Bigger motor than recommended

[Kassun]

I have a 14' sylvan bare bones aluminum boat that I just bought yesterday. It is rated for a 15hp, Can I safely run it with an 18hp Johnson? Basically I found a great deal on an 18hp.

 

[haskindm]

Re: Bigger motor than recommended

Do a search and you will find many discussions on this topic.
1. Many states will not register a boat with higher horsepower than capacity plate recommends.
2. Many insurance companies will deny coverage if they find higher horsepower than recommended.
3. Most manufacturers will deny warranty coverage.
4. If boarded you MAY be cited for reckless operation just because you have exceeded recommendation.

Bottom line is, the risk is yours if you decide to exceed builders recommendation.

 

[tashasdaddy]

Re: Bigger motor than recommended

this is what the coast guard says. if it were me i would do it. but i did not tell you that.

The United States Coast Guard has an opinion on this frequently asked question, and their answer from their website is reproduced below:
Can I use a bigger motor on my boat than what it's rated for?
It is not a violation of Coast Guard regulations to install or use an engine larger than specified on the capacity label, but there may be state regulations prohibiting it, and restrictions from your own insurance company regarding this.
There are no Coast Guard regulations against exceeding the safe loading capacity, however, there may be State regulations or restrictions from your insurance company which prohibit this. There is a Coast Guard regulation that gives Coast Guard Boarding Officers the power to terminate the use of a boat (send it back to shore) if, in the judgment of the Boarding Officer, the boat is overloaded. There is no fine for this, unless the operator refuses the Boarding Officer's order. We certainly hope that you will abide by the rating, as overloading may lead to capsizing or swamping of the boat.
NOTE: The Coast Guard Capacity Information label is required only on monohull boats less than 20' in length. The label is not required on multi-hull boats, pontoon boats (catamarans), or on any sailboats, canoes, kayaks, or inflatable boats, regardless of length.
As the Coast Guard mentions, local regulations may apply. For example, in the state of Ohio one should be guided by this regulation:
Capacity Plates
(ORC 1547.39 & ORC 1547-40)
No person shall operate or permit operation of a watercraft in excess of any of the stated limits on the capacity plate. When no capacity plate exists, no person shall operate or permit operation of a watercraft if a reasonably prudent person would believe the total load aboard or the total horsepower of any motor or engine presents a risk of physical harm to persons or property.

 

[wbeaton]

Re: Bigger motor than recommended

I've run a 60's 18 hp and an 80's 15 hp on my boat and they performed the same 43 kph / 26 mph.

 

[Tacklewasher]

Re: Bigger motor than recommended

As a kid, my dad borrowed an 18hp after the 3 1/2 we had tossed a rod. On a 12' rated for 15hp.

Only problem was it was an old, heavy motor. He could not get it to plane without water coming over the transom. Neither could my older brother. They used to putt around with it, barely off idle.

I was 13 at the time and a whole lot lighter than either of them. Man that boat flew once it was on plane

As long as it isn't overweight for the back of the boat, you should be okay.

 

[JB]

Re: Bigger motor than recommended

I had a wonderful Johnny 18 that I ran on a tinny rated for 14. I was young and ran it WOT most of the time. It flew.

After a year or two the boat started coming apart. Cracks developed in the bottom. . . from going too fast and pounding, according to my mentor. . . and the transom developed flex and started to splinter.

All that could have been just a flimsy boat or it could have been destroyed by overpowering and abuse. I don't know, but I really recommend that folks stay within the manufacturer's recommendations.

That is such a great engine I think I would go shopping for a stronger boat, one rated for 20HP, for example.

 

[boating virgin]

Re: Bigger motor than recommended

I am wondering, which has better fuel economy, a larger horsepower outboard running at low rpms or a smaller horsepower outboard running at higher rpms. ie. a 115 hp vs an 85 hp?

 

[tashasdaddy]

Re: Bigger motor than recommended

actually about the same.

 

[wildmaninal]

Re: Bigger motor than recommended

I am wondering, which has better fuel economy, a larger horsepower outboard running at low rpms or a smaller horsepower outboard running at higher rpms. ie. a 115 hp vs an 85 hp?

