bentherb4

I'm sure there aren't a ton of people running these, but maybe a few?? I purchased this blown up and stored outside for a period of years. I completely restored the boat and am just starting to run the boat. The engine is about 425HP. The duoprop set is F-9. I didn't add much weight to the boat so it shouldn't be a factor. Okay, now for the issue. The boat runs great with the trim all the way down. I am getting 62 on gps with 4 ppl on the boat and full of fuel and the same with just me and lower fuel. When I start to trim the drive up at all the boat starts to wobble. It doesn't feel like a chime walk and its "building" so you don't wait long before you trim right back down. I was able to get up to 65 by adding trim and making a long slow turn. I looked over the bottom and there isn't anything unusual for a production boat. Boat sets close to perfectly level by itself in the water. Boat handles waves at speed fine with great attitude. Has anyone else run into a similar issue with either a U-boat or maybe a Donzi 16?? I don't think trim tabs will do much, unless they make them skinny and 18" long so i can still turn the drive and get tab in the water... Any input would be appreciated.

Taboma

I have a U-19 with a modified multi-port EFI 351 width the same out drive and props as you. I am seeing 72 in mine with some "chine walk". I have had the boat since new in 1996 and I guess that I have just gotten used the oscillation. I do trim mine up approx. 1/4 way on the gauge to achieve any speed, start trimming immediately out the hole. It builds speed exceptionally fast! I have trim tabs, but only use them with balance at lower speeds with an unbalanced load (fat passenger). My wife starts yelling at 50 MPH in the U-19 because of the chine walk, but she has been 113 MPH in the Skater without a whimper! I think that you need to trim it up as speed increases to get the bow out of the water. It probably is searching with too much keel running in the water??? David

thirdchildhood

iTrader: (6)

These boats are Donzi Classic copies but are known for handling problems.

Taboma

Those "handling problems" were overstated in a powerboat magazine test in a prototype FourWinns U-19 that got trimmed way too much. They only need a small amount of trim. They do have some quirks, but what performance boat doesn't. Drive a 28 Skater and experience temperamental, but controllable handling. As with all performance boat diving, move slowly and learn their traits. JMO.

Kurt Hamilton

Do you make the appropriate steering corrections to drive it out of the chine walk?
Nearly every small boat with reasonable power will want to get up and ride on the small pad at back of boat (some don't have a flat pad, just a full v to the transom and they are even trickier) especially once trim is introduced. Once it's doing this you'll have to keep it on that pad with steering input or it'll just keep wanting to fall off that pad and bounce from side to side. Hence the chine walk. It's a real art to master!
Have fun

Pliant

I have a wellcraft 19 with a rounded keel...there simply is was no mastering that could be done. Tab's were the final solution they were just enough surface area to keep it running true.

Kurt Hamilton

Yea, a rounded or full v is very tricky! What does the U17 have??

Taboma

Both the U-17 and U-19 are rounded keels. They just take time and acquired skill to drive! That is why we have performance boats! They are not Lincoln Town Cars, the are Porsches!

Beanutputter

I have the same boat. Acts the same way. Have been considering tabs. Did you put some on? Figure anything out. By the way, love mine, it is a blast!

Taboma

Yes, I have tabs, but really don't use them to enhance performance, just to balance the boat when loaded non symmetrically. (fat people). You just need to learn to drive it when on the keel.