Singles versus Twins

colobear · Posted: Sat Mar 24, 2012 7:29 pm Post subject:

According to Les, Honda only makes left hand motors at 90hp and up so all of us with smaller Honda twins have right hand motors.

thataway · Posted: Sat Mar 24, 2012 11:22 pm Post subject:

I certainly would not be one to argue with Les, but my Honda 90 swings a right hand prop. Most single engine boats run right hand props.

Mercury makes a 90 hp counter rotating lower unit. There were some counter rotating engines back in the late 80's Not sure that there are any true counter rotating outboard currently.

lloyds · Posted: Sun Mar 25, 2012 12:35 pm Post subject:

My engines are the same, and I am pretty sure they are right hand. I have tried to even out every other possible cause. I ended up adjusting with the tabs on the engines and got most of it out but it seems like with about 20 degrees of adjustment in the tabs it doesn't make for the most efficieint running. I might try the 3/16 toe in and see what that does.

Spike · Posted: Sun Mar 25, 2012 12:47 pm Post subject:

As I have a single 115 and kicker it really does not pertain to me, but I am interested. How do you adjust "toe" on an outboard? Thanks

T.R. Bauer · Posted: Sun Mar 25, 2012 1:17 pm Post subject:

Spike · Posted: Sun Mar 25, 2012 2:45 pm Post subject:

T.R.
What bracket are you talking about? Do you shim one side of the motor as it hangs on the boat, or adjust using the tab under the cavitation plate? The mechanics of this intrest me. On my main I see no way of adjusting for toe. Maybe I'm missing something. Thanks

Chester · Posted: Sun Mar 25, 2012 2:47 pm Post subject:

Chester · Posted: Sun Mar 25, 2012 2:50 pm Post subject:

Yellowstone · Posted: Sun Mar 25, 2012 3:57 pm Post subject:

Just a thought. Having crossed the Pacific several times on the water and seeing ships with one propeller (although most trans- oceanic ships have twin or multiple screws) making the crossing. given the reliability of both 2 and 4 cycle motors properly maintained, the redundancy of twin motors may be more of a comfort factor than a reality one. But it really may depend on the nature of your boating. I guess I'm more confident in today's motors. Besides, twins gobble up space on the transom of a 22' complicating swim steps, steering and tabs, and simply are less economical on plane than a single engine. It is interesting to note that the Marinault is designed for a single engine; Les and his folks are comfortable with the single engine design. Then again, each person needs to scratch his fleas in his own way. John

Captains Cat · Posted: Sun Mar 25, 2012 4:02 pm Post subject:

Spike · Posted: Sun Mar 25, 2012 4:48 pm Post subject:

Charlie
I knew that I did not need to worry about toe in or out as I have a single with a kicker. I was wondering how a person set and adjusted the toe on a twin set up.
Chester
I did not even think of the tie bar between the two motors. Next questions, Can you adjust the toe in or out force useing just the tab under the cavation plate, and do you have to adjust for toe in/out when the motors are mounted farther apart as in a Tomcat or a larger mono hull deep V where the motors may be farther apart than say a 25 or 22 CD. Thanks

Chester · Posted: Sun Mar 25, 2012 5:29 pm Post subject:

Dora~Jean · Posted: Mon Mar 26, 2012 2:11 pm Post subject:

One thing to clarify is the definition of toe "in" vs "out". The way I understand it is, that for toe in, you adjust the front of the outboards outwards, more away from each other, as compared to exact parallel.

This increases efficiency and provides better steering centering by aligning them with the natural direction of water flow at the stern of the boat. You want the two wakes to merge correctly at some distance behind the boat at a given speed -- I do not know that speed/distance, it would vary by the length of the boat and the distance between the engines.

Is that what others understand?

thataway · Posted: Mon Mar 26, 2012 2:20 pm Post subject:

Teleflex says:

"Toe-out = props farther apart than engine centerline (the prop is the "toe" of the foot, the engine gear housing is the heel).

Toe-in = props closer together than engine centerline (pigeon toe!).

Although I don't know the percent of single screw commercial ships--it is very high. Many of these can de-couple a cylinder and then use 11 instead of 12 (for example)--Some can be repaired under day. Most commercial fishing vessels are single screw.