Making a Top Hat unsinkable?

[Shaun]

Gday,
Anyone tried to do this, or thought about it, or worked out how much floatation would be required

What type of floation & where?
cheers
shaun

[Shaun]

Just found this thread back on the previous pages, viewtopic.php?f=3&t=414
its a good start
cheers
shaun

[karl010203]

Interesting, given the ballast ratio of the tophat, I reckon the physics are already somewhat stacked against us if you were to swamp the cabin of the boat.

I would probably look at trying to keep water out with good hatches, massive bilge pump if this is of concern.

Would be interested to see what you learn.

[Phillip]

Now Shaun,

What are you trying to do, go over the Niagara Falls or do some other extreme voyage

Karl is right, the physics are dead against you.

Better to look at your seamanship, jack lines and other safety gear.

But, I reckon you will need two air lift bags, at least 7m long x 1m dia. Oh and 5 large scuba tanks with which to full and maybe a couple of spares if there is a leak in the bags and a couple of scuba divers with a couple of tanks each to fit the bags on.

Please tell us where you are going to store all this equipment and personel

Phillip

[bearmcnally]

Hello Mad Hatters

ummm What about the land yacht with air bags?

Bear

[Shaun]

But, I reckon you will need two air lift bags, at least 7m long x 1m dia. Oh and 5 large scuba tanks with which to full and maybe a couple of spares if there is a leak in the bags and a couple of scuba divers with a couple of tanks each to fit the bags on.

Please tell us where you are going to store all this equipment and personel

Phillip

Well Phil, I thought you could happily live in the bilge, & the other two scuba divers would have to share the enclosed toilet...

Ok, this is the scenario im looking to protect against....there you are happily sailing along offshore, then SMASH you run into some half submerged shipping container or a big fish...whatever...!! Thats unlucky!

I believe its possible to add enough foam, or have watertight bulkheads, locker covers, doors etc to at best contain the water/damage or at worst for the yacht to remain afloat, so you either have time to jury repair & effect your own rescue by sailing to port, or remain aboard a reletively large vessel (compared to a life raft) with all your stores aboard, waiting for rescue.
Imagine getting holed then not having time to get the liferaft out (if youve got one), forgetting the EPIRB, radio, grab bag water, radio etc.

I read somewhere an 11,000lb yacht(including a 3500lb keel), needs a 3sqM block of foam to maintain bouyancy when its filled with water, its possible for a TH, just would like to know whats required, its not a modification thats at the top of my list (still havent finished the Poop deck ), but worth thinking about anyway.

If you could make the lockers under the V-berth watertight that would help in a collision, its not impossible. plenty of space inside around the stern for foam. I think you would have to maintain a freeboard of at least 6 inches

Heres an intersting article: http://atomvoyages.com/projects/UnsinkableBoat.htm

cheers
shaun

[Phillip]

Ok Shaun lets get serious

Has anybody heard of a Top Hat sinking after hitting an object at sea?

AND

How many other types of yachts have there been sunk off Australia by hitting something?

Phillip.

[SeaLady]

You could fill the cabin with ping pong balls.
Would make for fun getting in to have a sleep.

[Swift]

I am with Shaun on this one, it's not only possible. it's easy! You could make your Top Hat unsinkable THIS weekend!

Step 1
Attach an extra hinge and catch to the cockpit lids so that each lid will now be held down in six places. Next rip off the old foam gasket and replace it with a fat bead of silicone. Before the silicone goes hard close the lid ensuring that you have first greased the lip of the locker to stop it sticking. Do not close the lid tightly yet. After the silicone goes solid, you should have to sit on the lid to get it to close and the seal should now be water tight.

Step 2
Diana is thinking in the right direction, but her balls ... ah I mean ping pong balls are too big! You need little balls. Buy 3 adult size (300 litre) marine bean bags plus one child size (150 litre). Total 1050 litres. Place all of these bean bags in the V birth area.

That's it! Total time 4 hours. Problem solved!

Ok, I 'm having a bit of fun with this, your average coastal cruiser is not going to want to drag a bunch of bean bags on deck before the family beds down for the night (your not going to get them through the V birth door without removing some beans) but for a solo world voyager in a hurry to get going it would be a workable solution. And it does provide an indication of the volume of flotation required.

A Top Hat weighs 2.58 Tonnes. When its flooded to deck level the reduced weight of the submerged mass plus the mass above water line (deck, mast and rigging) will be 1510 kg. (Even the heaviest item, which is the lead in the keel is 10% lighter underwater). Sea water weighs 1027 KG per cubic meter. The volume of the rear lockers plus the volume of the bean bags is 2 cubic meters which will float 2054 KG, less the weight of the flooded boat -1510 KG , less the weight of the bean bags -40 kg, resulting in 504 KG positive buoyancy. This, in theory, will provide 2 inches freeboard but in practice, due to wave motion, the decks would be awash.

Anyway, bean bags are better than inflatable bags, every boat can use at least one, they are just the thing for sleeping in the cockpit while the wind vane steers you through the night. Ah! the comfort of a bean bagwhile you lay comfortably in sickness and terror on the cabin floor while you get pummelled in a survival storm. But one bag is acceptable how do you get rid of those other 3 space hogging bags?

As Shaun mentioned, James Baldwin's Atom Voyages web site has lots of idea's. With a Top Hat, after sealing the rear lockers the next priority is the comparatively large forepeak. I would not use a hinged door though because its hard to get a good seal. A far easier approach is to use bolts inserted from the back and epoxied in place with wing nuts to hold a flat ply door in place. It would be 100% water tight .

I just realised another good reason for havinga a holding tank for the head is that at sea, when it's empty it will add to buoyancy. A 40 litre tank is another 40 kg buoyancy

Births have good potential but on a Mk 1 the bunks are very low so there's not a lot of volume under them. They could be built up, or alternatively, if the bunk and V birth cushions were replaced with closed cell foam 100 mmm thick (with straps to hold them down) it would add about 270 KG of buoyancy.

Foam beans placed in various sized plastic bags can be stuffed into every unused corner of the boat. These mini bean bags are also good for protecting stores.

The good thing about using foam beads instead of expanding foam is that you can move it around and you know exactly how much buoyancy you are putting into the boat. 1 cubic meter = 1,000 litres = 1,000 kg.

If your luck really runs out and you end up above water but on a reef you can always be like Steve McQeen at the end of the Movie Papillon where he jumps into the sea and floats to freedom on a sack of coconuts, except you could be much more comfortable on a bean bag!

Keith

[Miker]

Keith, you don't post often, but when you do it's always a brilliant read

Michael