More Help, Formula for Engine HP requirements

[cliffdale]

Thanks DavidC.

Next question, I now have a theoretical hull speed, how do I calculate the required HP for a diesel engine to push the boat?

Advise wiuld be greatly appreciated.

Thanks

Cliff Dale

 

[Guest]

Used to be 3hp for every ton displaced but is probably now out of date. I have a heavy long keeled yacht and it works out ok for me.

However, windage on a yacht is a huge factor and light dislacement would need more power in a chop.

If an engine is not just an auxiliary but for a motorsailor or powerboat I would suggest getting expert advice from a marine specialist.

Regards

 

[Guest]

I can't remeber of the top of my head, but "Ian Nicholson data book" tells you all bout it and what propeller in easy to use graphs and calculations

 

[seahorse]

Westerly Yachts web site had a programme to download, solves all your problems. If U can't get if post details of your boat & i'ii run it through 4 U.

 

[brianrunyard]

You can download a PropCalc program at http://www.castlemarine.co.uk/pitch.htm
Covers Hull Speed, Planing Speed, engine HP, prop dia and Pitch.