Another foam question...

[Coral Grimes]

First time poster...thanks in advance for your help.

My father gave me a 2000 Sylvan Explorer that needed a lot of work. It has been outside, uncovered for a couple of years. Over the past couple of months, I've practically stripped the entire boat. My plan is to take off the outboard and go with a trolling motor only set up, as most the lakes by me are electric only.

My question at this point (and I'm sure I will have plenty more) is whether I need to remove the existing foam. After pulling up the plywood floors (which needed to go), the foam actually looks good. See the attached pictures. The discoloration seems to be more from the plywood sitting up against the foam. It actually took a significant amount of prying to get the boards up. However, the foam seems very solid and not water logged at all. That being said, the boat has been in my garage for five months or so...i.e., plenty of time to dry out.

Can I leave this foam in place and just replace the boards over top of it? There are a couple of spots where I accidentally cut the foam or pulled off little sections. Should this impact my decision?​

 

[Watermann]

Welcome aboard Coral :wave:

Using a PDF to post a couple pics is a tough way to do it. I see your Starcraft brother the Sylvan is a tin boat. There is no way if the foam was soaked that it would probably ever dry out so if it's dry now I would leave it alone. You should test it out though in a few spots by taking a core sample down to the bottom of the hull.

Post some more pics of your boat using this tutorial.
http://forums.iboats.com/forum/forum-rules-and-guidelines/9938375-photo-upload-tutorial

 

[gm280]

First thing first. :Welcome: to iboats. Always great to have a new member...

Looking at your picture, if you can verify that no water is in the foam, then leave it and move on. And the easiest way to verify that is by drilling out some plugs all the way to the bottom to see what is in the foam from top to bottom. Some times the top will seem okay, but the bottom could be really saturated. So take a piece of PVC pipe, and make some teeth like cuts on one end and cut out a few plugs to see what it going on. If the plugs are totally dry, move on to the next item. JMHO

 

[Coral Grimes]

Thank you guys so much. I really appreciate the help. And, I'm sorry about the picture issue...I will get it right next time!

I will take a couple of cores. Just to be clear, this won't ruin the structural stability of the foam, right? Also, it won't create a void that will then capture water, right? I'm probably being paranoid.

It's interesting that water logged foam wouldn't dry out even after months indoors...

 

[jbcurt00]

Once waterlogged, the formerly closed cells that trap air making the foam a flotation foam, are open, or they wouldnt hold water.

And even if dried, that foam has usually lost its full flotation benefit.

W out something to pull the water out, it isnt likely to dry out much over time. And even if it does dry its cells are now open. More sponge like then you'd want in the product intended to keep your boat afloat when you need it to.

 

[ondarvr]

5 months in the garage won't dry out the foam, it would be just as wet as the first day you put it in there.

 

[Coral Grimes]

So, the foam is wet. Only in the stern section. Nonetheless, I'm going to pull out all of it and replace it after I fill the boat with water to check for leaks. Any suggestions on new foam to use? I'd prefer sheets or blocks of something as opposed to spray in foam...

 

[ezmobee]

You want extruded polystyrene. That's the pink (owens corning) or blue (dow) or green (Lowe's) foam. Do not confuse with expanded polystyrene which is the white stuff which does absorb water.

 

[Watermann]

Yeah we tin boat rebuilders pretty much all use the closed cell rigid foam board sheets.

 

[Coral Grimes]

Thank you guys again. Do you just cut to length and width and then stack to get the correct thickness (i.e., flush with plywood)? Do you do anything to hold the pieces in place? Or do they just lay there?

 

[Watermann]

It depends on the style of boat how the board gets laid in the bottom. On my SN it was easier to stack it crossway and my SS lengthway was better. The pic of the SS I was far from done, just forgot to take a pic of the finished foam job. The foam in mine is held in place by friction and it doubles as deck support if you cut it right.