Re: CONCRETE BLOCKS

hlg@pacbell.net
Thu, 18 Nov 1999 11:07:17 -0800


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West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
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Ron

The blocks probably were not an owner's experiment. Many Potter 15s were
manufactured with the blocks. If they are not in the way, why remove them?
The original Potter was designed to carry a lot of weight (water
containers, for instance) in the cabin. Most of us daysail and don't carry
much weight forward. As a result many Potter 15s are sailed tailheavy and
don't perform as well as they should. The weight alongside the centerboard
trunk may not help much in that regard, but it improves stiffness. The hard
chined Potters perform best at only about 10 degrees heel. My early P14
didn't have concrete blocks, but I now have two 45 lb batteries mounted in
the same location. (They drive my 24-volt, 70 lbf MinnKota.)

Lead is expensive but would be better than concrete. It is more dense so it
wouldn't take up so much space for the same weight and the center of
gravity could be lower. Jerry Barrilleaux has a billet of lead in the bow
locker of Breezy, the P15 that won the SCA challenge race last weekend,
skippered by Todd Barrilleaux.

Perhaps the concrete blocks were first added when the Mk II sail was
introduced and were intended to compensate for the higher center of effort
of the four-sided sail

No one except Larry Brown seems to like the idea of a wooden board for the
P19. The manufacturer strongly discourages the idea. Cement blocks inside
the hull won't provide anywhere near the leverage of that heavy keel under
the boat. The P19 seems to approach keelboat stability with its heavy
daggerboard; as a result, P19 capsizes are almost unheard of.

On the other hand, raising the heavy keel straight up raises the P19's CG
substantially, which can result in turning turtle if someone tries to sail
her that way. With a wooden board, a P19 could possibly be sailed in shoal
waters with the board partly retracted. The lightweight board could be
pulled up quickly for beaching and could be operated with a block and
tackle instead of a winch.
.

Harry Gordon
P14 #234, Manatee
Mountain View, CA

>John,
>1] It's {the blocks} are termed 'interior ballast'. the previous owner was
>probably
>worried about any heeling. Or if it was the dealership, they were
>'fudging' their
>demo rides as bit.
>
>2] Larry Brown, in one of his books, made the statement that he would like
>to see a
>LIGHT WEIGHT WOOD centerboard (in a P-19) with a "couple of CINDERBLOCKS"
>as the
>actual BALLAST. Someone might have been experimenting with this theory.
>
>3] The 'fastening' is probably epoxy or poly resin. I wouldn't want to
>suggest the
>usual method for breaking the bonds, it would probably damage the trunk
>itself. Try
>these two suggestions:
> A) get some DRY ICE, pack it around the base of the block (where the
>epoxy is)
>use duct tape & rags to hold it in contact. When it gets to freezing, put
>a board
>on top of the block (or on an end if the blocks are resting on the sole)
>and hit it
>with a SLEDGE or SHORT MAUL - whatever is heavy with a lot of mass that
>you can
>swing in the space available. WARNING - HAVE SOMEONE with you - outside
>the cabin,
>and have the forward hatch open and a fan blowing FRESH AIR INTO the main
>hatch.
>'dry ice' is CO2 and you can pass out from lack of oxygen.
> B) Get a 'block chisel' and cut the block as close to the trunk as you
>can,
>then try the 'Dry Ice' trick. Or try to carefully chisel & grind it flush.
>
>Regards,
>Ron Magen
>Ron's Backyard Boatshop
>Master - s/v Quahog (P-19, #575)