replacing rotten hull areas

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BarnacleBill
Posts: 3
Joined: Thu May 14, 2015 3:45 pm

replacing rotten hull areas

Post by BarnacleBill »

Hi everyone, I'm after a bit of advice about repairs to my GP14. It's an early one, 889 built in February 1956 by the Aln Boatyard, Alnmouth. The yard closed 40 years ago but had a fantastic reputation for quality of both its leisure and inshore Northumberland Cobles. The boat spent much of the last 10 years sitting in a garage in suburban Newcastle, a garage which appears to have had a leaky roof.

I pulled it out about a month ago and bought it for not a lot from the previous owner. I gave it a good prodding with a screw driver at the time and noticed a couple of areas that might need looking at. I consulted an experienced friend who suggested sticking some decent paint on it and getting it on the water for the season, sorting out the issues later.

So a few nights work, a minor strip down, sand and repaint of the decks and uppers and cleaned up the hardware etc.

Today I took it for a test on Derwent Reservoir this morning in a force 5. Raised the wee jib rather than a genoa and eventually, after some spineless refusal to get wet feet from the memsahib I got it away from a lee shore.

handles like an old GP14 should so I took her on a beam reach across the reservoir and back sans crew.

on the return I noticed that there was a good 3 inches of water in the bilge...uh oh. - no hole nor failed seams - the water was osmosing through the ply. I headed for the slipway and got her out the water.

application of a screw driver into the (now sodden) wood has exposed 3 rotten areas from the bow to the rear of the centerboard box, the screw driver cutting through the ply like butter in these areas. It's clear that these areas are patches on what appears to be a bodged repair from a serious grounding incident. Worse still - the repairs have been carried out using non marine ply and had rotted from the INSIDE out, the wood on the outer hull side was relatively sound but the 4 plys on the inner side were rotten, from the area affected I can safely say that this has been caused by standing water in the boat over a very long period of time. I didn't pick up on it because I tested the outside of the hull - (note to self) rather than the inside. as the boat cost a bottle of whisky, its not a total disaster.

So, the issue is that I need to get this boat fixed in the next 3 weeks without breaking the bank. My plan so far is this:

- flip boat
- heat gun, remove paint from lower hull
- identify ply panels to be replaced
- replace panels - using steam to mold the bow areas and secure with adhesive and bronze screws
- check the hog and replace where rotten
- check the keelson and replace where rotten (mahogany)
- caulk (suggestions please)
- paint outside with Epifanes primer and monoeurathane (to keep costs down)
- paint inside with epifanes primer and paint
- coat hull with an epoxy of some sort (suggestions?)

is there anything that I am missing?
On the whole the mahogany timbers and centerboard case are sound, they have only rotted where they have become exposed to the rotten ply and the rot isn't extensive.

Its clear that the standing water had soaked into the timbers and then was stopped by the outer coats of paint, tapped it waterlogged the wood, a few years of frosts etc....

It shows the importance of laying up the boat somewhere watertight and ensuring that it the bows are propped so standing water can drain out.


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JimC
Posts: 1721
Joined: Sun Oct 03, 2004 10:24 pm
Location: Surrey
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Re: replacing rotten hull areas

Post by JimC »

This is a very familiar area, and you'll find lots of relevant posts in back threads. You probably won't need to steam ply for a GP14.

Assuming the stringers are good if you use a modern glue you don't need to go overboard on the mechanical fasteners, which will save a lot of money. Personally I use steel staples and remove them afterwards.

No reason to assume non marine ply - marine ply rots just as well as any other, the difference is in the glue, not the wood.

Probably no need to caulk, gap filling glues will do the business.

Epoxy coating a hull can cost a lot of money, and probably is of marginal cost effectiveness on an old boat. If you can keep her dry and indoors away from frost over winter it probably won't make that much difference, and if you have to keep her outside and she doesn't stay dry it probably still won't make that much difference.

I might be tempted to, well, go the whole hog. [sorry!] You need to take it off to replace the skinds anyway, don't mess about trying patch repairs.
BarnacleBill
Posts: 3
Joined: Thu May 14, 2015 3:45 pm

Re: replacing rotten hull areas

Post by BarnacleBill »

Thanks Jim that's all exceedingly helpful.

First task is to bring the boat back to the garage!
roger
Posts: 3031
Joined: Mon Sep 20, 2004 12:08 pm
Location: Frome Somerset UK

Re: replacing rotten hull areas

Post by roger »

I agree with Jim, you wont need to steam the ply for a GP. Using an epoxy glue with some fillers and you shouldnt need to caulk.

The thorny question of epoxy coating.. for some it is the way forward for others myself included I would save the time and hassle especially if painting and not varnishing.
My reason for not likeing epoxy coating is that if you do get a ding (and you will sooner or later) any water that gets under the epoxy cant get out and you end up with rot setting in.

Good luck with the project. Gps are great boats especially in a blow.
Hornet 191 Shoestring,
Hornet 595 Demon awaiting restoration
Hornet 610 Final Fling
Hornet 353
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