Fibreglass Deck Delamination

mainshipsteve · Sep 10, 2019

This is my first post and my first potential boat over 20'. I have been in search for the right Mainship 34 for a few years now and found what I thought was the perfect boat for me, a 1978 MK I. Unfortunately, the survey revealed some "minor delamination" in four areas of the deck (sides and cockpit), as well as 25% to 30% moisture readings in these small areas. The surveyor suggested that these were not catastrophic and did not necessarily need immediate attention. He suggested, if I purchased the boat, to continue monitoring the areas over the next few years and go from there. With current limited options due to location, I got a couple estimates and both are a little scary. Knowing that I can negotiate something off the purchase price, my question is whether i should go ahead with the purchase or run for the hills? Thanks for your help.

dhays · Sep 10, 2019

mainshipsteve said:
This is my first post and my first potential boat over 20'. I have been in search for the right Mainship 34 for a few years now and found what I thought was the perfect boat for me, a 1978 MK I. Unfortunately, the survey revealed some "minor delamination" in four areas of the deck (sides and cockpit), as well as 25% to 30% moisture readings in these small areas. The surveyor suggested that these were not catastrophic and did not necessarily need immediate attention. He suggested, if I purchased the boat, to continue monitoring the areas over the next few years and go from there. With current limited options due to location, I got a couple estimates and both are a little scary. Knowing that I can negotiate something off the purchase price, my question is whether i should go ahead with the purchase or run for the hills? Thanks for your help.

Welcome. I had a 1983 Catalina 36 sailboat that had deck delamination issues. It didn't affect the strength or performance of the boat, but it significantly reduced how much I got for the boat when I sold it. I would reduce the purchase price by the amount quoted to repair it. Whether you actually have it repaired is another matter. There are some less than perfect ways to dry out the delamned areas and then make sure that you aren't getting any more water intrusion.

Simi 60 · Sep 10, 2019

Ply core?
Fix it now while its a easy fix.
In a few years it'll likely be much worse

Comodave · Sep 10, 2019

Welcome aboard. Replacing the wet coring isn’t a huge deal if you are a bit handy. Cut the top around the wet areas and remove the fiberglass. Dig out the wet core. Bed new core in thickened epoxy. Replace the top fiberglass by bedding it in thickened epoxy. Grind out a shallow trough around the cut areas and lay in some 1708 fiberglass and fair out. Then paint the deck with Kiwigrip. It is hard work but not too challenging technically. The 34 Mainship is a nice boat. I would negotiate based on the estimates and then fix it yourself.

bshillam · Sep 10, 2019

I wouldn't necessarily walk from a smaller area of wet core in a 78. This old of a boat your more than likely going to find areas of higher moisture in various areas. I had a 81' Tolly that had one soft spot on the deck. Enjoyed the boat and sold it with the same soft spot, showed the buyer and we all moved forward.

Jeff F · Sep 10, 2019

If that's the worst item on the surveyor's findings there's no reason to run away. It goes with the territory when you're shopping for 40 year old boats.

You'll find lots of information here and elsewhere on DIY remediation, and a few of us have sister ships.

SoWhat · Sep 10, 2019

At a minimum you have to find and repair the source of the moisture. It could be a fitting that simply needs to be rebedded, or the whole deck needs recaulking. Time consuming if DIY, expensive if the yard does it

mainshipsteve · Sep 10, 2019

Thanks. Gives me some confidence. I really want to get into a trawler!

boatpoker · Sep 10, 2019

mainshipsteve said:
Unfortunately, the survey revealed some "minor delamination" in four areas of the deck (sides and cockpit), as well as 25% to 30% moisture readings in these small areas.

You might want to talk to a surveyor who knows how moisture meters work.
They simply cannot determine a percentage of moisture.
Moisture Meter Mythology and Flir thermal imager

FF · Sep 11, 2019

Delamination or craizing is common on high loaded areas , the bottom of a ladder or steps.

Winch or windlass mounts. I would not worry much.

If its in the middle of a deck that is solid GRP (not buried plywood) it would be a larger concern.

jleonard · Sep 11, 2019

I owned a 78 Mainship I and repaired both side decks from UNDERNEATH. Easier than doing it from above, just messier. My method meant almost no finish work topside.
I also added backing plates for all the stations and cleats since I was in there.
I also re cored a very large section of the flybridge.
I can send you pictures of the flybridge job if you want.
Send me your e mail address in a private message and I'll send you the pics. Too many to post here.
Jay

Fibreglass Deck Delamination

mainshipsteve

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dhays

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Simi 60

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Comodave

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bshillam

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Jeff F

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SoWhat

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mainshipsteve

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boatpoker

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FF

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jleonard

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