Trying to find the right prop for my boat.

[Bluefin91]

I have a 1991, 19.5 foot Bluefin, Spectrum restoration boat that I am about finished with, It had no prop on it and I am trying to find something to go with it. it has an alpha 1 gen 2 outdrive. 130 Mercruiser engine I rebuilt . The boat is all aluminum. The prop is counter revolution, Left hand turning? I have no where to start on finding the right prop. Any info would be helpful. It will be used on Lake Erie for walleye and perch. Thanks

 

[Bluefin91]

The motor is a 140HP
sorry.

 

[WesNewell]

Try the prop finder here, or google prop finder for a list of them.

 

[jimmbo]

The prop is counter revolution, Left hand turning?

Counter rotating. Unusual to have one of those in a Single Engine setup. Can you post a picture of the drive with the current prop on it?

 

[Watermann]

I'd try at least a 17p or maybe even a 19p on that set up. See if you can scrounge up a used prop on the cheap locally and then go for a new prop and use that one as a spare.

So no thread here on your Bluefin resto?

 

[QBhoy]

Presuming you mean it’s a left handed rotation and not counter rotating props ? Would be almost certainly strange to have the latter. The former perhaps too. Likely the drive has been taken from the port drive of a much more recent twin engine boat...at some point.
Good news is that left handed used props are generally very cheap. I’d say a 19” be a good starter for 10. Go from there after getting details on how she performs. Good luck.

 

[Bluefin91]

Yes it is left hand rotation looking at the outdrive from the rear of the boat. The mercruiser manual says all 1991 140 HP sterndrive are left handed rotation. So a 19 inch is that the pitch or diameter, again this boat had no prop on it.

 

[QBhoy]

Yes it is left hand rotation looking at the outdrive from the rear of the boat. The mercruiser manual says all 1991 140 HP sterndrive are left handed rotation. So a 19 inch is that the pitch or diameter, again this boat had no prop on it.

Hi. Ok so what’s maybe happening here is that the drive is original....but
i almost certain what the manual says is that the engine is a left hand rotation.
The norm for most if not all single engine merc drives like this is for the propeller to be right hand orientated though. As in the prop will turn clock wise when viewed from standing behind the boat and in forward gear. Almost certain this will be the case.
The engine rotation and prop rotation is a different thing.
May be wrong, but I’d almost bet my boat I’m right, haha. Easily checked. Can tell by looking at the pitch of the blades on prop. Or send a picture and I’ll tell you in 2 secs.

 

[QBhoy]

I’m maybe wrong but just a presumption from what I know of these things. Never had a 3.0 and Alpha gen 2 but had older 3.0 and pre Alpha 145hp and then just about every small block and merc/VP after that.
Worth checking but I’d think the prop will surely be a right hand rotation. Often people will be fooled by turning the prop by hand when not running but in gear and thinking it is left hand. Not the case. Look at the pitch orientation

 

[QBhoy]

So this is actually a picture of my boat with its last prop it had on it. It’s from the Michigan marine site. They use this often with my permission for marketing etc.
This is a typical right handed prop set up on the Alpha 1 gen 2 single engine. Look at the way the blades go. Is yours the same or opposite?

 

[Watermann]

He's said a few times that there is NO prop on the drive and needs a recommendation of where to start.

He has confused the situation stating it's a counter rotating drive. I believe the outdrive serial would clear up that question.

 

[WesNewell]

The props in the photo are standard (RH) rotation props.

 

[Bluefin91]

Thanks for the info, I have the outdrive off now replacing the gimble bearing and lower water pump, Once I get it back together I will manually check the rotation.

 

[Bluefin91]

Ok, I checked the manual and it does say all stern drive engines are left hand rotation when viewed from the rear., not the outdrive. Which means clockwise rotation when viewed from the front. I put the outdrive in first gear on the bench and turned the driveshaft clockwise which would simulate the engine running and the prop shaft does turn to the right. Sorry for all the confusion. Again new at the prop stuff. So I need a right hand prop, just have to decide on the pitch, I guess from 19-23 pitch?

 

[jimmbo]

What is the Gear Ratio of the outdrive? It is located on the wrapround Decal on/near the upper gearcase housing

 

[Watermann]

Ok, I checked the manual and it does say all stern drive engines are left hand rotation when viewed from the rear., not the outdrive. Which means clockwise rotation when viewed from the front. I put the outdrive in first gear on the bench and turned the driveshaft clockwise which would simulate the engine running and the prop shaft does turn to the right. Sorry for all the confusion. Again new at the prop stuff. So I need a right hand prop, just have to decide on the pitch, I guess from 19-23 pitch?

No way that a 140 will come close to turning a 23p prop. I believe the recommendations were 17p to 19p tops. I would start with a 17p with there being no way to know the health of the motor due to it's age and unknown care in the past. You do not want to lug that motor for long or it will puke on you.

 

[QBhoy]

The props in the photo are standard (RH) rotation props.

That’s my prop. All the best.

 

[Bluefin91]

Wow did not know it was even there, 198R, serial no? OD639187

 

[Bluefin91]

I just rebuilt the 140 HP, had to go .040 over on the cylinders, new cam ,pistons etc.

 

[jimmbo]

1.98:1 right hand rotation.

I suspect your prop choice is going to be in the 18 - 19 in area, it would be a fair starting point.