Twin 9.9. I have to admit that is original!
I do have a couple of questions for you, have you thought about:
1) Rotation of props?
I have never ran twin O/B with the same rotating props, is that even effective, or are you going to have an excessive amount of torque?
2) Do these engines have alternators?
If so, you don’t want to run two different engine alternators to the same battery. That will cause problems, so you would need a second battery?
I don’t have the specifications for Suzuki, but their specs should be about the same as Yamaha, even though Yamaha usually has a better fuel burn rate?
Yamaha F9.9 weighs 91 lb X 2= 182 lb, @ 6000 rpm each burns 1.03 GPH (approx). Total burn would be approximately 2.06 GPH. If you run them at half throttle you will to be still burn about 1.0 GPH (about the same as a 40 @ 3000 RPM)? Tthe alternator(s) will produce 6 AMPS @ WOT
Yamaha F40 weighs 214 lb burns @ 1000 RPM 0.2 GPH, 2000 RPM 0.5 GPH, 3000 RPM 1.2 GPH, at WOT (6000 RPM) it burns 4.2 GPH, but you will be running about 30 MPH and the alternator will be producing 16 amps
Now I gotta ask, why are you thinking of putting two 9.9 engines on a 14 foot boat? I personally would find a new/rebuilt 40 HP and be done with it? I don’t know what you are trying to accomplish but running twin 9.9 HP over 40 HP @ isn’t going to save much in fuel and you are going to have twice the cost of maintenance. Based on what you are stating you really have no need for a trolling motor – you have more need for a 40?
IMHO
