I don't understand how there can be a 4" radius on a transom only 22" wide.
Could you mean 4" camber? Given the width of the transom and the camber of
the arc you can calcuate the radius of a circular arc. If you look under
"Boats" on my website you'll find a file of various formulae having do to
with circular arcs for boatbuilding, also a BASIC program which calcualtes
radius and points to plot on a circular arc for, say deck beams or cabin
sides. You'll also find a file on dry bending plywood. Sorry, nothing on
steam bending plywood.

I was barely able to get a 2" camber in a 2.5' arched transom by steam
heating lauan underlayment. There's photos of the completed boat,
Dogskiff, on the website. It's not a power boat so its much lighter
construction than your 15' skiff with a 3/4" bottom.

There might be another confusing word below. The angle where things are
attached to a hull is usually called "bevel" as in stem, frame, and
transom bevels. The word "scarf" is used to describe the joining of two
pieces of wood. The angle of the scarf is it's bevel.

Kevin ) writes:
I am building a 15" skiff... stitch and glue style. 3/4 merainti
bottom, 9mm okoume sides. I want to do a rounded or fantail transom. I
have scarfed the sides where I am going to attach the transom, and
will scarf the pieces to be bent prior to bending. The bent pieces
will be part of a conic section with a 4" bottom radius and a 12" to
radius. If I remember correctly the my template for the pieces to be
bent is 22" tall and 26" wide at the widest point. The exterior of the
sides are alread coated with 6 oz triaxle glass and the interior with
3 coats of epoxy. I will glues the scarf joint and then glass the
exterior and epoxy the interior of the fantail.

Thanks,
Kevin

Nope, I don't think the 5mm would go either. The three layers of three
MM might go. As far as the other types of wood you mentioned, why
don't you tell us what you are building and what it will be used for,
we might be able to provide more info.
Scotty


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William R. Watt ) writes:

I was barely able to get a 2" camber in a 2.5' arched transom by steam
heating lauan underlayment. There's photos of the completed boat,
Dogskiff, on the website. It's not a power boat so its much lighter
construction than your 15' skiff with a 3/4" bottom.

I just remembered that transom is two layers of 1/5" lauan underlayment
laminated with plastic resin glue. Of course that's the same as bending
one layer of 1'5" underlayment. If you look closely at some of the photos
you might be able to see the crease in each layer of lauan underlayment
because it was a bit more than it wanted to bend. The creases don't line
up and the transom is fine but some people are fussy about appearances and
would complain about the creases.

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William R. Watt ) writes:

I just remembered that transom is two layers of 1/5" lauan underlayment
laminated with plastic resin glue. Of course that's the same as bending
one layer of 1'5" underlayment. If you look closely at some of the photos
^^^^
and THAT should have been 1/5"

I also see your transom is not 22" wide but 22" high, and 26" wide. You
still can't have a 4" radius in a 26" wide transom.


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To clarify... the template (to fit over the buck that I made) is 26"
wide at its widest point.... but this includes the radii + several
inches of material that goes back along the side before the scarfs to
join the transom and the sides. This maximum width is at is at the 12"
radius area..... at the bottom the template is substantially
narrower.... The area being covered is the surface of a conic section
and so the template looks like a piece of pie with the tip cut off at
a radius... let me see if I can do it in ascii art
_ _
_- -_
\ /
\ /
\ /
\n/ template


Kind of.... with the scarfs along the edges. The bottom will be
bending around the tight 4" radius and the top around the 12" radius.
Does this make more sense?

Kevin

I want the transom to look something like this when completed.
http://www.montanaboatbuilders.com/skiff.htm

Jason Cajune (who builds the boats in the pictures) does masterful
work... and build the transoms by steam bending and torturing layers
of ply over a buck....

Kevin

(Kevin) wrote in message . com...
I want the transom to look something like this when completed.
http://www.montanaboatbuilders.com/skiff.htm

Jason Cajune (who builds the boats in the pictures) does masterful
work... and build the transoms by steam bending and torturing layers
of ply over a buck....

Kevin

Ahhhh. I get it now, cool boat! Anyway, I still think you may need to
use multiple layers of 3mm. Even if you could bend the 9mm around the
bottom of the "cone" you would have to leave a lot of wood to get
ahold of, or use a lot of pressure which would mean making a pretty
good mold and press. Another way might be to use a couple of layers of
3mm with a layer of fiberglass inbetween and on each side. You would
not need to use thick glass, just want to make it a laminated core
type structure. If you are worried you could go with three layers of
3mm.
Scotty from SmallBoats.com