Hi all, I'm newbie here; I'm about to start on a 34' sailboat using
cedar strip planking core/glass fibre. This is the first of many
subjects that I will ask your advice on.

I have the luxury of a joinery workshop, so I intend to cut up and
machine to size Red Cedar planks that my local (and very convenient)
supplier stocks.
My problem is that although my supplier tells me that the cedar comes
from Canada, I keep reading that it is Western Red Cedar which is the
stuff to use. I frankly do not know the difference - if there is one -
between Red Cedar that comes from Canada and Western Red Cedar. My
supplier in question is very forthcoming but as they are not normally
suppliers of boatbuilding materials, I guess that the knowlegebase
here will serve me better than to keep going back to my supplier.

Next question may cause a small bit of disagreement perhaps.

I have read that the cedar is ideally dried to below 15% but I know
that whatever the mc when the wood leaves the kiln, it slowly reverts
to whatever the average relative humidity of the air surrounding it
allows it to be. ie, kiln dried to 9 or whatever% is ok as long as the
stuff gets quickly put into the environment that you kilned it for (or
it needs to be stored in a proper manner - which doesn't mean allowing
a fresh air supply)
So although the cedar was probably kilned to maybe 12%, it comes from
Canada and maybe has travelled for a few weeks as deck cargo and then
spent a month or two sitting around in distribution sheds/timber yards
waiting for me to buy it, all the time arriving back to the 16-17% mc
that air dried timber will get to here, and whatever the local
timber merchant sells me, after checking, is normally at.
Luckily, not a problem for me, as normally I work with timber which
needs to be around the 8-12% mark so I have a kiln.
So no problem perhaps, except that as I need to build this boat in my
spare time and as it's winter here, whatever I kiln my wood to now, it
stands a really good chance of reverting back to around 15 plus % by
the time I get around to finally sealing it all up with epoxy .

Am I just going over the top with this, or is it really a problem? My
gut feel as a joiner is that once the stuff is encapsulated it stays
stable and I reckon 16/17% is fine. The only problem I have ever had
with wood is when it moves - and it only moves when the mc changes
(I'm talking of shrinkage here not flex although I know drier wood is
stiffer, or rather harder).

I am also very concious of the fact that I ain't a boat builder, so
what the **** do I know?.

I have also been told to temporarily fix the strips to the molds with
stainless steel nails, before removing them to lay the epoxy and
glass. I can see s/s nails costing a fortune, especially when I see
them lying, bent and buckled on the floor in the boatshed; and then I
have got to pick them all up! Surely there is another way??

One more question for now; I have seen tongue & groove and bead & cove
strip planking for sale; I can machine this myself, but are there
significant advantages over square section when using epoxy?

Hoping for some advice from you guys

ttfn
Pete

"Pete" wrote in message
...
Hi all, I'm newbie here; I'm about to start on a 34' sailboat using
cedar strip planking core/glass fibre.

between Red Cedar that comes from Canada and Western Red Cedar.

I doubt there's any difference. One way to tell if it is WRC is to measure
the density, which IIRC is about 20-23 pounds/cubic foot.

Am I just going over the top with this, or is it really a problem? My
gut feel as a joiner is that once the stuff is encapsulated it stays
stable and I reckon 16/17% is fine. The only problem I have ever had
with wood is when it moves - and it only moves when the mc changes
(I'm talking of shrinkage here not flex although I know drier wood is
stiffer, or rather harder).

This could be a risk. If you put it in at 9% and it gradually changes
to 16% there will be movement. Whether it causes any problems is
another question. Glenn Ashmore, who is building a 45' strip
planked/glass sheathed boat (www.rutuonline.com, better go read it!)
didn't have any problems until he glassed the outside of the
boat. The hull then started moving all over the place until he sealed
the inside.

I have also been told to temporarily fix the strips to the molds with
stainless steel nails,

Nothing temporary deserves stainless, or even galvanized.

One more question for now; I have seen tongue & groove and bead & cove
strip planking for sale; I can machine this myself, but are there
significant advantages over square section when using epoxy?

Tongue and groove can be fast, but I don't think all the grooves could
ever be fully filled with epoxy. The gaps in the grooves will wick whatever
moisture is present, and it would be up to you whether you think it will
be a problem. It certainly can be for blasa cored boats. The bead and
cove has a couple of advantages: You use less epoxy, and there is more
surface to glue (not that epoxy needs the help). Disadvantage is the
extra machining.

Good Luck!

Matt

Pete wrote:

My problem is that although my supplier tells me that the cedar comes
from Canada, I keep reading that it is Western Red Cedar which is the
stuff to use. I frankly do not know the difference - if there is one -
between Red Cedar that comes from Canada and Western Red Cedar.

"Western Red Cedar (Thuja plicata) grows in Northern California,western
Oregon, western and northeastern Washington, Northern Idaho. and
northwestern Montana. It grows also along the Pacific coast northward to
Alaska" (source: USDA Wood Handbook, 1953)
I would assume this includes the west coast of Canada.

I have read that the cedar is ideally dried to below 15% but I know
that whatever the mc when the wood leaves the kiln, it slowly reverts...

Gougeon Brothers says..boats can be built with moisture
levels up to 18% but in long term equilibrium may lose some moisture
which could effect structural integrity" (Gougeon Brothers on Boat
Construction, pg. 33)

I have also been told to temporarily fix the strips to the molds with
stainless steel nails, before removing them to lay the epoxy and
glass. I can see s/s nails costing a fortune, especially when I see
them lying, bent and buckled on the floor in the boatshed; and then I
have got to pick them all up! Surely there is another way??

Use large galvanized finish nails and remove them as you go after the
epoxy has set.Temporarily nail strips through the face of the
stripleaving the heads out for removal.
Also,edge nail one strip into the one below it and leave the nail in.

but are there
significant advantages over square section when using epoxy?

Advantages and disadvantages.
Bead and cove makes a tighter looking joint, provides a "gutter" for the
epoxy to sit in so it doesnt run down as much, makes aligning strips
easier and faster which results in easier fairing.
You may be able to use section molds spaced farther apart than with
square edge.
Square edge is faster to mill and uses slightly less material.
If you have the milling equipment readily available, I'd use the bead
and cove profile. If you have a power feed hooked up to a saw and shaper
it will reduce the effort of milling.

SteveJ

OThanks guys, that's a little bit of the fog cleared away.

Pete