[Rhodes22-list] Re: CB trunk, bottom paint

[Roger Pihlaja]

Lou,

Since I presume you don't want to have to get up inside the centerboard
trunk to repaint again any time soon, I would suggest using one of the hard
epoxy-based cuprous oxide bottom paints.  Pettit Trinidad would be a good
choice.  The red color has 75.8%wt CuO, which is about the highest biocide
content I've seen in any bottom paint.  The stuff will dry to a hard
slippery finish that won't sluff off or ablate away with time.  The high CuO
content should keep the fouling at bay for years inside a centerboard trunk.

You may be correct in your hypothesis regarding the swelling of the FRP
composite inside your centerboard trunk.  However, there is another
possibility.  Due to a hard grounding or the boat being dropped during
launch or retrieval, the liner in the centerboard trunk may have delaminated
and buckled in compression.  An internal build-up of water with freeze/thaw
cycles may have produced a similar effect.  If you find water inside the
shoal draft keel with your pilot hole; then freeze/thaw damage is almost
certainly the cause of the bulge.  I don't think you want to reduce the
thickness and strength of the FRP laminate by grinding away the bulge.

Let's talk some more after you've taken your pictures and drilled your test
pilot hole.

Roger Pihlaja
S/V Dynamic Equilibrium


----- Original Message -----
From: "Lou Rosenberg" <lsr3 at MAIL.nyu.edu>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Wednesday, December 01, 2004 11:05 AM
Subject: [Rhodes22-list] Re: CB trunk, bottom paint


> Roger,
>
>   Can you recommend a bottom paint for my CB trunk once I get it sanded?
>
>   I am going to try to pu the WEST SYS book on Fibreglass repair and
> Maintenance today if possible at WM.   I am praying that my trunk is
> not damaged due to water and the bulges I have noticed are not that
> much of an obstruction for sailing.  If  i need  to remove the board
> again using a jack from the bottom- I can deal with that.  I dont
> think i want to rip open my trunk if the (possible) delamination will
> allow me to sail it.   But I am going to assess it on Sat and will
> bring my dig cam to take  CU pics. I will grinding away some of the
> paint from the bottom of the keel near the trunk and will drill a
> pilot 3/16" hole to see if water is apparent.
>   Lou
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