Design vs actual displacement

[zefender]

If my boat has a design displacement of 8300kgs, how much might it have (roughly) when fully 'loaded' with post purchase pre-passage kit?

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[snowleopard]

the waterline as designed should allow for crew and a reasonable amount of stores. for extended cruising add around 1 ton

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[jimi]

So roughly 1000 Fray Bentos, 500 Cauliflowers & 200 cans of Boddington's based on Tilman's one drink per crew member on a Friday evening?

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[mikewilkes]

Excellent..nm

.

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[PeteMcK]

Is Tilman's "one drink" the same as "a wee drink"? If not, there could be a huge difference.

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[tcm]

um, i wd imagine that really you will have to talk to the designers?

I bet that seeing as how they are german, they are bound to have undertaken some very boring yet rigouous tests on the subject. If you buy a merc, frexample,then that have a chart showing how likely you are to have a crash based on the colour of the car. So, i wd imagine bav have already done some stats on how much gear you have on board, with a nice graph of increasing likelihood of sinkiness v kilograms of gear.


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[tcm]

um, i wd imagine that really you will have to talk to the designers?

I bet that seeing as how they are german, they are bound to have undertaken some very boring yet rigouous tests on the subject. If you buy a merc, frexample,then that have a chart showing how likely you are to have a crash based on the colour of the car. So, i wd imagine bav have already done some stats on how much gear you have on board, with a nice graph of increasing likelihood of sinkiness v kilograms of gear.


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[Twister_Ken]

Do the maths

Add stuff over and above standard spec, eg

Teak Decks
Anchors & Chain
Liferaft
Full tanks (water at 1kg per litre, diesel at .95kg per litre)
All sails
Tender & outboard
Electronic gear
Crockery, cutlery
Tinned goods
Spare fuel & water
Extra warps and sheets
Muttering cone
Bigger engine?
Contents of drinks cabinet
Tool kit
Average of 100kg per body, inc personal possessions
5% of that lot for luck, and hey presto.





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[tugboat]

Wot, no roasties? /forums/images/icons/frown.gif

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[Clive_Rigden]

Thought you were never going to post again /forums/images/icons/shocked.gif

Good to have you back /forums/images/icons/wink.gif

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[Sans Bateau]

Re: Do the maths

When we put Out To Play up for sale we emptied her of all our gear etc, she then sat 4 or 5 cms higher in the water! The tel tale mark around the boot top giving the game away.

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[Sybarite]

I remember reading a report about a Haliotis 38 (which is really a 35') saying that stabilty calculations took into account 2 tonnes extra fully loaded.

Just a broad indication because tankage will be a big differentiator.

John.

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[Becky]

Nobody has mentioned things like anchors and chain. I saw an article which mentioned the term 'light ship' as being the weight of the boat when she leaves the builders. I suspect that this will be the given displacement in the brochure. So the given displacement will be miles out when compared with a yachts in sailing trim. Poor Cornish Maid is laden down with two anchor chains of considerable lenght and weight, four anchors, dinghy (weight 35kg, I can just lift it) outboard, life raft, generator, loads of warps, galley equipment, already-mentioned water and fuel, and loads more. An extra ton could be quite conservative. Especially with my things aboard as well!!
Met someone who had an HR39 which registered over 10 tons (should be more around 8 tons 'light ship') when lifted. Lovely couple , they live in Guernsey.

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[Twister_Ken]

I\'m revolting

>Nobody has mentioned things like anchors and chain<

Oh yes they have!

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[Twister_Ken]

Re: Do the maths

I have a pal who refitted a 44' yacht and took over 1/4 tonne of old wiring and electrical gear out of her, not counting a generator.

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[zefender]

Re: Do the maths

Aargh teecha! I 'ate maths.

'Spose I was looking for a rule of thumb. Gawd knows how much extra the teak decks weigh (any ideas, Teech?) The dinghy, liferaft, tank water, fuel, anchor and chain must come to about 550kgs. Spare water, warps, radar make another 220kgs. So I'd reckon on 1,000kgs before the teak deck and maybe another 300kg of tools, extra batteries, food etc. I think up to 8 people and 20kgs each baggage allowance is within the design disp.

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[boomerangben]

The design displacement and hence waterline (for a defined water density) is used when developing hydrostatics, hydrodynamics, propulsion calcs and when designing the structure of the vessel. I guess it also used when quoting LWL and draft. So it could be seen as a maxium displacement. But how many boats have a means of telling what the actual displacement is? You could get the boat lifted and weighed, but has the boat been designed strong enought to be lifted at its max displacement?

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[Twister_Ken]

Weight of teak

Approx 3/4 tonne per cu mt.

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[Becky]

Re: I\'m revolting

Sorry TW, missed that bit. You didn't leave out much for the rest of us though, did you?

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[jimi]

Well I have'nt .. on that thread!

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