Motor Height Setup Question

Hello All,

Looking for some input. I just purchased a Lowe Roughneck DT17 with the 60hp Mercury 4 stroke. The boat is porpoising at about 19mph/half throttle with trim all the way down. If I put someone up front its better, but still can't trim up at all. Cavatation plate is about 1" above the bottom. I have 2 batteries and 6.6 gallon tank in the rear. Trolling motor and tackle up front. Do I move the motor up or down? Thanks

Honestly, I don't know/run those jon boat hulls at all, so I'd ask a Lowes dealer ...

There's a lot of variables that can exist, but I will try to help. Some people use trim tabs, some intentionally put a hook in the rear of the hull and some just put gear up front and trim the engine down until the bow digs a trench in the water.

I would bet your engine height is pretty spot on. I dealt with this with my little 25hp Yamaha on my 1448 and it was even worse with my 50hp Merc I run now. I tried running it on the bottom trim setting with all the weight up front and although that worked it handled like crap and knocked about 10-15mph off of top speed. Not to mention I don't always have gear or a human to put up front. My hull needed a hook or tabs plain and simple. After a few weeks of tinkering I finally ran it flat out yesterday and with me and one Gatorade on deck I ran 44mph flat as can be with the boat sitting on the very last few inches of the transom. My hull bottom extends about 3 inches passed the transom and I simply utilized that as a trim tab and BARELY bent them down. Maybe 3 degrees. It transformed how the boat rides and handles though.

Although your boat is rated for the 60 its still a heavy engine (260 pounds I think on those 4 strokes) You might try balancing your gear towards the front as most seem to do, but you still might not ever be able to trim it up to an optimal setting.

That hull flat or does it have some deadrise? Couldn't see that detail on the Lowe website.

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Lowe has a hull issue, you better smack those two tabs down pretty hard on the back of the boat and hope that is enough. I had a 2060 for a while and had to make additional trim tabs and I had two batteries and a 16 gal fuel tank all the way in the front and it was still terrible to I made the additional tabs.

Weldorthemagnificent said:

Hydrofoil stabilizer

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If considering a foil - and I endorse them on V-hulls (just have ZERO experience with jon boats) - get the SE Sport 200, as it is the best rated foil/fin for performance.

byrn71 said:

Hello All,

Looking for some input. I just purchased a Lowe Roughneck DT17 with the 60hp Mercury 4 stroke. The boat is porpoising at about 19mph/half throttle with trim all the way down. If I put someone up front its better, but still can't trim up at all. Cavatation plate is about 1" above the bottom. I have 2 batteries and 6.6 gallon tank in the rear. Trolling motor and tackle up front. Do I move the motor up or down? Thanks

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Sounds like a lot of weight in the stern. 2 Batts and 6.6 gals of fuel could weigh 200+ lbs.

My Lowe 1652VT is a jet tunnel hull and it had a 40 prop motor on it when I got it. It would porpoise pretty bad at 2/3 throttle. I sold the prop motor and got a 60/45 jet and it porpoised with that motor as well. I ended up putting the transom wedges in and that got rid of most of the porpoising. Then a year later, I moved the center console forward and put the battery under the console and it runs fine this way.

Agreed w/ above -- between a 60hp 4 stroke, fuel & batteries you're very *** heavy. Shifting weight forward would be your best bet, any other solution is to add drag to the rear of the boat in one way or another.

If redistributing weight isn't an option or fails you can add drag by lowering the motor mounting position so the gearbox sticks farther below the boat without purchasing tabs or beating a bend into your hull (worst option of all IMHO.)

After the free fixes I'd turn to a foil before tabs.

They're still using an old hull design. Way back when, a 60hp motor barely tipped the scale at 200 lbs. What's a new one? 250 lbs+? And the hulls are mostly the same as they were 15+ years ago.

You can fix it but you'd have to do some work. Try this. Get a bunch of JB weld, and put a "bead" of JB on the very end of the hull, where the transom/stern meets the bottom. All the way across, only needs to be maybe 1/8" thick bead. This may take care of it. I removed the biggest part (not all of it...just about 3/4 of it's thickness) of weld bead on mine (war eagle) and got a small porpoise on certain water conditions, but also picked up 3 mph.

Propping can sometimes have an affect too. What's your max RPM at what speed?

Something else worth considering. On the motor's mounting bracket. On the smaller manual tilt motors, e.g. 9.9-15-25, etc, they had a pin you could pull out and move "in" or "out" to change the "trim" angle. With PT&T, you'd think that it's "set"...but on some motors, you'll find a pair of allen head bolts with nuts in a similar fashion as the old trim pin would be. Sometimes a dealer will move those bolts to where he thinks it might need to be, which might be too far "out" or "in". If your motor has those, look and see if maybe they can be moved down a hole. I had a Mariner on a bass boat that had two stops where the trim rods would contact and I found that those two stops were "shimmed" out a little so it would trim out more than it was originally designed. I felt this worth mentioning just in case a dealer may have set yours up this way.

I just recently installed a bobs versa tilt and jac plate with the hydraulic tilt and manual jac on my 1546 Lowe today which is powered by a 2018 25 mercury with a 12.5 pitch prop the entire jac plate with pump weighs about 60 ponds. I tried the Boat out for the first time today and im having a few problems after installing it. My performance has been cut in half it seems like before the jac plat I was able to run a consistent 27 mph loaded at wot. Now with the motor height set 1" above the transom as it was before the jac plat my time to on plane is longer my top speed was barley 26mph with very very very little cavitation while planning and at wot I'm getting a lot of spray and the power trim doesn't seen to work when up on plane the motor wont trim up and with it trimmed all the way down it's porpissing like crazy. The boat rigged from Lowe has two battery's and charger and now a bobs hydraulic pump for the trim and tilt rigged in the back of the boat and the 6 gallon fuel tank strapped down up forward just behind the casting deck and on the bow I have a motor guide trolling motor. I am seeking anyone who has any knowledge on how to go about dialing in a jac plate for optimal performance. I greatly appreciate anyone taking the time to read this and respond.

Thanks

Marty.