Small boat mast climbing

Sophie19 said:
There is a reg plate in the galley that clearly says 3.5 odd tons. Could this be the difference between displacement and weight? Would be handy to know!
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That'll be your registered tonnage, or possibly Thames tonnage. Is there an official number with it? My Jouster, for example, is 1 tonne displacement but 4 Thames tons, and Jumblie is 3 tonnes displacement but 5 registered tons.

In the non-displacement sense tonnage is a measure of size - it's approximately how many tuns (big barrels) of wine you could carry.

I'm pretty sure a W21 won't displace 3.5 tons ... that's more than a 26' Centaur!
 
The registered weight of my boat is 10.05 tons, I think. The dry weight is 6.5 tons. I have had this explained to me but, sorry, I can't remember how it works, maybe something to do with a notional cargo capacity. As far as I know, actual boat weight and displacement are the same.
Allan
Dam! Lakesailored by someone who knows more than me!
 
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Sorry chaps

Right. My mistake, went metric for a while there LBS not kgms.

Weight = weight if hanging in a cradle, displacement = amount of water, er, displaced!

Still, W21 is still a lot heavier than my old Seawych and displaces a lot more water, but even so, I think son should not be 'mastheaded' while afloat!
Thanks chaps.
 
Sophie19 said:
Right. My mistake, went metric for a while there LBS not kgms.
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At least two sources quote my boat as displacing 6,800kg (it's actually 6,800lb) so you have company!

Still, W21 is still a lot heavier than my old Seawych and displaces a lot more water, but even so, I think son should not be 'mastheaded' while afloat!
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Agreed! Incidentally, if you are not already in the Westerly Owners' Association it's an awful good way of spending a tenner a year.
 
Ubergeekian said:
That'll be your registered tonnage, or possibly Thames tonnage. Is there an official number with it? My Jouster, for example, is 1 tonne displacement but 4 Thames tons, and Jumblie is 3 tonnes displacement but 5 registered tons.

In the non-displacement sense tonnage is a measure of size - it's approximately how many tuns (big barrels) of wine you could carry.

I'm pretty sure a W21 won't displace 3.5 tons ... that's more than a 26' Centaur!
Click to expand...

Tonnage refers to the capacity/volume of a vessel where a ton equates to 40cubic feet of freight, or 100 cubic feet of bulk cargo. It is not the weight of the vessel.
 
Sophie19 said:
Right. My mistake, went metric for a while there LBS not kgms.

Weight = weight if hanging in a cradle, displacement = amount of water, er, displaced!

Still, W21 is still a lot heavier than my old Seawych and displaces a lot more water, but even so, I think son should not be 'mastheaded' while afloat!
Thanks chaps.
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As you have made up your mind about your original question can I drift this thread a little? I thought the the weight and displacement you discribe above are the same, i.e. the weight of water displaced will equal the weight of the boat, am I wrong? Obviously only while it is floating!
Allan
 
Allan said:
As you have made up your mind about your original question can I drift this thread a little? I thought the the weight and displacement you discribe above are the same, i.e. the weight of water displaced will equal the weight of the boat, am I wrong? Obviously only while it is floating!
Allan
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I am going to be pedantic!

An immersed object will displace a volume of fluid equal to the immersed volume. The weight of the displaced fluid is determined by what the fluid is. The relevance here is the difference between fresh and salt water - a litre of salt water will be heavier.

The weight of the displaced fluid = buoyant force keeping the object afloat.
 
gasdave said:
I am going to be pedantic!

An immersed object will displace a volume of fluid equal to the immersed volume. The weight of the displaced fluid is determined by what the fluid is. The relevance here is the difference between fresh and salt water - a litre of salt water will be heavier.

The weight of the displaced fluid = buoyant force keeping the object afloat.
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If we're going to be pedantic ...

A floating object displaces a weight of fluid equal to its own weight. In the case you give, a floating object displaces a smaller volume of sea water than fresh but the same weight.
 
Have been up the mast of a lift keel Sonata in 35kn of wind. Felt a bit wobbly when people walked round, but didn't get the feeling she would fall over.

If nervous, the idea of taking lines from the mast to a pontoon sounds practical.

Bradwell gantry - have also done that! Indeed, very useful height.
 
No, unstep the mast and do it in winter !!!!

Please don't go up the mast she is on the hard, far safer to unstep the mast next winter, use handheld VHF this year.

I unstepped the mast on my 1975 Contessa 32 when I refurbished it totally in Freeport, Grand Bahama. I sanded, repainted the mast, installed new navigation lights and wiring (tri-colour/ anchor light, steaming light/ fore deck light) and VHF antenna with coaxial cable. Also, replaced all standing rigging (316 Stainless Steel 1 x 19, 1/4" wire and STA-LOK mechanical terminals) and chain-plates.

It took me 3 months of work on my own, but, please don't go up the mast on the hard, I have folded mast walking steps and would never go up her on the hard, much easier to fall from 4 feet when working on the mast in front of you at ground level. Also, give you a job for the long winter. Hope this helps.

Neil
 
Sounds a bit like the standard game used on courses when not enough wind to go sailing - see who can climb the highest up the mast on a floating Topper dinghy (minus sail).
It always ends in getting very wet, but good fun for the onlookers.
 
I used to climb my Sonata mast quite often. I didn't like the sensation when crew walked about on deck but never had any actual problems.
 
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