How heavy is your boat and who says so?

Re: 8 Tons?

Now this is rather interesting, been talking with Tom (tome) this afternoon, he was right my quote:

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The only post I can see claiming 8.6 tons is mine. Care to enlighten me?

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Was about the Oyster 37. It seems that although the Oyster web site says the boat has a displacement of 6593 kg and a BR of 42%. The Holman & Pye site says it is 8.6tons with a BR of 32%! /forums/images/graemlins/confused.gif All a bit confussing, who does know the correct displacement of any boat is it the designer or the builder?

I'm waiting to hear from Tom, I suggested he contact Oyster to try and get the anomaly clarified.
 
Re: 8 Tons?

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Now this is rather interesting, been talking with Tom (tome) this afternoon, he was right my quote:

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The only post I can see claiming 8.6 tons is mine. Care to enlighten me?

[/ QUOTE ]

Was about the Oyster 37. It seems that although the Oyster web site says the boat has a displacement of 6593 kg and a BR of 42%. The Holman & Pye site says it is 8.6tons with a BR of 32%! /forums/images/graemlins/confused.gif All a bit confussing, who does know the correct displacement of any boat is it the designer or the builder?

I'm waiting to hear from Tom, I suggested he contact Oyster to try and get the anomaly clarified.

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Not only will you get different figures at different times from the maker, but the actual will be different again. We have an Oyster 37 in our club and the weight on the crane load cell at lift out is 11.25 tonnes! Admittedly with all the cruising rubbish aboard but 2.5 tonnes of it? No way.
 
Re: 8 Tons?

Thats one hell of a lot of beer on board!

I dont want to get into the weight of one particular boat or another. Once a boat is loaded up with all the kit needed for cruising the weight changes a good deal.

SteveGorst and DJE have highlighted in two posts the point I was originally trying to get at, it shows how a AWB can be as heavy as a more mature design.
 
Re: 8 Tons?

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the weight I was told, and I have nothing to suggest otherwise

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Your sail area if known would be a useful cross check. An older performance design would not be less than 110 sq ft per ton.

Take my boat, modern racer/cruiser, 5.8 tons, 35ft LOA and a mast as high as 40 footers that carries about 860 sq ft. Even with a 2.2m draft I am thinking about furling the jib with 16 kts across the deck when single handed.
 
Re: 8 Tons?

But it's not simply a matter of weight. It is also a matter of hull volume and under water shape - Perhaps light and heavy are a poor choice of terminology - I think the 'comfort factor' figures are often a better guide to what people are meaning when the use the words heavy and light.
 
Mine's 4,500kg design weight but the crane driver tells me his guage says she's in fact about 5,700kg actual weight. But she's pretty well equipped (= plenty of stuff on board)
 
The biggest problems here are :

Manufacturers want you to feel comfortable with their stated weights and some do it empty dry weight ... some do it as per shipping rules of boat + limited as in Lightship Displ.

The other factor that haevily affects comparison is volume and keel weight to hull .... note I stay away from ballast weight / ratio - that is different. A modern boat will often have a lighter lay-up of hull but with a "cats cradle" giving it its strength ...

Therefore displacement weight can be misleading in some cases ... to indicate a light weight or heavyweight boat ... You must look at the boat overall and consider all aspects.
 
The one thing I am beginning to deduce from this, and I am sorry if it was so obvious and that I'm way behind everyone else, is; people are talking about the weight the crane driver tells them their boat is, eg SimonCr, that is the weight of the boat. The displacement is, surely the amount of water (in weight) displaced when the boat is floated. It is this weight that the manufactures quote in the specification.

If SimonCr's boat weighing 5,700 kg displaced 5,700kg, it would sink!
 
Sorry Archemedies principle the weight of the boat IS the weight of water it displaces if it floats!! eg SG less than 1.

I think the debate is more about dry weight, weight in use eg water soaks into hull a little esp wood and gross weight when fully laden with diesel drinking water and stores plus people!!
 
Erm I think you had better revise Archimedes before you take the exam!

If Simons boat weighs in at 5,700kg on the crane it will actually displace 5,700kgs of water, ie it will like most of our boats sit rather lower on its marks than the designer thought or intended, the difference in the immersed depth is the bit which accounts for the extra gear on board.
 
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Erm I think you had better revise Archimedes before you take the exam!


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Duuugh! Just go get my dunces' hat! Of course it is!
 
NEGATIVE !!!!! Displacement IS the weight in water ....

Boat weighing 5 tons WILL displace water of 5 tons. But to float the volume of the boat must exceed the volume of 5 tons of water...... without hole or leak etc.

The problem is many people confuse volume with weight ....

Second boat manufacturers I do not believe follow the marine standards when quoting boat weights .... IMHO many quote the design weight of the drawing board ...
 
Oh Dear .... what a palaver !!!!

sailfree ... you were correct until you added the " eg SG less than 1."

As long as VOLUME of the article is greater for weight to weight to comparison - the article will float. The SG (in fact we should talk Density) of the GRP boat is a lot higher than water ... but because it is a form with "empty-internal" volume the weight of the grp + wood etc. is less than equivalent volume of water.

Steve - you really started one here !!!! 10 out 10 for getting them out of bed !!

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Re: Oh Dear .... what a palaver !!!!

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Steve - you really started one here !!!! 10 out 10 for getting them out of bed !!

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Can you sort it out Nigel, I'm off! /forums/images/graemlins/grin.gif
 
Steve ..... you started it ....

You started it - you have to see it through !!!
 
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