How can I calculate the tonnage

I apologise I thought 11.4 was overall beam my mistake yes so 700ton is a good estimate with a Cp 53

 

ok max beam is 14

 

so block co efficient or prismatic , c p is .53

 

i must buy a planimeter

 

nzboy i was using a higher block co eff and got 900

 

Peter for what its worth download freeship and google freeship tutorial normally a very simple guide to designing boats comes up .This will get you started. I no nothing about how to design a boat using cad .Like you I can produce a set of offsets accurate to a mm. So it is possible to put these figures into the x y and z coordinates and you get lines plan, profile and 3d image and hydrostatic figures etc all very easy if you have the offsets .Just because I can do that doesn't mean I am a NA .Just a draughtsman I well remember my parents spending much money on a architect only to tear their hair out .They after wards approached a well known draughtsperson. Houses like boats contain a certain artistic element. Not all people can reproduce a clients wishes

 

I guess it comes down to what margin of accuracy is required, as to what method you adopt to work this out.

 

yes i have freeship, i must get the tutorial, thanks

its clear i have not had a maths teacher for 40 years

 

i cant produce offsets to a mm, because the scale is so big,maybe i can on a 3 metre dinghy

 

You could use graph paper and count the squares.

 

yes thanks

 

Peter, maybe I've missed this discussion but, if I could help with anything, I suggest the following:
- If what you need is to calculate the volume below deck, wooden model you have will help you to get a very accurate data. You only have to weigh it and divide this value by the density of the wood.Then you take into account the scale of the model and have used only half hull.
- If you want to know the ship's weight at full load, for example, the solution will be much more complicated.

 

thanks, i need the displacement only

 

MikeD had a good old thread on Simpsons, look it up
Freeship is a good idea and for a rough but better than Cp
I simply use pocket geometry free from the android playstore

 

thanks