On Wed, 13 Oct 2004 18:34:51 -0500, Jack Rogers wrote:

Hello--

I'm building an optimist dinghy for my son out of okoume plywood. He'll
be racing it, so its important that the boat come out at the class
minimum weight. Can anybody recommend a glass tape (and supplier) to use
on the seams? I want something light weight that won't soak up a bunch
of epoxy. This is a tiny boat (7.5 ft) sailed by kids, so loads are
relatively light.

Thanks for any advice!

Jack

Actually the question is a little strange. Do you like to reduce strength?

Some ways
# use lite weight (thin) glass cloth wich will absorb less epoxi. (all
waeves are intended for ~55%weave - 45% matrix
# use not as wide tapes....

Less glass weight = less reinforcement.
not as wide tapes = possible delamination.

AND ...the chines are the most stressed part of a hull and because of that
THIS is the most stupid place to save weight!


Morgan

Morgan Ohlson wrote:

On Wed, 13 Oct 2004 18:34:51 -0500, Jack Rogers wrote:

Hello--

I'm building an optimist dinghy for my son out of okoume plywood. He'll
be racing it, so its important that the boat come out at the class
minimum weight. Can anybody recommend a glass tape (and supplier) to use
on the seams? I want something light weight that won't soak up a bunch
of epoxy. This is a tiny boat (7.5 ft) sailed by kids, so loads are
relatively light.

Thanks for any advice!

Jack


-------------------

use 3 inch wide tape - let the weave of the cloth show thru instead of trying
to 'hide' the cloth weave with coat after coat of epoxy...

I've also just taped the outside of similar small boats and left the inside
untaped (but still smoothed with a fillet of thickened epoxy).

paul oman
www.epoxyproducts.com/marine.html

Paul Oman ) writes:

... let the weave of the cloth show thru

You wouldn't normally do this on racing boats as any rough surface creates
drag, but on a Optimist raced by junior sailors there will be much more
important factors in the race, like wind directon and trim.



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In article ,
(William R. Watt) wrote:

Paul Oman ) writes:

... let the weave of the cloth show thru

You wouldn't normally do this on racing boats as any rough surface creates
drag, but on a Optimist raced by junior sailors there will be much more
important factors in the race, like wind directon and trim.


Good point--the main reason this boat needs to be light is
psychological. When some kid gives my son a hard time because he's
sailing a wooden boat, my son can truthfully tell him that the woodie is
the same weight as a glass boat, but stiffer and tougher! Some people
spend upwards of $700 on Opti foils. That money would be much better
spent on quality coaching teaching the kid boat handling, tactics, how
to play shifts, etc.

Jack

Jack Rogers -you) writes:

....the main reason this boat needs to be light is
psychological. When some kid gives my son a hard time because he's
sailing a wooden boat, my son can truthfully tell him that the woodie is
the same weight as a glass boat, but stiffer and tougher! Some people

when plywood boats like the Optimist are built in fibreglass they usually
come out heavier. being overweight may not be a problem. being underweight
may be as people don't like racing against lighter, faster boats.

if the boat is to be built heavy of thicker plywood for toughness the
stiffness of thicker plywood may prevent it from bending to the shape of
the hull.

Skene's Elements gives the weight of fibreglass as 96 lb/cu ft, fir
plywood 36 lb/cu ft, fir lumber 32 lb/cu ft, and all the mahogonies
beetween the fir lumber and fir plywood.

something to note. sorry if it's been considered, I haven't read all the
articles in the thread.
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....and fill the weave w/ filled epoxy. Neat epoxy is a heavy filler.
Same inside.



Paul Oman wrote:

SNIP

use 3 inch wide tape - let the weave of the cloth show thru instead of trying
to 'hide' the cloth weave with coat after coat of epoxy...