npf1
Well-Known Member
Moody 1 - thanks for the clarification.
Net Tonnage to tonnes conversion
- Thread starter npf1
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VicS
Well-Known Member
[ QUOTE ]
Been digging through some paperwork and I think I've found the answer. Looking at the stabilty study of a sister vessel, the Arrival Load 10% Consumables is just a shade under 26 metric tonnes.
[/ QUOTE ] Just for fun i have been looking at some of the specs of boats for sale. The most credible figure I found was 56000lbs, Thats approx 25.45 tonnes (or precisely 25 imperial tons) It was for the pilot house cutter but it agrees pretty well with your figure.
For the people still arguing about tons and tonnes etc do not forget that a US pound is slightly different to a UK pound and that in the US they have short tons (=2000lbs ) as well as long tons.
Been digging through some paperwork and I think I've found the answer. Looking at the stabilty study of a sister vessel, the Arrival Load 10% Consumables is just a shade under 26 metric tonnes.
[/ QUOTE ] Just for fun i have been looking at some of the specs of boats for sale. The most credible figure I found was 56000lbs, Thats approx 25.45 tonnes (or precisely 25 imperial tons) It was for the pilot house cutter but it agrees pretty well with your figure.
For the people still arguing about tons and tonnes etc do not forget that a US pound is slightly different to a UK pound and that in the US they have short tons (=2000lbs ) as well as long tons.
Tranona
Well-Known Member
Yes, your net and gross figures cannot be the same if it was measured properly. My original Part 1 Certificate shows Gross Tonnage of 4.72 consisting of 3.61 "Under Tonnage Deck" (effectively the cabin) Plus .45 "Forecastle/Cabin Top" and .66 "Break", which I think is the cockpit lockers and lazarette. There is also a cubic metres equivalent at 13.36. On the right hand side of the certificate it has 3 potential "Deductions" Propelling power (engine space) of .32 Number of Seamen or apprentices for whom accommmodation is certified Zero. (My children were always disappointed with this bit when they were small) and "Other" which in my case is Chart Space .74. Total allowances 1.06. Therefore net Register Tonnage 3.66. All this lovingly entered in best copperplate and signed off by a SC Lawrence Registrar of British Ships in Plymouth. The details including the official number are carved in the main beam, although when I cut through the beam about 15 years ago to extend the coachroof some of the detail was lost. And of course I should have had it re-measured to reflect the additional cargo space that I created. Such is life!
Why all this detail? History. Net Register Tonnage was the basis for levying Light and Harbour dues - therefore the objective with the surveyor was to get the figure as low as possible. And of course ownership is calculated in 64 shares!
Back to the original question. Now we know it is a heavy displacement 53 footer then your calculated displacement of 26 tonnes seems reasonable and I bet the lift operator would have told you it was too heavy just looking at her!
Why all this detail? History. Net Register Tonnage was the basis for levying Light and Harbour dues - therefore the objective with the surveyor was to get the figure as low as possible. And of course ownership is calculated in 64 shares!
Back to the original question. Now we know it is a heavy displacement 53 footer then your calculated displacement of 26 tonnes seems reasonable and I bet the lift operator would have told you it was too heavy just looking at her!
john_morris_uk
Well-Known Member
[ QUOTE ]
Wikipedia discusses the volume of water displaced as shown by the tonnage, then multiplies by 2.8 tonnes for the mass of water to occupy that space.
[/ QUOTE ] Which just goes to show how unreliable Wiki can be. What's worse is that some people believe the unsubstantiated and unreferenced things it says.
Wikipedia discusses the volume of water displaced as shown by the tonnage, then multiplies by 2.8 tonnes for the mass of water to occupy that space.
[/ QUOTE ] Which just goes to show how unreliable Wiki can be. What's worse is that some people believe the unsubstantiated and unreferenced things it says.
rickp
Well-Known Member
[ QUOTE ]
Which just goes to show how unreliable Wiki can be. What's worse is that some people believe the unsubstantiated and unreferenced things it says.
[/ QUOTE ]
Almost as bad as people who complain about it but don't update it.
Rick
Which just goes to show how unreliable Wiki can be. What's worse is that some people believe the unsubstantiated and unreferenced things it says.
[/ QUOTE ]
Almost as bad as people who complain about it but don't update it.
Rick
damo
Well-Known Member
Hi Nigel - you may also need to bear in mind that if the displacement is close to the lift capacity, then get it done on a cool day! - the hydraulics may struggle when hot. Also, I can't remember your rig exactly, but the boat would have to sit exactly balanced in a hoist in order for it to achieve its max lift, which is sometimes difficult to achieve with eg a ketch.
Edit - it seems the Sealift is a submersible, so you can probably disregard the above in this case!
Edit - it seems the Sealift is a submersible, so you can probably disregard the above in this case!
Bajansailor
Well-Known Member
Wiki were sort of in the right ball park re the reference to 2.8 - but it is very misleading to try to relate a gross or net tonnage to a mass or weight.
The standard convention has it that one gross or net ton is 2.83 cubic metres of volume.
The standard convention has it that one gross or net ton is 2.83 cubic metres of volume.
john_morris_uk
Well-Known Member
[ QUOTE ]
[ QUOTE ]
Which just goes to show how unreliable Wiki can be. What's worse is that some people believe the unsubstantiated and unreferenced things it says.
[/ QUOTE ]
Almost as bad as people who complain about it but don't update it.
Rick
[/ QUOTE ]I would update it if I thought for one moment any academic rigour would be applied to my impromptu thoughts. You might have worked out by now that I can't stand Wiki - not because it hasn't got some good things in it: clearly it has, but more because students don't have the skills to tell the difference between balderdash and accepted/tested ideas.
I work in a field where there isn't always right and wrong - just different opinions, and Wiki is particularly poor in providing balanced answers.
It is also glaringly WRONG on some things where there is an established scientific body of opinion.
[ QUOTE ]
Which just goes to show how unreliable Wiki can be. What's worse is that some people believe the unsubstantiated and unreferenced things it says.
[/ QUOTE ]
Almost as bad as people who complain about it but don't update it.
Rick
[/ QUOTE ]I would update it if I thought for one moment any academic rigour would be applied to my impromptu thoughts. You might have worked out by now that I can't stand Wiki - not because it hasn't got some good things in it: clearly it has, but more because students don't have the skills to tell the difference between balderdash and accepted/tested ideas.
I work in a field where there isn't always right and wrong - just different opinions, and Wiki is particularly poor in providing balanced answers.
It is also glaringly WRONG on some things where there is an established scientific body of opinion.