Making a Top Hat unsinkable?

[storm petrel]

Yes it would be possible, but you would lose more than a third of the volume of your boat. If you are in a position that you are unable to stop your Tophat from sinking, you would be better off having a good quality life raft and a GPS-EPIRB than being stuck on an unstable boat with a few inches of freeboard. If you want something unsinkable you should be looking at surfboards or dinghys, not at an old, heavy displacement yacht like a Tophat.

Cheers,
Mark

[Shaun]

Thanks for the replies so far , I really like Keiths bean bag idea, there would be a fair bit of air between the balls, that would get filled with water tho', bags would have to be watertight (maybe thats possible with the small/med/large waterproof bags you can buy to keep contents of your backpack dry), or in bags that drain so the water can be pumped out eventually.
Losing a third of the interior volume is probably acceptable for a single-hander??, I dont know tho'.

Keith, are those figures just back of envelope stuff or have you sat down & worked it out properly?

If I could I'd also like to expand this thread to include scenario's that would lead to needing an unsinkable boat....
What are the possible causes of getting a boat load of seawater inside the boat?
Failing seacocks....Remove all unneccessary seacocks, keep bungs & rubber mallet near remaining ones, & more bungs & mallet elsewhere if you need to bung from the outside, what if you lose the propshaft? what about the propshaft hole? bungs ? anyone got any ideas?
Hitting something....create watertight bulkheads up front & where ever you can.
Keep washboards in when at sea.
Losing my keel stepped mast & ripping a big hole in the cabin roof, ummmm, depending on severity & damage surely would be better to jury rig sail, than getting into inflatable or liferaft.

cheers

[storm petrel]

I think the worst case scenario would be to loose a section of the cabin roof, the washboards or windows, or to hole/split the hull badly (eg hitting a submerged container, whale etc.). I suppose each half of the hull (or the deck /hull joint) parting company would also be a serious problem, but this is pretty unlikely for a Tophat. I would try everything to keep the boat afloat but if I was more than 20 miles from shore I would have a life raft (or some other small craft)on board as well just in case all my efforts failed and I had to STEP UP into it. Life rafts are a last resort but they have saved a lot of lives and they sure beat swimming.

Cheers,
Mark

[admin]

Auriga's v-berth storage space is currently dedicated to a couple of spinnakers and genoas along with other bits and pieces;

Just a thought; if you make the v berth sealed, and for one reason or another it fills with water, that's a fair bit of weight trapped forward with no means of ejecting it.. (on auriga it'd be a good 300+kg or so given the chamber size) kinda damned in you do/don't really i guess

another point of consideration, in the case of foam / bean bags etc, how would you restrain them against the hull to keep it afloat, i'd imagine that any form of glue or tethering is going to come unstuck in a matter of time, particularly in rough conditions.. the sea will find the weakest point and exploit it

[Phillip]

Mmmmm,

I suppose each half of the hull (or the deck /hull joint) parting company would also be a serious problem, but this are pretty unlikely for a Tophat.

No problem with the hull joint but Merv Howlett (the last Top Hat salesman) always had some regret that some Top Hats were sold with the decks not attached to the hull. These were attached by the owners but Merv always doubted that workmanship.

Do you have one of those


Phillip.

[Swift]

Shaun

Yes the figures in my last post were very much back of the envelope. I note from your post on storage that you are considering buoyancy in conjunction with storage problems. Therefore I thought I would provide some more accurate numbers. The volumes in litres listed below were calculated from measurements taken on the boat this weekend.

Forepeak locker 124
V Berths lockers 454
Starboard settee berth locker 89
Port settee berth locker 56
Settee berth aft lockers 209
Settee berth side lockers 57
Cockpit lockers 761
Locker under cockpit 385
Total 2,133

My best guess at the weights of various major components are:

Mast 90
Rigging 30
Cabin/Windows 80
Deck 200
Pushpit/Lifelines 25
Woodwork 120
Outboard 26
Additional Ballast 100
Ballast 1136
Hull 819
TOTAL 2626

FLOODED WEIGHT = 1,999
(Total weight of all components above the flooded waterline plus the submerged weight for components below waterline)

(The only weights that have a high degree of certainty are the designed displacement, the ballast and the weight of the outboard. The estimates for other components might be way out. Other opinions would be welcome).

The good news is that so far without loosing any interior volume the positive buoyancy would be 133 K, but that's not enough, so what else can be done?

Build locker between V berths 130.0
Raise settee berth by 100 mm 133
Raise V Berth by 150 mm 328
Build lockers along side of V Births 152
Build locker in head or install holding tank 25
Total Additional 768

The grand total is now over 900 KG of reserve bouyancy. This should provide almost 3 1/2 inches of freeboard. Just how high the boat will float will depend upon how much is stored in the boat. You can roughly work this out if you know where the designed waterline of your boat is. A Top Hat will sink 1 inch for every 586 pounds (266 KG) of weight. So if your boat normally floats 2 inches below that waterline you must have over 532 kg of additional gear and stores on board. Time to chuck something overboard! Remembering that all objects submerged but outside sealed lockers will have reduced weigh once the boat is flooded. For example petrol is significantly lighter than water but a 20 litre tank of petrol stored in the cockpit locker will add 14.74 KG (plus the weight of the tank) but the same tank stored on the cockpit floor will float when the boat is flooded and add no weight.

Obviously there are differences between models, for example Mk 1's have lockers above the berth, so this improves the available locker volume but limits the volume under the bunks because you need to be able to get your feet under the over-head (or should I say over-foot) lockers. So the differences sort of cancel out. Obviously an inboard motor presents a different range of issues.

For most of us VHF's, EPIRB's and life jackets are sufficient for coastal trips, or for longer voyages the easy pragmatism of a life raft is the usual way to go. However, I think the issue is as much about self sufficiency as safety - being able to save yourself rather than passively waiting for rescue. For anyone willing to do the work having an unsinkable boat is not only more self reliant it is a much much safer option than a life raft. The question is, how hard is it to do? Building new sealed lockers is not that hard, the challenge is in constructing the water tight access doors. With around 20 required this is not a trivial exercise and how best to do it is perhaps a post for another day.

For anyone interested in an example of a quick and easy solution see Roger Taylor's web site http://thesimplesailor.com. He made his 20 ft junk rigged Corabee unsinkable in 10 days and is confident enough that he refuses to have an Epirb. It reminds me of the story of Blondie Hastler who refused to have a two way radio on his junk rigged folkboat. He was asked what he would do in an emergency and he replied that he would drown like a gentleman. Hey! see the pattern emerging here? Those guys....... those crazy individualist and their junk rigged boats!

Cheers
Keith

[SeaLady]

Remember the Titanic. It was considered unsinkable.

I have managed to sink an unsinkable dinghy.

[Miker]

Remember the Titanic. It was considered unsinkable.

I have managed to sink an unsinkable dinghy.

So has Storm Petrel

Michael

[storm petrel]

Yes, well the moral of that story is to not overload your dinghy with beer and shipmates. Next time I will leave a crew member on board and concentrate on getting the beer to the clubhouse.

Cheers,
Mark
Storm Petrel