Wet Foam Core

[26N80W]

Looking at a boat with some areas of wet foam core as detailed in the survey. The boat is 20 years old so it's possible it has been wet for a long time. Most of the moisture is located around through deck mounted hardware.

Boat has sailed many trans Atlantics so I know she is sea worthy. I know wet balsa core will rot and lose all structural integrity. Foam doesn't rot. Does moisture just add weight and eventually cause delam if it get's bad enough? Cutting out all the wet core is pretty invasive. Is it possible to rebed hardware to prevent additional water ingress without rebuilding the boat?


Thoughts?

[psk125]

Wet foam core can lead to delamination due to freeze cycles. Rebedding the deck hardware might stop more water from getting in, but won’t help the situation with the moisture that’s already there. It may be possible to dry out the wet core with heaters and fans, but that does involve at least removing the fittings if not the fiberglass laminates as well. In some cases it can take months to dry things out properly before re-installing the hardware.

[Chotu]

What foam is it?

Most marine structural foam will dry in a couple hours since it's only wet on the surface. Closed cell, not porous.

Sealing up the issue isn't a great idea. Fixing it is better.

[psk125]

We dealt with a hydroscopic foam on my father’s skiff. It was supposed to be “floatation”, but ended up weighing about 5 pounds per cu ft with all the water it soaked up. We ended up cutting it all out of the bilge with a garden spade, replaced it with styrofoam, and rebuilt the cockpit sole over it. Hopefully 26N’s foam isn’t that kind.

[Rucksta]

Get a quote to repair the fault and renegotiate the sale price.

DIY fix could be pretty easy. Drill some holes though the inner skin and allow to drain. Vacuum bagging is really effective so are dehumidifiers if you have the time.

If delamination is suspected drill some holes in the top skin and flood with low viscosity epoxy.

Cutting out core material and or removing skins is OTT in most cases where structural foam is the core material.

[ozsailer]

Having gone through a process with a prior boat that ended very expensively for us I would say tread very very carefully. Foam cores of twenty years ago are not what they are today. A lot of foam from that period was not closed cell and water will migrate through it. Dependant on the foam used will have a marked difference on the best course of action. It could be a relatively simple repair or like us a full hull restrip - removed the old core and re-fibrglass. Trust me its not a cheap exercise.



Greg H
lagoon 440
Oz

[rbk]

The other side of that is when the styrene is leached out of the resin (that vinegar like liquid in hull blisters) it can attack certain foams, mostly older ones again.

[rognvald]

I'd never buy ANY boat with a wet core. It's a sign of abuse or lack of maintenance. Ever heard of Pandora's Box? Good sailing . . . Rognvald