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Go Back   SailNet Community > On Board > Gear & Maintenance > Making Your Boat Unsinkable
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Thread: Making Your Boat Unsinkable Reply to Thread
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Topic Review (Newest First)
05-29-2013 03:43 AM
MedSailor
Re: Making Your Boat Unsinkable

Haven't read all the posts in this thread so apologies if this has already been suggested. The complete how to do this is in Lyn and Larry pardey's book "The capable cruiser" pp 94-110.

There's a little more to it than one might originally think, but it's also not difficult for the right boat.

BTW, don't use the term "unsinkable", it pisses off King Neptue (see also: Titanic) try the term "positively buoyant" instead.

MedSailor
05-28-2013 05:38 PM
Brent Swain
Re: Making Your Boat Unsinkable

Quote:
Originally Posted by Hudsonian View Post
Locally when salvagers attempted to float a sunken boat by inflating bladder they had put in the cabin, they pulled the deck off.
Simple solution. dont build such a flimsy deck, and try out your inflated bladders before they are needed.
Innertubes are free.
05-28-2013 02:59 PM
MrGaston
Re: Making Your Boat Unsinkable

Quote:
Originally Posted by Stu Jackson View Post
The weight of any additions, especially foam, will make your boat a sea slug, which will, in turn, INCREASE the chances of being pooped.

You're a scout, right? Be prepared is still the motto. So, instead of faulty bailout conditions, learn to sail the boat. Learn to reef. Learn to sail with only a jib or only a main when it's windy. Learn to NOT go out when it's questionable.

I think adding stuff to make the boat perform worse is not a good idea. A small boat like yours is very dependent on the amount of weight it carries and the distribution of that weight.
There have been several posts that have said to learn how to sail and your boat won't sink. This sounds a lot like familiarity breeding contempt. If you are such a good sailor that you know you can always keep your boat right side up and you know that you won't hit anything or let anything hit you then flotation would surely not be necessary.

If I were going to sail a fiberglass boat out far from help, I would like to have some sort of flotation.
05-28-2013 12:26 PM
Stu Jackson
Re: Making Your Boat Unsinkable

The weight of any additions, especially foam, will make your boat a sea slug, which will, in turn, INCREASE the chances of being pooped.

You're a scout, right? Be prepared is still the motto. So, instead of faulty bailout conditions, learn to sail the boat. Learn to reef. Learn to sail with only a jib or only a main when it's windy. Learn to NOT go out when it's questionable.

I think adding stuff to make the boat perform worse is not a good idea. A small boat like yours is very dependent on the amount of weight it carries and the distribution of that weight.
05-28-2013 10:21 AM
Hudsonian
Re: Making Your Boat Unsinkable

Locally when salvagers attempted to float a sunken boat by inflating bladder they had put in the cabin, they pulled the deck off.
05-28-2013 12:30 AM
MrGaston
Re: Making Your Boat Unsinkable

Ok, how about this? A large inter-tube or two in the bow and in the stern. Anchored with some sort of strap securely attached to the hull. All inter-tubes would have a small hose attached to the valve stem of the inter-tube going to a centrally located appropriately sized CO2 tank, big enough to provide the necessary gas volume without overfilling the inter-tubes. The inter-tubes would normally be deflated and folded so they use very little space. If the boat is filling with water, open the CO2 valve and you have flotation.

This is very similar to the big air bladder or inflatable dingy ideas except much cheaper and very easy to anchor. Anchoring is very important. You don't want your flotation floating out your companionway.

I read in a similar thread somewhere that the deck of a fiberglass sailboat is not attached to the hull well enough to support a system that applies the buoyancy pressure to the deck. Apparently the deck will come off. I don't know, just read that some where.
05-27-2013 11:35 PM
RickWestlake
Re: Making Your Boat Unsinkable

I have one hugely-unpopular thing to say about this:

MacGregor 26.

Roger MacGregor built foam flotation into his boats, so they're 'unsinkable' ... it can be holed and full of water, but the hull won't sink.

Of course, they're boats that are generally limited to day-sailing and maybe weekending, though I have at least a couple of friends who have done more with them ... and I did some pretty cool things with Bossa Nova, my own 26X.
05-27-2013 10:15 PM
Waltthesalt
Re: Making Your Boat Unsinkable

There was a company in RI quite a while back that sold a system called Yachtsaver. It was inflatable bags that would keep a boat afloat when activated. They has small models for your size boat. So maybe something like storing an inflatable liferaft below decks that has a CO2 bottle for inflation in an emergency.
05-27-2013 08:09 PM
Brent Swain
Re: Making Your Boat Unsinkable

1 inch of foam will float 1/8th inch steel plate.1 1/2 inch wil float 3/16th steel plate.
Tried it, it works.
05-27-2013 07:05 PM
KeelHaulin
Re: Making Your Boat Unsinkable

Quote:
Originally Posted by CarpeAquam View Post
I probably should have reefed in the 35 mph gusts that blew out my sail slugs...
If a 30kt gust blew out your slugs; you did not have the main hoisted properly. If the luff is not tensioned tight enough to make a bit of pucker in the sail when the sail is luffing then it's not hoisted enough. With this amount of tension in the sail the slugs should not be pulled laterally enough to rip out.

On the issue of flotation I think your factor for fiberglass might not be correct. It seems that glass/resin would be more dense than water by a higher ratio. If the glass/resin ratio is 50% (assuming it's dense fiberglass) then you would have a density of fiberglass that is 1.9 g/cc. Fresh water is 1g/cc. That would give a ratio of ~0.5 to account for the buoyant force acting on the fiberglass. Also; you are assuming that everything other than the keel is glass; and there is no extra gear aboard (including passengers)which is not the case. So you need to factor that in; say you make the fiberglass ratio 0.66 to account for that. That would double your hull weight number when you calculate the amount of flotation needed.

Floatation can also be gotten by having sealed compartments; so if you make locker hatches and their interior watertight you negate the need for putting Styrofoam in. But don't fill the lockers with heavy stuff or you'll lose the buoyancy provided by the air space.

Keeping the hatches/lockers sealed and preventing water from going in is the main necessity to preventing a boat from sinking. Cockpit drains that can quickly drain the water is the second necessity. With those two criteria met the chances of a sailboat sinking by boarding water is very low.
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