# Mercury 9.8 VS 15hp outboards



## bobcat_fisherman (Feb 13, 2012)

I'm looking at re-powering my 14.5ft old Sears Semi V-hull boat. Right now it has a 1976 Evinrude 9.9hp on it that has some mechanical issues.

Does anyone have one of the newer 4 stroke Mercury outboards on their boat? Is it worth it to buy the 15hp? My other concern is the weight of the motor.

I'm only looking to spend around $2K or so for a new motor. If there are any other brands I should look at, let me know.


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## fool4fish1226 (Feb 13, 2012)

Check out nissan/tohatsu same motor different decals less money


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## Pappy (Feb 13, 2012)

For the amount of money you have alloted you can purchase an older 15hp Johnson/Evinrude in stellar shape and leave over a thousand of that allotment untouched.
Smart money in my book. What are the issues with your current engine?


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## overboard (Feb 13, 2012)

X2! I also believe the 4 stroke is a lot heavier than a 2 stroke. I also think the 2 stroke 9.9 merc can be made into a 15 , just by changing carb. the 9.8 can't, if i'm correct on this.


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## UtahBassKicker (Feb 13, 2012)

I have a '05 Johnson 15HP 4 stroke on my 14footer and it has been a very solid motor. It pushes the boat well, sips gas, and runs very quiet. I picked it up for about $1000 a year or 2 ago.


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## chrispy186 (Feb 13, 2012)

Its not worth buying a new 9.9. The new 9.9's are the same thing as a new 8hp, only difference is the carb. If your going to buy new, spend the extra few hundred and get the 15hp. Whats the difference between the new 9.9 and 15 you ask? Well, the new 9.9 is about 209cc, and the 15 is around 351cc. If your talking cubic inches, the 9.9 is around 12.9 where the 15hp is around 21 or so. As you can see, the 15hp is much more motor than the 9.9. I dont know when or why they decided to choke down the 9.9 so much, but they did. If hp restriction is an issue, you are better off going with a used older 9.9, say in the 2000-2007 range. For comparison, a 2007 johnson 9.9 has a displacement of 18.4 cubic inches, where as a brand new mercury 9.8(made by Tohatsu) has a displacement of 12.8 cubic inches. I second the Tohatsu recommendation, since they make the 9.8 motors for mecury, and the tohatsu name is much cheaper. Sorry for rambling, but in short, I think you will be dissapointed with the performance of a new 9.9.


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## bobcat_fisherman (Feb 13, 2012)

I figured there would be a lot of different opinions on this topic. New Vs Used, fixing the original motor, etc. To expand on this...

1) Buying a New Motor - Easy breezy, comes with a warranty, mechanically in great shape, has newer options that weren't around back in the 70's when my motor was built. The downside would be the higher cost. I sure could use that extra money for things like a trolling motor.

2) Buying a Used Motor - I've seen a few 2000 and newer 9.8-15hp motors on Craigslist for sale. However, they're all wanting usually $1200-$1500 or so. I can buy a brand new motor with a warranty for $500-$800 more. But is it really worth it to go for the newer engine? If old 70's motors are still all over the place I would think a 5 or so year old motor would still be in excellent shape. Then again, they don't make things like they used to.

3) Fixing up my existing motor - I will do so either way just to have as a back up or sell. It hasn't ran in about 2 years, the gear on the tiller handle is broken, new choke pull knob, needs fluids changed out and a carb rebuild. I'm not sure on the water pump impeller until I get it started up. All of those things are not majors repairs, but do cost money that I could be putting toward a newer more reliable engine. 




Broken gear that connects to tiller handle.


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## bobcat_fisherman (Feb 13, 2012)

chrispy186 said:


> Its not worth buying a new 9.9. The new 9.9's are the same thing as a new 8hp, only difference is the carb. If your going to buy new, spend the extra few hundred and get the 15hp. Whats the difference between the new 9.9 and 15 you ask? Well, the new 9.9 is about 209cc, and the 15 is around 351cc. If your talking cubic inches, the 9.9 is around 12.9 where the 15hp is around 21 or so. As you can see, the 15hp is much more motor than the 9.9. I dont know when or why they decided to choke down the 9.9 so much, but they did. If hp restriction is an issue, you are better off going with a used older 9.9, say in the 2000-2007 range. For comparison, a 2007 johnson 9.9 has a displacement of 18.4 cubic inches, where as a brand new mercury 9.8(made by Tohatsu) has a displacement of 12.8 cubic inches. I second the Tohatsu recommendation, since they make the 9.8 motors for mecury, and the tohatsu name is much cheaper. Sorry for rambling, but in short, I think you will be dissapointed with the performance of a new 9.9.





Another thing I was told at the local boat supply store was that a 15hp would be too heavy for my 14ft boat. What are yall's thoughts? Another question I have relating to engine weight is, would I have to add some extra bracing or strength to the transom of the boat so that it doesn't crack? For right now, I went with a temporary replacement transom. I nailed and glued two 3/4" peices of plywood and coated them with water sealant. I needed 1 1/2" thick transom to replace the old rotted wood. Will I be fine with the temporary transom or do I absolutly need to replace it with a solid 1.5" wood transom? Another idea I had was to buy some Aluminum Tread Plate from home depot and screw it to my wooden transom where the motor mounts to it.


