Collision Bulkheads

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Re: Collision Bulkheads

Postby Troppo » Thu Feb 28, 2013 10:07 am

Wild Rose wrote: . . . .
Next question.. which Mk TH is best??? :)

Dave


Bahahahaha!



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Re: Collision Bulkheads

Postby Phillip » Thu Feb 28, 2013 11:20 am

Point taken Greg. Over it anyway. Still waiting for good weather to fix those scratches!!
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Re: Collision Bulkheads

Postby bearmcnally » Thu Feb 28, 2013 2:50 pm

Life raft !


Cheers Bear
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Re: Collision Bulkheads

Postby storm petrel » Thu Feb 28, 2013 5:05 pm

Given a loaded (diesel powered) Top Hat probably has a displacement of about 3000kg, it needs to displace 3000 litres of water just to achieve positive buoyancy. If you want it to float you probably need to build in a safety factor of at least another 500 litres. That is 3.5 square metres. If we make a guess that the solid parts of the structure Below the waterline displace 1.5 square metres then we need at least 2 square metres of air below water level to barely stay afloat. I do not think there are enough nooks and crannies in the whole boat to store 2000, 1 litre bottles or even 1000, 2 litre drink bottles and as Greg mentioned hydrostatic pressure means you may need to add even more. You can get a feel for the amount of air needed by going below and looking at where the water comes to on the bulkhead. There is a lot of air space in the cabin below the water line in a Top Hat.

As to storing a life raft. A 4 man raft in a valise is about 600x450x320 and weighs about 30-35kg and if you were single handing you could stow a smaller raft. I have thought about getting one and stowing it in the 1/4 birth - out of the weather and harms way.

I am not going to enter into the best Mk debate other than to say if the Mk 1 was the best why did they change it and sell more of the later Mks? Quality marketing?
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Re: Collision Bulkheads

Postby Jeremy » Thu Feb 28, 2013 7:28 pm

Bear, love the cartoon!!
Hilarious!!


But seriously, mkII is far superior. ;)
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Re: Collision Bulkheads

Postby Troppo » Fri Mar 01, 2013 5:33 pm

Jeremy wrote:Bear, love the cartoon!!
Hilarious!!


Me 2.

Perhaps Clive Palmer will be buying up a few dozen Top Hats to use with his replica of the Titanic instead of using modern life-boats.
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Re: Collision Bulkheads

Postby Tales » Sat Mar 02, 2013 5:54 pm

Hi Dave,

Yachting Australia requires all boats competing in races Cat 0 - Cat 4 to have a watertight "crash" or "collision" bulkhead.

Cat 4 has the less stringent requirements and is for "Short Offshore races, close to shore in relatively warm or protected waters, normally held in daylight".

You can view or download the details at http://www.yachting.org.au/default.asp? ... 2/21782/0/

by accessing 2013-2016 Special Regulations Part 1 for Racing Boats - Effective from 1 July 2013. (See Sect 3.05.4)

A lot of cruisers going off shore use the recomendations included in "The Blue Book" but I don't know anyone who has put in a watertight bulk head unless they were also racing in one of these categories.

All the best,

Tom
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Re: Collision Bulkheads

Postby steve » Sat Mar 02, 2013 7:25 pm

Hi Tom,

Doesn't the crash bulkhead requirement apply only to multihulls? I am not sure of the logic of exempting monohulls. Maybe multihulls are expected to be travelling faster and therefore are more susceptible to collision damage.

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Re: Collision Bulkheads

Postby Tales » Sat Mar 02, 2013 9:29 pm

Hi Steve,

You are right mate, I just read it again!

I do know a bloke who had one fitted to a mono hull for the Vanuatu race a few years ago but thinking about it, he is a very cautious type.

Thank's for that!

Tom
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Re: Collision Bulkheads

Postby storm petrel » Sun Mar 03, 2013 7:49 am

Pleased we sorted that out. I thought it was strange because I know several monohulls that ocean race out of Gosford that do not have waterproof collision bulkheads.
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