Jet drives & jack plates??

[ted655]

I'm moving to an area where the water is thin & some mild rapids will be encountered in summer months.
I'm looking at putting a jet kit on my OB. They recommend raising the motor 6".
That means a jack plate. So...., before I go picking a plate for this 50 HP Merc, I thought I'd ask advice. My main question is the setback. Because it's a jet drive, will a longer set back, (fresher water supply), be of value? A 5,6,8, or 12"? If I get a 12" setback, can I then raise the motor, (sometimes) up behind the bottom of the boat, counting on that extra pool of water? Not extended running, but just for "spots".
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The boat is custom, welded aluminum plate. Flat bottom 20' skiff, I've no worries about the boat, so's not to start a tangent thread.
.
Thanks.

 

[kynolan2183]

Re: Jet drives & jack plates??

Remember that on a jet you are going to loose 33% of the horse power.
That would put the 50hp at the performance of a 30hp.
Seems kind of low for 20 foot skiff.

Look at the plate on your boat and find the MAX horse power allowed and multiply by 66%. That number will be the minimum for the boat and if it is lower than 30 hp then you will be fine, it not then I would not put the Jet foot on the motor or you will be very unhappy.

Kyle

 

[ted655]

Re: Jet drives & jack plates??

Thanks. There is no plate on the boat. It's custom built. I knew I'd lose the 30%. It will be OK. 35 will more than plain this boat.
One of the suppliers just replied to me. They advise to keep the set back as short as possible. In fact they advise a short 12" wide plate be added to bottom of hull, to extend completely back to intake.