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Laminated Plywood

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John

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Aug 25, 2002, 11:07:33 PM8/25/02
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Does anybody know a source for the thick blocks of wood you see on outboard
motor brackets?
Could I just glue a bunch of marine ply together in order to obtain the
stock thickness?
What would you recommend for glue/epoxy?

Thanks from John


William R. Watt

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Aug 26, 2002, 9:35:34 AM8/26/02
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"John" (john...@rogers.com) writes:
> Does anybody know a source for the thick blocks of wood you see on outboard
> motor brackets?
> Could I just glue a bunch of marine ply together in order to obtain the
> stock thickness?

I'd use plywood, fir would be my choice for lower cost. It would get
chewed up faster than a block of hardwood and might have to be replaced
depending on how important appearances are on the boat.

> What would you recommend for glue/epoxy?

assuming the wood is above the waterline (not constantly immersed in
water), and the block will also be held together with mounting bolts, then
any moisture resistant wood glue will do. read the instructions first to
see if it has to be thickened for laminating. any of the following should
outlast the motor mount.

I've used plastic resin (urea formaldehyde) to laminate the curved transom
on a small skiff and to lamintate plywood butt blocks. It comes as a dry
powder and includes thickener (wheat or rye flour) for laminating. This
boat is kept out of the water under cover. There have been no problems
over 3 seasons. The only drawbacks are it has to be over 70 deg F to
cure, and I can't find it locally in quantities less than a pound.

I've used polyurethane construction mastic (PL Premium brand) on chine
battens and plywood butts. It is cheap, readily avialable, easy to apply
with a caulking gun (after which I spread it smooth with a scraper or
putty knife), needs no thickening, and will cure at 50 deg F.

Epoxy is strongest and completely waterproof, more than is needed for this
job. It needs 70 deg F to cure. I haven't used it for laminating and do
not know if it requries thickening. Lots of people who post here will know
about laminating with this glue.

No matter which glue is used it is a good idea to spread 2-3 coats on the
edges of the plywood before painting to keep out mosture and prevent
splitting.


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Ron Magen

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Aug 26, 2002, 1:53:28 PM8/26/02
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John,
Not wood, but I've seen pre-shaped piece of hard material {like a hockey
puck} in a number of catalogs.

Regards,
Ron Magen
Backyard Boatshop
{who applies varnish & wax to his wooden one every year}


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Lew Hodgett

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Aug 26, 2002, 9:07:32 PM8/26/02
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If you want to do this job ONE time and never again, I suggest the
following:

Buy a sheet aof 1/2" CDX construction grade plywood. 4 ply is better than 3
if you can find it.

Buy a big jug of TiteBond II (waterproof carpenters glue).

Cut out as many blanks as you need, and laminate them together with TiteBond
II.

Trim your finished laminate to size.

Now comes the fun part.

Get some epoxy and some double bias glass cloth, (17 Oz works well) and some
unidirectional glass, at least 12 oz.

Cover each of the faces with a couple of layers of double bias glass.

After it has cured and been sanded to size, seal and wrap all the exposed
edges with unidirectional glass.

After it has cured, lay piece on side and pour some more epoxy in the crack
brtween the "uni" and the double bias, and let it cure.

Flip piece over and repeat.

Sand off the excess "Uni" and you are almost finished.

Locate the necessary holes for mounting hardware, drill holes and seal
exposed woo with more epoxy.

Mount and enjoy.

Trust me, the day will come when you jack up the motor bracket and drive a
new boat under it.

Worried about some UV damage, slap some cheap paint on it, end of UV
problem.

HTH


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures

Arnold Shore

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Aug 27, 2002, 6:01:54 PM8/27/02
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I've epoxied 3/4" two pieces of teak together, and placed some 1/8" aluminum
where the outboard's teeth bite, to protect the wood/finish.

The alum is available in 3" widths at most hardware retailers, and fastens
to the teak with fh screws.

I finished the teak per the rest of the teak aboard. Nice.

Arnold Shore
Annapolis, MD USA


John

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Aug 28, 2002, 7:20:54 PM8/28/02
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Thanks fellows for your feedback.

Cheers

Johnny


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brian.clode

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Sep 5, 2002, 5:35:09 AM9/5/02
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Finished one a couple of months ago. 3 layers of 1/2inch marine ply and use
waterproof glue. Cut it to shape. Drill the holes before you varnish, and by
the third coat it should look fantastic,
Brian

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