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Old 28-10-2011, 17:39   #46
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Re: Making a Boat Unsinkable with Expanding Foam

There is a DOW thermal insulating foam Panel that is closed cell foam and also gasoline oil proof.
DOW Thermax

http://www.fabricationspecialties.co...ermaxwhite.pdf

Comes in sheets. It could be cut in strips and put in the hull. Perhaps if needed glued in with PL premium construction adhesive.

Styrofoam is closed cell but gas will dissolve it likely oil too.
To me I was thinking of packing the aft stern area of the boat with Dow thermax sheets. My old wood 37 foot 1970 cruiser has no iron keel. All I need is about 3000 lbs of flotation and the boat wont sink. I have a lot of open bilge areas I could slide sheets of Thermax into all over the bilge area.
I have twin 150 gallon fuel tanks. They provide excellent flotation even if full since fuel weighs 6lbs a gallon and water is 8.
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Old 28-10-2011, 18:07   #47
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Re: Making a Boat Unsinkable with Expanding Foam

Quote:
Originally Posted by sdowney717 View Post
There is a DOW thermal insulating foam Panel that is closed cell foam and also gasoline oil proof.
DOW Thermax

http://www.fabricationspecialties.co...ermaxwhite.pdf

Comes in sheets. It could be cut in strips and put in the hull. Perhaps if needed glued in with PL premium construction adhesive.

Styrofoam is closed cell but gas will dissolve it likely oil too.
To me I was thinking of packing the aft stern area of the boat with Dow thermax sheets. My old wood 37 foot 1970 cruiser has no iron keel. All I need is about 3000 lbs of flotation and the boat wont sink. I have a lot of open bilge areas I could slide sheets of Thermax into all over the bilge area.
I have twin 150 gallon fuel tanks. They provide excellent flotation even if full since fuel weighs 6lbs a gallon and water is 8.
I've heard people mention diesel tankage as floatation before, it always tickles me. How long do you think the diesel will stay in the tanks once the vent is submerged? Probably only hours. Then they too will fill with water. I would not rely on tankage for floatation calculations without major planning and retrofit.
Also remember when making calculations, you are trying to achieve positive buoyancy, not neutral buoyancy. If you provide floatation equal to the vessels displacement, it will still sink, just slowly and not very far. The amount of floatation requred above the point of neutral buoyancy to keep the decks just awash would depend on conditions, ie in big waves substantial positive floatation would be required.
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Old 29-10-2011, 12:17   #48
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Re: Making a Boat Unsinkable with Expanding Foam

Welcome to the forum Nick.
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Old 29-10-2011, 18:28   #49
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Re: Making a Boat Unsinkable with Expanding Foam

cor what a brilliant reponse. thanks to all info and welcomes.
from what ive read it now seems that i have all the info to work correct quantity and quality out. if any others have got any info im all ears untill i actually commit to fit this stuff, thanks again to all..nick
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Old 02-11-2011, 16:29   #50
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Re: Making a Boat Unsinkable with Expanding Foam

Quote:
I've heard people mention diesel tankage as floatation before, it always tickles me. How long do you think the diesel will stay in the tanks once the vent is submerged?
actually the fuel will mostly stay in my tanks after I make a few changes to the vent system, like plumbing the vent line back to the tank fill nipple, and making a small 1/4 inch vent line that goes up high and comes back down in an inverted u.

People perhaps should redesign their old style vents or put a valve in there, of course closing a vent valve will be the last thing on their mind when the boat is sinking. So make it a more passive safety item.
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Old 03-11-2011, 03:07   #51
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Re: Making a Boat Unsinkable with Expanding Foam

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My thinking was as theres a large area under my v-berth that goes above the waterline and can be made water tight.
I figured that if I stuffed it full of closed cell foam (pressure can expanding foam) should I get holed forward then the foam would restrict the amount of water ingress to a bucketful or two.... instead of a threatening X gallons in an empty space....
Am I being naive...??
I have been thinking along similar lines - just not got to the point needing to do anything about it

My "plan" is to only start squirting foam after a holing event - and not neccessarily where the hole / crack is!

