Alumacraft Trophy 175 porpoising

[reelguy]

I have a 2011 Trophy 175 with a 115 Yamaha on it. I have noticed some porpoising ever since I had it but not too bad. I had some paint warranty work done over the winter. Alumacraft did the work and it appears that they took the whole bottom off and either replaced it, or took it off to paint it. Now when I got it out on calm as can be water, it porpoises like crazy. I first noticed it when I had a full tank of gas and three guys in the boat. It seemed to get better as the week went on and we used the gas up in the tank. When I had a 1/4 tank or so and just two of us, it seemed to run pretty smooth. When it was really bad, I tried messing with the motor position, speed and the such but nothing helped much. I did notice that when I cornered it ran nice and smooth. Any suggestions from guys that have had this happen? I remember someone mentioning a problem similar before and having Alumacraft beating the bottom of the boat will a hammermbut that seems like an extreme measure.

[TruthWalleyes]

You sound rear heavy, trimming the motor down or adding trim tabs should lower the front end.

[delcecchi]

They took the bottom off? What makes you think that?

[CaptainMusky]

Yeah, that would be extremely odd if they took the bottom off. Unless there was something else wrong that they noticed going in to the repaint job.

Regarding the porpoising, you may need to look into lowering your motor as it mounts in the transom. Trimming the motor all the way down like truth said should eliminate porpoising, but you should be able to trim it out without porpoising. If it is then I think the motor needs to be lowered.

[Savage Brewer]

Curious, try putting 200 pounds way up in the nose and see if it still does it.

A friend of mine had problems, with his, and then when we installed both batteries up front along with the trolling motor and moved his anchor up front it went away. The boat was designed to have that extra weight up front

Usually I would lean towards weight distribution.

Do you usually load all your gear and boxes in the back?

Otherwise, I would go talk to your alumacraft dealer.

[Ufatz]

Highly improbable they removed the bottom to repaint it!!

Weight distribution.

[reelguy]

Thanks for the info guys. I was leaning towards the weight distribution but I don't have that heavy of stuff in the back that it should make that much of an issue. I will have to try and move some stuff around to see. I also tried filling the front livewell to add water weight but that didn't do a ton. As far as the bottom goes, they did something because the rib looks like it was pealed back with a can opener and pounded back. Maybe it was to get paint underneath for some reason? I don't know but looks bad from below and kind of irritating. Thanks again.

[Savage Brewer]

Did a dealer do this work? Or Alumacraft at the factory?

Really doesn't sound like something Alumacraft would do.

[reelguy]

Alumacraft did the work.

[Ufatz]

If the bottom of your boat looks as bad as you describe it you have a REAL beef with the people who did that job. Based on what you tell us, that is just NOT the way a simple boat repainting is done. You'd better havea talk with somebody in management and send them some photos to get the conversation started.

[PerchJerker]

You should also talk to Alumacraft about the porpoising problem. Years ago I had an Alumacraft boat that I didn't think ran quite right. Brought it in to Alumacraft. They didn't like the way the dealer had it set up on the trailer, they made an adjustment to the trailer, made an adjustment to the hull, and it ran much better.

[Moose-Hunter]

What I believe Alumacraft did to PerchJerker's hull is what they call "peening". What happens is they open up the seam at the bottom of the transom just a little bit with a wide chisel and mallet. Enough to create a make shift "trim tab", if you will, typically the full width of the hull. Sometimes it was done a little on both sides leaving the middle "flat". Essentially this purposefully puts a slight hook in the hull forcing the bow down. Hoping it eliminates the porpoising.

Alumacraft has known about this issue for YEARS and thought they had it licked with the 2XB hull... I had a 2011 Trophy with a 150 Yamaha and T9.9 kicker that bucked worse than the mechanical bull at Gilley's. The only thing that slightly helped was to raise the engine one hole on the transom. Less drag, less stick and release. ie: Less "Flipper". Did that, redistributed all my equipment, added bow weight, removed stern weight, relocated the battery, peened the hull slightly... Even threatened to install hydraulic trim tabs! My final, cure all fix...

A 2012 Lund 1875 Pro-V.

In my humble opinion, after throwing a fist full of dollars at it, all the new props, adding parts... I feel the Alumacraft 2XB hull has a severe design flaw the doesn't permit decent performance in a 18' or less configuration. Longer... Yes. But not the 175 series.

If she's still there, Talk to Dakota in Alumacraft customer service. She's a sweetheart to work with and I felt she had an honest concern for my problem. The techs and engineers... not so much.

Best of luck with your quest!!