Just had a custom engine built for my 96 27 Powerquest, Haven't tested the speed on a GPS but Its alot faster and at WOT its not stable at all..Anything I can do to make the ride better like better trim tabs?

Got any information on speed, rpm, gear ratio, prop brand, # of blades, pitch, rake, or X-dimension?

Once the OSO braintrust gets that info, they'll be able to cook up some ideas.

Or, you could have simply overpowered the hull.

("We're gonna need a bigger boat...")

Try a 4 blade prop. Do the tabs help?

be very careful here. Lets not forget the unfortunate lesson leaned by KOOK. WHen dudley biult his engin he made a very similar post complainging of chine walking and so forth. I think we all pretty much remeber what happened.


small unstable hull + big engines / inexperienced driver = major accient

Yeah, how fast?

Over 70, external steering is important - over 80 it's a must.

give us more info here, as well as your driving background in small fast boats.

Does the 270 have wedges on the bottom at the out edges near the transom? The 260 does and it takes some driving to keep it from chime walking on glass smooth water. Do you have the same problem running in a 1' chop or if you make a very slight turn at speed.

Be careful.

What do you mean by unstable? Chinewalk? Try not triming too high. Bigger tabs would help. 280 K-planes. Also with that power I would add hydraulic steering. I have a 260 with stock power runs 62.7 GPS and I can get a little chine walk if I trim all the way up in calm water. I just tap the drive down a little and it settles out.
rbtnt,
What do you mean by wedges on the bottom? I did notice a slight hook built in when I put a straight edge on the bottom when I was mounting my tabs.

Yea, the whole kook fiasco comes to mind.

I never felt that trim tabs were a real solution to chine walking. To me they were always the last resort. Heck, if you are going to always drag tab, then why not put a smaller engine in? Chine walking is caused by a number of issues. A worn gimble and steering would be one definite issue. A external tie-in ram would help. Different props will also help or hurt chine walking. I've found the hydromotive to be very stable. The hull also has a major factor in chinewalking. Every hull has it's limit and kook exceeded his. The final factor is the driver. If the boat is loose and wants to chinewalk then the driver needs to learn how to drive the boat. The boat will generally want to fall off to the right, so a twitch of the steering wheel will throw it back on the pad. It'll take a little practice, but a skilled driver can tame a dangerous boat.

We need more details! Lets define unstable......One of the common problems seen with High HP is to much stern lift...which we know will make the boat feel unstable. Ther are some prop solutions which may assist with this but, specific details are definately needed here.

Julie

Hydromotive 22pitch prop 4blade modified
5300rpms with 510tq and 514hp and 1.5 to 1 gear ratio brovo 1 outdrive