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9.9 vs 15, maybe a 20?

PostPosted: Wed Sep 04, 2019 2:28 pm
by casjoker
I just bought a used 1448 Jon boat with a 2003 9.9 two-stroke Mercury. It will be mostly a duck hunting rig for flooded timber with occasional use in the rivers around Knoxville for hunting. Thinking about upgrading to a 15 or 20hp. One, is it worth looking into a 15hp motor vs the 9.9? From what I read you only gain a couple of MPH but the difference between a 20 and a 9.9 is huge speed wise. Also, I have read you can "upgrade" the 9.9 to a 15 with just a carb change on the older motors. Most of what I have read talks about doing this with a four-stroke, can the same be done with a 2 stroke?

Re: 9.9 vs 15, maybe a 20?

PostPosted: Fri Sep 06, 2019 4:05 pm
by Crosshairy
I have a 1442 with a 15 hp mercury 4-stroke

I don't duck hunt in it much, but when I do it has always been cruising at slow/moderate speeds through flooded timber, so speed was never really important. If that was going to be your situation, I'd say "don't bother upgrading".

If you think you are going to hunt rivers at all, I would check on the average river flowing speed for the areas you are in and make sure that the extra horsepower wouldn't make a significant difference in your *actual* travel speed. If you are only going up-river at 5 MPH with a loaded-down boat, an extra 2-3 MPH is a giant boost!

The last factor that I consider is weight... A 4-stroke 15-hp weighs around 100 lbs and is not very easy to handle solo due to the weight distribution, so if you think you might ever want to pull your motor off with any regularity, that might also be a consideration (although you might be a big dude who can do it with less problems than me). Obviously the 20 hp is heavier. There are a few times I wish I could just snap my fingers and take the motor off of mine, as I could put a trolling motor on the back and get into some really, really skinny water for hunting and fishing, but it's just not worth the trouble to move it back and forth most of the time.

Whatever you pick, make sure it has the shallow water drive tilt-up. Electronic trim adjustment is also very, very nice (I wish I had it). With smaller motors, that attribute is less important. It's rough picking a heavy motor up manually to tilt it while wearing lots of clothes or being stuck on a log...

Re: 9.9 vs 15, maybe a 20?

PostPosted: Tue Sep 24, 2019 7:10 am
by scn
There should be a Coast Guard "plate" with capacity, weight, and maximum HP somewhere on the boat. Make sure your choice doesn't go over the maximum HP.

From what you described as the way you will be using it, I'd stick with what you have if it is running good.

Re: 9.9 vs 15, maybe a 20?

PostPosted: Fri Sep 27, 2019 2:10 pm
by casjoker
Well, I took the plunge and purchased a new 20hp Tohatsu. Figured it would work well on this boat and can easily transfer it to a different/bigger boat in the future (16' or so). After researching the 9.9 it just wasn't going to really cover all the bases. I like to get out and explore and at times cover a lot of water. Plus fishing some tailwaters the extra HP would be helpful. At least that's how I talked myself into buying a new motor. :D :rotf:

Re: 9.9 vs 15, maybe a 20?

PostPosted: Fri Oct 25, 2019 3:10 pm
by Westtnduckhtr
Tohatsu's are great motors, you will enjoy it. I have 5 or so from 40HP down.