# School me on outboard jets and rocks



## gotmuddy (Mar 7, 2010)

I run the white river and after yesterday I have decided I need a jet. I have a 1994 mercury 25hp that I want to find a jet pump for. I chewed up a prop bad yesterday but if I would have had a jet I could have breezed all the way up the river. Any links or info would be super.


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## BigRiver01 (Mar 8, 2010)

I would check out outboardjets.com and just do a search on your search engine of outboard jets. The jet pump will take alot of your speed away just to warn you. Good luck!


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## Captain Ahab (Mar 8, 2010)

A 25 hp motor with a jet will loose a lot of power. The jet is not nearly as effective as a prop and thus you will have reduced your actual output to around 15 hp

You are better off purchasing at least a 40 hp motor with a jet - or just get a jet boat


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## gotmuddy (Mar 8, 2010)

Captain Ahab said:


> A 25 hp motor with a jet will loose a lot of power. The jet is not nearly as effective as a prop and thus you will have reduced your actual output to around 15 hp
> 
> You are better off purchasing at least a 40 hp motor with a jet - or just get a jet boat




I realize that I will lose speed, I am not too concerned with that because when I need it I dont want to be going that fast. I already have a 25hp so it makes sense to keep it and just get a jet.


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## willfishforfood (Mar 8, 2010)

a 25 jet works good on a 12' boat. I have a 50 Yamaha with a jet and my speed went from 40mph with a prop to around 25 with the pump.
WFFF


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## gotmuddy (Mar 8, 2010)

I have a 16'x41" flatbottom. I will do some power upgrades if possible on the 25.


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## Captain Ahab (Mar 9, 2010)

I agree it will work - just not well. Do not know about the rivers near you but here in SE PA a 25 jet will not be enough to get around - the Delaware river in particular has a very very strong flow.

Now you need a jet head for that motor!

Keep in mind that you will still need enough HP to get your boat up on plane for teh jet drive to work in shallow water. "We lose about 30% of the HP when converting from propeller to jet drive. With less than 25 HP, it is difficult to plane a boat with two people. If it won't plane, it will not operate successfully in shallow water."

https://www.outboardjets.com/faqs.php#Why dont we make jet drives for less than 25 HP


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## gotmuddy (Mar 9, 2010)

Captain Ahab said:


> I agree it will work - just not well. Do not know about the rivers near you but here in SE PA a 25 jet will not be enough to get around - the Delaware river in particular has a very very strong flow.
> 
> Now you need a jet head for that motor!
> 
> ...




what I am hoping is that I can upgrade mine to a 40hp, since *most* outboards use the same components for 25-40hp models.

**edit**

I have seen a few 25hp jets running around on the river here, and they were on 18-20' fiberglass river boats, both the ones I saw were 42-44" wide.


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## Captain Ahab (Mar 9, 2010)

Where is here?


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## gotmuddy (Mar 9, 2010)

gotmuddy said:


> I run the *white river *and after yesterday I have decided I need a jet. I have a 1994 mercury 25hp that I want to find a jet pump for. I chewed up a prop bad yesterday but if I would have had a jet I could have breezed all the way up the river. Any links or info would be super.




I should have elaborated. I run the white river in Northern Arkansas. It is a minor trout fishing stream.


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## Lawdog (Mar 16, 2010)

gotmuddy said:


> I have seen a few 25hp jets running around on the river here, and they were on 18-20' fiberglass river boats, both the ones I saw were 42-44" wide.



Howdy. When you say 25 jets, I suspect you are seeing factory jobs that produce 25 _at the jet_, which is a lot more power than _converting _a 25 prop to a jet, as was pointed out above. Another consideration is the life of the motor too, but someone more knowledgeable than me can better comment on this. That said, I was warned not to convert a used-prop to a jet because of the change in RPM. He said jets will run a motor about 5900 RPM*, higher than they're used to with a prop. For this reason, I was advised to not convert a motor from prop to jet, but instead to acquire a motor (new or used) that has been a jet all its life. *_Update: The poster below is correct about the RPMs. My Mercury jet runs up to 5500 rpm with its jet, according to the spec sheet it came with. _

I am about to post up my new boat in the mod section and will detail its capabilities there. But, in short, I have a 1648 Alumacraft with a 25 Merc jet... It does about 15 mph against current with 2 people and light gear. Slows to 12-13 loaded down for duck hunting. 22-23 with the current. As you note, a jet will take you great places. I run mine in 6 inches of water. Remember to keep on the gas when you hit shallow water! Gotta be on plane to run shallow!


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## JohnnyRazorhead (Mar 16, 2010)

You will be fine with a 25 jet on the white river. They are all over it on 20' river boats. A nice new one docked up by wildcat shoals last time I was there fishing. I run a 40 jet and it is more than enough for the white. 

fortgot to add. Jets do not run higher rpms than props are capable of. Jets typically need to be ran at a higher rpm to stay at desired speed than does a propped out motor. My jet won't turn 5900 unless I cavitate.


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## gotmuddy (Mar 16, 2010)

thanks for the replies. I am going to look for one(so far no luck) to at least try it out. A few months ago on craigslist there was a awesome deal on one. '95 25hp merc electric start with jet for $500. motor had low compression. :shock: 

I didnt buy it though


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