Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

I have been researching the threads on flotation foam as I need to replace the foam in my boat. I own a 16 ft Hewescraft with another fellow and we decided to redo the plywood floor as it was beat after 20 some years. Once we pulled off the deck we noticed the floatation foam was in pretty rough shape so we pulled it out. Both the plywood and the foam were pretty wet. The foam was packed so tight that water had a tough time getting out. We will be epoxy sealing the plywood to reduce water ingress. I think we will end up removing 50 lbs of weight overall.


So we started the research about the best way to replace the flotation. Initially I thought poured in foam would be the way to go but after reading the threads I was concerned about the foam getting saturated as the water may not get out. Living the the Pacific Northtwest we get lots of rainy days on the water! So I thought that if I could place a channel under the foam I could keep it relatively free of water. One of my thoughts was to place a rain screen material against the hull to provide a drainage path. Good idea I thought but then the challenges of putting a permanent foam in place and it made me rethink my plan. My big concern was clearing out the foam if I had to again, seeing some of the other threads it is quite a job.

Now that I have found a source for Urethane Foam sheets I plan to stuff the spaces with the sheet foam. I have heard that many people suggest that it is necessary to seal the urethane foam but that seems like a lot of finicy work seeing that the builder didn't do it. If I get 10 years before I have to redo the foam I think I could live with that. I am still thinking about adding the rain screen to provide a drainage path.

So Iam wondering if anyone else has considered this and what opinions were out there. Thanks

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

If you are planning on using sheet foam, you shouldn't need to seal the ends. Many of the threads I've seen with "tin" boats, they simply cut the foam to stand it on end throughout the hull. The goal is to try to keep the foam off the bottom of the hull so that water can run freely to the back. I would also build yourself a little bilge compartment in in the stern and mount a bilge pump. This will keep water from building up and "saturating" the foam.

Check out Watermann's thread on his Sea Nymph rebuild and you'll see what I mean. I think it maximizes the greatest use of the foam sheets. With your concern with water, I would notch out the bottom corners of the pieces closest to the keel to allow water to flow from front to back.

http://forums.iboats.com/boat-resto...pair/1978-sea-nymph-ss160-resto-590579-5.html

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

Here's a couple drawings.


In the second picture, you could lay a foam sheet on top of the lateral stringers and then stack pieces on end on top of that. That would keep a clear path under the foam for water to run into the bilge.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

If you boat in wet conditions/climate, you should consider a "working bilge".

This is a bilge design that allows water to enter and exit the bilge freely. The water will enter the bilge via a deck drain and will exit through the bilge pump or bilge drain when the plug is pulled. A working bilge is designed to hold a certain amount of water below deck until it can be pumped out or drained.

My Tracker has a working bilge, and it looks like this:



... and the deck drain:


My bilge holds quite a few gallons of water, and this has a couple of advantages.
1. It keeps water off of the deck while the bilge pump gets rid of it.
2. It ballasts the keel to keep the boat floating upright in case of swamping instead of capsizing.

The deck drain also allows for air movement in the bilge when the drain plug is pulled, this gives below deck moisture an escape route and keeps the bilge nice and dry when the boat isn't in use... a huge plus.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

Wouldn't urethane foam sheets be hella expensive? Most of us are going with extruded polystyrene (pink, blue, or green sheets from Lowes/Home Depot/etc). Drainage is important for whatever method you chose.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

The Hewescraft Searunner has excellent longitudinal drainage. There are two rectangular box stiffeners attached to the hull plating 1" x 3" running fore to aft with transverse ribs. The ribs ride on the stiffeners and are attached to the hull at outboard end and to the face of a deep longitudinal on the interior.

My concern about using two part foam was how to keep the drainage free as it fills every available space. Trying to shape it and contain it seems like a huge amount of work. That is why I decided to go back to Sheet foam. I know Urethane foam is pricy but polystyrene such as some guys on this board have used is susceptible to fuel and oils. So it is a challenge to decide what to do. I considered bagging the polystyrene but that seemed like it would be difficult as well.

Thanks for all the advice so far. I will try and get some pics uploaded.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

Does the Hewscraft have a deck drain?

Shaping and containing the expanding foam isn't that big of a deal, post pics of your boat and I'll see what I can come up with to help you with that if you want.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

The deck flows into a "bilge" at the rear so no deck drain is needed. I need to figure out how to add photos to this site. Any assistance would be appreciated. I did find Polyisocyanurate Foam sheets tonight at Lowes that are supposed to be closed cell with aluminum facing. Very similar to what we took out of the boat.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

I've seen that polyiso foam before and just cannot imagine that it deals with moisture real well.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner






Some pics of the open hull.You can see the gap below the stringers in Stringer View as well as the Box ribs. You can also see the challenge of filling the openings with two part foam.

It is hard to tell from the pcis but the deck is not sealed from the underside. The Plywood floor butts up against the hull and it is not possible to seal it.

Re: Another question on Floatation Foam - Deck refinish on a Hewscraft Searunner

How about some pics of your bilge/deck drain system?

Does your bilge have a drain plug, or is there just the deck drain plug?... or maybe you have both?