Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

[FL2AK]

Hi folks, been a few years since I posted. I did a search, but didn't find much; forgive me if I'm duplicating a previous discussion.

I need some input on comparing the OMC 9.9 and 15 horsepower engines and, perhaps, the old 9.5 "low profile" outboard as well. My dad, who an OMC mechanic most of my life always told me that the J/E 9.9 and 15 outboards were the exact same product, the only exception being the carb. As I remember it, the 9.9 had only 9.9 hp because it had a smaller barrel carb. My Dad is long gone now, and I'm asking here if anyone can confirm this.

Why I ask is that I have an opportunity to buy a 1983 Johnson 15 hp, which I intend to place on a 1969 Grumman Sport Boat, which is a sort of square stern canoe, 15' long with a wide transom, aluminum and weighs 120 lbs. A friend who really knows canoes has suggested that I'm overpowering, that the 15 will consume more fuel (as to be expected) and weighs more, which will be harder on the transom. It is my contention that the 15 will weigh the same as 9.9; I just need to not use all of the throttle. My friend recommends a 9.9 or the older 9.5.

My current engine is a 2013 Yamaha 4 stroke 4 hp (the boat is rated for 5), which I am extremely unhappy with, and I intend to sell it in the spring. That engine replaced a 1969 Evinrude 4hp that I can not get to run.

This boat is to be used, among other things, moose/caribou hunting in Alaska. I am "overpowering" because a.)virtually everyone up here does because b.)I'm afraid of getting down some shallow, rocky river someplace, loading 800-1000 pounds of moose into it, and then not having enough power to go back against the current.

So, how would you compare those engines for this type of boat and use? Can I just buy the 15hp and use it the same as I would a 9.9, or should I wait for a 9.9 to come along (or perhaps a 9.5)? Small outbaords (they call them "kickers" up here for some reason) are very hard to come by in Alaska. Those who have them rarely sell them. I'm afraid if I let this pass by, I may not get another chance for a long time. On the other hand, I don't relish spending $550 on the wrong engine, only to either tear up the boat or have to resell it and buy something else. (I've already done that with the 4 stroke Yamaha.)

Thanks for your input and sorry for the long-winded post.

 

[JimS123]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

I have a good bit of experience with all 3 on the same boat. The older 9.5 is a do-everything motor. It never let me down even after being run almost WOT all of her life. When a put on a newer 9.9 I immedialtly noticed the improvement in speed. The 15 didn't act any different than the 9.9, so my conclusion was to stick with the 9.9. I believe they were both the same weight, give or take a pound or 2.

The next step up was an 18, which gave a noticable improvement. But this was a different block.

I must note that the boat was rated for a 25, so I never was overpowered with any of them. When I DID put on a 25, it WAS overpowered (even though it may not legally have been), and that's when I went back to the 9.5.

Its funny when you finally find out that the grass is NOT always greener, but what you have is actually the best.

 

[roscoe]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

The 9.9 and 15 are ALMOST the same engine.
There are a few internal differences and tuning that give the extra hp.

It is more accurate to say the 15 is 15hp, and the 9.9 is a de-tuned 15.

They weigh 78-85#, depending on the year/model.

Thats a lot of extra weight over what you are currently running.
Its also a lot of power, and torque, so be careful.

 

[nwcove]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

The 9.9 and 15 are ALMOST the same engine.
There are a few internal differences and tuning that give the extra hp.

It is more accurate to say the 15 is 15hp, and the 9.9 is a de-tuned 15.

They weigh 78-85#, depending on the year/model.

Thats a lot of extra weight over what you are currently running.
Its also a lot of power, and torque, so be careful.

yes be carefull! you are looking at overpowering by 150% , and adding an extra 30 or so lbs to the stern of a canoe. maybe buy the 15 and try to trade down to an 8hp 2 stroke? jmo

 

[Sea Rider]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

Used to have a Evi 9.9 2 stroke 1996 engine, was identical as the 15 HP older brother. To pass it to 15 had to change carb, reed valve assembly & gaskets to boost it to 15. Prop was same for both models-

Happy Boating

 

[jrs_diesel]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

Here's a good article on the entire OMC 9.9/15 HP series of engines. That site was made by one of our members here (the machinist).

Initially for the first few years, the only difference was the carb.