Funny you should ask that question, I have a 78 model 85hp E'rude on a 15ft tri hull bass boat and my brother has a 75 model 115 E'rude on a 17ft tri hull bass boat and if you ask me he actually gets worse gas milage then me but he hasn't done any tune up on his motor in ages. I run mine on a 6 gallon tank and he runs his on a 12 gallon tank. I went 3 days fishing 2 times a day (durring a holiday weekend) traveling a good distance from where we docked at to where we fish at and I had a hair less then a quarter of a tank left in my boat after all that time. I haven't figured out how to calculate the mpg yet but when and if I do I can bet that I get better mpg then my brother's 115. Now keep in mind I haven't got my motor to run out at 5500rpm yet because I haven't found the right prop for it yet, I have to big a prop that is only letting me run at 4500 rpm.

As for the horse power rating on your 14ft boat, I would say it is your call, I don't know if they would have a cowling with 15hp on it that would fit that 18hp but that would be the way I would go if it were possible . The previouse owner of my 13ft fiberglass (project) boat (that I'm thinking of junking) had a 35hp on the back of it when it was rated for 25hp, but he never ran it full throttle. Now I thought about going back with a 35hp myself because I have one that I can put on it if I keep the boat but I know I'm taking a risk.

I must add this.... Say you bought a 15hp motor and ended up rebuilding it, so now say you bored the cylinders and in the long run it actually gives you a couple more horses under the hood, what is the difference between putting the 18hp on the back of that boat then putting a rebuilt and bored 15hp on the back of it other then the one motor still has a 15hp cowling and the other has an 18hp cowling on it.

 

[JB]

Re: Bigger motor than recommended

Virgin, hijacking someone else's thread is very bad manners. If you have a new question start a new thread.

 

[alamosaddles]

Re: Bigger motor than recommended

this is what the coast guard says. if it were me i would do it. but i did not tell you that.

The United States Coast Guard has an opinion on this frequently asked question, and their answer from their website is reproduced below:
Can I use a bigger motor on my boat than what it's rated for?
It is not a violation of Coast Guard regulations to install or use an engine larger than specified on the capacity label,There are no Coast Guard regulations against exceeding the safe loading capacity. There is a Coast Guard regulation that gives Coast Guard Boarding Officers the power to terminate the use of a boat (send it back to shore) if, in the judgment of the Boarding Officer, the boat is overloaded. There is no fine for this, unless the operator refuses the Boarding Officer's order. We certainly hope that you will abide by the rating, as overloading may lead to capsizing or swamping of the boat.

Thank you for posting this. Really tired of seeing some people incorrectly state otherwise. Only "some" states regulate this, many do not.

 

[boating virgin]

Re: Bigger motor than recommended

Virgin, hijacking someone else's thread is very bad manners. If you have a new question start a new thread.

Thanks for the tip. Did not mean to hijack or offend anyone.

 

[pine island fred]

Re: Bigger motor than recommended

In reference to the top post. What state or juristiction registers the HP. on a boat? Is the registration void if a different motor is later hung?
Who carries insurance on a 14 ft. boat with a used motor? Is there such a thing as a warranty on a 14ft. alum. boat? Who will board a 14 Ft. boat and be concerned about HP. of the motor?
I can submit that overpowering a boat can be dangerous, personal experience, but 3 hp. should not be a problem. Just enjoy and boat safely. FRED

 

[ebry710]

Re: Bigger motor than recommended

I sometimes feel sorry for the designer of a boat who puts his/her time and energy to create specifications that people ignore.......but as the captain or operator of a vessel, you should have the right to modify your equipment has needed to to meet a unplanned conditions or requirements.

There isn't much of a functional difference between a 15hp vs 18hp outboard. Even if there was the operator should only use the hp needed and safe for the operation.

Rookies though should not push specifications until experience kicks it, then they are not rookies.

