: I thought I'd try a strip style coaming for my new Pygmy S&G. So far it's
: been very rewarding and I can tell that it will look nicer than the
: typical plywood coaming that the kit comes with but I've run into a bit of
: a challange with bending the strips for the edge.

: Basically I bought a piece of 1" x 6" x 6' phillapine mahogany and
: cut 1" by 1/4" strips out of it. Then I cut some of those 6 foot
: stips 2" lengths and built up the vertical portion of the coaming. I
: ripped a second batch of the 6 foot strips to 1/4" by 1/4"
: (probably closer to 5/16") to be used as the horizontal edge of the
: coaming.

: Next I built a wood steamer out of a 6.5' piece of 4" PVC pipe I had
: hanging around. I capped on end and drilled a hole for a 1 inch piece of
: clear plastic tubing that runs down to a cheap pot. I drilled a hole for
: the tube in the lid of the pot and sealed both ends so the assemble is
: essentially "steam tight" (the pot lid is held in place by a
: couple of pvc clamps...) Also, down the sides of the PVC tube, I drilled
: holes and inserted dowels to keep the wood out of any condensed water and
: I sealed the other end of the tube with a damp rag (there are a couple of
: 1/8 in hole to release a bit of steam if necessary - they're also
: currently plugged).

: Ok so... attempt 1 - I put the edge strips in the steaming tube and heated
: water with a propane burner, steamed the wood for about 4 hours and
: couldn't get it to bend around the forms I created for the coaming. So,
: perhaps it needed soaking and hotter steam....this leads to: Attempt 2: I
: soaked the wood in hot water for about 36 hours, then used an electic
: burner (on the kitchen stove - my wife just loved that!) to heat the steam
: hot enough that the PVC tub bent. The wood steamed for about an hour and a
: half but still wouldn't bend around the forms.

: Anyone have any idea what I'm doing wrong? Should the strips be thinner?
: (1/8th inch or less)

: Thanks for any input.

: Taylor Warren

Ash, Hickory, WHITE oak, and northern white cedar are THE preferred woods for bending
because they possess natural bending properties unlike other woods. This why stripping
with northern white cedar is easier than other woods

Yes, you can bend other woods, but not as easily and with as much success as with these woods.

Air dried wood bends much more readily than kiln dried wood. The natural glue, lignin, that hold
the wood cells together can be softened in air dried woods with heat. The lignin in kiln dired woods
has been altered so it does not respond to heat in the same way.

The best stock would be quarter saw wood (cut on a radius from the log center) which will
not have any grain run out, which might cause the piece to break during bending. Typically,
we buy flat sawn boards and cut strips from the edge. The strips have a consist tight grain,
with no figure to it. This is what quarter sawn wood looks like.

While steam bending works you have to know how to do it and what will happen. For instance,
if you have a form to bend your wood around, your form must be smaller than the finished size
of the bend to allow for the springback that will result when clamps are removed.

If you have a cockpit shape cut into your deck it will probably be easier to bend 1/4" thick wood
such as ash, with a heat gun and a vise. You can pre soak the wood but don't boil it! because this
will permanently weaken the wood.

As I mentioned before, air dried woods bend very easily with the heat gun because
the natural glue that holds the wood fibers together, called lignin, becomes plastic
when heated. Kiln dried woods will not bend as well because the lignin has changed in
the drying process. But they will still bend if you go slow and try a few test pieces to
get the feel for working with it.

An important point to remember about wood bending is that nearly all the bending happens
on the compression side of the wood (inside of the curve) so to use a heat gun effectively
you must apply heat to the inside of what will be a curve.

Again, as with any wood bending clear straight grain is important for success.

Clamp one section, near where you will bend the wood and hold the other end with a
leather gloved hand (that heat is very hot!) and apply the heat from the heat gun to the flat
of the strip. Hold the end of the heat nozzle about two inches from the wood and keep it moving
back and forth. Twist or bend the wood with your hand building tension into the wood. You will
feel the tension release as the wood reaches the right temperature. Kiln dried woods will take
more heat often toasting the wood surface before tension is released and sometimes you'll hear
the wood start cracking as it starts to break on the tension surface (outside of the curve).

You have to over bend the piece because it will spring back. If you end up with a tighter bend
than you wish you can just reheat it and straighten it a bit.

Try some test pieces of different woods in a vise to get the feel before you work on your boat.

All the best,

Rob Macks
Laughing Loon CC&K
www.LaughingLoon.com