Engine weight vs Max HP

keepitsimple

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May 24, 2011
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Hello everyone, (long time reader, first time poster here)

I've got an older Grumman 12' that has a plate that clearly states 10HP max(it actually says how many mega, zillion Gigga Watts or something since I'm in Canada, but I'm old school so all I know is it's 10 bloody HP :D ). The boat is late 70's early 80's if I were to guess. I purchased the boat with an old Johnson 9.9 that, for the sake of argument, is done. So, looking at my options I've seen all the pro's and con's for getting a 4 stroke vs a 2 stroke and for me it's coming down to the fact that I'd like to get a 4 (keeping with a 9.9) but I'm concerned about the weight of the engine itself.

Now, I'm a bit of a noob here, this is my first boat, but everywhere I read it says, "don't put an outboard over the rated HP" yadda yadda, and I'm good with a 9.9 on this boat (even though with it's build quality and overall size I think it would handle a 15 easily). I'm concerned that back in the days this was built, 2 strokes were the only thing going. I'm not sure that the weight of the motor was a concern when this boat was built and it's limitation was more that of thrust and direct torque on the transom.

There are a lot of 4's to choose from and their weights do vary quite a bit from the "relatively" not so heavy Tohatsu(Nissan) / Yamaha's 84lbs to the scale tipping Honda / Suzuki's 114lbs.

Should I be concerned about the weight of the engine as long as I stay at 9.9HP or am I just being paranoid?

If weight is an option then I can slim down to an 8HP-4 or just look for a good used 9.9HP-2.

Your expertise is greatly appreciated.

Bones...
 

rbh

Fleet Admiral
Joined
Mar 21, 2009
Messages
7,939
Re: Engine weight vs Max HP

Hello from BC and welcome aboard.

I am thinking that a 10 HP 2 stoke engine from the 70's probably weights more than a
10 HP 4 stroke from today.
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Engine weight vs Max HP

The new Tohatsu's are really close to the same weight as a two stroke. You'll be fine with a 9.9 4 stroke. You'll really miss that nausiating 2 stroke smell and the early morning smoke on the water though...LOL.. The 4 stroke will idle all day long so you'll also miss all those fouled plugs.
 

keepitsimple

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Joined
May 24, 2011
Messages
5
Re: Engine weight vs Max HP

Hello from BC and welcome aboard.

I am thinking that a 10 HP 2 stoke engine from the 70's probably weights more than a
10 HP 4 stroke from today.


Excellent point, however, funds are limited so whatever I get won't be brand new. I'll be looking to pick up a 5+ year old motor to save on $'s. Given that manufacturers have come a long way in a short period of time weight wise with these "newer" 4 strokes, the one's I'm looking at may be a tad heavier than the brand new ones.

I guess I'll be ok looking to stay under 100lbs if I can.

Thanks for your advice.

Bones...
 

keepitsimple

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Joined
May 24, 2011
Messages
5
Re: Engine weight vs Max HP

The new Tohatsu's are really close to the same weight as a two stroke. You'll be fine with a 9.9 4 stroke. You'll really miss that nausiating 2 stroke smell and the early morning smoke on the water though...LOL.. The 4 stroke will idle all day long so you'll also miss all those fouled plugs.

I can't wait to miss all that with a quiet 4. I really like what I've read about those Tohatsu outboards. I guess a lot of people also like them too as I've never seen one used and forsale! Always a good sign of a quality product. I'm personally more of a Honda guy but I can't justify the price/weight at this time even though there are a few kicking around on the used market.

Bones...
 

NYBo

Admiral
Joined
Oct 23, 2008
Messages
7,107
Re: Engine weight vs Max HP

There should also be a weight limit on the capacity plate. A heavier motor will, of course, eat into that. Just keep within the limit and balance you load properly, and you'll be just fine.
 

444

Senior Chief Petty Officer
Joined
Jul 16, 2010
Messages
704
Re: Engine weight vs Max HP

A fat guy versus a skinny guy will weigh down the back of the boat MUCH more than the few pounds of difference between a 2-stroke 9.9 and a 4-stroke 9.9. I wouldn't worry about it in this case.
 

jrs_diesel

Chief Petty Officer
Joined
Mar 3, 2010
Messages
552
Re: Engine weight vs Max HP

I have a 1986 Johnson 9.9 that weighs 72 lbs. That is for the short shaft, rope start model. Electric start added 5 lbs (not including battery), and the long shaft was 5 lbs more as well.

That is a lot lighter than modern 4 stroke 9.9's and some modern 8 HP motors as well.
 
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