2019 Mercury 9.9hp or '76 Johnson 15hp?

JohnnyGuy

Petty Officer 2nd Class
Joined
Aug 24, 2017
Messages
176
Good day all,

My brother-in-law and I currently have a 12' aluminum and we are looking to upgrade to a 14' aluminum for some additional "elbow" room.
My brother-in-law and I are the primary users of the boat, mostly for fishing (most of which is trolling for Lake Trout in South-Central Ontario), we get out maybe once or twice a month from May through October, so we don't use it ALOT; pretty low running hours.
He is ~230lbs and I am ~185lbs.

Our current 12'r came with a '76 Johnson 15hp.
It runs well, we've done all the work ourselves to get it to where it is now running nicely.
In fact, in doing that work ourselves, it has led myself down the road to repair and bring back to life other old JohnnyRudes. I have really enjoyed doing this and it has started to become a bit of a "hobby" of mine as I learn and progress.

I have recently come into the opportunity (through NO cost to me) to power our boat with a brand new Mercury 9.9 4 Stroke.

I am fairly certain my Brother-in-law would like to keep that motor, but personally I am torn between what to do in the situation.
Do we sell the 15hp (which I know, really isn't the BEST powerplant for trolling) and keep the new Mercury, or Vise-Versa?

I enjoy having the power of the 15hp for getting somewhere in a "hurry" but I have no experience with new motors.
Should I really expect the new 9.9 to be much slower than the older 15hp (esp. considering the change in how HP's were rated from then, to now)?

When/if something goes wrong with the 15hp I feel pretty confident in being able to diagnose and repair the issue. I have NO knowledge of newer 4 strokes in this regard (though I'm certain some same principles still apply).

I like the idea of the newer motor being a little quieter, a little better on fuel, better for the environment, as well as the likelihood of being a little more reliable (to begin with anyway).
With that being said, I do enjoy the nostalgia of the older motors, the sound, the smell, the fact that something that is older than I am, is still being used and going strong (I realize there are conflicting feelings here, that's part of my dilemma!).

The weight of the 9.9 is about 10lbs more (dryweight) than the 15hp, but I am not too concerned about weight, as if we're looking to get into some smaller back lakes we would probably be using one of the other motors that I have ('75-2hp; '53-3hp or '81-4.5hp).
We have a 9.9 cowling for the 15hp so we're not really restricted by HP restricted lakes, nor do we have many around that we'd be fishing. So that's really not a concern either.

I wanted to know what some other people thought of the situation and what they might do.
I invite you to share and provide your opinions!

Much appreciated.
Thanks in advance!
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Is the 15 HP motor rated at the prop ? Those Mercs 9.9 and 15 HP motors are 333 CC engines. Better would be going for the 15 HP whch is the upgraded 9.9 HP version, will work, push, transport more load on a larger boat than with a 9.9 model.

If liking 2 strokes get a Tohatsu 18 HP motor in excellent running conditions if possible to find one, much better than any 9.9-15 HP motor by way far...

BTW those Merc's are rebadged Tohatsu models, costs bit less for same HP motor...

Happy Boating
 

JohnnyGuy

Petty Officer 2nd Class
Joined
Aug 24, 2017
Messages
176
Is the 15 HP motor rated at the prop ? Those Mercs 9.9 and 15 HP motors are 333 CC engines. Better would be going for the 15 HP whch is the upgraded 9.9 HP version, will work, push, transport more load on a larger boat than with a 9.9 model.

If liking 2 strokes get a Tohatsu 18 HP motor in excellent running conditions if possible to find one, much better than any 9.9-15 HP motor by way far...

BTW those Merc's are rebadged Tohatsu models, costs bit less for same HP motor...

Happy Boating

My understanding is that the 15hp, being as it is a 1976, is 15hp rated at the powerhead.
Whereas the 2019 Mercury 9.9hp is 9.9hp rated at the prop. The mercury is indeed built by Tohatsu.

I'm not really interested any other motors, it's either the '76 15hp Johnson or the '19 9.9hp Merc.
But I do appreciate the recommendation!

Cheers.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Don't think there's a huge price difference between both same weight Tohatsu 2019/ 9.9 and 15 HP motors ? In the good old boating days with 2 strokes motors you could upgrade a 9.9 to a 15 if both were same CC powerheads for peanuts cost. With 4 strokes can't, need to install a new 15 HP CPU on the 9.9 motor and that could be a costly. swap if upgrading later.

Anyway if going for the 9.9 motor install an induction tach as as usually loaded, run a wot test once break end period has ended and check if motor revs inside min 5400 to max 6100 wot rpm range factory stated, better if revs at middle to max wot rpm range, if not, will need one less pitch prop from factory delivered one to pull wot revs up for motor to achieve its full HP range.

Happy Boating
 

JimS123

Fleet Admiral
Joined
Jul 27, 2007
Messages
7,993
I own more outboards than I care to admit to. Plus, I LOVE old JohnnyRudes. I love to tinker, like you, and i run a variety of motors as time permits. Your 15 is a sweet motor.

However.....after running a new Mercury 4-stroke kicker, I ended up buying another for my other boat. Simply no comparison.
 

JohnnyGuy

Petty Officer 2nd Class
Joined
Aug 24, 2017
Messages
176
I own more outboards than I care to admit to. Plus, I LOVE old JohnnyRudes. I love to tinker, like you, and i run a variety of motors as time permits. Your 15 is a sweet motor.

However.....after running a new Mercury 4-stroke kicker, I ended up buying another for my other boat. Simply no comparison.

Thanks.
This is exactly the kind of input I was looking for!
Cheers!
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,961
A 43 yr old motor, or a brand new motor with a Warranty, for free, boy I would lose a lot of sleep deciding on that one. NOT!(unless it 'fell' off of a truck). The old 15 is crank rated, and the new 9.9 is prop rated. The 9.9s were/are under rated(HP regulations regarding Licencing and Hp restrictions on some bodies of water), so there might not be as much of HP difference as the numbers would imply
 

JohnnyGuy

Petty Officer 2nd Class
Joined
Aug 24, 2017
Messages
176
A 43 yr old motor, or a brand new motor with a Warranty, for free, boy I would lose a lot of sleep deciding on that one. NOT!(unless it 'fell' off of a truck). The old 15 is crank rated, and the new 9.9 is prop rated. The 9.9s were/are under rated(HP regulations regarding Licencing and Hp restrictions on some bodies of water), so there might not be as much of HP difference as the numbers would imply

Thanks jimmbo.
For the record it did not fall off of a truck, I won it in a contest.
I've decided to keep it.

Cheers.
 
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