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Thread: 40 HP jet on 18-ft Jon?

  1. #1

    Default 40 HP jet on 18-ft Jon?

    I have an 18-ft Jon boat with a 40 HP Yamaha prop on it. I would like a jet on this boat, if I keep the same motor and swap a jet unit out for the prop, will I be too underpowered? Suggestions for minimum HP with a jet for this boat?

    thanks!

  2. #2
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    If it's a lgiht 18footer you will be okay, if it's riveted you will be fine. Fine as in you and a buddy and maybe a small friend can fish in it and still actually jet. If you want to haul, you would be much better off with the 60 or 70 hp powerhead. So 40 hp is the min. If it's a welded sea ark or something like that, then the mine is 60. You lose up to a third of your punch with the jet unit, and all the torque.

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    Member theultrarider's Avatar
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    I really doubt you would be happy with your boat if you jet put a jet on your 40. Step up and run max jet hp that the boat is rated for. Much safer. Better handling. And usually better fuel economy. Back off and pick your speed. But have the hp and thrust to keep you out of trouble.

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    You will most likely want more power. A 60/40 or a 90 would be much better

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    Member Gerberman's Avatar
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    Fuel use will go up a lot for an underpowered jet. A friend had one that I borrowed, had to carry a lot of extra gas.

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    Member Sobie2's Avatar
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    Go to BassPro in Anchorage and check out and price their 115 Fourstroke with a jet (80hp). And also check out their 60/40 jet. I have a SeaArk 1860 with a Honda 90/65 and I'd hate to have less than that. I had a 1652 with a Tohatsu 50/35 and it did the job but was a little light on the HP side and it really had to be run near wide open all the time.

    Sobie2

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    Member boondockinak's Avatar
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    My good friend just bought a new Merc 60/40 from bass pro for his 18/48 tracker, and it seems just about right. If you plan on doing anything serious with this boat besides just banging around the lake, it probably needs at least a 60/40. Depending on whether you are rivited/welded and your bottom width etc, you may need to beef up the transom. My buddies tracker jon needed some reinforcement, but now it's a ripper and can haul a load. If you're coming from a prop and not experienced running a jet, it's a totally differance animal. I have 310 horses in my 19/72, and sometimes I still wish I had more motor when fully loaded.

    Also, if you are wider than 48, you're probably going to want more ponies. IMO, an 18/52 is probably pushing it with a 60/40 when fully loaded with guys/gear/moose. The kind of situation where 6.5 gallons/hr turns into 10+ really fast. I've read about alot of guys being unhappy with the performance of their 18/52 and 18/60 welded jons with less than a 80 horse powerhead.
    ~Alaska born and raised~ •'04 Duckworth, 5.7 w/ 3-stg. •High side Lowe, '13 Yami 25 prop+Merc 40/30 jet
    •Ranger 6x •CAT atv w/ 27" rubber •A very large moose buggy •M7 153" "Earned, NOT given"

  8. #8

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    Thanks everyone. I was alreay leaning towards a 60/40 as a min. You have confirmed my thoughts. BTW it is an 18/48 riveted Jon. Sounds like the 60/40 is the way to go. Budget is a little tight so I'll be looking for a used one and selling my 40HP prop. Anyone have a motor for sale that would fit my needs?

  9. #9

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    60/40 is the minium id go, my 1860 tunnel hull does fine with me by myself, I have a f40. Wish I had the next size up. We have had 2 guys and a full size moose in mine, did just fine but really slow. Also been in a 1648 with 2 guys and a smaller moose, talk about fun with a 40/30, but we made it just fine. Only disadvantage to a larger motor is your rear sits lower in the water, which is why I moved my console forward 30 inches, way better balanced when by myself. If I ever put a larger motor on Id weld up some extension for the rear to give a little more buoyancy.

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    I'll be the disenting opinion here. I have an 1852 riveted flat bottom with a 40/30 yamaha four stroke jet. It works great for what I use it for. I can put 2 guys, a light weight camp and a moose in it and still get on step (not moving fast, but on step). It burns ~3.5 gals an hour at wide open throttle and I rarely need to run wide open, but I'm ok with being the slow boat in our group.

    Be aware that if you hang a 60/40 four stroke motor on the back of your riveted boat, the transom will likely need to be reinforced, especially if you are regularly trailering it. With that 60/40, your boat will be dang fast.

    What kind of motor do you have? Maybe you can find a used jet unit and try to see if it'll work before dropping a bunch of coin on a new motor. I think on your riveted boat, a 60/40 jet would be the biggest motor I'd want to run on it.

  11. #11

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    here is my old 18 foot riveted alumarine boat!...60/40!.

    that motor is heavy but with the kicker on.and 2 guys, 20 gallons of fuel i cruised at 20mph and top speed 25ish?.....
    ....i liked this boat but felt it was slightly under powered for hunting!
    ..would a 40/30 work?...prob yes, but i would want more hps!!

    29' Wooldridge Pilot House, Twin 200 Hp Etecs! "...Pez Gordo..."
    18' Wooldridge Sport with 200 hp sport jet. "...Little Pez..."

  12. #12
    Member mudbuddy's Avatar
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    You'd be happy with the 60/40
    weight & power ratio should fit your bot pretty good
    boat brand / picture?

    still, you'll will miss the response & power of the 40 Yamaha.

  13. #13
    Member ptarmigan's Avatar
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    I have a 1752 Alweld with a Tohatsu 50/35. I've carried 4 adults and 2 kids no problem up Delta Clearwater. If I didn't use it on the Kenai I would have put a 60/40 on it though. Still it does everything I want it to do the way it sits.

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