Okay, I've got a 15ft xpress jon boat with a 15 hp johnson outboard.

In order to reach optimal performance I need to jack up the outboard 2 in.

Is this worth considering getting a fixed jackplate? Would I see any significant speed? I find it hard to really think so but that is why I am asking you folks.

I am also in the shallows a lot so that would be another reason to consider raising it.

Thanks for any input!

I just don't think there's enough potential in a 15hp engine to warrant a jackplate. I feel like a 1-2 mph increase would be a huge accomplishment for that. For instance, I installed a 6inch adjustable jack plate on a 18' aluminum boat with a 90. After playing the height to find my sweet spot AND playing with different props I only gained 5 mph. Also caused the boat to be more proned porpoising.

Explain to me what your consider optimal performance? That boats should run no more 23 mph. No porpoising. And raising the motor up two inches would help much on preventing hitting things in shallow water. Just think, once on plane in that boat, your drawing minimal water on the transom, none at the bow. You get within two inches of the gearcase with a stump, you'll find a higher one in just a second that will throw you out of the boat.

No porpoising at WOT, highest point of recommending RPMS, and top speeds around 23MPH, that will be optimal performance for that boat.

What I am really wanting is to be able to go shallower and hopefully get a tad more speed. Right now with just me i get around 21 mph. I will try and post a pic up possibly tomorrow.

Well regardless of what people will tell you, and outboard is not designed for super shallow water. Three feet deep in soft weeds, yea sure. Throw stumps on that equation and no way. A gearcase will run you a lot of money, depending on the motor. Plus you start sucking up debris and ruin that water pump, you'll be paddling back. The really only way is with a mud motor. It really dependent on the body of water you are boating. But I also forgot to mention that with raising the motor, you risk aerating the prop and the inlet screens for the water pump, which will cause poor performance and overheating.

The only time a jackplate is going to really help with shallow water is if you have a tunnel hull and then you have to start looking at low water pick ups.

Hevishot, I went out today and jacked up the motor with a short 2x2. The clamps are still gripping the transom well.

Do you see anything wrong with doing this granted I do a good job of securing the motor? I want to just see if there is any difference in performance, especially before considering jacking it up permanently.

This is where it's sitting on top of the 2x2 and I used a straight edge to show where it is in relation to the bottom of the boat

measure your transom height and measure your midsection height. Their is a shortshaft and a longs haft shorts haft is 15" and long is 20".

Th marine Mini jacker jackplate will fix you problem if you only need 2".

That looks like a 20" shaft motor on a 15 or 16" inch transom. If so, the motor isn't right for the boat. That's why you feel like your performance is suffering. Running it on a jackplate will not help it, you need an elevator. It will raise the motor higher on the transom, without scooting it away too much. A jackplate will scoot the motor too far back, putting the gearcase in the turbulence of the wash of the boat, causing overheating. I don't care how much performance you think you'll gain with a jackplate, over heat it and you'll put a rod through the cowling. John boats do not do well with a jackplate unless it's built with a pad or a step hull, which yours is not.


You need a 20" transom boat, or a 15" inch motor

The serial number says J15RSDR. I always thought it was a 15" shaft but I could be wrong. I can't find my dang tape measurer at the moment either.

That mini jacker was what I was thinking about getting if i decided to raise it. I didn't realize the set back on a jackplate would do that. I would be fine with just elevating it if need be.

Here's another picture. Maybe yall can get a better idea of whether is a short or long shaft.

That LOOKS like a short shaft on a 15" transom to me, hard to tell in that pic though.

What width is that boat, 48"? If it is, my advice would be to sell that 15 and go with a 25. In all honesty, that's gonna be the only way to safely give you the performance your looking for. The motor you have could sell for 1000-1200 dollars realistically, and you could use that towards a 25. There's a guy on here selling a 25 2-stroke yamaha that would be ideal on your boat if its a 1548. That would be the best thing to do in my opinion. May not be what you want to hear, but it's the truth.

If it's not a 1548, and is maxed at 15hp rated, your stuck with what you have, but just a warning, those clamps in your pic are not safely secured. That motor will come off in some point, you better bolt it through the transom

It's a 1546 rated for 25 hp. I have definitely thought about going to a 25! I know I would be happier with a 25. I'm glad you mentioned the clamps. I might just take that 2x2 off and put it back like it was. It's a great running motor. Just gotta decide if the juice is worth the squeeze. Besides being a little underpowered I don't have any complaints with it.

It's a short shaft.

The TH Marine mini jacker will do what you want and not cause any issues.

get you a 25 buddy, that's what I would do. either a 2 stroke 25 yamaha, or a 2 stroke 25 Mercury, 1995-2001 era. Thise are two of the best little motors that have ever been made. I would rather have a 2-stroke over a 4 stroke for the weight difference. A 25 4 stroke yamaha will weigh around 170, where as a 2 stroke will weigh around 115. big difference in the weight on the transom. Less weight on the transom, the less it squats in the back, less it draws water, the faster it is to an extent. Plus the easier to get on and off by yourself. A 2 stroke has better hole shot than a 4, top end is almost the same, the only draw back is that it will use a tad more fuel, but you'll only get around a mile less distance compared to a 4 stroke. And their cheaper, but harder to find.