what are the physics of porpoising

[Taxus812]

I'm looking for what is actually happening when my boat porpoises.

For example, I put adults in the back and have my trim neutral then get on plane my boat will porpoise until I put in some down trim.

Is the boats bow high and it just stalls (sorry airplane guy here) or is the bow is high and the prop ventilates causing it to loose power until the angle is lower and it bites again?



of am I way off


does anyoneone have any good vids

 

[Frank Acampora]

Re: what are the physics of porpoising

Porpoising is very much like chine walking in that it is almost a feedback loop.

With the weight in the back, the prop lifts the bow until there is not enough hull on the water to support it and the bow drops. Then it starts again. The cure is to move weight forward OR increase speed so the added water pressure will support the hull on the reduced wetted area. (maybe) Sometimes this works and sometimes it doesn't, depending upon hull design and just like feedback, the porpoising can get worse with increased speed.