Water found in foam cored hull. Does the foam absorb/retain water?

conrad503

Cadet
Joined
Jul 4, 2021
Messages
18
I recently bought a '95 Maxum 1700xr (Force 120 outboard). The engine(s) came in boxes, and there were almost enough parts for two. I put one together and it runs great. We've been on the water several times in the past few weeks. I put some trim planes on the back and noticed a fair good bit of water running out of the holes I'd drilled. The holes weren't at the lowest point in the hull so I'm assuming there's more water that hasn't drained. I'm going to drill a couple drain holes at the lowest point today and see what flows out.

The boat collects water in the bilge, but the pump clears it fast enough. It looks like it's leaking around the plastic grommets on one of the two 1.5" holes that allow the splash pan area (not sure what it's called) in front of the engine to drain seawater. I notice that the back of the boat is usually under water past these holes when we're cruising even with just my 80lbs son and I aboard, which is when the water trickles in. I have nothing to compare it to, is the boat running low in the water? If so, I'm thinking I might be carrying a lot of extra weight from water logged foam cores. Can the core foam retain water? If so, is there anything I can do to dry it out?
 
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JASinIL2006

Vice Admiral
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Feb 10, 2012
Messages
5,680
The foam on a boat is a two-part, closed cell foam. If the foam is exposed to water, especially though freeze-thaw cycles, the closed cells are broken and water begins to intrude and eventually soaks the foam. At that point, the foam basically has become a sponge.

If your boat is draining water like that, it's highly likely the foam is saturated and there is NOTHING you can do to dry it out. It has to be physically removed and replaced with good foam. The part that is especially unfortunate is that the foam likely has held water against the structural elements of your boat (transom, stringers and bulkheads). Those structures, on a '95 boat, are almost certainly made of wood encased in fiberglass (and often, the structures aren't encapsulated particularly well). As a result, it's very likely the wood is saturated as well, which means you likely have rotted wood that is supposed to be serving as the structure of your boat. If this is the case, that is bad news and means some repairs need to be made.

It's really important that you check to see what problems have been caused by this water, because your boat could be quite unsafe to use.

Sorry for the bad news, but we see this all them time. Some of us have been in your shoes and know the sinking feeling of finding out your boat may have significant problems. Luckily, you are in the best place on the web to get help, should you find out you do have rotten structure and you decide to fix it.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
49,823
go to the stickies at the top of the forum

sticky number 4, link # 14. read it in its entirety.
 

tpenfield

Moderator
Staff member
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Jul 18, 2011
Messages
18,083
New foam would not absorb water . . . 25+ year old foam may very well, since the closed cells have broken down over time.
 
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