HP Rating and Jets Question

[EBass]

I have a 14' jon boat that's rated for 25HP. I have a 25HP Merc Prop on there. So it's maxed for the HP.

Now, if I put a jet lower unit on a 25HP powerhead I loose 1/3 of power at the jet so I'll have about 17HP . Can I legally put on a 35-40HP Powerhead then get 25hp at the jet? Is the law talking about the weight or the push?

I'm wondering what everyone thinks. I'll prolly have to call the DNR to find out for sure. But it would be interesting to hear what people think.

[Ralph Wiggum]

I wouldn't risk it if it says 25HP on the powerhead, just to be safe. I'd definitely call them, though. Good question.

[EBass]

I called the DNR and left a message with someone. I talked to 2 people @ the DNR but they didn't know. I'll update this thread when I hear back.

[LABS4ME]

I used to have a 40 hp Yamaha jet drive (till somebody decided they needed it worse than me ) and I talked to the DNR, sheriff water patrol and also the Coast Guard on the St. Croix. They all asked me what my hp was on my motor as it was a factory jet drive unit and the hp wasn't marked on the hood (just said yamaha jet drive). I posed the same question to them and they do not take the hp loss into consideration (I was maxed at 40 hp). You must keep the powerhead at the proper hp for the boat not the hp at jet thrust. I know a couple guys who painted over their motors or changed hoods or decals to get around it with their boats, but if they look at your rating and can discern that you have a bigger powerhead, you may have problems.

Good Luck!

Ken

[Kevin Turner]

I'd hafta check the Coast Guard regs again, but the the wt has nothing to do with max rated HP. There is a formula using the hull measurements that dictates HP rating.

In MO, the Water Patrol goes by HP at the jet. I don't know how MN sees it....KT

[PerchJerker]

I don't think it's a matter of if it's legal or illegal. I think the risk with putting on a bigger motor is when you get into issues like insurance, warranty, and liability if you injure someone or damage property.

[Valv]

Since late '80s the HP is measured at the prop, if you remove a prop lower unit and add jet, it will actually reduce HP as calculated, so you whould be fine, you might have to keep paperwork (receipts, etc) to prove it in case of debate.

It's one of these issues where each CO will have it's own decision, then you will have to dispute.

The issue of insurance liability might stay since it's a modified motor.

[kwkfsh]

Most factory jets are rated with the loss figured in 40's are 28 or 25 jet power, 50's are 35 jet power, 90's are 65 jet power, etc, etc.

With a factory installed jet you could probably run a 40 depending on manufacturer. However a 14' with a 40 jet will be one squirrely unit when you crack the throttle with a light load or only one person. It will not be that much fun to drive as it will create a sphincter factor of 9+.

[EBass]

The DNR called me back and said that the HP rating for the boat is the max HP that I can put on. It doesn't matter if it's a jet drive or prop drive. He mentioned the insurance factor. And this law as far as he knows is for MN and WI. So as they said in the movie Jaws, "We're going to need a bigger boat."

I'm bummed as I want a jet, but not 17HP at the jet.

Thanks for the replies

[Kevin Turner]

EBass, How wide is the bottom of your hull?

[Valv]

Maybe K.T. can build a "special-edition-gas-saver" RiverPro 14ft...

[MSRiverdog]

A 16 with a 175 Sportjet would make him rich I tell ya!!

And it would be a trip to run. Your thought's KT?

[hydro]

Or, get a boat over 20' in length and the Coast Guard rating goes away! Drop in a crate big block Chebbie and a Berkely pump and go make some waves!

[Kevin Turner]

Quote:

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Or, get a boat over 20' in length and the Coast Guard rating goes away! Drop in a crate big block Chebbie and a Berkely pump and go make some waves!

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No rating on inboards under 20'...

I've built some 15 footers with the 175 Merc Jet. Worked great, but no one would buy them...

[EBass]

KT,

I believe it's 52" or maybe 54" - I'd have to check to besure.

It's a Lowe "Big Jon" LOL I said Big Jon.

[kwkfsh]

The Lowe Big Jons have the 48" bottom. Rover Jons are 40" and Olympic Jons are 52".

[MSRiverdog]

Quote:

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I've built some 15 footers with the 175 Merc Jet. Worked great, but no one would buy them...

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Got one laying around at discontinued merchandise prices? Very cheap of course, they're just gathering dust and taking up space.