Tonnage Plaque?

[Tim Good]

So I know a lot of boats have a plaque with the year of build, some other. It's and often the tonnage.

Is that referring to just Tonnage... I.e the cargo carrying capacity of a boat? Or is it a measure of volume like gross tonnage?

My boat is 43ft and it says tonnage is 28.8T. Surely it couldn't carry 28.8T of cargo!

 

[Rafiki]

I believe that it's Thames Tonnage which is some form or arcane volume/ load carrying measure. Quite meaningless these days I think.

 

[sailorman]

I believe that it's Thames Tonnage which is some form or arcane volume/ load carrying measure. Quite meaningless these days I think.

Yes & a search engine may well assist the OP in that endeavour

 

[Motor_Sailor]

https://en.wikipedia.org/wiki/Thames_Measurement

 

[sailorman]

https://en.wikipedia.org/wiki/Thames_Measurement

Your "spoon feeding " the OP now

 

[pvb]

I believe that it's Thames Tonnage which is some form or arcane volume/ load carrying measure. Quite meaningless these days I think.

No, it's not Thames Tonnage. Registered vessels have to have a survey to determine registered tonnage, which is a complex formula laid down by the Merchant Shipping (Tonnage) Regulations. The notional tonnage figure is volume related, my 37 footer has a net tonnage of 14.30.

 

[Tim Good]

No, it's not Thames Tonnage. Registered vessels have to have a survey to determine registered tonnage, which is a complex formula laid down by the Merchant Shipping (Tonnage) Regulations. The notional tonnage figure is volume related, my 37 footer has a net tonnage of 14.30.

Thanks PVB! Whilst the others were quick to lay down the sarcasm I didn't think it was so straightforward. There appears to be several possible tonnage meanings each calculated in a different way. So are we saying that It neither Gross, Net, Deadweight or Thames Tonnage? And something else you refer to at National Tonnage?

 

[fisherman]

Very illogical measure. My boat 14.5t deadweight, was decked and the tonnage was the underdeck volume, 8.1t. A smaller boat with a loose deck was measured to the gunnels, 12.3t. Doesn't matter until tonnage comes into licence value and permitted fishing.
It would also relate to carrying capacity obviously, as once I'm down to the deck that's it, you could carry more in the smaller boat.

 

[Buck Turgidson]

Here is the actual law
http://www.legislation.gov.uk/uksi/1997/1510/made

 

[Tranona]

Thanks PVB! Whilst the others were quick to lay down the sarcasm I didn't think it was so straightforward. There appears to be several possible tonnage meanings each calculated in a different way. So are we saying that It neither Gross, Net, Deadweight or Thames Tonnage? And something else you refer to at National Tonnage?

If it is the tonnage plate for Part 1 registration, then the figure will be the result of the specific survey calculation.

In practical terms it is completely meaningless. The calculation is made as for commercial vessels and is the basis for some statutory charges such as light dues. None of these apply to leisure craft, but the registration process is the same.

This is well trod territory (comes up here regularly) and very easy to understand with a quick google which might explain the nature of some of the replies!

There are other amusing quirks, at least in the old measuring method. My boat was measured in 1963 and my children loved the fact that there was an allowance for "apprentice space" as well as other more logical ones such as "chart space" and "machinery space". Clearly there were lots of opportunities for owners to influence surveyors to maximise the size of these allowances as it reduced registered tonnage and therefore expensive charges such as light dues, pilotage and port charges.

 

[pvb]

Thanks PVB! Whilst the others were quick to lay down the sarcasm I didn't think it was so straightforward. There appears to be several possible tonnage meanings each calculated in a different way. So are we saying that It neither Gross, Net, Deadweight or Thames Tonnage? And something else you refer to at National Tonnage?

No, I said the notional tonnage figure is volume-related. Nothing to do with the weight of the boat.