Maintaining Johnson/Evinrude 9.9 part 1

 

[jbjennings]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

The 9.9hp weight and 15hp weight will be virtually identical. If it will handle the 9.9, it will handle the 15. The low rpm torque on the 9.9 and 15 will be similar as well. It won't get the 15hp until higher rpm's. I'd get the 15 over the 9.9 every time.

 

[bonz_d]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

Sorry but a 9.9/15hp on a square stern canoe would scare me.

 

[jbjennings]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

Sorry but a 9.9/15hp on a square stern canoe would scare me.

I looked it up and it does appear that the transom is pretty weak for a 10 or 15hp motor. SOunds like a 7.5 would be about all that thing could handle. The boat looks a little wider and more stable than a lot of canoes, but double and triple the rating is a little much.

 

[FL2AK]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

Well thanks for all of your various opinions; I very much appreciate it. Yeah the Sport Boat is a little wider (43" amidships and 23" at the stern") than your typical square stern canoe, even another Grumman. JBjennings is the first person (other than myself) who thought it was a good idea to go with the 15. (My reasoning, as stated earlier, is there's no difference in weight, thus no difference in stress on the transom.) I wonder how much (and how) weight and horsepower figure into stress on the stern/transom. It seems to me that the weight would be more of a factor than the power.

So, it seems the general consensus is a 15 is a bad idea. (Not just here, pretty much everyone I've discussed it with.) I had kind of already semi-committed to buying this 15hp, so I have to call that guy and be a jerk. Guess I still need to come up with a balanced option for an outboard that is light enough yet powerful enough for heavy loads/heavy work. I hate to do it, but if it's the wrong engine, it's the wrong engine. Come spring and I still haven't found an engine for this thing, I'm gonna be upset.

 

[tomhath]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

I have a 9.9 Evinrude with the 15hp carburetor and a stock 9.9 Johnson. People say the 9.9 is a derated 15, but I suspect it's the other way around; that the motor was really designed as a 9.9 and marketing talked them into putting on a bigger carb and turning up the RPMs a few hundred to call it a 15. I say that because they made several tweaks to the 15 (reed valves, manifold, etc) in the years after it was introduced trying to make it actually produce 15 hp (I've read that the carb conversion only gives you about a 13 hp motor).

I really don't see much difference between my two motors, perhaps because I use them on a light boat so the 9.9 doesn't have any trouble spinning the prop at max rpm.

OMC was building really nice motors in 1983. How much difference is there is weight between a 7.5 and the 15? I suspect maybe 20 pounds; doesn't seem like much difference.

But running up a shallow rocky river with 1000lbs of cargo in that boat sounds like asking for an event.

 

[nwcove]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

Well thanks for all of your various opinions; I very much appreciate it. Yeah the Sport Boat is a little wider (43" amidships and 23" at the stern") than your typical square stern canoe, even another Grumman. JBjennings is the first person (other than myself) who thought it was a good idea to go with the 15. (My reasoning, as stated earlier, is there's no difference in weight, thus no difference in stress on the transom.) I wonder how much (and how) weight and horsepower figure into stress on the stern/transom. It seems to me that the weight would be more of a factor than the power.

So, it seems the general consensus is a 15 is a bad idea. (Not just here, pretty much everyone I've discussed it with.) I had kind of already semi-committed to buying this 15hp, so I have to call that guy and be a jerk. Guess I still need to come up with a balanced option for an outboard that is light enough yet powerful enough for heavy loads/heavy work. I hate to do it, but if it's the wrong engine, it's the wrong engine. Come spring and I still haven't found an engine for this thing, I'm gonna be upset.

no other guys around that would trade a nice mid 1980's 8hp ( just a tweaked 6hp) for a 15? the 6/8 hp are light, rugged and dependable motors.

 

[FL2AK]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

no other guys around that would trade a nice mid 1980's 8hp ( just a tweaked 6hp) for a 15? the 6/8 hp are light, rugged and dependable motors.

Well, it's a question of availability. People up here who have these small outboards rarely let them go. For example, I've been watching Cragislist in both Anchorage and Tampa. In Anchorage there are currently 3 small outboards for sale, none of which fit my needs. In Tampa, there are like 8, almost any of which would work. But shipping an outboard to AK ain't cheap. When one does come up for sale, they usually are gone before I even know about it. They're a scarce commodity up here and in high demand.

 

[64osby]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

I say buy the 15, run it 1/2 throttle unless you need the extra power with the extra 1000lbs. I think it would be well suited for that boat and your use.

