TOPIC: Nagging Question

Can anyone tell me why most inboard boats have engines that spin counter-clockwise? No matter if they drive from port or starboard or the engines are mounted standard on backward, they all seem to spin the prop counter clockwise. (to the right when viewed from the rear)

As far as I know, all outboard motors also spin counterclockwise. There must be a reason but I have no idea what it is. I have powered boats with "standard" rotation (to the left when viewed from the rear) and I encountered no handling problems. So...what's the deal?

I can only make an uneducated guess, but I would narrow it down to 2 reasons. easier to make props, if they are all the same rotation. Probably more importantly, by spinning counter, then using standard threads, the prop nut will be tightening.

Or, it could just be a communist plot to cause you confusion.

Will

Nautilus wrote:

Can anyone tell me why most inboard boats have engines that spin counter-clockwise? No matter if they drive from port or starboard or the engines are mounted standard on backward, they all seem to spin the prop counter clockwise. (to the right when viewed from the rear)

As far as I know, all outboard motors also spin counterclockwise. There must be a reason but I have no idea what it is. I have powered boats with "standard" rotation (to the left when viewed from the rear) and I encountered no handling problems. So...what's the deal?

With regards to your 1st paragraph, engine rotation (crankshaft) & prop rotation are two different things. Also, when a prop has right hand rotation (like a common right hand thread) that is CLOCKWISE, not counter clockwise.

With regards to your 2nd paragraph, most outboards (probably all) have clockwise crankshaft rotation when viewed looking down and standard prop rotation will also be RH or CLOCKWISE. (Counter rotating gear cases will spin the prop LH or counter clockwise).

Assuming RH rotation, torque will try to rotate the hull left (as in lifting the RH side) so by placing the driver (with no passengers on board) on the right, torque will try to level the ride.

I believe some if not all of the Scott/McCollugh props turn counter clockwise.

As for inboard props turning clockwise...it's probably because the motors are from wheeled vehicles and clockwise rotation became a standard so engine and driver train mfg. were on the same page.

In order for the prop to turn to the right (clockwise), it needs to be driven by a reverse rotation engine. (an engine the spins counter-clockwise when viewed from the front. This is what boaters call a right hand engine.

All automotive engines (at least here in the U.S.) are standard rotation engines that spin to the right when viewed from the front. Therefore, a standard rotation engine would spin a prop to the left or counter-clockwise when viewed from the rear.

I understand about torque and a single driver but I have seen boats that drive on the port side that still have right hand props, particularly outboard boats. I guess it's just a "manufacturer's choice" thing.