Porpoising issues on triton 176v magnum...any help appreciated

[CBrake]

I have a 2003 Triton 176v magnum with a 2017 115 4 stroke pro xs. I've had several motors swaps and prop changes and the boat has a bad bounce when trying to lift. I'm currently running a 19x13 solas SS 4 blade with a 4 inch manual jackplate at 5.75" prop shaft to boat. Speed is good, 49.8 at 6000-6100, Me and 25 gal of fuel and normal gear, still bounces at mid range, but can work it out at wot. Add a passenger and its very hard to get past the bounce. Not worried about speed, but I'm looking for ride without as much porpoising. Moved weight all around the boat, and it didn't change anything. Motor to low? Too high? Prop? Any help or direction would be appreciated. Thanks

[alanhore]

I am gonna say to low, but hopefully others will chime in also.

[176mag]

I have a 2002 176 magnum with a classic 90 Mercury no jack-plate, 22 laser II prop. Motor is mounted in the third hole up(fairly high). On issues with proposing is if you over trim at mid Range speeds. If I starts proposing increase throttle or trim down. That stops the proposing. The 176 Magnums are trim sensitive.

[CBrake]

Thanks for the advice from you both, trim is very sensitive with this hull. I’ll move up on my jackplate and see what happens.

[TheSilverFox]

Do you have a water pressure gauge? Wouldn't be a bad idea if you're trying to optimize performance to get one. Motors aren't cheap anymore.

[CBrake]

Yes sir, it showing 30+psi at wot

[gatorglenn]

Yes sir, it showing 30+psi at wot

Keep moving up until it helps. But I would stay somewhere between 18 and 20 psi. Some may go lower, but I don’t like to.

[tcesni]

I have a 2002 176 magnum with a classic 90 Mercury no jack-plate, 22 laser II prop. Motor is mounted in the third hole up(fairly high). On issues with proposing is if you over trim at mid Range speeds. If I starts proposing increase throttle or trim down. That stops the proposing. The 176 Magnums are trim sensitive.

I second this post. When I owned a 176Mag I also had my motor (90 Opti) mounted on the 3rd hole and had little issue with bouncing unless I over-trimmed.

[richg99]

Smart Tabs

[Original Tin]

You might also check your hull bottom. Sometimes a dent or depression near the stern can cause proposing and other issues like excessive prop cavitation. The depression might even be minor to the point its almost undetectable with the naked eye but the negative effects of such a depression can be drastic. Examine your hull closely...use a straight edge to be sure your hull bottom is flat and smooth.

[madtackle]

Just sell your boat to me and I will fix it! I regret selling my 176 magnum and now they are hard to find one in good shape

[GeauxTide]

I had a Lowe 18HP, which is a descendant of the Triton. Only way it stopped porpoising was an 1/8" welded bead on pad and 1st Step. It was still trim sensitive and would not lift the boat past the console.

[CBrake]

Doesn’t appear to dented, but I’ll check with a straight edge. Would like to tell all of you thanks, and to Trent @ Clark Marine in Franklin Tn for his assistance, their service is top notch.

[richg99]

Seriously, go to the Smart Tabs site ( http://nauticusinc.com/smart-tabs/ ) and watch the videos.

I've put them on three different boats and had great results on each one. Now, I won't say that fully adjustable tabs (Lenco/Bennett) aren't better in many ways. But, for simple "stop the porpoising" issues, the inexpensive Smart Tabs do the job well. You will also gain the ability to plane at slower speeds; the ride will be better, and you won't lose any speed. At least I didn't. Properly adjusted, they are the best addition I put on any of my boats.

[Original Tin]

Seriously, go to the Smart Tabs site ( http://nauticusinc.com/smart-tabs/ ) and watch the videos.

I've put them on three different boats and had great results on each one. Now, I won't say that fully adjustable tabs (Lenco/Bennett) aren't better in many ways. But, for simple "stop the porpoising" issues, the inexpensive Smart Tabs do the job well. You will also gain the ability to plane at slower speeds; the ride will be better, and you won't lose any speed. At least I didn't. Properly adjusted, they are the best addition I put on any of my boats.

This is good advise... I've heard nothing but good about Smart-Tabs and they would probably solve your problem. You might also look into a custom hydro-foil for your lower unit. A BBC member by the name of Chris Bailey makes a really nice SS one for just about any application. Here is a link to his Profile page...cbailey And here is a link to his hydro-foil thread...foils for sale.

Chris made an aluminum one for me and it works perfect... He's a real good guy.