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Old 04-11-2012, 05:23   #16
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Re: Sink proofing

You may be interested in's "float a boat".


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Old 04-11-2012, 05:50   #17
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Re: Sink proofing

Whilst I share the idea of the "horror" of such a device "prematurely ejaculating" whilst inside yet the idea does have merit and perhaps boat designers and builders should be looking at ways of incorporating such a system into new designs . . . after all how many of us drive vehicles with air bags?

Internal inflation will only keep the vessels neutral buoyancy yet she'll still likely be swamped plus when you do see lifting bags being employed they're external to the hull. So, shouldn't the answer be a hull design with these bags incorporated into a "blow out" false gunnel? With say internal access panels to check and replace the air cartridges and a manual activation with some form of security cover the end result wouldn't be too different from that of recovery . . .

. . . and thinking about the alternative "air bag" thrown over the side called the life-raft what are we advised in the event of problem? Stay with the boat as long as possible.

What d'you mean "scrap it"? She's cost more to repair than she cost to build!!
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Old 04-11-2012, 06:09   #18
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Re: Sink Proofing

Was it not in one of the Pardey's books that such a device was advertised?

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Old 04-11-2012, 06:59   #19
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Re: Sink Proofing

Originally Posted by barnakiel View Post
Was it not in one of the Pardey's books that such a device was advertised?

I think there was a review in Practical Sailor sometime in the 1980s or 1990s.
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Old 05-11-2012, 08:35   #20
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Re: Sink Proofing

I don't think it's a bad idea. It has been tried, as has been mentioned, but has not been a commercial success. I think the reason is a combination of the space that it takes up, and the high price.
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Old 05-11-2012, 10:20   #21
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Re: Sink Proofing

I've thought of something like get a few dunnage airbags and a scuba tank and have a few places to fit them into, say cockpit lockers, chain locker, and inflate manualy, then when the fix can be made pump her out. I'd still have a lot of water damage, water over the top of engine.
Submerged Juniper should wiegh about 4000-4500 lbs so I would need about 75 CF of air bags, I could fit an 8'X2'X1.5' bag in each locker if emptied, and 2 3'X3'X1.5' bag in the chain locker if the anchor rode was removed,
I have seen something for small power boats that you pull under the hull then inflate and it lifts the boat out of the water. It has two 3 foot diameter tubes most the lenght og the boat with straps keeping the tubes 2-3 feet apart that the keel rests on. So that idea could work for a sailboat if made for the shape of the hull, say using inflatible fenders 20 of Fender Inflatable 16 X 48 Gray these and make a web harnass to make to rows, it would be expensive could be done, and you would have fenders galore. Or use 4 of these Fender 32""X 77"" All Navy Blue but where would you put them normally?
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Old 05-11-2012, 10:46   #22
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Re: Sink Proofing

Be aware that each cubic foot of air will support 64 lbs of boat. For a 20000 lb boat, figuring 60 lbs bouancy to make up for thesausage weight etc... that's 333 cubic feet required just to get to neutral!
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Old 05-11-2012, 10:47   #23
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Re: Sink Proofing

There is a company called ETAP yachts that markets a range of "unsinkable yachts". I don't know if they are still in production, but if not, they were certainly built recently enough and in sufficient numbers so that one could be picked up second hand. They are double skinned and I think have foam between the skins. Etap claimed that when flooded they retained enough freeboard to sail home. This would negate the issue of inflating bags.

If you think of the changing demographic of yacht owners, I would say there definately is a market for such a yacht. People who buy yachts these days are not necessarily people who have been boating all their life. They may not be naturally at home on the water and anything which gives an assurance of unsinkabilty could have a market niche.
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Old 05-11-2012, 14:32   #24
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Re: Sink Proofing

Hey there,

Just a wholehearted thank you to everyone who has added their two cents to this thread.

The thought of carrying equipment that could also be used to salvage some of the wrecks I've seen in remote places is attractive to say the least, since I am a professional dumpster diver.

Yes, double-skinned hulls with a foam sandwich have been around for a long time and make very good sense to me, but it must lead to a major increase in production costs. However, could this be offset by insurance companies offering lower rates to unsinkable yachts?

Can you imagine the reaction when the guy (let's not be sexist here, "or lady") invented airbags for cars? You know, the person stands up in a board meeting and says: "let's put an explosive charge in the steering wheel...."

Looking forward to reading more comments, so keep 'em coming...
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Old 05-11-2012, 14:54   #25
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Re: Sink Proofing

A couple of cases of Great Stuff and a really good hair dryer so it can set like in 20 seconds.

You can buy similar in 50 gallon barrels Ive seen it used for shipping in 200 gallon containers and a smaller activator container. It sets in a few seconds. Just needs a pressurized delivery system. Kind like Demolition Man where Stallone wrecks the car and it instantaneously fills with safety foam.
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Old 05-11-2012, 15:04   #26
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Re: Sink Proofing

I know of one that went down in 20 ft of water. We put a 5000 pound air bag in the salon and aired it up, only to dammage the deck and take out a few portlights. We had to use that bag and two more under the boat to get it sitting up right - still on the bottom though. I think it would work better on a boat that dosent have thousands of pounds of ballast in the keel.
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Old 05-11-2012, 15:57   #27
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Re: Sink Proofing


"What's this button do?"



"Hmmmmmph! MMMmmm!"

"What? I can't hear what you're saying. If you're squished up against the deckhead, mumble once. If you're wedged in the settee locker, mumble twice....."
Ps 139:9-10 If I take the wings of the morning, and dwell in the uttermost parts of the sea; Even there shall thy hand lead me, and thy right hand shall hold me.
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Old 05-11-2012, 16:38   #28
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Re: Sink Proofing

I suspect the reason cruisers focus so much on keeping motor and batteries in good shape is because these will keep the bilge pumps going which will keep the motor and batteries going which will keep the bilge pumps..........
I'm a newbie so I don't really know, but, I've been getting my systems tuned & I'm planning to add bilge pumps.
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Old 05-11-2012, 16:46   #29
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Re: Sink Proofing

My boat would be heavy even if submerged, however I know 27ft'er with a lot of batteries, an electric motor a bit of bouyancy which would probably float flooded if he heaved all his batteries overboard his.

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