Gross Tonnage Calculator

[chinny]

I'm trying to figure out the gross tonnage of a mid 80's Hunter 34. I'm interested in this both for documenting my sea experience for a USCG Captain's license and for a mooring application. I think the formula is LxBxD (depth not draft)X.67? I'm wondering if any of you proud owners have this handy on your documentation.Thanks in advance,Christian

 

[Fred Ficarra]

It's been too long

But your boat is 12 tons. Maybe you can reverse the formula.

 

[Peggie Hall HeadMistress]

How to calulate a vessel's tonnage

Tonnage has nothing to do with the weight of your boat. It is a measureof how much wine a vessel can carry.The word "tun" was originally a size of a cask used to ship wine fromSpain & Portugal to England. In 1347 a tax of 3 shillings per tun wasimposed and this was called "tonnage." A ship's size became known by thenumber of casks it could carry, and the word tonnage started being usedto describe a ship's size.There are several kinds of tonnage: The first two are used by the taxcollector. The next two are used by designers. The fifth and sixth areused by freight salesmen and canal operators and the last one is used bythe USCG for documenting boats. I'll skip the others and go straight the one you need:Take the horizontal distance between the outboard ends of the boat notincluding rudders and bow sprits. Multiply that by the maximum beam outside to outside.Multiply that by the distance from the sheer line not including bulwarksor cap rails to the outside bottom of the hull not including the keel.Add the volume of the deck house/cabin top. Multiply by .5 for sailboats and .67 for power boats.Divide by 100.This will give you the "Gross Tonnage". Net tonnage is 90% of gross forsailboats and 80% for power boats.

 

[Rick Messier]

Vessel Documentation Center

Chinny:If you go to this link at the NVDC, there is an interactive form for calculating your gross and net tonnage.I am in the process of documenting my new 44 DS and I have used this form. Very simple.Hope this helps.Rick

 

[chinny]

Wheew!

Thanks for all of the good information. Who knew it could be this convoluted? Now I can safely say 'I know.'Thanks everybody.