Need help w/ new motor setup

[MikeEiden]

delcecchi I thought the same thing as you. I tried moving batteries around one day without any change. Trim can influence it and that's where I'm concerned with how things are set up because I don't see why I have to run with my motor pretty much full trimmed in everywhere. I can trim out some and see some gains but it isn't long before the bounce comes. That part is irritating but the hole shot, well that's just down right disappointing.

Boatfixer thanks for the great info. Is a brand/type of prop you would recommend that would lend itself to these traits?

[MikeEiden]

Tried a 17 pitch aluminum prop today. Made a pretty good difference in hole shot. Lost a few mph but it was nice to actually get up on plain in a reasonable time. It was just me in the boat but I can live with this hole shot. We'll see how it goes with the family in there. Still got the bounce but at least I'm getting in the right direction.

I have some pictures of the motor height if someone can help me out in posting them. The cav. plate is right at the bottom of the 'V' so it's not as high as I first anticipated. I'll let you experts advice on this area.

[boatfixer]

Email me Mike

[311Hemi]

MikeEiden, Can you take a picture in the driveway? Trim the motor all the way in, have a helper place a straightedge at the bottom of the hull out past the prop. Post the picture here. That will identify the mounting height of the motor, the cavitation plate location, and the angle of the propshaft relative to the bottom of the boat. We can take a shot at the problem with that information.

Trimmed in:

Trimmed in (2):

Quarter trim out:

Trimmed in:

[311Hemi]

Mike a couple thoughts:

1) I would have to check my trim level at home as compared to my gauge, but since you said you have never been able to trim out very much even with your old motor (assuming your going by the gauge when you say 1/4) is it possible your gauge could be reading funny? Or is this by feel that you say you can't trim out very much. Maybe a dumb question, but I assume your motor trims pretty slow but with tilt much faster once it reaches a certain level?

2) If your prop is cavitating when you are trimming up and give it more throttle, a SS prop should resolve that. I had an aluminum 17p Hustler that would cavitate bad if I tried to trim up much at higher RPM's. The SS prop resolved that issue completely.

3) I believe your hole shot would improved with the proper SS prop as well.

4) Not very experienced with porpoising, but if it were me I would probably try putting at least 100 lbs in the very front of the boat to see if that helps anything (no additional weight in the rear other than you), and then I would try moving the engine up one hole (only after adding a SS prop). After seeing how both of those react, if raising the engine did not do anything I would look at trying the wedge on the engine.....they are not very expensive. I have also read of people using the hydrofoils to cut down on porpoising, but that requires drilling holes if I remember correctly.

[hydro]

Mike,

Some things from the pictures:

1) Motor height looks fine, and I would not change it for the sake of solving this problem. Trim also looks workable and I would not try to trim too far up with your rig. Note the bottom pic where the top blade of the prop is above the bottom line. It is not designed to do that and will lose bite if trimmed too far up.

2) The prop also looks like it does not have much rake, and it is not cupped. As Boatfixer said above, SS props can carry more bow load and do so by keeping a bite on the water. That should lessen the porpoising problem.

3) On the steering torque issue, you have a trim tab behind the prop and that can be turned a little bit sideways to counteract steering torque when necessary. Save that for a final adjustment.

4) Last, as mentioned above, porpoising is usually caused by too much weight in the back of the boat. You mentioned family, so why not take a child out for a ride, having them try sitting in different places to experiment with load distribution. A good experiment and fun for all involved!

[311Hemi]

For comparison sake, below is my engine position at 75% trim and 100% trim per my gauge. I usually run optimal between these two levels. Not sure how different boat make would affect trim levels, but IMO your engine is pretty high for only being trim out 1/4 from the bottom on your gauge...assuming the picture position is not skewing how we are seeing it and the line I drew in your pic.

BTW, is your current prop or were any of the props you tried vented (e.g. holes like the one visible on the prop in my pic)? Venting can help with hole shot....something to talk to those prop guys about.

Trim up to 75%:

Trim up to 100%:

[gregg52]

hmmmmm thats quite a difference i run mine at about 34%

98% of the time unless i feel racie on flat water i'll trim it up

just to see how fast i can go for the fun of it

could be the difference in glass vs. tin

2 vs 4stroke

or horsepower vs. not horsepower....lol

[MikeEiden]

I think some difference is the transom angle between boats. The dealer said I had a pretty flat transom.

If anything I at least was able to see and feel the potential of the motor and I'm a little more enthusiastic about it. I hoping your guys are right about a different prop also helping with porpoising. I don't care if I can only trim it out to 1/4 I just don't like how finicky it is with the trim. I'm going to try and make some time to talk with the mentioned prop shops try some different things out.

Hemi, the only prop that was vented was my 19 pitch hustler prop. The 17 and 15 were both Solas. The one pictured is the Solas 17.

Hydro, I forgot about the trim tab. If I find a prop that works great but I run into the torque steer again I'll be sure to adjust/fine tune it.

[TR21HP]

Mike, why aren't you running a Merc prop on that motor? Try the Trophy or Tempest also. You will find a lot of people put Merc props on most every make of motor. They are basically the industry standard.