How do you figure displacement tonnage on a boat?

[fish assassin]

I'm trying to figure the displacement tonnage on my boat. Is there a formula (length/width/
height/material) to figure this? It isn't as simple as taking it to a truck scales and weighing
it and then subtracting the trailer weight, is it?

Thanks,
-assAssin-

[danger]

Be a little more specific. What exactly are you trying to figure out? If you just want to know the weight of your boat, then a truck scale minus the trailer weight would work. If you want to know how much water it will displace, take the boat weight and divide by 62.4. This will give you the volume of water that the boat will displace in cubic feet,(convert from there).

[fish assassin]

Excellent!! That was exactly the number I needed to know ... 62.4.

Thanks for the reply

-assAssin-

[KChookem]

Maybe this is not what you are looking for, and/or may be more info than you want, but here is some info found through 'Chapman's Piloting & Seamanship'...

The following link takes you to the USCG's Marine Safety Center...

<http://www.uscg.mil/hq/msc/T3.htm> USCG Marine Safety Center (http://www.uscg.mil/hq/msc/T3.htm)

From the MSC home page you can go to the "Tonnage" link, and get the formula for figuring gross and net tonnage (found in Form CG-5397).

FYI - For vessels under 79 feet, 'Chapman's' shows the formula for non-sailing vessels as 0.67(LBD/100) for gross tonnage; with net tonnage as 8/10 of the gross. [L=overall length; B=overall breadth; and D=depth].