Wet foam in bilge

[Steve & Pauline]

G'day,
We own a 1979 Sparkman & Stephens 40 ft ketch (GRP hull).
We found osmosis in the hull & decided to hard stand her for 1-2 years while we complete a major refit & repair the osmosis.
It's been about a year now & we thought she was dry. We cut a hole into the bilge under the bulkhead in the engine room to fit a sump & found the foam (ontop of the lead in the keel) was quite wet. Has anyone had this problem?
How can we dry it out, without digging out all the foam, drying the area & replacing foam? We are unsure how far the foam extends along the keel, and don't really want to cut more holes.

 

[Stu Jackson]

What purpose can the foam be serving? Is there anything that indicates why it was installed? It may have been put in to make the bilge less deep, which in itself has drawbacks. If it was my boat, I'd try to figure out why it's there to begin with, remove it all if it's rotten and then decide whether replacement is necessary at all.

FYI, most of the respondents on this board have "production" boats and, thus, do not have the kind of "one-off" issues that you have described.

Have you considered searching for a Sparkman Stephens owner's group website? Is there still an S&S office anywhere? Reason I ask is that I remember hearing just recently that there is a company producing a boat "designed by S&S," so 'someone' may still be around.

Good luck.

Stu

 

[kenn]

I'm guessing the foam is just there to support the liner.

Water can get in via deck leaks, like around hardware or alongside the mast. It would bother me that this water isn't going directly to the bilge where it can be pumped out but is instead ending up in between the hull and the liner.

I wouldn't be afraid of drilling a few more access holes just to check the extent of the water. Perhaps you can open it up enough to promote drying while the boat's on the hard, and poke some channels in the foam to lead the water to a lower spot where it can be pumped out.

This is just theorizing; I don't know your boat.

 

[Ross]

My boat has a deep full keel but the ballast occupies only about half of the length. The area aft of the ballast was filled with hot asphalt, like roofing tar.
The foam that you have may be an owner added effort to fill a large deep cavity that could turn into a pit that trapped dropped screws. Probe it with a long straight wire to determine the depth and extent of the mystery.
Since it is wet, digging it all out seems to me a good option.

 

[Steve & Pauline]

Thank-you for the reply, we will drill a few more holes to determine the extent of the moisture.
Another idea that we will try is to sit a bowl of desiccant in the cavity we created for the bilge sump & seal the top. Hopefully this should absorbe the moisture.
We have discovered that the water was entering through the plywood bulkhead/bilge join. We also found that the bilge pump mounting screws had actually passed through the fibreglass & into the foam. The bilge fibreglass is about 3/8th thick over poured polyurethane foam.
Our yacht was a "production" boat in the late 70's, Swallowcraft made about 37 Swift 40's in Korea to an S & S design for the US market.
She is a beautiful boat & we will do anything to bring her back to the best condition.
Thanks again for your ideas.

 

[Ross]

Air circulation is the best drying system you can get. Use a wet/dry vacuum cleaner to remove any free water and by any means posible get a good air flow into those wet areas.
Consider a wet towel. If you hang it on a clothesline by one edge it will dry quite quickly. If you fold it over the line it will take a bit longer. If you fold it for storage while it is still wet it will mildew before it dries.

 

[RichH]

Steve & Pauline -
Is this 'foam' located between the outer skin of GRP and an inner skin of GRP? Inotherwords are you describing a foam core of the hull structure?

If this foam (possibly Airex foam coring) is between the inside and the outside of the hull structure, it will have to be totally removed and the hull section entirely rebuilt.

OR ... if the foam is totally exposed to the inside, it may be nothing more than an insulation layer applied to prevent the hull from 'sweating' when the boat is in very cold water. If its not 'structural' than you can simply rip-it-out. If its structural, then a *very hard decision* will have to be made if the water ingress is extensive.
A digital picture of this 'foam' would be helpful. Can you take a pic and post it here?

 

[capejt]

Foam can't be a good thing. It ends to hold moisture which is the last thing you want. I'd say lose it altogther. Get things dry!