What is the actual HP rating for the boat?

 

[JimS123]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

I say buy the 15, run it 1/2 throttle unless you need the extra power with the extra 1000lbs. I think it would be well suited for that boat and your use.

What is the actual HP rating for the boat?

Saying "well suited" is irresponsible! He already said its rated for a 5. That boat is not suited for the intended purpose, regardless of what HP you put on it. The best advice is get a bigger boat. If you don't take that advice, then wear two life jackets.

 

[FL2AK]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

That boat is not suited for the intended purpose, regardless of what HP you put on it.

LOL. Spoken by someone who doesn't know or understand life in the last Frontier. People have run these boats up here on these rivers for decades for this purpose. (Actually, the preferred is the 19' Grumman square stern, which is more "canoe-ike i.e. narrower at the middle and narrower at the stern, but also rated for 5 hp.) Most folks run a 9.9. Some beef up their transom, some don't."Get a bigger boat" is not an option. Bigger boats require deeper water and won't go where the moose/caribou/ducks are. These Grummans are almost an Alaskan Do-It-All boat. They'll go up rivers into caribou tundra where a 4 wheeler won't and into spruce marshes for moose. They'll let you cover dozens of miles per day moving from one hunting spot to another. They'll anchor in a lake and make a decent duck blind. (I can launch my 90 lb Yellow lab after ducks without capsizing.)You can fish flat water from them, or you can run up and down river during the salmon runs with a dipnet and pull fish right out of the river. I might even be tempted, given good weather and staying close to shore, to go out into Prince William Sound after crab. About the only thing they won't do is water ski and anything off shore.

I appreciate your concern, Jim, but you have to check a lot of Lower 48 rules at the door when you come up here. I was really just trying to get an accurate feel for the true differences between a 9.9 and a 15. I think running a 15 at 1/2 throttle would work, but if the 9.9 (or an 8 or 9.5) are better suited to the boat and the tasks at hand, I prefer to spend money the right way the first time. (Kinda late since I already bought the 4 stroke 4hp.)

 

[FL2AK]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

the 6/8 hp are light, rugged and dependable motors.

You know, the more I think about your comment here, the more sense it makes. If the 9.9 and 15 are the same weight (and someoen mentioned 120-ish pounds??? I didn't think they were that heavy.), then, if the 8 is significantly lighter, I'd trade the 2 HP for the weight. There are some places I go that require a portage. (up and over a hill half a mile). I'd trade 2 hp for 30-40 pounds, especially given I'm already dragging a 120lb boat. Do you happen to know the weight nan 8 hp OMC?

 

[SumDumGuy]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

FYI the 9.5 and 10 (and thus I would suspect that the 15) are not 120-ish pounds.
I have both a 9.5 and a 10 and neither of them are near 100 pounds. I can hold the 9.5 easily with two hands and move it about up/off transom and to a storage rack.

I would buy the 15 but that's 'cause I've been looking to get a 15.

 

[FL2AK]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

FYI the 9.5 and 10 (and thus I would suspect that the 15) are not 120-ish pounds.
I have both a 9.5 and a 10 and neither of them are near 100 pounds. I can hold the 9.5 easily with two hands and move it about up/off transom and to a storage rack.

I would buy the 15 but that's 'cause I've been looking to get a 15.

Yeah, I mis quoted earlier. After rereading posts here, I saw someone listed 85 lbs. My mistake. And yeah, I told the guy I was going to buy the 15 from to go ahead and sell it (he was holding it for me), and, at the same time, I told him I expected to regret it later.

 

[jrs_diesel]

Re: Comparing OMC 9.9 or 9.5 to 15 (horsepower) 2 Stroke engines only

A short shaft Evinrude/Johnson (1973-1993) 9.9/15 with manual start weighs in at 72 lbs. Add 5 lbs for the electric starter (77lbs), not including the battery. A long shaft will add 5 more lbs, 77 or 82 lbs, depending if it has electric start or not. These are the lightest 9.9/15 HP motors, especially when compared to the newer 4 stroke motors avalable today.

The 9.9 is a great engine. The 15 is an even better one, it will have more power throughout the RPM range due to more air and fuel being available at any given time, and the modifications OMC made to the 15 (tuned exhaust pipe and leaf valve shims). The one area where the 9.9 shines over the 15 though is trolling at low speeds. The 9.9 idle and run a little better at low speeds than the 15's.