When is a dirty hull a structural problem?

[whitejw1967]

I know, the question sounds stupid. But, I am interested in a CD25 that is in decent to good shape (haven't yet seen it as it's a three hour drive away). But from what I've been told and the one photo I've seen, the bottom is filthy to the point of obvious growth below the bootstripe and browning a few inches above. I've no problem with hauling, power washing, and painting. But I don't want to go to the trouble if excessive growth has compromised the integrity of the hull. Does such growth encourage blistering (I'm assuming it does)? Has blistering or osmosis-related issues been much of a problem of later CDs?

Also, does the lazarette size accept most outboard engines in the 7-9.9 hp range? Does it require a long-shaft?

Advice is welcome.


John

[mashenden]

I'm pretty sure blistering is mostly the result of a problem during the curing stage of epoxy at the time of build... impurities, bad epoxy, wrong temps, etc. It causes voids that moisture gets into, then gets worse over time popping a divot of gel coat off causing a pit, some very large pits if serious. I've seen it so bad that digging out the soft spots left notable holes where you could actually see into the bilge - almost like wood rot (but NEVER that bad on a Cape Dory!!). But again it was because the epoxy was not up to par to begin with. Barriers have a tighter molecular structure that prevents moisture from getting to the gel coat/epoxy.

My main point being that I don't think you can assume a dirty hull means a higher likelihood of structural problems, but it gives reason to do a good inspection (meaning hire a pro if you are not), since lapses in hull maintenance could be a sign that the seller's maintenance regiment, in a general sense, was not the best.

The brown stuff above the water line comes off remarkably easy using MaryKate On & Off. Spray on, wait a few minutes and wash off with a sponge. Gone. It is a chemical so many recommend gloves and mask, but I can't say I did anything more than stay upwind of the cloud. This was my experience with solving the brown stains that are common in the NC areas, which was where my CD came from (not sure about your area, though).

[tartansailor]

does the lazarette size accept most outboard engines in the 7-9.9 hp range? Does it require a long-shaft?
Advice is welcome.
John

X long shaft is a must.
6 hp is plenty enough.
Dick

[Stan W.]

I second what Matt said except that, like virtually all fiberglass boats built in the 70s and 80s, Cape Dorys were built with polyester resin, not epoxy resin. Polyester is much more permeable than epoxy and, therefore, much more prone to blisters.

[mashenden]

I second what Matt said except that, like virtually all fiberglass boats built in the 70s and 80s, Cape Dorys were built with polyester resin, not epoxy resin. Polyester is much more permeable than epoxy and, therefore, much more prone to blisters.

Good point - It would have been more relevant if I had used the terms resin and/or polyester, rather than epoxy. There are differences.

Still, its worth reiterating, there are plenty of 30+ year old boats in their original form and w/o blisters (or with very small blisters that debatably are not even worth fixing).