thru hub vs non-thru hub prop interchangable ?

[mrmuskie]

I have a 1986 us marine Force 125hp that uses non-thru the hub exhaust props. Does anybody know what problems I may encounter if I use a thru the hub exhaust prop on a non-thru the hub engine? Pitch is the same, number of splines is the same, only difference is the hub design as it applies to the exhaust.

 

[rickdb1boat]

Re: thru hub vs non-thru hub prop interchangable ?

Muskie<br /><br />Will not work...

 

[Capn Mike]

Re: thru hub vs non-thru hub prop interchangable ?

OK, I'll bite. Why not? There might be an undesirable vacuum behind the non-functioning exhaust hole, i.e., the cone-shaped prop hub on the original prop may be more efficient, but I can't think of any problems otherwise. Help me understand.

 

[Walker]

Re: thru hub vs non-thru hub prop interchangable ?

I don't see why it won't work if you can find a thru hub prop that fits. Now, the other way around is a definite no-go.

 

[rickdb1boat]

Re: thru hub vs non-thru hub prop interchangable ?

I don't know exactly why it doesn't work, but I tried this on a 28 Johnson some time back and it felt as though the prop was dragging the motor down. Lost all holeshot and just plain ran bad. Maybe it will work for other motors, but I gave up pretty quick. Must be something to do with the exhaust holes in the prop, but I never found out.

 

[Joe Reeves]

Re: thru hub vs non-thru hub prop interchangable ?

Rickdb1boat.... Sounds like the lack of power would be due to a loss of exhaust back pressure when using the through hub prop? Strange, one would think it would be the other way around. I'd be interested in the proper explanation of that problem.

 

[rickdb1boat]

Re: thru hub vs non-thru hub prop interchangable ?

Hi Joe<br /><br />All I can figure is the thru-hub props exhaust holes, along with the larger "Flat" hub facing the incoming water, are fouling up the flow of water around the prop. I do know that it didn't work well at all in my case. This occured when I was at a Marina on the water trying to get a new prop after I broke a blade on my old one. They didn't have the right one and the Mech. gave me a used thru-hub to put on. Well, it fit on the shaft and I had to get home without tearing up the LU(Vibrating Bad), so I stuck it on there. Got me home very slowly..

 

[Chinewalker]

Re: thru hub vs non-thru hub prop interchangable ?

Mi Mr. Muskie,<br /> I actually did a similar experiment some years ago when I lost the prop off a 1961 Mercury Merc 400 with a solid hub. The only prop I could find that would fit was a through-hub off a 1969 Merc 350 and it worked just fine. You're certainly not going to hurt anything, so go ahead and try it, with an eye towards finding the correct prop somewhere down the channel...<br />- Scott