Very touchy to get Lund 115hp on plane properly

[Iluvfishin]

I have a 2005 Lund Pro-sport 1700 Adventure with a 2004 Yamaha 115 four stroke. I have to have the motor trimmed down very far to get it to plane and once it's on plane it's about one small touch up on trim button and it starts jumping or one small touch down and it feels like it's plowing the bow... Just got the boat and my old tri hull didn't really matter where I had it it rode smooth on plane. Is there a special trick or are they all that touchy? I already put a fin kit on the leg and it seemed to do a tiny bit but not much.

 

[WIMUSKY]

Sounds like you're tail heavy. The 4 stroke is making it worse. Move as much weight forward, if you can... I have the same issue, different boat. If my daughter sits in front of the helm I can trim up a lot more with 3 of us in the boat and she only weighs 120#s. I'm thinking of filling my forward livewell, it's 20 gals..... I have a 4 stroke too, just smaller.... My gas tank is too far to the stern too. I can't do anything about it tho.... Crestliner has since fixed the tank placement....

 

[Brian 26]

Sounds like you're tail heavy.

I was just about to say the same thing. I driven that same set up (except a crestliner hull) and not had an issue.

 

[Iluvfishin]

It is rated for that engine. (Max tho) getting it on plane isn't the worse. It's just so finicky with it having to be perfectly trimmed to plane without jumping. Is that because it's too tail heavy as you say? Would a better fin on the leg help at all? What I've got now is a cheap one. Even if I have my passengers sitting in the bow is still hard to not make it jump like a kangaroo while on plane. Is possible but very touchy.

 

[smokeonthewater]

Ditch the fin and get smart tabs... It will be a whole new boat guaranteed.

 

[Mi duckdown]

Get rid of the fin. proper trim and speed is the answer

 

[Watermann]

Does the motor have a trust bar on it that could be set too high?

Smart tabs add planing surface and nearly eliminate any porpoising while the fin thing not so much.

 

[WIMUSKY]

If you had people in the bow and it does the same thing, that eliminates the tail heavy issue. How about a pic from the side showing the AV plate on the motor and the transom? May need to adjust the motor height....

 

[snowman48047]

Get the fin off the motor. Adjust the motor height so it is correct. Post a pic if you can. There is no way that this boat needs trim tabs. There are thousands of 17' boats around with max hp without having porposing issues. Maybe I'm totally wrong on this but if weight distribution doesn't matter then there is something not right. Water in bilge maybe. Hook in hull?

 

[Teamster]

Might need a lower pitch prop,........

 

[Alumarine]

I think we need a picture of the motor in the full down/in position from the side with the boat out of the water.
I don't think the motor is trimmed down/in enough.

 

[Iluvfishin]

No Title

Here is a pic. Is the angle good enough? This is with trim all the way down. I have a 17p prop and it takes off like a scared rabbit but I think it revs way too high at WOT. But that I don't think should affect the jumping?

 

[Alumarine]

It looks like it would trim in enough and also the height looks good.
Try it with the tail off and see what happens.

 

[smokeonthewater]

Order the smart tabs.... You will LOVE em.... There are naysayers EVERY time this comes up but each time they actually get installed on the boat the response is that of a thrilled boat owner.

 

[mdunn]

I have a 17.5 Smokercraft and smart tabs made the boat so much more drivable and slowed down dramatically the proposing.
BUT you should check the motor location for optimum height by running a string or straight edge on the keel and seeing where the cavitation plate is in relation.
Should be even or 1" above I believe
I have same motor by the way
I just think any aluminum boat that size with that hp will hop like a bunny.
Smart tabs helped me tremendously

 

[Watermann]

Motor placement looks good although from the angle of the pic it's tough to be 100% sure.

So if the motor is set correctly then it comes down to stern weight.

I agree with the smart tabs solution for being stern heavy. My Chief has an 800 Lb load just with the V6 motor and outdrive. Obviously it's a different application between IO and OB but with the smart tabs on I can't make the boat porpoise, the exhaust starts growling up out of the water before it even thinks about starting to hop.

 

[smokeonthewater]

Looks like you MIGHT be able to raise the motor on hole.... Hard to tell from that angle.... Try it and see if it runs out better and doesn't start ventilating in turns.

 

[Teamster]

I'd be inclined to try a stainless steel prop,...

 

[Iluvfishin]

Is there a certain brand of smart tab I should get? I had the motor 2" higher to try it and it seemed a bit worse. It does a bit better on turns far as ventilating with it lowered as in the pic.

 

[mdunn]

Here's the link to Nauticus and their selector tool to pick the correct smart tabs for your boat.
http://www.nauticusinc.com/smart_tabs_sx_price_list.htm