Adding Urethane Foam for better flotation

[lenny2113]

I am thinking about adding a flotation foam to my boat.<br />Does anyone have any suggestions on adding a <br />POLY-U Foam?<br />How should it be done? What should I be aware of?

 

[Capt. Bob]

Re: Adding Urethane Foam for better flotation

I don't have an answer for you but I always wondered what the advantage was to adding floatation, other than the obvious...to keep the boat afloat should it get swamped? <br />Do manufacturers add the foam to stiffen the hull?<br />Why add foam to a boat that never had foam? <br />Is there a formula for calculating the amount of foam needed to keep the boat afloat?<br /><br />Foamignorantantly yours,

 

[Spidybot]

Re: Adding Urethane Foam for better flotation

Foam has been used by many manufacturers since it was made available and was formulated so, that the fumes didn't kill everything alive. It's ideal for places where you cannot make polystyrene blocks fit as you pour it in as a fluid and it expands to fill all corners. Has been used extensively in cars as well. It expands according to a given scale so it is possible to calculate how much it fills. It sticks agressively to anything but a few types of plastic and this can be used when shaping it. If you wanna fill an open space, simply cover with a board covered with plastic. Once it's ready you remove the board and the foam is formed accordingly. This adds the benefit of giving way should the expansion be greater than expected.<br /><br />Once hardened (after a few minutes) the foam can be cut with a knife.<br /><br />The expanding process must be respected - it will continue until ready and will make it's way even if it has to push other objects away.<br /><br />Has been used a lot for masts tops on small sailing boats. Some inces of foam here prevents the mast from sinking should the boat capsize and makes it a lot easier to get upright.<br /><br />Although it forms closed cells, it can swamp and contain water over time, so a tight seal is preferable over cavities treated.<br /><br />The foam even comes in spray cans and is used for filling around doors and windows in houses. You can even mount a complete window by foaming the gap between the frame and the house wall.<br /><br />Before doing any work with it, I'd suggest a little testing by filling various objects.

 

[john50]

Re: Adding Urethane Foam for better flotation

that 2 part foam is goog stuff. it doesn't just add extra flotation to your boat, but also adds extra strength to the floor. i replaced the transom,stringers,and floor in my hydra-sport. after i installed the floor..i tilted the boat up as far as i could, drilled a series of holes and filled every crevis with foam. my floor is like walking on concrete now.

 

[epresutti]

Re: Adding Urethane Foam for better flotation

Lenny2113,<br /><br />There are multiple types of two part foam, some is structural, some is not.<br /><br />I foamed my hull under the deck for emergency floatation and sound proofing, it also added some degree of structural support for the deck, the foam I added provides 60lbs of floatation per cubic foot. I figured I used about 30 cu feet.<br /><br /> http://www.fgci.com <br /><br />Has some foam products and how to's.<br /><br />Here are some pics.<br /><br />

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<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.

 

[KCLOST]

Re: Adding Urethane Foam for better flotation

If you don't have any foam where you want to add foam now, think about something first....<br />Have you ran all the wiring that you think you'll ever need? If not, I would suggest running plastic wire conduit through the spaces that may be used to hold wiring. I would also suggest running the wires through it also so it's already done...<br />Otherwise, without conduit, you're screwed!<br /><br />Just a suggestion....

 

[epresutti]

Re: Adding Urethane Foam for better flotation

Also forgot to mention I left the last 12 " by the transom without foam to give some space for water to drain, in the event water gets under the deck. I also added holes between the stringers for water to drain into the bildge in the same area.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.

 

[lenny2113]

Re: Adding Urethane Foam for better flotation

Many Thanks to all for your replies.<br />My boat has foam in it now, but sits low because the original foam is soaked.<br />All wiring is in place and the boat still runs very good. I notice that the water line is higher then supposed to be, so it would be a good thing to add new foam to raise the stern by an inch or two.

 

[mellowyellow]

Re: Adding Urethane Foam for better flotation

here's the catch 22... foam gets wet and HOLDS<br />water. this is the trade off. if it's gonna get<br />wet in any way it's like a sponge. stringers don't<br />like this. how about a thread explaining how to<br />keep foam from ever getting wet?<br />PS. like the pics. of the foam job, plenty of room<br />for water to drain. I'm thinking of sealing those sides with something to force the water into the middle then to the bilge? or would this cause dry rot?<br />I have to undertake this job(removing wet foam)<br />over the winter. just thinking how to best do it.<br />regards,<br />M.Y.

 

[epresutti]

Re: Adding Urethane Foam for better flotation

MellowYellow,<br /><br />The method I used was to only foam the outside stringers, once I had the deck on, there are no deck weep holes for the foam to get wet. There are deck drains to the bildge and also from the anchor well.<br /><br />You must have a bildge for collecting deck water, unless the design is such that there are deck drains above the water line.<br /><br />The only way the foam can absorb water is if the bildge fills (most likely the bildge pump has failed) then the water would weep up through the rear holes in the stringers by the transom. There would have to be at least 6 inches of water in the bildge for this to happen because of the V design. If this happens, I probably forgot to put the plug in <br /><br />My reason for the foam was to keep the boat afloat in the event of a catastrophic event where the hull had been breached. Otherwise it serves as deck support and sound dampening.<br /><br />There was foam in the hull when I started the rebuild, it was in the same location as you see in the pictures, there was just less of it. It didn't completely fill the compartments. The foam that was in the hull was not saturated with water for the most part. I think the CG requires a certain amount of floatation in new boats, don't know what the specs are though.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.

