Prop is too tall, NOW WHAT!!

[Boat Show addict]

I have a 91 Mercruiser 3.0 liter, Alpha drive, with a 15 1/4" diameter, 15 pitch, 3 blade, standard rotation prop on it. I damaged it so I bought a new one from Solas. The new prop is taller than the one I took off by about 1 1/2". When rotated it hits the trim anode. It attaches fine to the shaft and isn't rubbing anywhere.

1. Can I trim the anode so the prop will spin and if so, how much clearance should I give it? Or just buy an offset trim anode..
2. Because the prop is longer, will it put excessive stress on the shaft in any way? ( I question this because I would think that the center of thrust on the prop has now moved rearward due to its being longer)

Am I OK to leave this prop on or am I asking for trouble..

 

[Rocky_Road]

Re: Prop is too tall, NOW WHAT!!

I had the same issue, and I chose to replace the trim tab. You can do the same or grind a section out of your current one.

Your prop shaft will be just fine!

 

[TilliamWe]

Re: Prop is too tall, NOW WHAT!!

Yep, get the offset anode.

BTW, "taller" is not the correct term. The replacement prop has a larger "Diameter", than the old damaged prop.

 

[steelespike]

Re: Prop is too tall, NOW WHAT!!

Yep, get the offset anode.

BTW, "taller" is not the correct term. The replacement prop has a larger "Diameter", than the old damaged prop.

Yes a taller(to tall) prop could be interpretated as to high a pitch.
no big deal

 

[Bondo]

Re: Prop is too tall, NOW WHAT!!

BTW, "taller" is not the correct term. The replacement prop has a larger "Diameter", than the old damaged prop.

Ayuh,.... I'd think more Rake is the issue...
After all, it can't be much Bigger in diameter, there's only 8" from the propshaft center to the Cav-plate...

BSA,....
#1,... Either will work,... 1/4" is Plenty if you decide to trim it...
#2,... No Problem for the propshaft,... you might get alittle more bow lift with the added Rake...

 

[TilliamWe]

Re: Prop is too tall, NOW WHAT!!

Ayuh,.... I'd think more Rake is the issue...
After all, it can't be much Bigger in diameter, there's only 8" from the propshaft center to the Cav-plate...

Oh yeah, good point Bond-o.

See, incorrect terminology only leads to confusion.