly a necessity. Epoxy is no
guarantee of seaworthiness or durability.

Ed

well, give it a couple of coats of primer and then a coat of your
favorite anti-fouling. (personally, the only things I use wood for is
interior trim and of course, the fireplace. if I was building yet
another daggerboard, I'd use foam core and fiberglass/epoxy. different
tech. for different folks, huh?)

I guess I should have thrown in a smiley or a (grin).... Different
strokes, not only for different folks, but for different applications.

I had a Luders L-16 many years back. A 26' loa cold molded plywood boat.
It was made with mahogany and resourcinol glue which I used to match up the
repairs it needed when I got it. It seems to me that that would be the
"perfect" material (only sub'ing epoxy for the glue) for a larger boat. All
the best points of both wood and plastic.

For a simple daggerboard (and again, depending on the application) the
simple method described by the OP seems fine to me. The last dagger I made
was 1/2" plywood. I rough cut it with a bandsaw, sanded the profile with
various power and hand sanders, filled the voids with a glue sawdust mix and
it has about 12 coats of polyurethane on it. It works great and has lasted
(with no new coating) for about 3 years so far. It was for a Snark (the
styrofoam covered with plastic sheathing boat). As is, it was more work
than the boat is worth. But "worth" rarely fits in a discussion of boat
building or repair. If it were a boat I was racing (not likely, another
"not my bag") I'd have probably put more into it. (grin)

Ed

L-16 is still on my list of most beautiful boats.
OK, I'll admit it, I had a snark too.