 

[crab bait]

Re: Adding Urethane Foam for better flotation

LENNY... addin' foam to the 'INSIDE' of boat .. isn't goin' to make it have more lift... it doesn't work that way...if you wanted it to do that ,,, foam would havta be on the outside/underneath of hull..<br /><br />also i was once told by 'HOOTY' that when mixin' the 2 part foam ... it hasta be mixed E X A C T L Y .... or you just made a sponge...

 

[lenny2113]

Re: Adding Urethane Foam for better flotation

Thank you, crab bait.<br />Is there another way of lifting stern, other then transferring weights (battery, gas tank, etc…) to bow? <br />I don't see how to add foam under the hull.

 

[epresutti]

Re: Adding Urethane Foam for better flotation

Lenny2113,<br /><br />I didn't pick up on what you were saying earlier, Crab Bait is right on. Water line is directly related to hull displacement and weight. As I said earlier my reasons for foam were for failures, sound and support.<br /><br />You need to check for water saturation in your transom, deck etc. Water adds a lot of weight. On my boat there were two compartments at the stern that were completely saturated with water, they were foam filled and when I cut one of them open water poured out.<br /><br />To raise your water line you could also consider a "Gil Bracket", this fits to the transom, has bouyency and moves the motor back considerably. Some brackets incorporate a swim deck.<br /><br />Here is one site that shows what they are:<br /><br /> http://www.gilmarine.com/products/gbracket/brackets.html <br /><br />Hope this helps.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.

 

[lenny2113]

Re: Adding Urethane Foam for better flotation

Appreciate your time Ed,<br />My boat is a 17ft Galaxy I/O, so Gil Bracket won’t work for me since it is only for outboards. There is no water in the bilge and no water in the hole in the center of the boat (sorry, not sure what it’s called). Is there another level of floor under the bilge where water could accumulate? <br /><br />Thank you.<br />Lenny

 

[epresutti]

Re: Adding Urethane Foam for better flotation

Lenny,<br /><br />You said earlier that the foam was saturated with water. If you mark the waterline now, before you remove the foam. Then after you remove the old foam and before you add more mark it again (float test), I think you may be surprised how much weight saturated foam can add. You may find the water line comes right back up.<br /><br />The one big area that can soak up water is the transom, if the seals around the outdrive allow water to weep into the transom this can add significant weight. Look for a brown "syrup", if this is present on the transom or any areas that have wood encapsulated in glass, then you have water saturated wood under the fiberglass.<br /><br />There are several different methods of solving this type of problem, but first you have to know where the extra weight is comming from.<br /><br />Hope this helps.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.

 

[lenny2113]

Re: Adding Urethane Foam for better flotation

I think all replies have gotten me on the right track. <br />I was sitting looking at the picture of my boat when an interesting thought came across my mind. The engine cover on my boat is most likely not original and is made out of ½ inch Plywood covered with industrial carpet. I believe that the original cover was missing and the previous owner of my boat had installed this plywood cover. This construction is extremely heavy and I think that this is exactly what could be adding extra weight. If I can reduce the weight of the cover I will know for sure if it’s worth touching transom.<br />Obvious thing and I didn’t notice it.<br />Maybe there is some kind of universal, fiberglass engine cover that will be right for me? <br />Anyway, this is were I think I will start <br /><br />Thank you all for your helpful tips,<br /><br />Lenny

 

[epresutti]

Re: Adding Urethane Foam for better flotation

Lenny,<br /><br />Run a simple test, loosen the cover screws, put the boat in the water, cover still in it. Take cover off, set on dock. See what you have then.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.

 

[CalicoKid]

Re: Adding Urethane Foam for better flotation

On foam in cavities.. I have a small f.g. fishing boat with molded structural hollow seats. I wanted foam in them for stiffness and also to displace water should it be able to seep in there somehow. Of course foam would have soaked it all up and made things worse so I lined to seats with primitive water proof membranes. Heavy duty trash bags! I drilled a 2" hole in each seat, stuffed the bags in with just the open ends out the hole and started filling keeping a gap open for air to escape around the outside of the bag and out of the seats. After the foam cured I sealed the bags and glassed over the holes. Worked nicely. The boat actually has slightly less flotation now as the air in the seats was lighter than the foam bags that replaced it. Seats are quieter, stronger now.

 

[mellowyellow]

Re: Adding Urethane Foam for better flotation

I still have some questions... is there any way<br />to seal the foam to prevent it from ever getting wet? like a rubber or plastic membrane over that beautiful job Ed did on his hull...<br />is there a new type of foam that won't soak up water?<br />thanks,<br />M.Y.

 

[epresutti]

Re: Adding Urethane Foam for better flotation

MelloYellow,<br /><br />I could have lined the compartment with 4 Mil plastic and heat sealed the top. This would have kept out most of the moisture (discovered this after I foamed), condensation would be a problem for any air/moisture that is in the material, however, the weight would be constant and it wouldn't absorb any more moisture. I am not sure how long the plastic would remain pliable and if it moved at all abrasion would be a problem.<br /><br />I will let you all know over the next 1,2,5,10,20 years how it goes with water absorption.<br /><br />The technique I described above is similar to how some life jackets are made.<br /><br />You raised my curiosity on foam designed to keep out water, and I found this ( http://www.polywater.com/ductseal.html ) web site.<br /><br />It looks like this stuff is specifically formulated to keep water out, although the application seems to be for HVAC.<br /><br />I didn't look much further, but it looks like the answer is "yes" there is a product specifically designed not to absorb water.<br /><br />It looks like the absolute best way to add floatation is to create air tight compartments (honeycomb style) without any foam.<br /><br />Hope this helps.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.