hydraulic jack plate on this ?

[laki101]

got this boat,used to be a inboard, and is now converted for a outboard, I have a 150 EFI 2-stroke on it, a few monts ago, only drove it once for 20 min's , so did not really have time for some fine tuning and mesuring, waiting till spring for now :smow:
In the meantime I have found a great deal for a hydraulic jack plate, but my question is will I gain anything on a hull like this ? I have only seen jack plates on some flat speed boats, never on something like this, but if I can save fuel and/or gain speed by lowering/raising the engine depending on the weight of the load I would get the jack plate, but if its just a waste of money I would skip it so need some advice

 

[Chris1956]

A Jackplate will likely provide some gain in performance, IMHO. The amount of gain, and its value is still to be determined. I doubt that hull with 150HP will exceed 45MPH, with a Jackplate, so the question is "is it worth it"?

​You will adjust the jack plate based upon trim and speed, not load weight. You want to achieve as much bow lift and least motor drag as possible.

As you raise the jackplate, the bow lifting effect will diminish, so you will want to find the happy medium. A lot of that happy medium is based upon on how much bow lift that hull will allow.

One other thing. If you have a jackplate, the motor must be trimmed all the way down to start any planning. The jackplate may need to be all the way down as well. You must then trim the motor and adjust the jackplate each time. This will make the boat nearly undriveable for an amateur (wife, GF, friend).

I presume the transom has been reinforced to take the power of the OB?

My .02

 

[ondarvr]

Pretty much what he said.

You will be able to fine tune it, but it may not mean much on that hull with a 150. Frequently they end up being set in one position and left there, the minimal gain makes the hassle of adjustment not worth it.

But?if I had one, I?d probably put it on just to play and see what?s possible, then eventually lose interest if the gains weren?t big enough.

 

[Scott Danforth]

most jack plates are used to get into skinny water

 

[Texasmark]

I think it will benefit you since the engine is on a bracket so far astern. The water displaced by the hull starts rising to the surface as soon as it leaves the transom coming up on plane....for me the onset of "on plane" is right where the turbulent water at the transom starts to recede and form the V wake out astern of the boat.

With that said, as you come up on plane the transom is buried in the wake bad enough (sitting too deep in the water), but to have an engine mounted on a bracket a couple of feet farther back puts it so low in the water that water can and does come up and touch the cowling and all that lower unit in the water is excessive drag you don't need at that time, not to mention problems getting on plane in somewhat shallow water......like maybe as shallow as 3 ? -4'.

With a Jack plate you can (tweaking for best performance here too) raise the jack and keep it there until you are well onto the plane, and then when the rpms start to come up and speed starts looking like it wants to stay steady or fall off, drop the engine as necessary, keeping the rpms under control and the speed increasing.

I remember a guy with an OMC Ocean Runner or some special OMC engine/boat combination that was a special OMC setup that had just the problem I am mentioning. He had a real hard time getting on plane and engine problems and all that. We worked him to a suitable solution but he didn't have a JP and with his custom OMC arrangement there wasn't a place to put one.

I never personally did what I suggested herein, but if you think through it, it makes sense. Personally, I'd do it in a hearbeat, especially if I were running in 2 situations: 1. Big water....lots of following wave action, or 2. Boat full of folks and a couple of them on slalom skis wanting deep water starts.

 

[bajaunderground]

These guys hit all the points I would add. Max MPH is costly and to go faster means more costlier...IMHO in a hull design such as what you have, I wouldn't spend any money trying to increase my speed...once you find that "sweet spot", you'll always want to run there!

Sell the 150, take the capital and the capital you had slated for the hydraulic jack and get a 250 (or larger) OB and play with the trim...