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Thread: Jack Plates

  1. #1
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    Default Jack Plates

    Any of you guys running a river boat with the motor mounted on a jack plate?
    I am getting ready to have a new motor mounted on my Wooldridge Alaskan. I will be running a prop while we moose hunt but it would be nice to be able to run a jet the rest of the summer.
    My plan was to have the motor mounted on the jack plate for this year and then add the jet next season. The jack plate would permit the motor to be lowered enough to use the jet. Wooldridge tells me the jet loses efficiency if I use the jack plate because the motor is mounted further back and the water flow to the jet is disrupted. I can live with a little loss in efficiency.
    If I get the motor installed first will the holes for mounting the jack plate line up with the ones drilled for the motor? I dont want to end up with a transom that looks like swiss cheese.
    Tennessee

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    Default

    I have one on my 18ft Alweld. The guy that owned it before me made a plastic extention of the tunnel that is like 2-3 inches to make up the difference of the jacker plate.

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    Default hydraulic model

    I use CMC's hydraulic model on my 22' Alweld w/ a 150hp Yamaha. It works pretty well all in all. Your weight will be placed 6" further back, which does not seem like much, but that much arm x weight, does give a lot of momentum.
    Transoms do crack and bend with the set up I describe. Check with the shop you are doing business with and ask about previous known damage. Be prepared to beef up the transom a bit and/or use a rest or pole under the lower unit while trailering.
    Normally a small piece of aluminum angle is welded to the transom. Then you can bolt on a piece of uhmw or aluminum that essentially lengthens the bottom of the boat so that it comes close to the jet foot.
    In shallow water your motor, due to the angle of the boat, will ride a bit deeper in the water and you won't run quite as shallow as you would if the motor is bolted on to the transom. The difference is not much though.
    What I do like is that while running the prop, I can lift the motor once on step to reduce drag and the rpm too. I get better fuel performance that way. I also can run shallower this way too.
    I think the CMC lift gives a guy a lot of advantages.

  4. #4
    Member JOAT's Avatar
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    They are great items and I wouldn't run a larger skiff without one; of course that is a remote controlled hydraulic model with a dash guage that shows the motor position. The mounting holes do match the standard outboard hole pattern, so you usually don't have to change anything there. As mentioned, they push the motor back plus add a bunch of new weight. On smaller boats this can really mess up the way the boat handles. I've seen a couple cases of them installed on too small/light river boat and they ended up removing the jack because of the negative effect on your center of gravity. As for the jet, it's pretty easy to add an extension to keep the water clean. There are at least a dozen ways to accomplish that task.
    Winter is Coming...

    Go GeocacheAlaska!

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    Thanks guys. My boat is 23 feet long so I doubt it will affect the handling or weight balancing that much. I was concerned if I added the jack plate next year it would require more holes in the transon.
    Seeing I have to buy the motor soon and rig the boat with electronics ( its new) I just didnt want to add a nice jackplate till next year.
    Once I install the jet it will be on till moose hunting season. What are some of your thoughts on manual versus power jackplates?
    Tennessee

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    Default yessir on hydraulics

    I have only used the hydraulic CMC lift, and I like it. Mine needs a seal changed in it as it leaks a bit after 5 years, but it works well. I have blown a couple of fuses, but spares are a part of my boat kit that is under my seat in the boat.
    The CMC is not fast by any means. If you get in shallow water, you can not depend on the lift to move fast enough to raise the motor out of trouble. I have heard that there is a model used for racing that is quicker, but never looked into it to know any more about it.
    Once again, plan on a brace while trailering to reduce the load and subsequent damage on the lift.

  7. #7
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    Default

    I have the CMC hyd lift on my boat. What I leaned, is that you need 6 to 7 inches of travel, the height is very important for the jet and not so much for the prop. There is a place in Anchorage that sells a lift that is a special design it is made just for changing for prop to jet and allows for 7 inches of travel. Be aware that your engine cowling can be damaged if the jack plate is lowered and the engine raised, the cowling can contact the transom. You will need to use a longer splash guard. With everything there is some trade offs, for me being able to run a prop and carry the extra weight is worth the cons for me. I would get the Hyd because you can do the change over by yourself and it would also be easier to change on the river.

