RT188 jack plate set up questions

[Klapointe17]

Looking for some input. I'm running a 2021 188 with a 90etec, 4" hydraulic jack plate & 19 pitch aluminum 3 blade. Before I added the jack plate the boat ran great, speeds around 38 with room for improvement, great hole shot, plenty of bow lift and no porpoise. Now, with the jack plate, I barely get any bow lift, porpoise when trimmed up and lose prop grip while running full trim/wot after just bumping the steering wheel one way or the other... what is going on here?

Side note/question... could my transducer location be effecting the "water quality" if it's mounted in line with the prop? I know this may be a stretch but I'm really trying to think of everything. Thanks!

[rangerguy35]

I've seen a lot of guys with RT boats say the jackplate did not improve ride or performance. Some even lost mph. I personally do not have a jack plate because of the negative stuff I have seem on them for my boat. I feel it isn't needed unless I want poles or for hydraulic abilities.

[Mechanic Bob]

I added a jack plate to my rig to get into some skinny water, not for performance.
I raised the motor up one hole on the plate.

I need to have my motor trimmed all the way down and jack plate down, at any speeds below WOT, or it will porpoise. (I do have the stern loaded with two Talons, Jack plate, 3 AGM size 31 Batteries, and cranking battery.)
Once above 5000 rpm, I can then trim the motor for top speed, just south 55 mph. I can then raise the jack plate if needed.
I have no idea if the jack plate improved or lowered the performance of my rig as I installed them before I ever had it in the water.

[GeauxTide]

I've spent a lot of time and money on Jack Plates and Props with only 2mph and squirrelly performance to show for it.. 1st - Change your prop to a SS 4 Blade and mount your motor to hole #3. 2nd - Sell the JP 3rd - Upgrade your electronics with the money from the JP.

[FloridaFlyer]

If you were running 38 on this boat without a jp...WITH A 90 HP MOTOR... That is pretty good. I would do a GT said above - sell it.

The jp will not get noticeable better speed on a 188, and as for helping with shallow water --- I don't think it will help a lot. I can trim up and idle through very very shallow water. I have nevervseen the need for one myself and believe me, Florida has the most shallow water of anywhere.

If it was me, I would sell it.

[bassfisher444]

How much have you adjusted the jack plate? It takes several adjustments to get it right. I would start with it in the lowest position and adjust it up in 1/2" increments until you lose speed or no longer gain speed, then move it down about 1/4".