Another idiot tonnage question

[machurley22]

I have recently (last night) applied for my first ever Ships Radio Licence and was invited to state my "gross tonnage (1 ton = 100cu.ft.)"

I started messing about with the design weight converted to the volume of seawater this would displace and came up with a figure of 62cu.ft. ie 0.62 tons before giving up and stating my design weight.

How is a gross tonnage figure calculated? Please.

Dave

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[Inselaffe]

My copy of 'Basic Ship Theory' by Rawson & Tupper says:

Tonnage is related to the volume of cargo

The volume of a ship is expressed in tons of 100ft^3 & is referred to as its tonnage.

The gross tonnage is the sum of the underdeck and overdeck tonnages plus volumes of hatchways (less one-half per cent of gross tonnage computed without hatchways), plus light and air spaces which are included at the owners request in the measurement of the machinery spaces. !!!

The new formular tonnage regulations came into effect in 1982:

Gross tonnage, GT=k1*V

Where: K1=0.2 +0.02*log10(V)
and: V= total volume of all enclosed space in m^2

But does this apply to boats as well as ships? I don't remember much about all this stuff to be honest, but that's what it says here!






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[machurley22]

Thanks for that - I think. I'm only slightly wiser but at least now am completely unashamed to admit I do not know my gross tonnage. I suppose my real question should have been "What do others put in the gross tonnage box when applying for a Ships Radio Licence?"


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[LadyInBed]

I think I put displacement.

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[jimbouy]

I put the quoted weight of my boat from the original brochure.

The questions arising are.

What is the relevance of gross tonage to radio lic.

Will they ever check up.

<hr width=100% size=1> "It is a pleasure to give advice, humiliating to need it, normal to ignore it"

 

[BrendanS]

Don't feel a complete idiot. I asked Mike Martin why this question was so obscure last year when I applied. It's a legal thing apparently, but I suspect they now think my boat is about 10x bigger than it really is, as I didn't know how to calculate it at the time until I'd done more research

<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant

 

[Inselaffe]

found another one, much simpler!

Thames Tonnage = [(L-B) X B X 0.5B]/94 (All dimensions in feet)

That's from Boat Data Book by Ian Nicholson

Can't remember what, if any, difference there is between thames tonnage and tonnage.

Interested to know though...

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[MIKE_MCKIE]

From my very long ago Mates ticket, Gross Tonnage is the entire cubic capacity of the vessel in cubic feet divided by 100. It includes cargo space,, engine rooms, accommodation & storerooms. Nett Tonnage is Gross minus "non revenue earning" spaces ie acommodation, stores, engine room etc. Thames tonnage is a yachting version of Gross tonnage.
All these are purely a rule whereby port authorities, canal authorities & customs can charge you lots of dosh on a consistent basis ( not necessarily fair, but consistent) it has to be said, most yottie places charge per foot/metre which is a bit fairer until you include cats & tris!!
Commercial Shipping companies pay naval architects vast sums these days in order to reduce the Gross as much as possible, while increasing the Deadweight. The deadweight is the physical carrying capacity of the vessel and is the difference detween the actual weight of the vessel empty, and full (of cargo, passengers whatever)
Hope you are lots wiser now that you have all this somewhat archaic & mostly totally useless information!
My own boat has a Thames measurement of 6 tons and a displacement of 2.6 Tons (not tonnes!!) I put the displacement on my Radio License Application form & no-one has queried it for the last 3 years.
Keep the pound, feet & inches & PINTS, say I, and confusion to the bureaucrats!
Cheers
Mike


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[chas]

If it is any help, my displacement is 4.69 tons and gross tonnage is 9 tons 31 cwt.

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[Brian_B]

I didn't fill the section. They still took my money and sent me a licence.

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