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## chrispy186 (Feb 13, 2012)

Do you know what your transom is rated for? I had a 1436 that was rated for 20hp. Considering the new motors are only a 10-15lb weight difference between 9.9 and 15hp, I believe a 15hp would not be too heavy for your boat, unless otherwise specified. Also by looking at the size of the boat, its alot bigger than my old 1436.


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## Jdholmes (Feb 13, 2012)

Depends on the boat...my 14 ft is rated for 25 hp...I have seen some not rated for more than 10...

Beefing up the transom can of course improve your odds.


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## bobcat_fisherman (Feb 13, 2012)

chrispy186 said:


> Do you know what your transom is rated for? I had a 1436 that was rated for 20hp. Considering the new motors are only a 10-15lb weight difference between 9.9 and 15hp, I believe a 15hp would not be too heavy for your boat, unless otherwise specified. Also by looking at the size of the boat, its alot bigger than my old 1436.




I have no clue what it's rated for. Does anyone know where I could find out? I bought the old boat about 6 years ago. The title says its a 1960 Sears V-Hull. I know there has been a lot of misinformation printed in Titles over the past 50 years, especially on little aluminum boats. There's a possibility it's not even a Sears boat. I'd appreciate any info on this.

I guess I could weight my 1976 9.9hp Evinrude thats been on it. 

I measured it with a tape measure. It's 14.5 ft from the transom to the tip of the bow. I didn't measure the width but its about 48" across the bottom. Maybe a little more. I know this because a cut down piece of 4X8 plywood fits in between the middle and rear bench seat without cutting the width.


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## Pappy (Feb 13, 2012)

As far as the Johnson/Evinrude engines go, the 9.9 and the 15 are identical weight. Your 14' boat should be rated around 15hp anyway unless its a featherweight cartopper or something.
The issues you describe are easily cured. Would go that route first since you indicated you would repair it anyway. Then run the boat with that engine and see how well you like it.
A couple threads away there is a fellow who just started running his 16' aluminum with a 9.9 and has so far been pleased with the performance.


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## chrispy186 (Feb 13, 2012)

I havent been able to find any specs for that boat yet, however I did find someone with the same boat running a 25hp on it, without any issues. As previously said, I would rebuild the transom and put a 15hp on it, call it a day.


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## turbotodd (Feb 17, 2012)

I wouldn't worry so much with the transom, so long as it's sturdy and not rotted. I vote for a 15. And I also vote 4 stroke. What part of TX are you located? I'm in Arkansas. 9.9's and 15's are a dime a dozen here because all of the duck hunters want a 25 2 stroke because they're lighter. Lighter=faster. Still amazes me to see 100 boats sitting at the ramp...then at 4:30 AM, they all leave the same ramp, headed for the same "holes"...and the guy who gets there first gets that hole. Too much competition for me. Neighbor guy bought 2 9.9 Johnnyrudes for $400 on littlerock CL. They both run just fine. Guy who sold them wanted a 25 for his duck boat. The 9.9 just would not get him there quick enough, and he had the other one for a spare. Was also a Yamaha F15 on there a while back mounted to an older Alumacraft 14' Jon for $800. I missed it-sold before I could get there.

Weight is not a huge issue. I put an F25 on mine (replaced a Yam 25ESH which is about 26 lbs lighter). It also had a group 27 battery which was 65 lbs. I dropped my Optima red top into the tray (39 lbs) and saved a good portion of the weight I gained with the 4 stroke. But I also gained a quieter, smoother, more fuel efficient engine. And I got rid of the 6 gal tank in favor of a 3 gal-so there's more weight savings.


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## bobcat_fisherman (Feb 22, 2012)

turbotodd said:


> I wouldn't worry so much with the transom, so long as it's sturdy and not rotted. I vote for a 15. And I also vote 4 stroke. What part of TX are you located? I'm in Arkansas. 9.9's and 15's are a dime a dozen here because all of the duck hunters want a 25 2 stroke because they're lighter. Lighter=faster. Still amazes me to see 100 boats sitting at the ramp...then at 4:30 AM, they all leave the same ramp, headed for the same "holes"...and the guy who gets there first gets that hole. Too much competition for me. Neighbor guy bought 2 9.9 Johnnyrudes for $400 on littlerock CL. They both run just fine. Guy who sold them wanted a 25 for his duck boat. The 9.9 just would not get him there quick enough, and he had the other one for a spare. Was also a Yamaha F15 on there a while back mounted to an older Alumacraft 14' Jon for $800. I missed it-sold before I could get there.
> 
> Weight is not a huge issue. I put an F25 on mine (replaced a Yam 25ESH which is about 26 lbs lighter). It also had a group 27 battery which was 65 lbs. I dropped my Optima red top into the tray (39 lbs) and saved a good portion of the weight I gained with the 4 stroke. But I also gained a quieter, smoother, more fuel efficient engine. And I got rid of the 6 gal tank in favor of a 3 gal-so there's more weight savings.



I live down in Houston. Seems like all the motors for sale down here have a boat attached or are way to expensive. Some guys are wanting $1500-$2K for motors built in the 90's to mid 2,000s. I can buy a brand spankin new motor for a little over $2K for a 2011-2012 model.


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