Do you know?

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Guest

Guest
I have a Pt 1 Registered boat that has a gross tonnage of 7.68 Tons, it also has a registered tonnage of 7.68 tons! - I am sure there should be difference.

I am attmepting to re-prop and would like to know what the formula is for working out gross tonnage, maybe I can work back to an approximate start point.

Many thanks.

Phil
 
Trev

You're dead right..sorry about the terminology. I need to find out how much the boat weighs in the water.

I had thought that gross tonnage and registered tonnage related to what the vessel weighed with and without a load - rather like Gross Vehicle Weight.

Thanks.

Phil
 
My Princess 32 has a registered tonnage of 6.65 tons and when lifted recently with almost full fuel and water tanks the crane driver gave me a deadweight of 4 tons. I f you are repropping though this is only a minor part of the equation. You need to take into account engine horse power and revs, gearbox reduction ratio (is it shaft drive or outdrive?) and hull shape.
I agree with Col......phone Steel Developments and they will help you decide what prop(s) you need 0208 874 7059

' that shouldnt cost much to put right....or is it a v*lv* ? ;-) '

www.boatsonthethames.co.uk
 
Part 1 tonnage

Yep, the part 1 tonnage is quite different from the actual weight of the boat, so it is irrelevant in choosing a prop
 
Thanks for this.

I have an RLM 32 Entice with outdrives, I have recently re-engined using Peugeot 1.7 Turbo's. I have used the prop calculations, together with all the other factors you have suggested, available at www.boatdiesel.com and I have used 6 tons as the maximum weight when cruising.

The prop calcs say that I should use 13x11 as the optimum. I was just trying to check what the 'dead' weight was as a starting point.

Phil
 
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