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Snake River  King

yamaha jet motors???

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Hello Im looking at buying a new river boat and Im looking at purchasing a 2008 1648 mv alumacraft jon boat and putting a 2009 yamaha 30hp jet motor on it and I was woundering what you guys think of a rig like that? I run on the snake river and there is a few places were it gets a foot or less of water! does anyone have any expirences with a jet motor? thanks SRK

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sorry.. I don't have any experience with jet motors.

What is the max hp that boat is rated for? I'm wondering if it won't be a little underpowered...

marine_man

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Guys in the Catfish Forum are plenty experienced and knowledgeable in the jet market, both inboard and outboard jets.

One thing to remember is an outboard jet is about 70% efficient, meaning you are putting a 30hp on your boat so power at the pump will be approximately 21hp.

I think that hull is rated for 40hp, and if I'm not mistaken, its the jet hp that matters. So a 60/40 OB Jet would be as big as you could go. 60/40 meaning 60 engine hp, 40 hp at the jet.

From what little I know, you are going to be right on the border of being able to plane the boat with 2 people in it with a 30hp outboard.

Boat hull design is also critical when you are talking jets. You need a hull that is flat and smooth in front of the jetfoot so there is less water disturbance or turbulence.

Basic suggestion with any boat will hold true, max the hp IMO.

EC30_06, KyleB in the Catfish Forum both run Outboard Jets, there are also a bunch of guys in the Mississippi North Forum that run Outboard Jets as well. I'd poke around in there and see if you can find some advice.

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Down here in PA Jets are very popular because of the Rivers. Yamaha Jets are very popular. Many prefer 2-strokes because of the out of the hole performance they offer over a 4-stroke. I have a family member who has a Honda 30hp Jet, he never mentioned any problems with it. He did say he wish he would have got a 2-stroke Jet because of the extra power they provide. A lot of dealers in my area take a 25hp 2-stroke yamaha 15" shaft motor and put a jet lower unit on it. Hope that helps. I would get as much HP as possible and put a jack plate on the back.

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the mv 1648 jon boat is a max rating of 40hp and the yamaha 30hp jet is actually a 40hp outboard but because you lose so much power from the jet its rated at a true 30hp jet. dkf what dealer does that??? cuz I would be fine with a 1448 mv and a 25hp jet yamaha?

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yammi ob jets come rated with the jet hp already on them. You would be correct in that your motor is a 40 hp, 30 hp jet. One draw back with 4 stroke is the extra weight. Not as big of an issue with the smaller ones. When you start looking at 300/225 jets then the difference is several hundred pounds between 2 and 4 stroke. You can put a motor on that is jet rated for your maximum hp. So you could go all the way up to a 60/40 jet with a boat rated at 40 hp.

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the mv 1648 jon boat is a max rating of 40hp and the yamaha 30hp jet is actually a 40hp outboard but because you lose so much power from the jet its rated at a true 30hp jet. dkf what dealer does that??? cuz I would be fine with a 1448 mv and a 25hp jet yamaha?

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I'd check around some of your local dealers. As I said before, all they do is buy a short shaft 25hp Yami 2 Stroke and put a Jet lower unit on it. Then they can sell the proped lower unit. I'm shure any dealer could do it for you if they are willing. I have a 25hp Yami 20" with a prop it is a reliable powerful little outboard. The Susqehanna River is shallow and narrow mostly and these little Jets are favored for them.

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There are a lot of dealers in MN that will put factory jet motors on. I know merc sends them out from 25/20 all the way up to 150/110 from the factory.

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Some places will convert motors for you too. I had a 115 evinrude converted to an 80 jet.

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