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I have finally decided to repower my '86 17' Montauk and am waiting for the new 90 hp Yamaha four stroke to arrive, which is going to take at least another week I am told. Does anyone have any experience with installing a jack plate with this setup - if so please share it because I am trying to decide whether or not to do it myself. In addition, please let me know how you like the engine on this boat. Thanks to all.

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Unless you have a specific need for a Jack plate and know exactly what you want from a Jack plate, then there is no need for one.

Tell us why you need a Jack plate.

You are already adding a fairly heavy motor and installing it on a Jack plate will make the motor sit back even further possibly bringing the bow up more.
See these weights.
http://www.whalercentral.com/articles...ticle_id=5

Hopefully you never plan on putting on a kicker as your transom would already be maxed out.

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I do a good bit of shallow water fishing, and I have heard jack plates were useful for drafting less water when on plane. I know that engine is heavy, but I really wanted a four-stroke Yamaha after fishing on an offshore boat that uses them and has had zero problems over the years. I hope it performs well.

I have also heard that jack plates can help performance and efficiency. They also look really cool...

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I just put a CMC powered jack plate on my 1986 Montauk which has a 86 Merc inline 6 90hp which weighs about 315lbs I believe. I also have a 6hp Kicker that weighs about 60lbs.

The jackplate so far has raised my top speed from 39mph to 43mph, If I went higher in prop pitch I should be able to go above 45mph.

Of course running shallow is much better, I can clear the skeg from the bottom of the boat with just a little tilt with the jack plate full up and maneuver well in less than 12" of water, and in deep rough water I can put the motor back down to get better bite.

I can perceive no change in my static trim from before the jackplate, which weighs in at 45lbs, but I did move my battery from the rear of the boat to the console and added a second house battery in there as well.

IMO a powered jack plate is a great upgrade for a Montauk making an already versatile boat even more so, especially if your like me and run very shallow regularly while still going near offshore.

Only issues I had with installation where having to nib off some aluminium corner on the frame to fit between the splash well drain tubs as one of my drain is closer to the centerline than the other by about 1/8". Also I had to extend the power wire from the unit so I could mount the relay's in the console, CMC makes it long enough to put them in a rear bilge area, which the Montauk doesn't have, or inside the motor cowling, which I didn't want to do.

Also be sure to get a water pressure gauge for the motor, you want to be able to monitor it to see how far you can raise the motor on plane before water pickups suck air, in my case I can lift it about an inch below max height on a plane before water pressure starts to fall off.

I did the install myself with my engine hoist, it's not a difficult job so long as you have enough slack in your steering/rigging to handle the extra setback and lift, otherwise you get in to new cables, etc. I ended up drilling new bottom holes for the mount bolts as my motor was rigged kinda strange from the dealer.

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If you are not going run a modified lower end with low water pickups, be careful. I've seen a lot of burned up impellers and more than a few toasted motors from running powered jack plates and stock pickups. A water pressure gauge is a must IMO. Running straight with good pressure and the motor high on the jack will quickly change with even a slight turn.

I ran a Bob's Machine Shop jack plate on my Maverick flats boat. Its a great addition but as I've gotten older and wiser I make much more of an effort to avoid shallow conditions while under power. If I don't have more than two feet of water under my boat, I just don't have any business running my engine and risk disturbing the bottom and fragile ecosystem. Even being able to clear the bottom with the skeg still causes damage to the bottom from prop-wash when moving on plane. Being able to jump through eight inches of water while on plane just isn't my game these days like it was when I ran charters back in the 90's.

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As a F90 Yamaha four stoke owner with a 6hp kicker on my Montauk, be careful about how much weight is back there. I believe the F90 weighs in at 369lbs. With the kicker mounted, waves come right over the stern if you are not careful. I have 2 batteries in my console am considering moving my gas tank in front of the console.

I have gone through 3 different kicker engines to wind up with the 60 pounder (2010 Yamaha - 4 stroke) I have now. I cannot imagine adding another 45 pounds back there. Fortunately, with my quest for my ideal kicker engine, i managed to double my money on the 15hp (120lbs) and 9.9 (98lbs) Yamahas that didn't work out. Gotta love Craigsist!!!

The weight in the stern really changes the way that the boat handles.

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Listen to mb466. Too much weight in the stern can ruin a great boat. The Yamaha F90 is a very heavy 90. I would not put it on a jackplate at all; it will only upset the weight distribution even more.

I would bolt the motor to the transom as high as it can go, use a good prop (like the Stiletto Advantage) and avoid having a kicker motor at all.

Moving the battery(s) to the console will help.

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It would be very interesting to see someone actually weigh all of the current 90 HP engines on the market, as they are actually installed on the boat. That would include oils and SS prop.

My guess is that you would be shocked to see the misrepresentation on ALL of them.

Yamaha in the past has been recorded as being a big offender on weight. A Bass boat mag weighed one of their 225HP V-max HPDI engines and found it to be 60lb heaveir than advertized!

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Larry -- That is amusing. I have heard you repeat that story several times. The weight you cite seems to change each time. Once you said the Yamaha was 40 pounds over. Another time you said it was 45 pounds over. Now you say it was 60 pounds over.

What you fail to mention is that the magazine, Bass & Walleye Boats is no longer in business and that furthermore, before they folded, they had to print a retraction where they admitted they got their weight measurements wrong.

At any rate the motors weighed were not 90 HP motors like stover86montauk is putting on his Montauk. Thank goodness he's not getting a Mercury FourStroke 90; that thing is a monster, MUCH heavier than the Yamaha F90. It has to have the worst power/weight ratio of any 90 HP outboard ever made.

I drove by one yesterday in downtown Seattle. It was on the back of a very nice late 1980s Montauk on the way to the ferry terminal. I had to do a double take because it was so huge and at first I thought somebody had put a 200 HP motor on a classic Montauk!

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Thanks for the help guys. I think I'll take the advice and go without the jack plate.
I am installing hydraulic steering as well, which I am also excited about, even though it may not be worth the money.
I'll be sure to post a photo when it is all rigged. It should look sharp; I have refinished the teak.

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Good. Just be sure to mount the motor HIGH on the transom and use a good prop.

The Yamaha Performance Series three blade, Turbo 1 and Stiletto Advantage would all be good choices.