Prop rotation on Single
 

I'm going to need a new prop this spring and a budy has one that may be a good start, but it's left hand rotation.

Does my Bravo 1 care which way it spins? Can I just reverse the shift linkage and run a left handed prop on a normal engine/drive?

Thanks

I asked the same question a ways back and the general consensus was that it's probably not a good idea. The drive isn't really the issue, it's the handling of the boat. Some people had tried it and didn't notice a big difference and others didn't like it at all. If your buddy will let you try out the prop, go for it.

Rene

I agree test the boat and see how she handles.....just proceed with caution as the boat may or may not appreciate the change.

Julie

If you have the steeringwheel on the right you would normally want a right spinning prop. The prop torque compensates for the weight of the helm + driver (when alone in the boat)

Can someone tell me why the single engine fountains are set up with a starboard helm and a lefty rotation? A friend has a 27 and tried both R and L and the L handled better and was faster. Others have made the same observation. Any Ideas why or is this one of the worlds great mysteries?

No real mystery! The boats are faster with a left hand rotation on them. So the boat is then set up for the LH rotation. ie: weight distribution and CG's

Julie

I have heard you will have less clutch cone issues spinning a lefty, any truth to that?

If a boat was perfectly balanced side to side, and the hull is straight, the left rotation of the prop could off-set the torque roll created by the engine rotation.
As stated above, most boats are heavy to starboard do to the helm, so right hand is the norm.
As for the drive, I have heard that spinning left puts added stress on the Bravo drive top cap.

If a boat was perfectly balanced side to side, and the hull is straight, the left rotation of the prop could off-set the torque roll created by the engine rotation.

My understanding is the following chain of logic;

1. We drive on right side of the road
2. The driver sits on the left to have a good view of the road and the meeting traffic
3. Car engines are spinning left for the engine torque to counter act the weight of the driver
4. For economical reasons the boat engine manufacturers use engines from the car industry, ie left spinning engines
5. To mitigate the torque from the left spinning engine, the prop is set up to spin right in a single engine boat.
6. Because of the gear reduction in the drive the tourque form the prop is stronger than the torque from the engine
7. The helm is therefore put on the right side of the boat

Bottom line, the helm in a boat is on the right because the helm in a car is on the left. :D

Not true...

A left hand spinning engine rolls a boat to port unless you mount the engine in backwards.
A right hand prop also rolls a boat to port.
A left hand prop rolls the boat to starboard; the opposite of the engine.

On my boat, I run with a right hand prop. With just one person in the boat, she run nice and level with no tab. The extra weight from the helm and driver on the starboard side offsets the roll to port from the engine and right hand prop.
If I add a passenger riding on the port side, I do need to lower my port tab to keep the boat running level.

Well, I disagree. A left spinning engine (as seen from the stern) rolls the boat to starboard. When the burning fuel pushes the pistons down and push on the crank it will create a force in the opposite direction and hence lead to a right spinning torque on the engine block and the boat which the engine block is bolted to (as seen from the stern).

Well, I could be wrong, and it would not be the first time, but engine rotation is viewed from the front of the engine. A left hand engine turns CCW as viewed from the front.

Well, this may be the miscommunication, I think you should view the engine from the flywheel end of it when defining what is right (CW)and left (CCW). http://www.propowermarine.com/faq-rotate.htm

Anyway, since the torque of the prop is stronger than that from the engine, the end result will be as you describe it, the boat will roll to port.

Your are correct...
http://www.perfprotech.com/home/Repowering.

If you are running a lot of power you will be putting more stress on the top bearning cap turning a left hand prop. Something worth considering.

Another interesting characteristic with single engine boats is the tendency to list in the opposite direction as the rotation of the prop when the motor is near it's torque peak.

Many applications when run at 3500-4000 (depending on the torque peak of the motor) will list to the port, with a RH prop. As the speed and RPM increases the boat will level out. This is because as the engine RPM gets above the torque peak there is less torque at the prop which will allow the boat to level out.

You need to screen your passengers a little better!