Builder's expanding foam

snowleopard

snowleopard

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Builder\'s expanding foam

6 months ago on this forum there was a debate about which foam, if any, to use for filling buoyancy compartments. Builder's foam was mentioned but some said it absorbed water.

I did an experiment to test this and I can now reveal that after 6 months immersed in fresh water there was no trace of absorbed moisture. When cut open the core was completely dry.

Not scientific nor conclusive for long-term use but better than supposition and hearsay so I'll be happy to use it on the boat in future.

Incidentally a piece of expanded polystyrene also remained dry in the same test.
 
Re: Builder\'s expanding foam

If you can make the compartment watertight in the first place, I think that would be a good reason for just leaving it as it is, rather than adding extra weight (and possible complications later on) by filling it up with foam (?)
 
Re: Builder\'s expanding foam

May I ask a question?

Did you just spray a blob onto summat and then when set immerse it? If that is what you did, then I would think it would be dry on the inside because the foam forms a skin on the outside when exposed to air. Try cutting it open and then immerse it, I think you will find that it will take up moister quite well?

However, there is a lot of supposition in the above, but I do know that only certain types of expanding foams are suitable for marine use. The expanded polystyrene, is ok though, seems to be used by a lot of people to pack bouyancy chambers in various boats.
 
Re: Builder\'s expanding foam

If I am allowed, I would like to pass on an observation.

The forward section of a certain make of boat I know of has the area beneath the forward berth foam filled. OK this does rob you of storage space, but if this vulnerable area should get punctured on rocks, floating debris etc then the foam would slow up the ingress of water, plus provide valuable buoyancy. So the use of foam could be more useful than just a watertight locker.

OK the cynics wont believe this will work, but I do! /forums/images/graemlins/smirk.gif
 
Re: Builder\'s expanding foam

I have carried out similar test and got the same result. I have also tried it with buiding insulation boards, you know, the Kingspan type with foil facings as well as the flexible foam pipe insulation and they don't seem to absorb any either.

The only comment I would make about the builders foam is that the various brands I tried ( 3 in total) had different foaming characteristics. Some generated very large cavities and others smaller more consistant ones. I too, would be happier now to use them if necessary on the boat.

The reason I tried the Kingspan stuff was that expanded polystyrene melts in contact with resin so is awkward to glass in. The kingspan wasn't affected in my test.

Fun isn't it trying to find convenient alternative materials to use?
 
Re: Builder\'s expanding foam

Good point Stephen! I think I can guess what the certain make of boat is....... I hadnt thought about foam filling the space under the forward berth - it does make sense there for sure, as it can be / is a very vulnerable area re impact.
 
Re: Builder\'s expanding foam

No, the sample had some glazed surface but also some broken areas where the raw foam was exposed. In the broken areas the water had penetrated to a depth of less than 1 mm.

If you squirt it into a closed compartment the surface will all be either bonded to the hull or glazed free surface, except perhaps where overflowing excess has to be cut off.

With regard to filling crash tanks, I chose to leave mine empty because I can tell if the hull has been breached by removing the bung. If there is a leak it means I'm carrying half a ton of water in the bows so I might consider foam-filling if I were expecting to be offshore for a long time and unable to make repairs.
 
Re: Builder\'s expanding foam

I have filled up both my forward watertight lockers with empty plastic milk containers. They would add buoyancy if the worst happened and they are useful when painting anti fouling, making dingy bailers etc.
 
Re: Milk Bottle buoyancy

I am saving up my milk bottles for the same purpose, ie to put in the buoyancy compartments of a little 16' power cat I intend to build soon...... how much greener can you get than that?! /forums/images/graemlins/grin.gif
 
Re: Milk Bottle buoyancy

Milk bottles are OK but not Mount Gay!! Is the Regency Cove still there in Rockley Beach? I stayed there 30 years ago and used to eat at a catering training college 3 days a week. Happy days.
 
My weekender out here had similar ...

Up in bow and stern sections were hundreds of plastic 2 litre pop bottles strung together .... In fact there were so many - I removed most ....
One problem with them was the previous owners who had put them in - hadn't thought to secure them in place - so if there was ever any breach and water came in - they would have been washed out of the space into the cabin etc. proving useless ....

