New Motor weight question

Kurt Hendricks

Kurt Hendricks

Member
I have a glass over cedar sneak box. Length is 11'9", with is right around 63". I currently run a 1979 Johnson 15hp which is about 75 lbs give or take. That motor has given many a year of good service. I have been thinking about getting a new motor. Honda or a Merc, 15hp and both are in the 120lbs class. The boat has never been a speed demon being a displacement hull. With the tide and wind going with my 11 kts is my top speed, so speed is not my goal.
What I am looking for is opinions on how this will affect the boat increasing the weight by 40% give or take. The boat is a tank and I routinely take it out into our bays for divers. Never have felt unsafe in it. Is it too much added weight?
 
Who was the builder? What is the transom height? ( Not the motor board but the transom) What is the width of the transom?
Most decks on old wooden BBSB's would go under water with that much wight if you went to remove a decoy anchor line off the prop.
Phil
 
The merc was the lightest one I looked at....121 pounds. The builder is unknown, but the boat is old. When I got it she was still rigged as a sailing model. Barn find. The transom is 8 X 39 give or take. And yes.....the transom goes under with me on the back getting decoy line out of the prop with the present motor. I have learned with old age not to do that. I row to pick up the blocks!! I kind of figure a new motor is going to be too heavy. But you know duck hunters...lol....it might work. Just gauging other's experience.
 
Kurt, If it were me I would take my time and find a newer 2 stroke 15 or 9.9 and keep the older motor for a back up.
Phil
 
Given its a displacement hull, would a 2 stroke 6 or 8 be enough? Save some more weight.
 
No, I would never go less than than a 9.9. One reason is that the lower units and props rare not built strong enough to handle all the possibility's of running aground. And the other is that a BBSB with rocker will nose through the wave and chop with out having enough HP to keep the bow up. The boats were designed to row and sail, and definitely not for a outboard motor. But a motor on a BBSB is one of the most safest way to hunt.
Phil
 
That's what I was initially thinking. Thanks Phil for talking in from the ledge.
And you are right on both counts. I ran a 9.9 for a while and always worried about a following sea. Just didn't have the power. That motor wouldn't push the boat past 6 kts. And as I said before, I have never really felt unsafe in any sea condition, sans a following sea, which is much less of a worry with the 15hp.
 
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If you could find a late model 15 yamaha two stroke I think you'd be set. I want to say they come in at 79 lbs.
 
Kurt

Can you borrow a buddy's motor and see if it is too much weight or if it will work? A test run would answer all questions.

Eric
 
Kurt
I am not too far from you. I have a 15 merc ss if you want to try it. It's an 04 weighing about 84lbs
 
Jmac, that is a nice offer, and I think I might take you up on that after the holidays. I have a lot going on....trying to find some ducks with a predicted 60 degree day on Saturday with a light SSE wind. Oh yeah and Christmas.
 
If weight is your only concern, can't you simply add weight to your existing setup to see how she trims out? I can't be the only one with a bunch of dive weights around. Strapped to the back of the motor board to get the weight positioned correctly and take her for a spin.

Scott
 
Excellent idea, Scott.

I've also been wondering if my boat can handle a heavier (more powerful motor) and happen to have dive weights on a belt too.

Thanks for sharing your wisdom.
 
2-Strokes are the way to go!
Yamaha was the last to make them in the 80 lb range for 15 hp....I believe 2010 was the last year.
I bought two Yamahas...in like new condition..a 2007 and 2008...as an investment, since 2-strokes are gone forever....a darn shame. [frown]
 
I believe you are correct, Yamaha was the last to make them and 2009 was the last year. 2010 new regs kicked in that ended them. From 2005 to 2009, Yamaha was only EPA compliant OB manufacturer, and to do so they prescribed 100:1 mix. I picked up a left over 2009 in 2012, still in the box from a dealer. Mike Braden found it for me in Alabama! Love this motor! I run 50:1 in it since my limited research found no changes in the parts list from a 2004 to 2009 motor, so am not willing to run it on the 100:1.
 
2004 manuals say to use 50:1?
Interesting....I too, was leery about mixing 100:1...it just seems too lean. I was going to do something like 75:1.
I'm using 50:1 now since they're so new...maybe I'll just continue at that ratio.
 
BrentS said:
2004 manuals say to use 50:1?
Interesting....I too, was leery about mixing 100:1...it just seems too lean. I was going to do something like 75:1.
I'm using 50:1 now since they're so new...maybe I'll just continue at that ratio.
Click to expand...

I've been running 80:1 in my Yamaha (2008 model 15hp) It did not like a constant diet of 50:1 ratio. (rough idle and acted like it was too rich)
 
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