Formula for Boat Length Vs Beam

[Captain Pugwash]

Hi.

I know there is not going to be an exact answer here, but I'm looking for a general guide for how the length of a boat affects it's beam.

For example, if you have a 12 metre motoryacht, then what would be it's likely approximate beam. If you had a 14 metre motoryacht, is there a general formula that would support what it's beam would have increased by - and so on.

Is it linea, or does the ratio/formula alter as you move towards 20m+ boats, etc.

I am looking for the general ratio/formula for both sailboats and motoryachts.

Can anyone help?

Thankyou

CP.

[Raggi_Thor]

It's not possible to find a simple formula.
You can try to collect data from boats you like and put them in a spreadsheet. Then if you plot beam vs length you will see the dots are spread around a curve, maybe. Short boats have relative more beam than long boats. L=2.5 x B for a small dingy for example.

It's more like this:
You want a boat of a certain size to carry something, or you want so many bathrooms etc, then you find you need a certain length and beam, then you estimate weight, and if you want a specific speed you estimate power, add more weight for the engine(s) and fuels and start again.

For a given length, displacement, speed and power there may be an ideal beam, but most boats are compromises as you know

[Raggi_Thor]

From http://www.cyberiad.net/library/mult...p/multipep.htm