What is the hollow keel made of? Fiberglass (even most epoxy resin
composites) will not hold up to the heat released by that much lead. If
you can cast it, do so. Melting 350 kg of lead is not all that big a deal.
The advantage of casting is that it will be much more dense. A bucket full
of those little square lead weights will reduce in volume by more than 30%
when melted. The COG will be lower giving more stability without violating
any class rules.
A few ideas for casting ballast for a FRP keel: This will require some help
from a few friends and some lifting equipment but it will preserve the
strength of the FRP and simplify the casting process:
Figure out exactly how much weight you will need.
Divide by 11.340 to get the equivalent volume of water.
Level up the keel and pour the water in.
Mark the water line inside the keel.
Line the inside with poly sheeting and pour in some plaster of Paris up to
the waterline. (Use some scrap blocks of wood pressed into the plaster to
reduce the amount required and give something to lift the plaster out
with. )
Using the hardened plaster as a plug make a mold in Quickcrete or other
hardware store concrete mix.
Let the concrete cure for a few days then build a small charcoal fire
inside. You want to heat it well above 100C for several hours to drive out
any free moisture.
Melt about 1/3 of the lead in a 20L pot over a propane burner. Skim off the
dross.
Pour it into the mold but leave a little in the pot to make the second batch
start melting faster.
Repeat until the mold is full. (You may have to direct a propane torch over
the previously poured lead to keep the surface molten while the next batch
melts.)
Break out the mold.
Smear a thin layer of slightly thickened epoxy inside the keel.
Place the lead casting into the keel.
--
Glenn Ashmore
I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at:
http://www.rutuonline.com
Shameless Commercial Division:
http://www.spade-anchor-us.com
"sam" wrote in message
...
I scored 350 kg of lead over the weekend for free from various tires
centres. I found outwhat the trick is.... go to tire centres where they
sell a lot of mag wheels... they use adhesive backing instead of clips to
attach to the wheel. I still have weights with clips but not as many. In
the mortal words of Homer Simpson...YoooHooo!!!!
They are to go int a hollow fin keel for a hartley 21. Should I fust pour
them in and cover with epoxy or should I melt the lead and poor into the
keel?