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Thread: Difficulty in swapping lower unit from prop to jet?

  1. #1
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    Default Difficulty in swapping lower unit from prop to jet?

    Hi-

    Im thinking of having a small pilothouse boat built for use on my shallow rocky river (winter use) but wanted to be able to convert the outboard jet to a prop for use in the bay... Grant Wooldridge says he can build the boat... I just want to know how difficult it would be to swap the lower units... Is it a two person job? Im pretty handy with a socket wrench and that is about it. If switching out units is a big pain I may just go with outboard prop and get a heater for the river sled.

    Thanks in advance for any input.

    Mike

  2. #2
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    very easy... once you've done it a couple times, you'll be changing over in less than 40 min. BUT !! you will have to Lower your motor for prop use and Lift it for jet use! Usually about 6". (Drive shaft lengths must match, IE ya can't run a jet w/ 20" shaft and a prop w/ 25" shaft) Consider investing in a adjustable (height) transom lift $$$. Good luck!

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    Moderator AKmud's Avatar
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    +1 to what ref+10 said. Not a big deal switching them over at all plus its a good time to check out the water pump impeller and whatnot. We went with this setup - Transom Jack
    AKmud
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    Ok. Thanks. That is good news. Does anyone know what the largest motor (H.P.) that can be purchased that would have a pump option? I saw that outboardjets.com makes a unit for a 200 H.P. Honda... I think that is what I would be looking at for the Wooldridge 20' pilothouse.

    M.

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    Member Akgramps's Avatar
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    Power trans lift has 7"of stroke http://www.powrtran.com/cgi-bin/cart...?parts_id=9662
    I have had good service from one with a 140 hanging on it, and the power feature allows for trimming on the fly.
    It takes me a good hour to swap, I could do it quicker but as AKmud said its a good time to inspect the water pump and usually the Impeller can stand some sharpening as well. The real PITA.....is swapping the cables, on my motor I have to split the lower cowling to do it, small clips that are easy to lose on the shift cable. I made a bell crank arrangement so I dont have to take the cowling apart.

    I have looked at the big Hondas for bigger boat w/jet, good motors alright.....but consider how much time you might spend with a jet as those 200/225 Hondas will suck some fuel, just speculation on my part, but I honestly think you could run a IB/jet and burn less fuel......

    If most of the time is on the prop then it would make sense........IMHO
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    Member Sobie2's Avatar
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    I used to swap lower units all the time. It is very easy. Some brands of outboard do not require an adapter plate and that saves time too. I used a manual cmc lift for my 50HP and it was ok, but I should have spent the additional money and got a cmc powerlift which would have been 2x faster for the whole job. I opted to remove the reverse bucket totally on my jet for a number of reasons and it saved time when switching lower units.

    I would gather that you loose to much HP when using an outboard jet for a 20' pilothouse. A 150 prop (plenty of power for that boat) is a 105 HP at the pump. Though the Suzuki 140 makes for a great outboard jet because it can use an oversize pump and foot due to its gearing design. I know the 20' pilothose is short on deck space so you aren't thinking about the inboard jet, BUT have the Wooldridge folks think about an outback design where the sportjet is set on an extended transom and therefore the engine is housed outside of the fishdeck.

    Sounds like an interesting project.

    Sobie2

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    Well, Im kinda thinking we will want a jet for our river in the winter and the prop for the Chesapeake Bay in the summer. We are planning a trip to Seattle to look at a few projects that Grant has under way. I really need to get aboard the 20' and see the layout, etc.

    The outback design is an interesting idea. Would a jet work well in the chop? I know my Jetcraft sputters when I hit another boaters wake but maybe a heavier boat would help prevent cavitation.. Either way, if we get started I'll post info on the forum.

    M.

  8. #8
    Member Rob B's Avatar
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    Hmmm. A 20' Pilothouse with a sportjet or other IB? That sounds interesting.
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