 

[dajohnson53]

Re: Bigger motor than recommended

In reference to the top post. What state or juristiction registers the HP. on a boat? Is the registration void if a different motor is later hung?
Who carries insurance on a 14 ft. boat with a used motor? Is there such a thing as a warranty on a 14ft. alum. boat? Who will board a 14 Ft. boat and be concerned about HP. of the motor?
I can submit that overpowering a boat can be dangerous, personal experience, but 3 hp. should not be a problem. Just enjoy and boat safely. FRED

I don't know about state regulations. Not exactly responsive to your question, but some waterways (lakes, rivers) have HP restrictions, and enforcement officers will in fact not only visually check your engine's HP, but they will investigate further (serial/model number) because of people putting lower HP cowlings on higher HP engines. That said, I've never personally heard of anyone "enforcing" HP capacity for a given hull - not to say it isn't done, I've just never seen it. I was boarded by the USCG once in salt water and all they checked was safety equipment: PFDs, flares, horn, etc.

As for insurance: I think what I'd be worried about is not loss insurance, but liability insurance. I think anyone with any assets would be a fool not to carry liability insurance on any boat they operate. I have never been in the position, but it would't surprise me at all if an insurance company would refuse to cover liability if they found out a boat was being operated with an engine that exceeded recommended HP - but a simple call to one's insurance company would answer that one.

Now, I personally do not believe an 18 HP on a boat rated for 15 would be in any way dangerous and the only concern I'd have is liability. In fact, depending on the year of the 18, it could actually be the same HP as the 15 (prop rated vs. powerhead rated). Weight might be a consideration. I do believe that exceeding weight limits is not safe.

If it were me, I'd check out the USCG published formula for establishing HP ratings for hull (Width, transom height, length, etc.). IF (big if) that formula came up with a higher HP than 15, I would ensure that the capacity plate is no longer present or readable, call my insurance company with the info on the boat and tell them explicitely that it has an 18 HP on it. Lacking a manufacturer's capacity plate, I believe the insurance company would use the USCG formula to determine if the 18 would be covered or not.

 

[BMOLCHANY]

Re: Bigger motor than recommended

That much of a difference would not be that huge of an issue to me but if something would occur then you would have fingers pointed at you by everyone.

 

[RCNO]

Re: Bigger motor than recommended

I run an old 15ft Skeeter hull thats rated for a 25, I run it with a 48 Johnson. My neighbor has the same hull but 3 years newer and he runs a 3cyl 50 yamaha. My boat and his, at WOT will do 38.6 on a GPS. It doesnt bounce, chine walk or anything else that is unsafe and actually handles really well. I fish with this setup EVERY weekend, and will usually run at close to WOT for 15-20 minutes at a stretch in 1-2 ft seas. I inspect the hull regularly and i cannot find anything wrong with running it with the bigger motor.
Down here in South La, its not uncommon to see twice HP rating on the back of boats. Its nice to have when its time to outrun the bad weather!
Just remember, Just because it its there doesnt mean you have to use it!
Would I run an 18 in place of a 15...sure, in a heartbeat.

 

[jbjennings]

Re: Bigger motor than recommended

I think it's according to how well your boat is built. If it's a flimsy light-built boat I wouldn't. But if it's even decently built I wouldn't think twice about it. I know this isn't your question but I totally don't recommend a 12 foot boat with an 18 on it. I've run a well built 12 foot boat with an 18 and it's just plain dangerous. I think a 50's 18 or '60's 18 is just about comparable to a newer 15. I would do it and not worry a bit about it. If the boat is narrower than 34 inches on the bottom, I wouldn't run a 15 on it, either.
How about posting a pic of your boat? Then you would get a better guess, I'll bet. Is it a flat bottom or v-hull? If it's a v-hull, I might also think twice about the 18 unless it's nice and wide.
JBJ

 

[freddyray21]

Re: Bigger motor than recommended

my only issue with it would be the letting the insurance company have an out if anything every happened where they were faced with a claim. It doesn't matter whether the extra horse such as it is had to do with anything on the claim it just gives them an automatic out.

 

[ebry710]

Re: Bigger motor than recommended

If it is an insurance problem, ask your insurance agent. What the heck.