Author Topic: Foam Floatation  (Read 61 times)

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kennneee

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Foam Floatation
« on: August 15, 2017, 10:27:29 PM »
Hi Guys- wondering now many of you have added foam, in any form, to your GA's?  Going back and forth on wether it is worth doing on my OB26 build.  The volume of the compartments that would have foam would not provide enough buoyancy to keep the boat from sinking.  I am planning on having a collision bulkhead and chamber forward but am having a hard time seeing the utiltiy in putting foam in the bilge if it won't float the boat.  Almost floating doesn't seem good enough. Any input appreciated.
Cheers,
Ken

Cannon

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Re: Foam Floatation
« Reply #1 on: August 15, 2017, 11:38:13 PM »
I added pool noodles supplemented with rigid foam (hard to find pool noodles in the winter here in Oregon. Each cubic foot of appropriate type of foam will displace one cubic foot of water. One cubic foot of water weighs 8.3453 pounds. The idea is not to completely guarantee the hull doesn't take on some water, the idea is to keep it from sinking giving you refuge until help arrives.
But, if you think about it, the amount of water displaced the hull should float at pretty much a normal draft.
Running offshore, there are lots of dead heads, I usually see four or five every trip. Those are the ones I see; the ones I don't see are the ones I worry about. Laying just below the surface, out of site, waiting for you.
Yes, I have a six man life raft, but in reality, I would rather remain aboard and limp home as opposed to abandoning ship, because she is taking on too much water to remain safe. Worst case scenario, you get time to collect the things needed while you abandon ship.
I had the same debate with myself and there are guys on both sides of the argument.
Remember, the ark was built by amateurs; the Titanic was built by professionals.
Started building Paula J the 2nd Week of June 2015, finished her the second week of July 2016.

Brian.Dixon

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Re: Foam Floatation
« Reply #2 on: August 16, 2017, 07:55:29 AM »
Wood boats float.  Glass, and aluminum don't.  Fuel does.  The bottom line is that most of your boat will refuse to sink, but you have a big anchor bolted onto your transom that'll make your boat sink on one end, and stick the bow up on the other.  My philosophy is like Cannon's ... better to limp home than float away in a raft after giving up on your pride and joy boat.  Bottom line?  Try to get flotation into the stern, preferably higher, to keep that motor head out of the water ... sometimes, the gentlest forward motion is all it takes to drive water back out of the scuppers and get a boat emptied out.  Flotation up high and skegs on the bottom (to grip on) are sometimes 'just enough' to turn a boat back upright.  Noodles or foam (that allows drainage!) under the decking help reduce the volume of water that your boat can carry ... less to shed is good.  These things give you a chance.  The difficult thing is how to get up-high flotation into the stern?  Hidden chambers in the corners, foam up under the gunnels or long chambers built under the gunnels etc.  You have to be creative.  Some types of foam, BTW, are smooth and can be painted, but are unsuited for constant submersion ... these can be glued-in (backed with screws and washers ... lots of force on them during capsize) and used in place like underneath gunnels since they aren't submersed.  We used to have a foam dealer in our neighborhood that sold every type of foam available on the planet  - their whole business - and they were the ones that first told me about this foam, and about sealed-cell polyethylene which refuses to absorb water or fuel or oil, even if submersed for years.  There are good answers out there, but you'll have to do some phone calling and be creative on how to work the foam into your boat project.

Brian


kennneee

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Re: Foam Floatation
« Reply #3 on: August 16, 2017, 09:01:54 PM »
Thanks for the thoughtful input guys.  I have been on the fence trying to decide on wether or not foam was worth the bother.  Of course I want my boat to float if it is taking on water but have not been sure I could get enough foam in this boat to actually make it worthwhile. Graham, the designer, has been less then enthusastic about it. He doesn't think a boat this size will have enough to room to make floatation effective. I suppose having  some added floatation, while not enough to keep this boat afloat when completly swamped, would buy some time. I will have a collision chamber forward in either case.  It isn't likely that i can get much floatation up high but can certainty get some in the bilges.
Ken

Brian.Dixon

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Re: Foam Floatation
« Reply #4 on: August 17, 2017, 06:35:58 AM »
Well .... there is no need for a black and white type of answer.  If you cannot find enough space to float the boat in spite of a full swamping up to the gunnels... then what's wrong with floating the boat if the swamping has not completely filled the boat?  Wouldn't you want a boat that resists rolling over if it's got water in it and is rocking too far from side to side?  That 'not enough' amount of flotation in the gunnels might just be what keeps you upright long enough to open scuppers and get the boat underway to start sending water out over the sides and stern where it belongs.  And there's nothing wrong with making a boat float a little higher if YOU are the one that has to hang onto it while you wait for help, no?  Anyway .... boats are full of trade-offs.  Go forth with good understanding and make your best bets along the way, and enjoy the sun, wind, and water.... and the fish blood as soon as you can manage!

Brian


kennneee

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Re: Foam Floatation
« Reply #5 on: August 17, 2017, 07:57:31 AM »
Well said!

Todd j

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Re: Foam Floatation
« Reply #6 on: August 27, 2017, 03:22:23 PM »
Just for the point of discussion it should be noted that 1 gallon of water weighs 8.343 pounds.  There are 7.48 gallons of water in 1 cubic foot.   Soooooo 1 cubic foot of water weighs 62.4 pounds not the 8.343 mentioned above.