advice please on 15 hp versus 9.9 hp outboards

[alansmith]

Guys, my 29 foot sharpie is almost restored below the gunnels. I will open a new thread on the exact costs of restoring an old beat up boat when I finish topsides.

My 29 footer has a motor well that had a 4hp stroke Johnson. I want a stronger engine because she is shallow water craft and many times will be sailing against tide and wind in the delta of Sacramento and Joaquin rivers. The dimensions on the motor well is 12 inches side to side and 17 inches fore to aft.

When I started doing my research on 4 stroke engines it quickly became apparent that the 4 stroke engine heads with cowling were substantially larger than the 2 strokes. Sawzall time coming up....

So, here are my questions. And I know many of you, are diesel guys...I have truck and car diesels. If there was a reasonable power size for small boats in an outboard I would be all over it.

1. Would you stick a 9.8-9.9 Japanese o.b. in there or a 15 hp? There is no difference in cowling or weight...or should I say appreciable difference? The cost is about 500 dollars more in most of them. Should I stay smaller or does more power give you goose bumps...and why?

2. Are there any regulations that come into play for a sports/recreational boater when going up in power? Seems like I heard something about why manufactures stay at <10 hp for a reason. Some dark thing lurking amongst the other zombies that keep me awake late at night.

3. Is there an appreciable difference in cost of fuel consumption between the two hp's?

4. I am leaning towards the Yamaha because it has a hose spigot to wash the head out without restarting the engine when you leave her sit in the water or put her back on the trailer. I also like that it has a bigger prop with better low end grunt than any of the other Japanese manufactures. She also has the smallest head of the 4 manufacturers...Suzuki, Honda, Tohatsu. She is also the most expensive. Down side- are cost and the electric start model does not have a manual pull cord. Some say parts not as easy to get on west coast. I will sail mostly sea of Cortez, San Juans, Channel Islands off of Ventura, Lake Tahoe, S.F bay, and heavily in the Delta above Benicia.

5. Tohatsu has pretty good reputation amongst boaters in S. F. ...any comments?

6. the guy who owns Porta Bote says he only sells Suzuki because he got tired of dealing with all other manufactures. I think I have a master's degree (smile) in ethanol associated problems for o.b.....how to run them dry, fuel additives, stabilized gas...etc etc....any other advice solicited or volunteered welcomed.

It has been a wonderful thing restoring this boat that Steady Hand found on craigs list. I am truly smitten with her beauty and proud as hell of her as she comes back to her former beauty under my and my wife's toil. Can't wait to show you guys later what she was and what she is now. Respectfully, alan

[Soton]

My mariner long shaft 5hp sail drive outboard pushes my 24 ft , 1.5 ton boat along at Hull speed easily. A 9hp in your case would have loads of power in hand. BTW I hanker after a sharpie myself.

[44'cruisingcat]

Yamaha does a high thrust version of the 9.9 that is ideally suited to displacement boats. Bigger prop, deeper reduction gearbox.

That would be my choice.

[CSY Man]

Change a part in the carburetor of a Yamaha 9.9 four-stroke and you get 15Hp.
Some guy here in Florida specializes in the surgery and buys up every 9.9 he can find.
The part cost about $25.
I bought a 15HP from him last year, runs strong no issues.

[a64pilot]

Originally Posted by 44'cruisingcat

Yamaha does a high thrust version of the 9.9 that is ideally suited to displacement boats. Bigger prop, deeper reduction gearbox.

That would be my choice.

I second this, the draw to Suzuki is that so far the fuel injection seems both bullet proof, and ethanol immune, the 15 and 20 HP anyway as they are the same motor.

[Roy M]

Conversion of 9.9 to 15 HP:

https://www.youtube.com/watch?v=aF7VxM0x8_k

ADDITIONAL VIDEOS OF CONVERSIONS:

http://zuclip.com/watch?v=NC1xbFVFQnV2ejQ

http://zuclip.com/watch?v=b0dUVmdJLVFjVHc

ADDITIONAL DISCUSSIONS:

1998 Johnson 9.9hp 2-stroke conversion to 15hp Page: 1 - iboats Boating Forums | 623140

9.9hp to 15hp conversion how hard ? - The Hull Truth - Boating and Fishing Forum

There are plenty more sources of info. I Googled Outboard carburetor conversion 9.9 to 15 HP. Try doing so with specific year, make of your desired conversion.

[softdown]

What does your boat weigh and what is the keel configuration?

9.9hp is enough per all of my readings. Was using 5hp with my ~5400 pound deep keel in the CA delta. Would not have been enough in many conditions. I recently bought an old 18hp Johnson. It is very hard to find long shafts in Colorado. I've also had great luck with old Johnsons. Old Mercurys did not have stainless steel drive shafts until sometime in the 70's.

