Which was do they turn ?

[tronic72]

Hi,

My motors were removed about 5 years ago and we are preparing the new ones.

One engine spun one way and the other spun the opposite way. I want to make sure the new engines go on the right sides and am making preparations. Can members please confirm which way these propellers spin?

[sailormed]

Port CCW Starbord Clockwise

[tronic72]

Originally Posted by sailormed

Port CCW Starbord Clockwise

So to confirm, based on what you've said. The "standard" rotating engine which turns counter clockwise would be installed on the Port side (left) and the non-standard rotating engine would be on the Starboard (right side).

Just to be clear the Velvetdrives don't reverse rotation, one engine rotates in a non-standard direction (Clockwise, looking at the flywheel).

Thanks in advance.

[Bruce K]

Looking from the stern forward, on a monohull the top blade of the prop turns outward, on a power cat the top of the blade turns inward. Someone told me why this is so on a cat, but I can't remember why!

[skipperpete]

Your new engines are contra rotating as were your old engines and the gearboxes are contra rotating velvetdrives. To be absolutely certain the engines go into the correct places you might want to start em up before craning them in to avoid a lot of extra work. I’m curious to know what brand the replacement engines are, initially I thought Detroit diesels but they would probably be too powerful for the Borg Warner’s so are they going to be gasoline engines?

[motion30]

The starboard side is standard rotation the portside is reverse rotation

[rslifkin]

Typically you'd have the standard rotating engine on the port side, reverse rotation on the starboard. That gives outward counter rotation in forward gear (which is what your props are set up for).

However, there's one potential gotcha: The transmissions. If they're Velvet Drives, you need to check the data tags on the transmissions and confirm exactly what model and ratio you have. Most Velvet Drives rotate the output same as input, but there's one ratio that rotates output opposite of input. If you have that ratio, you'll need to swap the engines (reverse rotation on port) to get the correct prop rotation.

Post the Velvet Drive model and ratio here and I'll double-check the book to confirm how they rotate.

[capt jgw]

Most all twins are set up with the props "outward turning", or port CCW and starboard CW as viewed from the stern. If you do it the other way the boat will handle weird. Even worse of they both go the same way, the boat won't go in a straight line. Some of the WW2 landing craft did that and the Coxswains hated them. I can see in the photo that the original set up was the standard outward turning. As others have said you do need to know if one or both of your transmissions reverse the rotation. 30 or 40 years ago one of the engines would have turned the other way, but now days not so common. They do the counter rotation in one of the transmissions.

[Shrew]

Hopefully this should help

[Nicholson58]

Turn off the fuel. Engage the starter and observe the rotation.

[rslifkin]

Originally Posted by Shrew

Hopefully this should help

That graphic is backwards, at least from an engine perspective. A standard inboard rotates counter-clockwise when looking at the flywheel. Clockwise is counter-rotation. Clockwise is only the standard rotation for an outboard or sterndrive prop, but that is irrelevant to inboard engine rotation.

[Bowdrie]

Originally Posted by capt jgw

Most all twins are set up with the props "outward turning", or port CCW and starboard CW as viewed from the stern.

^This.
Whether by engine rotation or the gearbox.

[tronic72]

Originally Posted by Nicholson58

Turn off the fuel. Engage the starter and observe the rotation.

Clearly you didn’t read my original post.

[tronic72]

Thanks to everyone. Port is counter clockwise and starboard clockwise as per the images posted. Thanks again.

[Sailorman97]

Originally Posted by skipperpete

Your new engines are contra rotating as were your old engines and the gearboxes are contra rotating velvetdrives. To be absolutely certain the engines go into the correct places you might want to start em up before craning them in to avoid a lot of extra work. I’m curious to know what brand the replacement engines are, initially I thought Detroit diesels but they would probably be too powerful for the Borg Warner’s so are they going to be gasoline engines?

You don't even have to start them. Simply hook up the power and turn them over for a second and that will tell you which way they rotate.

When you do this make sure they will not start, perhaps by removing the coil wire if they are gas, or by having having the fuel shut off levers in the off position if they are diesel. That last thing you want is a engine purring away on its side in the grass while it jumps around because everyone is too afraid to get close to it.