Planing Hulls

I would appreciate a lot if someone could enlighten me about my problem?

Let's say that I have 4 different forms for each of the 31 planing boats. I have to choose one of the forms for each boat.
I have picked the forms according to their prismatic coefficients in round hulls comparing their froude numbers, many graphs area available in internet and as well as larsson's book. However for planing boats I do not know what could be the criteria for choosing.
I have scanned some books and net but could not come up with anything.

To help you in answering, I have the forms, engine and speed of the boats.


Thanks!

 

Straight and parallel buttock lines in aft 40% of LWL - good. Non straight or parallel, bad.

The faster the design goal, the more important the above rules.

Lower displacement = faster and/or lower power

At speed/length ratio over 2.5, beam/length should be about 0.35.

Just starting points and these can be attacked from many angles but may be useful in eliminating some of the choices.

 

thanks for the reply, it is useful, it would be wonderful if you could advise me some sources that I can find more detailed information or maybe you would like to inform more in other aspects....
Thanks

 

This link will provide a means to calculate the power required for particular hull forms:
http://illustrations.marin.ntnu.no/hydrodynamics/resistance/planing/index.html
The calculator will also indicate tendency to porpoise.

Generally the ride quality will improve with increased "V" and increasing slenderness.

A deep forefoot increases tendency to broach when running but make the bow more buoyant and keeps the it up when at rest and at low speed.

Steps in the planing surface can be used to reduce drag. You can find references to stepped hulls.

I like the idea of a flat triangular planing surface the flattens the 'V' across about one third of the transom. I believe it improves ride quality without increasing power compared with a simple 'V' but I have not seen any analysis of this hull form.

You need to specify what you want from the boat and then see which one best fits the requirements. There are many aspects of the boat above the waterline that will need to be considered as well in terms of the boat meeting requirements.

Rick W

 

Look Further !!!!!!!!!!

IT IS AMAZING HOW MANY RECURRENT QUESTIONS ARE ASKED IN THIS FORUMS AND HOW MANY INFOS, OR USEFUL DOCS/SPREADSHEETS/LINKS ADDRESSES HAVE BEEN PROVIDED AND MOST OF THEM DISREGARDED !!!!!!!!...........TRY THIS ONE FOR EXAMPLE AND SEE FIRST IF COULD BE OF ANY HELP............

(N.B. SAVE IT ON THE DESKTOP BEFORE OPENING IT...)


http://www.boatdesign.net/forums/bo...rd-chine-high-speed-planing-crafts-20495.html
http://www.boatdesign.net/forums/at...peed-planing-crafts-planing-hull-1-master.pdf