2 motors on same boat

popsmazz1

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Oct 13, 2006
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has anyone tried using to small motors at the same time on a 16 foot boat? I have a 6hp and a 9.5 that are both to small by themselves, I was wondering if it was possible to run them both together?
 

steelespike

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Apr 26, 2002
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19,069
Re: 2 motors on same boat

Anythings possible but the complication of 2 motors, tiller steering ,hand throttles ,2 gas tanks and/or hoses 15 1/2 hp that performs
like a 12, a fun experiment but not practical.What type boat? A 9.5 should work on a 16 ft aluminum utility.
 

popsmazz1

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Re: 2 motors on same boat

thought it would be a fun experiment, the 9.5 will just barly get it on plane with just me in it, 16ft aluminum with wood floors. why would it perform like a 12hp? to much drag with two legs in the water?
 

Silvertip

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28,771
Re: 2 motors on same boat

Sell both and buy a 15 - 20 HP and a lot less complication.
 

jsimms724

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Re: 2 motors on same boat

Does not sound like a good idea. If you actualy does this, post your results .
 

Frank Acampora

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Re: 2 motors on same boat

I have at times run both my kicker and main engine at the same time.

In your case, the larger one will tend to overpower the smaller engine but if you play around with props you should get some decent results. There are MANY examples of smaller boats with twin engines in the 9.9 to 20 Horsepower range. Typically though both engines are the same size. It is not the size that matters to these people, but the twin engines. They do sing a sweet song.

Try it, experiment for best performance, and come back, posting results. I think many on the forum would be interested.
 

popsmazz1

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Re: 2 motors on same boat

going to have to wait for spring, just for the heck of it I"m going to try it and see what happens, by the way I am going to get a 25 or 30 hp. next yr.
 

Boss Hawg

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Re: 2 motors on same boat

This is why i love this place!
Just when you think every question on every subject has been covered :p
 

Texasmark

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Dec 20, 2005
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14,897
Re: 2 motors on same boat

When a teen I was launching my boat one day and a guy had already launched his boat and was cranking his engines; a smooth cowled (50's model) 25hp and 15hp rude on about a 14' plywood boat (pretty light hull). He got them both cranked and he gave the 15 the throttle first and the boat started moving and then he gave the 25 the throttle and after a couple of seconds the 15 just kicked up. So, looks like the prop pitch/gear ratio/rpm of the 25 was such that it moved the engine through the water faster than the 15 and it became a drag element and politely kicked up......letting it's big brother steal the show.

So, if 2 they need to push in unison or one will lead and the other will follow.

Mark
 

IamCanadian

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Re: 2 motors on same boat

I would be most worried about over revving the smaller motor and blowing it up.
 

Home Cookin'

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Re: 2 motors on same boat

I think you'll go in circles.

And when the props on the two tiller steers sitting next to each other start exchanging molecules, it will get right ugly right fast.

Although frank may be right about the props, unless you have a box of them or someone who will let you try them, you will spend as much as buying the right motor.
 

cyclops2

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Apr 19, 2011
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Re: 2 motors on same boat

I ran a Evinrude 9.9 with a Evinrude 28.................The 28 did not need the 9.9. ........in a 15" shortshaft 16' Lowe Aluminum.

9.9 is enough & I can run wide open all the time for 5 FULL days on 6 gallons. Easily. I cross over in 8" to 10" of water.

fishing styles & location determines which motor ...or...oars I use. :)
 

popsmazz1

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Re: 2 motors on same boat

you know what tommorrow is supposed to be warm, I am going to try it, I will post back with the results.
 

popsmazz1

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Re: 2 motors on same boat

ok guys, tried it out today, with the motors placed about 30 inches apart works better than I expected. I set the 6hp at full throttle straight ahead and ran the 9.5 3/4 to full and steered with it, gps sead 20mph, with the 6 out of the water the 9.5 only ran 13mph. If they are to close it doesn"t work as well, so that is the results.
 

cyclops2

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Re: 2 motors on same boat

Did you have the 2 BIG guys in the boat ? :)

Remember to get the 2 motors vertical. Helps.


Enjoy :)
 
Joined
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Re: 2 motors on same boat

ok guys, tried it out today, with the motors placed about 30 inches apart works better than I expected. I set the 6hp at full throttle straight ahead and ran the 9.5 3/4 to full and steered with it, gps sead 20mph, with the 6 out of the water the 9.5 only ran 13mph. If they are to close it doesn"t work as well, so that is the results.


Hmmm, interesting how all the opinions in the whole wide internet didn't predict the results from a single little test.

So... you're saying that once you got up to speed you steered with the 9.5 and just took your hands off the 6 and it pointed in whichever direction you were going?
 

steelespike

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Apr 26, 2002
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19,069
Re: 2 motors on same boat

Actually the 9.5 is rated to make about 20 on a light reasonbly fast boat.
I would think carefully setup on your 16 if your not too heavy 15 to 18 would be possible.
 

mrmamiller

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Mar 7, 2011
Messages
167
Re: 2 motors on same boat

Ditto on the thought of over-revving the smaller motor. Did the same thing and lost a crank on the smaller motor a short while later.
 

popsmazz1

Petty Officer 1st Class
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Oct 13, 2006
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Re: 2 motors on same boat

I guess my boat is heavy, has a wood floor and a wood deck in front and 2 side compartments, I don"t think the 6 would over-rev can rev as fast as the 9.5. I don"t plan on doing this all the time, I was just curious to see what would happen. I may do it if I have a couple of other guys in the boat. anyway in the spring I am going to get a 25hp. motor, then the 6 will be used for trolling.
 
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