The basic idea being to displace water back outside (water won't rise above sea level - leaving aside the effects of motion).......with a few semi watertight doors / emergency bulkheads should be able to restrict the serious flooding to 1 in 4 parts of the boat (won't be bone dry elsewhere - but should not be flooding either)...........and then use foam (squirted inside a bag placed inside a locker or 2 to remove places that water can fill (I figure that a hole in the hull not so serious with only 20 gallons inside and not 100!) - will need to experiment on all that , maybe simply a bin bag?, or a holdall? - or even some of those sealable plastic holdalls (so that the foam does not get sucked / washed away. and clean up should be easier ). Am expecting that during this process the foam won't stay dry, and also afterwards - but as long as it does not waterlog (therefore defeating the entire purpose ) then I can live with not being durable after a year or 2

Time will tell on how all that goes (or hopefully not! )
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Old 03-11-2011, 05:04   #52
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Re: Making a Boat Unsinkable with Expanding Foam

Quote:
as long as it does not waterlog
you really need a closed cell foam. A lot of ways for water to get in open cell foams. They are like kitchen sponges over time the water goes in and they dont dry out. What I like about Dow Thermax is it is closed cell and gas-oil wont dissolve it like styrofoam.

If you put Styrofoam pellets peanuts in heavy duty plastic zip bags, then you got closed cell foam protected by the outer plastic and since you will have so many perhaps only a few will be compromised over the long time you own the boat.

What is the heaviest duty plastic zip bags you can get?
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Old 03-11-2011, 09:11   #53
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Re: Making a Boat Unsinkable with Expanding Foam

Although intended to apply to boats of less than 20 Ft. LOA, you should find some useful information in ABYC’s Standard “H-8" (BUOYANCY IN THE EVENT OF SWAMPING)
http://newboatbuilders.com/docs/H-08.pdf
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Old 03-11-2011, 10:45   #54
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Re: Making a Boat Unsinkable with Expanding Foam

Try this site:

Flotation Foams for Marine Applications
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Old 03-11-2011, 11:34   #55
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Re: Making a Boat Unsinkable with Expanding Foam

Several years ago, one of the sailing magazines did have an article about finding enough places on a cruising boat to place foam to make it less likely to sink. Now if just sometime in the next year or so I happen to find it...
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Old 03-11-2011, 11:40   #56
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Didn't someone say something about being unsinkable on the Titanic? ...lol j/k it is a great idea tho
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Old 03-11-2011, 11:58   #57
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Re: Making a Boat Unsinkable with Expanding Foam

The builder had called it "Virtually unsinkable" with press reports seeming to find the "virtually" part uninteresting. And the original design had provisions for many more lifeboats, but the line decided they cluttered the view and promenade too much, if I remember correctly. Both the ship's captain and designer went down with their ship.
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Old 03-11-2011, 12:24   #58
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Re: Making a Boat Unsinkable with Expanding Foam

I intend to rebuild the crash-boxes during this refit.
In another thread a poster mentioned the compartment was full of water due to leaking deck fittings.
Would it not make sense to fill them with foam(expanding or other)?
Surely lighter than being full of rain water - and better during impact/hull breaching...
At least have an inspection hatch.
In regards to the expanding bags - would the material be prohibitively heavy. Like a life raft...Maybe the foam would be lighter?...
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Old 03-11-2011, 12:37   #59
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Re: Making a Boat Unsinkable with Expanding Foam

If you were to unbolt the keel after being holed lets say, would a sailboat float full of water?
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Old 03-11-2011, 13:36   #60
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Re: Making a Boat Unsinkable with Expanding Foam

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If you were to unbolt the keel after being holed lets say, would a sailboat float full of water?
It might float on its side, or more likely upside down unless the mast were gone.
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