Standard Rotation, car engines and who’s who in a boat

[ibrw1]

This is hopefully correct, please feel free to step in. Rotation is viewed from the back of the engine looking forward. Single engine boats are standard rotation, left hand, counterclockwise, just like a car. So the left or port engine (Twin Engine Boat) is standard rotation, left hand rotation, counter clockwise like a car engine. counterclockwise, just like a car. In a (Twin Engine Boat) the starboard or boats Right Side, is the odd ball.

 

[Chris1956]

Just so you know, Sterndrives and Outboards can have counter-rotating gearcases, eliminating the need for counter rotating engines

Standard rotating engines and gearcases use right handed props, which rotate clockwise in forward, when viewed from behind the boat. I believe (not sure), that on twin motor set-ups, the Starboard motor has the CCW gearcase.

 

[Scott Danforth]

RH turning engines went by the way of the dodo bird in the 70's with advancements in gear cutting. for the in a twin setup, one drive runs in reverse while the other runs forward.

 

[ibrw1]

Yes, I’ve read about the drives, this was regarding left and right motors and how to tell. lots of good information! Thanks!

 

[Scott Danforth]

unless your looking at a boat/motor from the 50's to 70's they are all Left Hand motors

if you are looking at boats/motors from the 50's to 70's would depend on the motor.

Early Chryslers had a complete different motor casting for the RH turning motor (later chryslers followed what GM did)
GM and Ford based motors had a large tag on the motor with the new firing order and stating it was RH turning motor (the cam is gear driven and not chain and crank is ground different )

 

[Chris1956]

Also, not all twin motors have CW gearcases. There are some twin sterndrive boats with two standard rotation gearcases. Likely the same situation for twin OBs as well.

 

[shrew]

Also, not all twin motors have CW gearcases. There are some twin sterndrive boats with two standard rotation gearcases. Likely the same situation for twin OBs as well.

I've seen it, so I have to agree to their existence. However, I don't agree with them in principal. I had a friend with a Fountain with both drives rotating in the same direction. It used to create torque and boat always had a list at speed which needed to be corrected with tab, which then caused a slight pull like a car out of alignment. It also makes is trickeir to dock without being able to used the advantage of prop-walk with counter rotating props.

 

[Chris1956]

Yes, counter rotating props are better for handling, however, they cost a bit more. OEms therefore sometimes choose to skip them.

 

[dingbat]

https://www.suzukimarinepress.com/m...-world-first-in-outboard-motor-technology/EN/

Now, in a move that will please dealers and boat builders alike Suzuki has announced the introduction of Suzuki Selective Rotation, which means that one outboard model can operate in either regular or counter rotation modes.

This technology will first be introduced on the new DF300AP. In its standard form, this new model will operate in regular clockwise rotation, using the forward gear. Now, by changing the gear-shift mode and adding a counter rotational propeller, the same outboard can operate in counter rotation mode (anti-clockwise).

 

[Chris1956]

Dingbat, The press release looks to be pure marketing. All counter rotating gearcases that I have seen have better reverse gear bearings, and reverse bearing retention devices, versus std rotating gearcases. That is why they cost a bit more.

The Suzuki press release seems to claim that all Suzuki motors will have the better reverse bearing, so all may be used as counter rotation. So Suzuki is building in extra cost into all their motors, for the few that will be used as counter rotating? Not much engineering sense just appears to be marketing.

JMO...

 

[72fj40]

Our Volvo AQ280 is designed to run in either direction. To change directions you simply move a small shift rod in the shift linkage.

 

[Chris1956]

And how often do you move that little lever, and use that feature?

 

[72fj40]

We considered it when we were shopping for a new prop, but we decided to stay with the left hand rotation so our old prop could be used as a spare without having to move the linkage, plus it had been running that way for 40yrs. Now we have removed the single prop lower and adapted a duo prop lower unit to the leg, which requires it to stay in the left hand rotation position. The Volvo AQ series are unique, because the rotation direction is in the upper gear box with a cone clutch and the gear ratio is in the lower housing.

 

[dingbat]

Dingbat, The press release looks to be pure marketing. All counter rotating gearcases that I have seen have better reverse gear bearings, and reverse bearing retention devices, versus std rotating gearcases. That is why they cost a bit more.

The Suzuki press release seems to claim that all Suzuki motors will have the better reverse bearing, so all may be used as counter rotation. So Suzuki is building in extra cost into all their motors, for the few that will be used as counter rotating? Not much engineering sense just appears to be marketing.

JMO...

Been in production manufacturing to long to believe the bean counters would have agreed to such a project if it didn't add "value" to the product.

I'll guarantee you it's cheaper to spend a couple hundred bucks to beef up a reversing gear than to manufacture and support two different drive configurations.

A win for the dealer as well...it simplifies and helps keep inventory levels to a minimum.

 

[Bondo]

Our Volvo AQ280 is designed to run in either direction. To change directions you simply move a small shift rod in the shift linkage.

Ayuh,..... Same deal with the Merc Bravo drives,.....

Just change the linkage over,.....

 

[pullin]

For Bondo:

Do Bravo 3's have this feature too? Or do manufacturers rely on the (already) counterrotating props to take care of torque in twin engine settings?