All of the foreign outboards? Fine for many. about all I drive is Chevy, Ford, and Dodge/Jeep. Well....there is the Suzuki buggy running on propane with an oil pan about 3' off the ground.

[Ken Z]

you would be fine with the 9.9 I have used a 9.9 or 10 hp honda on sailboats to 32' and have only on a few times , in inlets or crowded clown staging areas used full power and usually for a minute or so, usually trqveled at 5/8 poweror less. I d stay with yam, honda or mayde suz. I d read reviews service , parts impt.elec. start is handy with motors in wells.

[taxwizz]

Originally Posted by CSY Man

Change a part in the carburetor of a Yamaha 9.9 four-stroke and you get 15Hp.
Some guy here in Florida specializes in the surgery and buys up every 9.9 he can find.
The part cost about $25.
I bought a 15HP from him last year, runs strong no issues.

I believe that 9.9 hp outboards are all 15 hp motors with a restriction that is designed to make them legal where the motor must be under 10 hp.
I also believe that all 9.9 hp motors can be "fixed".
Anyway, this is what I have heard.

[basssears]

No experience with a 15 so can't compare, have always been satisfied with my Yamaha 9.9 on our Nimble 20, which is ~4,000 pounds loaded and has a sharpie style flatter hull.

I did replace the standard prop with their dual thrust propeller which doesn't seem to have changed regular forward travel any but seems to make reversing a little better and provides a bit quicker acceleration from standstill. I imagine the true high thrust 9.9 would be even better suited for my boat but again haven't tried it.

I will say this, the thing ain't light! Goes all the way from bed of the pickup into the motor well and back every year on the rig/derig cycle and it's a bear to move around, especially as it's long shaft.

-- Bass

[taxwizz]

Originally Posted by basssears

No experience with a 15 so can't compare, have always been satisfied with my Yamaha 9.9 on our Nimble 20, which is ~4,000 pounds loaded and has a sharpie style flatter hull.

I did replace the standard prop with their dual thrust propeller which doesn't seem to have changed regular forward travel any but seems to make reversing a little better and provides a bit quicker acceleration from standstill. I imagine the true high thrust 9.9 would be even better suited for my boat but again haven't tried it.

I will say this, the thing ain't light! Goes all the way from bed of the pickup into the motor well and back every year on the rig/derig cycle and it's a bear to move around, especially as it's long shaft.

-- Bass

And....
It will get heavier every year as you get older.
Bummer.

[Cheechako]

I agree about the high thrust models. Not sure how many companies have them. But the big props etc are a bonus vs just looking at HP.
More importantly, look for engines that have readily available remote controls, that's a big bonus on a setup like that. Remote start, remote shift and throttle. There are small engines that have that available. Some even have remote tilt, but I doubt you can do that with a well.

[alansmith]

Thanks guys. Yup, good luck trying to lift 105 lbs out of a motor well when I weigh 170 lbs and Mid 60's

No one really addressed the main question though. Would you pay the money for 50% more power if u r already spending that much money for a new one?

One guy asked about the hull configuration. Double ended with upswept stern. They were used as oyster boats before 1900's and then to deliver mail from offshore packet ships over breaking sand bars.. surf boats.. I draw less than 2 foot with centerboard up. Pointy at both ends with excellent speed off of the wind. Not great upwind since she is a schooner with unstayed masts. I don't even have a single winch on board. Just pulleys, jam cleats, and rope.

[S/V Alchemy]

Originally Posted by CSY Man

Change a part in the carburetor of a Yamaha 9.9 four-stroke and you get 15Hp.
Some guy here in Florida specializes in the surgery and buys up every 9.9 he can find.
The part cost about $25.
I bought a 15HP from him last year, runs strong no issues.

Yes, this is common with 9.9 hp models, which only exist because of some regulatory or tax reason. They are for the most part 15 HP engines with a restrictor on the carb or an RPM limiter or some such. I'm sure you could do this yourself, too.

That said, pushing a three ton 29 footer is far more a function of the prop design and drag issues than it is the raw horsepower.

[CSY Man]

[QUOTE=taxwizz;2406865]I believe that 9.9 hp outboards are all 15 hp motors with a restriction that is designed to make them legal where the motor must be under 10 hp.
I also believe that all 9.9 hp motors can be "fixed".
Anyway, this is what I have heard.[/QUO

Yes,
. Only a small part, probably a jet in the carburetor, let you increase to full RPM for the last remaining 5 HP.