Onto Builders foam ... having used quite a lot in the house we are rebuilding out here filling cracks etc. in timbers etc. One property I think that is cause for care in use ... it has incredible expansion characteristics and creates immense pressure when it cannot expand out ... We had one window being fitted and the braces / wedges put in ... builders squirted foam around to form the seal ... window actually broke wedges and forced braces to bend with the foam pressure. I would never have believed it without actually witnessing it ...
 
Re: Rum Bottle buoyancy and Regencys

You can buy Mount Gay rum in half gallon plastic bottles here - they are much more sturdy than the 2 litre milk bottles, but it takes a lot longer to get through a rum bottle than a milk bottle (at least for me it does - I am sure that many members of this forum would disagree re this statement.... /forums/images/graemlins/grin.gif )

Mount Gay is also obtainable in 1 gallon glass bottles, but these are very heavy..... /forums/images/graemlins/frown.gif

Re the Regency Cove, yes it is still going strong, pretty much the same as ever, doesnt seem to have changed over the years.
 
Re: Milk Bottle buoyancy

[ QUOTE ]
I am saving up my milk bottles for the same purpose, ie to put in the buoyancy compartments of a little 16' power cat I intend to build soon...... how much greener can you get than that?! /forums/images/graemlins/grin.gif

[/ QUOTE ]

.. by throwing away the power bit and using a mast and sails?
 
Re: Builder\'s expanding foam

Expanding PU foams are inherently waterproof due to their closed cell bubble structure, as shown by your absorption test. The comments about different brands are interesting, but a bigger factor in the behaviour of these materials is ambient temperature and humidity. The foam reacts with atmospheric water vapour to cure, and the rate of reaction is much greater in warm conditions. If you use the foam in cold weather it can help to pre-heat the cans by standing them in a bucket of hot water and shaking well before use. I second the warning about the pressure which can be generated by expanding foam - large sections are best built up in layers to achieve a more controlled build and more uniform curing.
If you have a lot of foam work to do it really makes sense to buy an applicator gun, rather then use the DIY cans. The ability to start, stop, and control the flow turns the foam into a useful material rather than an uncontrollable disaster.
 
Re: My weekender out here had similar ...

[ QUOTE ]
I would never have believed it without actually witnessing it ...

[/ QUOTE ] But then again, I was very, very drunk................ /forums/images/graemlins/wink.gif
 
Re: My weekender out here had similar ...

Fire!

Polyurethane foam may have a fire retardant added ...
BUT polurethane foam when ignited, I believe, gives of cyanide.

Bog standard white foam I believe, when ignited, makes the same gas as used in the 1914 - 1918 war, as a weapon!
 
Re: My weekender out here had similar ...

Don't know about that. I can't believe, what with EC regulations and HSE, that anything sold for use in building homes would be that lethal.
 
Re Foam

When Malc Campbell crashed 'Bluebird' in Conniston water back in the 60s the whole lake was covered in ping pong balls.

why on earth he thought he might sink from a slow leak at 200 mph I have no idea.

When it comes to that, the whole boyancy concept is pretty illogical.

1)
What percentage of yachts actually sink from being holed?
Sure a tiny few get holed on rocks, upon which they founder, but not sink. An even tinier number hit floating objects with enough force to make a breach, and a tinier still number of these sink before the crew can stuff a pair of socks in the hole.

2)
Can you actually put enough boyancy into a yacht to make it float? (mine displaces 7 tons of water, so would need 7 cubic Metres of air to keep it afloat, I figure if I filled every locker, the engine compartment, the fridge and the toilet with crazy foam, it might just about do it!

Of yachts that actually sink, most do from dodgy skin fittings, stern glands, etc. so invest in new hose clips instead of foam

Then of course there are the yachts that sink because people leave the windows/hatches/companionways open in rough seas.

Anyway, I'm not going to worry for a minute about sinking. There are FAR greater risks in life, and even in yachting.

PS. official - more people drown in CARS than in BOATS.
 
Re: Re Foam

[ QUOTE ]
2)
Can you actually put enough boyancy into a yacht to make it float? (mine displaces 7 tons of water, so would need 7 cubic Metres of air to keep it afloat, I figure if I filled every locker, the engine compartment, the fridge and the toilet with crazy foam, it might just about do it!

[/ QUOTE ]I have only two words for you, "Sadler" and "Etap" /forums/images/graemlins/wink.gif /forums/images/graemlins/grin.gif
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
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