I added substantial power to my boat ( 05 270 Hallett 2 step ) this winter, now when driving through 70 on to 80 it develops a major
porpoise...I'm running a Bravo 1 4 blade 30P My question is : would a propeller change alter this ? which prop ? Thanks !

Can you acually get through the porpoise?

Some props may help more or hurt more. Depending on the scenario, more rake angle could help to carry the bow as well as increased trasom lift could reduce the desire to carry the bow and stop the porpoise but may scub speed.

Yes, I can but have to drag the tabs...as speed increases I can slowly raise them to full up...but the porpoise zone is annoying...

Trimmed out I get porpoising with both the Bravo and P5Xs.
Mine is a little scary at higher speeds. Hopefully more seat time with my increased power will help.

I would recommend trying some stern lift props on the boat to change the lift.

Julie

What drive are you running? Is it a shorty? I can get the same thing if I'm just maintaining speed and not accelerating. Doesn't do it in light chop. Very pronounced on glass. Never considered more stern lift but maybe that would help if I can't maintain the bow lift.

I'm running a shortened imco extreme ..same thing as you, chop no
hop, smooth water = equals a lot of hop

Hallett Fan,

Can you give me a call when you have a chance. I'm currently building a high HP motor and have some questions for you.

In regards to your post, my old 502/whipple motor porpose all the time at 75mph and then I went with a 5 blade Maximus and the porpusing went away due to extra bow lift and reduced slippage on the prop.

My number is 702-210-0088 Thanks