a little jet edumacation

Never did understand the terminology when someone with a jet outboard says

" It has a 60/40 2 stroke merc Jet."

What does that 60/40 mean?

TIA
Tim

An outboard with a jet lower unit loses roughly 30% of its rated horsepower. A 60/40 would mean its a 60 hp motor if it were using a standard prop lower. But since its equipped with a jet lower its now effectively a 40 hp motor. Outboard hp ratings are taken at the prop shaft since around 1985. People like to advertise the 60/40, 115/80, 50/35 etc. to let you know what powerhead the motor actually has.

If someone had said they have a 40hp Mercury jet instead of 60/40.. You could come to two conclusions. 1.) its a 40hp powerhead thats been converted to a jet thus making it effectively a 28hp motor. OR 2.) its a factory made 40 hp Jet (says 40 on the cowling) which has the same powerhead as the 60 hp prop motor. By just saying 60/40 clears the confusion...

So if my flat bottom is a 14/48 and it is rated for a 25HP prop motor. Could it handle a 60/40?
Because 40 on the cooler actually equals 28HP?

Fish On Taxidermy said:

So if my flat bottom is a 14/48 and it is rated for a 25HP prop motor. Could it handle a 60/40?
Because 40 on the cooler actually equals 28HP?

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The size of a motor on a boat is more than just the "push" the motor provides being transferred through the boat, it's also the weight of the motor on the transom. A 60hp engine is at least an extra 100lbs hanging off the back compared to a 25. How's that going to affect performance, sink the back, etc? Are you going to hit a bump going down the road and peel the transom off your boat?

Also some places are strict about boat power vs max sticker recommendations. It may vary by state, but they're strict enough in my state that I wouldn't risk arguing it with a game warden.

A lot of 10hp lakes around here. Everybody runs old Tohatsu/Nissan 9.9 outboards with 15hp carbs. Stickers say 9.9hp and even the factory data plate does too. They will ticket you for motors over 10hp.

Pappy said:

You always hear about "Well I know a guy who knew a guy who got stopped one time" ...............

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You've caught me, Pappy. That's exactly my situation, knowing a guy who knows a guy. Although I have been in a boat twice where capacity plates get checked, but that was for bodies in the boat, not HP.

Fish On Taxidermy said:

So if my flat bottom is a 14/48 and it is rated for a 25HP prop motor. Could it handle a 60/40?
Because 40 on the cooler actually equals 28HP?

Click to expand...

A 60/40 jet motor has 40 hp at the jet. It compares to a 40 hp prop motor. I had a boat rated for a 20 hp motor that I wanted to put a jet on. I tried a Tohatsu 50/35 jet on it because the small 25/18 jets just have a hard time pushing most boats, There wasn’t an issue with being too much power for the hull, but it was too much weight for the boat especially with the starting battery back in the stern.

Frankenfish said:

Pappy said:

You always hear about "Well I know a guy who knew a guy who got stopped one time" ...............

Click to expand...

You've caught me, Pappy. That's exactly my situation, knowing a guy who knows a guy. Although I have been in a boat twice where capacity plates get checked, but that was for bodies in the boat, not HP.

Click to expand...

That's not fishcops, that's coastguard.

Coastguard patrols are allowed on out private lake (Club) for safety (Horn, lifejackets, capacity) and if they see you with a huge motor for the size of your boat it might get you looked at. I saw an Avenger (Ski boat) with a Black Max 175, about twice the rated HP for the hull get stopped, but it was for speed, not the motor.

Other than that they mostly look you over coming off at the ramp and its no big deal.

how ironic

I got checked this morning for license, reg, etc. At the ramp as I pulled in at 0600. It worked out pretty good because there was so much fog on the water it wasn't really safe anyway. So during his check, he did ask me if my little 25hp was actually 25hp or if it was a 40 with 25 stickers. First time They've ever asked me about it. This is corps water, FWIW.

At one point, one of the local duck hunting areas was 25hp max. Well, only about zero of the million + people and boats that showed up actually ran a stock 25hp. Most of them were modified 25's, or 40+ with 25hp stickers. One was a 90hp with 25 stickers. Greenjeans got wise to it too. Whether or not there were any citations is outside my knowledge. But they knew of the issue. I think they removed the 25hp max restriction and now guys are running legitimately 90hp+ motors on 14' boats well into the 60 mph zone and quite a bit more on a few of them. With a 1553 powered by a 90, pods are required as you can imagine.