15 horsepower outboard on a 10' jon boat?

[blackdeuce]

My son recently purchased a nice Landau 1044 jon boat. It came with a like new trolling motor and battery.

He thinks he needs a gas powered outboard for crossing a large pond or small lake.

The boat is conservatively rated for a 3hp outboard. I think a 4 to 6 horsepower motor would be fine. But, he found a nice 15 horsepower Mercury locally for a good price. It weighs at least 60 pounds more than a 6 horsepower motor.

Do any of you have experience with this type of situation? What would happen if we put a 15 horsepower motor on the boat? My son can weld aluminum, so we could reinforce the back of the boat.

Weight gets to be a concern as well. My son weighs about 180 and his fishing buddy is around 250.

 

[Autococker07]

WOOHOO!!!!!


He may want to think of filling the seats with Styrofoam, or something else cause if the weight distribution aint just right, or if he hits a log/nutra/ect at speed that flat bottomed boat is gonna sink like a stone.... he will have a LOT of fun with it otherwise.......

In all seriousness, if he can keep his fishin buddy up forward, (and be VERY careful with the throttle) he will probably be ok with it.... and he can always trade it for a smaller sized motor when he discovers its waaaaaay overpowered

 

[sureshotbob]

I used to have a 14 ft. aluminum john boat it was rated for a
10 hp motor .I ran a 7 1/2 hp on it . I'd say that the 15 hp is going to be too heavy IMO.

 

[klausinak]

I think that between the two of them, gear & outboard, there's not going to be a lot of free board...

Just my .02

 

[CajunBass]

I'd say weight is going to be the problem. A lot of small outboards have a built in gas tank (at least they used to). A 15 is probably going to have an external 3 or 6 gallon tank. That's even more extra weight than just the engine.

I'd look for a smaller outboard.

 

[A10]

I had a 7.5 on a 12 foot trihull glass boat, that thing would jump up on a plane real quick and flat get with the program! That 15 would certainly keep things interesting!

 

[OFT II]

The weight of the motor and driver in the stern may make it sink. If it doesn't, there's the chance that when taking off the boat will stand up and flip over. If all this doesn't happen then the game warden or lake patrol will likely write your son a safety citation.

 

[CAJUNLAWYER]

10 foot jo boat??? he needs to find a friend about 70 pounds lighter.
I'd stick with a little 2.5 hp-they don't need to be putting any more weight in that boat no.

 

[Geno44]

He is considering an outboard that is 5 times the power the boat is rated for? This is nuts and illegal. If he is stopped by conservation police, he will (and should) get a ticket and a fine. If he has an accident with this outfit he may get sued. The boat should have a tag on it that shows maximum legal horsepower and maximum weight which includes people, engine, fuel, gear, every[thing on board. I can't imagine a 10 foot boat would handle the type of weight you are talking about.

 

[blackdeuce]

Thanks for the input.

I've read conflicting opinions on the internet. That's why I posted here. Some guys say it's o.k. Others think it's crazy. I hadn't found anyone say that it was dangerous, or illegal, or I would have squashed the idea already. The biggest reason he is considering an oversized motor is because he may move to a bigger boat later. But, if it isn't safe, it isn't going to happen.

We had a state park ranger tell us that we wouldn't get ticketed for running a motor larger than recommended for the boat. He was trying to sell us a 6 hp motor, so he might have been telling us this so that he could sell a motor.

Sounds like we need a bigger boat, but I don't have any place to keep a boat with trailer. The jon boat is small enough that it fits in the back of our El Camino and we can carry it into the back yard for storage. We might get a 12' jon boat to work which gains us quite a bit in terms of weight capacity.

I have no sense of what a 4 to 6 horsepower motor would do for that boat. I had a boat motor salesman tell me that a 3 horsepower motor wouldn't be much faster than the electric trolling motor. There's no real gain to that. Would a 6 horsepower motor propel the boat well?

 

[kozmic]

This is one of the few times when I would disagree with Tim "the tool man" Taylor and suggest "more power ain't the answer". I don't believe the tiller/prop would accurately or safely steer the boat with all of that torque and power. Especially only 10 foot long with, I'm sure, a very narrow beam (even with 450 pounds of "dead weight" aboard).

He might find himself spinning in circles out in the middle of the lake because of torque steer.

