Predicting speed for a given prop hp

Due to a whole new crop of electric conversion threads I have been trying to find a way to predict the speed of a hull with a given amount of hp applied at the prop. Basically a spreadsheet where you can enter basic boat information and it will kick out an aproxamate amount of power needed at displacement speed for a standard monohull sailboat (the ability to predict a cat as well would be nice).

Does anyone have something simple that can acomplish this?

 

Any of the basic design books has that. Kinney, Gerr, etc. The power required is irrelevant of source. This nomograph works well.

 

You took it from Nicholson's "Boat Data Book", right?
It is one great book, one of the most odd ones I've had - but definitively very useful.

 

Yes, I think that is where it came from. I've had that for years. It is surprisingly accurate.

 

Gonzo,

I appreciate the chart, but I have absolutely zero idea how to read it. Is there a guide to it somewhere?

 

That is the example. If you follow the lines. Start with the length and make a line crossing the displacement until it intercepts the right baseline. From that point, make a line intercepting the HP until it crosses the left baseline. From that point make a line to the B/D of the shape type of your boat. That last line crosses the speed line on the expected speed of the boat.

 

Got it, thanks.