Installing a jack plate questions

[learningasIgo]

Some of you know that I am in the process of acquiring all the items (okay, the major ones that I'm not forgetting at the moment) to put together my boat project for this winter. It is a Voyager 1670 flat bottom jon that will have a console, front and rear deck, pedestal seats, live well(maybe 2), fish finder, gps, trolling motor, etc. This boat will be set up to run two different motors - a jet for the river (we have some pretty shallow water) and a propped motor for the lake. I know some will say to just set it up and run one motor, but bear with me if you will please.

The propped motor that I am planning on running is a '56 30 hp Evinrude Lark long shaft. The jet motor is a '71 Johnson 20 hp. Long story short, I am considering installing a jack plate as I am sure the two motors will need to have different heights and I know I will need to raise the Lark to accommodate a short transom and a long shaft motor. So here's the starting questions:

Would a 5" jack plate be appropriate for me?

Should I plan to get a jack plate with power trim?

What is the "proper height" to set the motor at in relation to the bottom of the boat transom (call me ignorant, but is this referred to as the keel when talking flat bottom boats??)?

I was reading another thread about motor adjustments with jack plate, prop, trim, etc, and "smart tabs" kept being recommended. What are they?

Thanks for the help guys.

 

[metriccrescentwrench]

Re: Installing a jack plate questions

IMHO a 5 or 6 inch jack plate would work well for what you've got in mind. If you can afford it a hydraulic jack plate would be great, but you'd likely do just as well with a manual one and put a couple of index marks on it so you know where to position it for either engine.

In general most people say to place engines so that the AV plate is level with the keel, but that's not necessarily the case when you're running a jackplate. Since the prop is further aft and in "cleaner" water you can run the prop significantly higher which usually results in less drag (and higher speed) and better handling. For instance my 18-1/2 foot Checkmate with a 200 Johnson has a 6 inch jackplate which allows me to run the centerline of the prop at 2 to 3 inches below the pad (that's WELL above what's "normal") - but if you try going that high make sure you've got good water pressure. You'll just have to experiment to see what engine height works with your particular boat/engine/prop combination.

Smart tabs are like trim tabs on each side of your transom that will help to keep the boat level at speed, and maybe get it on plane quicker. I don't have any experience with flat bottom boats so can't say if trim tabs would help you or not, maybe someone with first hand experience will chime in on that.

 

[learningasIgo]

Re: Installing a jack plate questions

Thanks for the reply. Was just wondering if anyone else had some input on this.