    Steve

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    Default good point

    Stid makes a couple of good points. The CMC that I use has 6" of travel. It is more than enough to trim out the motor for prop or jet. I ays start our Yukon River Safaris out with the prop unit on. Depending on our final destination I plan to change to the jet enroute. That would be pretty difficult without the hydraulic lift. Even for deep water destinations I take the jet unit so I have a "spare tire" in case something happens to the prop lower unit.
    The last boat we had rigged (by a dealer) was a 24' tunnel with 150 E-Tec. We were setting it up at the last minute due to some problems beyond our control and did not have time to run it with a load prior to launching for our trip. (go ahead, say it, BAD, BAD, BAD)
    The boat loaded, with a 19 pitch prop, could not get on step. We did get on step with a 17 pitch, but could not adjust the motor up at all, and the hole shot still stunk.
    Needless to say, we had to scrap the trip, go back to town, and start over. Be sure to give yourself plenty of time to test drive the boat with a load comparable to what you will carry for your big adventures.
    One other tip. I get schematics from the dealer of the lower units, both prop and jet, and the wiring harness diagram, and laminate them. I also write out a step by step procecure for changing the lower units out. I inlcude bolt head size and any other information that I might forget after 9 months of not doing this task. That too is laminated, and all of them, along with spare bolts and parts, live under my seat in the boat.

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    Default

    Great information, thanks guys.
    What should I expect to pay for a good hydraulic jack plate? I may just have it added with the initial motor install.
    Tennessee

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    Order one from cabela's and have them put it on when you have the motor mounted, it shouldn't cost that much more, if it does, put it on yourself, it is super, super easy. I say order one from cabelas as it will be $300 to $400 cheaper than buying one up here.

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    Default Price in FAI.

    I just called the Boat Shop in FAI. Their price on a CMC Model PL-65 5" lift is $850 FOB FAI. Install would be a couple hours. That gives you a starting point.
    They also said they are getting in a new model/style. It is supposed to sit closer to the transom and give more lift/drop. I don't know the name or other info. Call Mike at the Boat Shop to check it out.

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    What does FAI stand for?
    Tennessee

  13. #13

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    FAI = Fairbanks... I'm guessin

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    Buy this one from Cabela's, get the one without the guage, and put it on yourself before you get the motor mounted. It should take all of 30 min to put on.

    http://www.cabelas.com/cabelas/en/te...lift&noImage=0

  15. #15
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    Default

    The gauge is a very good thing to have. Once you find the "sweet spot" for prop depth on step, you can mark that position on the gauge and go right to it every time. My guess is the same principle would benefit your jet unit by knowing the right depth without any trial and error. You already have to run wiring to the console and mount a switch, so the little gauge isn't much added effort for the install.
    Winter is Coming...

    Go GeocacheAlaska!

  16. #16
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    Default guage or no

    I have never used a lift with a guage. I use rpm/throttle setting coupled with a gps. Not a bad idea to have it though. I do like my tilt guage on my Yamaha tach. That is nice.
    Yep, FAI = Fairbanks. Seem to always abbreviate it.
    Snowwolfe, if you are doing all of this now, you should be able to get a bit better deal from your local shop for the purchase price and labor. I am not about throwing $200 out the window, but maybe you can get them closer in price, support the local small guy, and get continued good service. Just a thought, especially if you are buying a new motor from them too.
    I will be curious to see the new lift the Boat Shop is getting in. My minor complaints on the CMC are speed and distance from the transom. Maybe, just maybe they found a better "mouse trap".

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    Back to basics for a second, When you folks are using a jackplate and a prop the jackplate is for the most part in its lowest position. Then when you remove the lower prop unit and install the jet the motor is raised approximately 5 inches?
    Tennessee

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    Default basics

    When pulling out of the hole, i.e holeshot, you will normally have the prop unit all the way down and trimmed bow down (depending on load). As you come up on step and start to plane, you should be able to trim your motor for bow up, the rpm will start to climb, and you'll throttle back to keep a consistent rpm. As speed continues to build, you'll start lifting the motor to get rid of drag. Rpm should continue to climb so you'll be able to pull back on the throttle some more.
    The jet will be higher when you start out but should not be up all the way. As I think back, mine is mounted/rigged to ride about in the middle to upper 1/3. You will just have to play with the lift and tilt to maximize the performance. I do find that when I am trimmed with the jet on the edge, I tend to cavitate in corners. I usually ride with the motor just a bit lower and trimmed a bit bow up, but again that changes with load.
    Make sense?

  19. #19
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    Yes it does. The jackplate is installed to keep the prop unit at a low position then the motor can be raised as needed to improve efficiency. Then you find the happy medium for raising the motor to run the jet.
    Tennessee

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