D'ohBoy wrote:
On Jul 10, 10:46 pm, "Tom Dacon" wrote:
"BobFilipczak" wrote in message

...



Shiver me timbers, but I'm going to be in the position this fall of
building a mast for the new (old) sailboat I've acquired for next-to-
nothing. The boat is sound, but the mast is glued together and
threatening to come apart in many places. The boat is an old 1968 C
scow from Johnson Boat works in White Bear Lake, MN. The mast is about
22', and from what I can see, it's a kind of torsion box design with
lots of hardware holding it together. The box probably makes up 3/4 of
the total mast, and the last 5 feet are probably solid wood as it
tapers to the end.
Any reason I can't duplicate it with new lumber, put the hardware in
the exact same spots and be confident that it will hold together for
10 years?
Anyone on this list ever done this? [For what it's worth, I also plan
a pilgrimmage to the boat maker to quiz anyone I can find there with
some history and woodworking sense].
Get clear straight-grain quarter-sawn spruce, in the longest lengths you can
find. Get it as soon as you can and put it down to season, sawn into about
1"-thick planks. If it's green, plan to give it at least another six months
if you can spare the time, or better a year, which would be just about right
for one-inch thick stock. Kiln-dried wood could be usable sooner. If you
can't find full-length stock, learn to do good long scarf joints. Epoxy
would do a good job of gluing it up, probably better than resorcinol for
someone new at it. I like West Systems, myself, but there are others.

That C scow is a powerful boat, and it'll want a well-built spar. So you
should do your research. There's a lot of information available in books on
boat building. West has a good manual on using epoxy for boatbuilding tasks,
and it'd pay to study it.

A pleasant project - I envy you the opportunity to do it.

Good luck,
Tom Dacon

P.S. you might also take a look at the old stick. Depding on its condition,
it's possible that you might be able to get it apart, clean it up, and
re-glue it. That wouldn't be a bad approach if the condition would allow it.
For sure you'd end up with a spar that met the original specs.

My father repaired his cracked spruce Nite (iceboat) mast via a
similar methodology. This may be your best route. Spread the crack,
used some powder-based water-mix glue, positioned the mast to cause
the glue to flow into the crack and taped it tight with packing tape.
Worked like a champ and still in use decades later.

D'ohBoy

Wooden boat had an article on spar building. Go to
http://www.woodenboat.com/wbmag/idx/index.html and look for
"Sparbuilding, Hollow". I believe it's in issue 149, July/August 1999.

The technique uses a bird's-mouth joint. Basically you rout a 90-degree
rabbet in one edge of each plank with the rabbet set at an angle
appropriate for the number of planks in the spar (e.g., 45 degrees for
an 8-sided spar). You glue up the planks with the square edge of one
plank settled in the rabbet of the adjacent plank. Glue 'em up all in
one session, round off, install hardware, and yer done!

Crude plank illustration:

_______________________
square edge |_______________________ rabbeted edge