I'd absolutely pass on 15hp in this case. YMMV!

If he goes ahead with the 15 hp motor PLEEEAASSE take video and post it here!!!!!!!!!

 

[RYNO]

Bad idea for all the above reasons, not to mention that thing would be so dang unstable and squirrely.

A C.O. would ticket them for sure if they were spotted.

 

[Engineer1911]

Making it simple!

How about a 426 Hemi in a PT Cruiser? Maybe 3 tons of 22 LR in the back of your 150 / 1500 pickup truck?

Your son and his buddy excede the load capacity of that boat without a motor, fuel tank, or fishing tackle.

I had a 14' jon boat I hauled in the back of my Ford F150 standard cab pickup with a 10 HP outboard on it. Motor, tank, fishing stuff, and two adults exceded the max load of that boat by 150#. When I was driving and Earnie sat in the middle, we had 2" of freeboard (top of boat to top of water) just before I put the motor in gear. When we got on plane, we had about 6" free board. When we fished, I was in rear seat, Earnie was in front seat, and we had 4" freeboard maybe.

NO, NO, NO ! ! !

 

[blackdeuce]

I think we'll keep looking for something in the 4 to 6 horsepower range.

Thanks for the input!

 

[glowe]

Just plain DANGEROUS. Make sure to wear the kill switch at all times, because you will be in the water and don't want the boat coming back to get you.

I have had a 15 hp Mercury for years on a shallow 12 foot aluminum boat that was rated for 15 hp max. One calm day, 3 people were in the boat and for no apparent reason, it torpedoed without notice. I think is was too much weight forward, but it remains a mystery. This is something you do not want to do during a cold duck season return trip to the launch after dark. I immediately bought a new deep hull boat with a 30 hp rating and 3 times the capacity rating. I love it and the 15 hp is perfect.

Bottom line is a 10' Jon boat is inherently unstable and is dicey even without a motor and only one person and gear in it. Only thing worse is a pirogue, but that is another story.

 

[rburg]

I used to get lambasted by all the ninny's and Coast Guard Aux in the past. I'd just bought a little flat bottom Checkmate with a 140 on it. It was made prior to them putting a CG approved HP on the number plate. Well, I fried the 140 Merc and put on a 155XS. And that really set all of them off about how unsafe it was, etc. I finally got a bellyfull of the idiots and borrowed a wraparound from a friend's 115. Then everything was just great. Except the fool watercraft officer who decided his mission in life was to inspect me and the boat everytime he saw me. But watercraft officers don't have sirens, just little lights that flashed. And somehow I never noticed him falling back in the distance. He insisted I should stop for his nonsense anyway. But I agreed I needed to be inspected once a season. So when he got wise and just parked his boat at my harbor a buddy just pulled my trailer across the river and we loaded it up. Then quietly pulled it back to the harbor and parked the thing. It was part of what biased me against fool cops, watercraft or not.

So what I say to the OP is to suggest a test. Get the advertised weight of the proposed engine. Then just launch the boat and keep adding concrete blocks to the stern. See how it looks. Then have the son and fishing buddy get in. OK, have them wear life jackets!

I don't worry about too much HP. More is better, too much is just right. You've got to learn how to feather the throttle. You're right in the efficient operating range. Two stroke engines tend to suck fuel wide open. At part throttle they sip it. Going faster than the other guy isn't all that painful.

 

[rwsmith]

No bones about it....

A 15 hp motor is too big for that boat.

Sell the 15 hp and get something appropriate.

 

[jarhead1178]

Back in the 1940s. My grandfather had a old heavy wood 14 foot boat with a sears 1 1/2 hp motor that we used on Candelwood lake in Danbury ct. The prop was like 2 tablespoons, it pushed the boat at about 3 miles per hour. It was a lot better than rowing. Stay with a 3 hp its fast enough for fishing and a lot safer.
good luck

 

[Salty RI]

10ft jon boats are unsafe to begin with, use the trolling motor or row it.

 

[Kanewpadle]

I think this is more of a consideration of weight more than it is power. 60 pounds isn't much but in a 10 foot boat it's a lot considering two men and gear. A 4, 5, or 6 HP should be sufficient.

Just my opinion as I don't own a boat. Boat my dad had when I was a kid had a 350 Olds inboard!