Getting the proper prop

[brooksville_rebel]

We have a 1998 24 ft Grumman pontoon with a 2002 ELPTO 40hp Mercury. This weekend me and a buddy were out with his dad and dog and it was low tide. Bounced the prop of the bottom and cracked one of the fins. One of the other fins was chipped when we bought the boat. I can't find any info on the prop telling what the current one is. If I recall right they supposedly changed the prop once with a used one.
So went to the Mercury site and put in the info and it comes back with a aluminum Black Max 12.25 " 3 blade 9.0 pitch RH rotation.
Now checking the price of a SS there is a big difference. So wondering if having a SS and bottoming out like we did would have or could have caused alot worse damage. ? I mean the aluminium one cracked would the SS one just dug in and stuck and seared something in the lower end or in the engine ?
We mostly take the kids out to the flats to play and swim and do some fishing a little farther out. Boat is 2600 lbs and any where from another 300-1200 lbs when we load up on average.

Does that prop sound right ? Would a SS be a more worthy investment or stay with the aluminum ? Appreciate any advice, insights and feedback.

Thanks
Mark

 

[alldodge]

Re: Getting the proper prop

We have a 1998 24 ft Grumman pontoon with a 2002 ELPTO 40hp Mercury. This weekend me and a buddy were out with his dad and dog and it was low tide. Bounced the prop of the bottom and cracked one of the fins. One of the other fins was chipped when we bought the boat. I can't find any info on the prop telling what the current one is. If I recall right they supposedly changed the prop once with a used one.
So went to the Mercury site and put in the info and it comes back with a aluminum Black Max 12.25 " 3 blade 9.0 pitch RH rotation.
Now checking the price of a SS there is a big difference. So wondering if having a SS and bottoming out like we did would have or could have caused alot worse damage. ? I mean the aluminium one cracked would the SS one just dug in and stuck and seared something in the lower end or in the engine ?
We mostly take the kids out to the flats to play and swim and do some fishing a little farther out. Boat is 2600 lbs and any where from another 300-1200 lbs when we load up on average.

Does that prop sound right ? Would a SS be a more worthy investment or stay with the aluminum ? Appreciate any advice, insights and feedback.

Thanks
Mark

A SS prop is better if you have sufficient HP that will cause the blades of an aluminum prop to flex under high load. Your 40HP does not produce enough power to make this happen. A SS prop will not bend of chip unless hit hard enough. The amount of impact to cause damage to the prop will probably destroy your outdrive. Even a smaller impact to a SS prop may not hurt the prop but could damage your drive. As you found out, that if an aluminum prop is hit, it takes the damage and protects your drive. If I was in your position I would stick with aluminum

 

[SkiDad]

Re: Getting the proper prop

i 2nd aluminum - get 2 of em.

 

[brooksville_rebel]

Re: Getting the proper prop

Thanks guys. Will do.
Since I can't read the prop info on it how can I tell the prop size and pitch ?
Thanks

 

[alldodge]

Re: Getting the proper prop

Thanks guys. Will do.
Since I can't read the prop info on it how can I tell the prop size and pitch ?
Thanks

Have you looked all over the prop including the hub area (front/back) for any kind of numbers?

 

[jestor68]

Re: Getting the proper prop

If you go over 500 lbs for people and gear, it drops to 8" pitch.

If cost is your major concern, then stick with the cheaper aluminum prop.

If performance and durability are concerns, consider SS.

If you talk to the engineers at Mercury Marine(the ones that design the motors and props), they'll tell you that the shock absorbing hub will slip before any damage is done to the drive line.

Most folks damage their lower unit by the unit sticking something hard; not just the prop.

Here's a graph that illustrates how it works.

 

[brooksville_rebel]

Re: Getting the proper prop


Thanks guys will take all this into consideration plus my bank account balance.
Here's the damage I did to the prop when I bounced it off the bottom.

 

[alldodge]

Re: Getting the proper prop

View attachment 221173
Thanks guys will take all this into consideration plus my bank account balance.
Here's the damage I did to the prop when I bounced it off the bottom.

That prop can be fixed by a prop shop and cost less then replacing it

 

[Fastatv]

Re: Getting the proper prop

We have a 1998 24 ft Grumman pontoon with a 2002 ELPTO 40hp Mercury. This weekend me and a buddy were out with his dad and dog and it was low tide. Bounced the prop of the bottom and cracked one of the fins. One of the other fins was chipped when we bought the boat. I can't find any info on the prop telling what the current one is. If I recall right they supposedly changed the prop once with a used one.
So went to the Mercury site and put in the info and it comes back with a aluminum Black Max 12.25 " 3 blade 9.0 pitch RH rotation.
Now checking the price of a SS there is a big difference. So wondering if having a SS and bottoming out like we did would have or could have caused alot worse damage. ? I mean the aluminium one cracked would the SS one just dug in and stuck and seared something in the lower end or in the engine ?
We mostly take the kids out to the flats to play and swim and do some fishing a little farther out. Boat is 2600 lbs and any where from another 300-1200 lbs when we load up on average.

Does that prop sound right ? Would a SS be a more worthy investment or stay with the aluminum ? Appreciate any advice, insights and feedback.

Thanks
Mark

Takes very little to damage an aluminum prop. I ran aluminum once, about 37 years ago, damaged it, had it repaired, damaged it, then went to stainless. Have hit small logs, tree limbs, and had the stainless in mud, sand ( of course none of these by choice ) and never damaged an outdrive, and with zero damage to the SS prop. The sand and mud just shines them up a bit. All of my local boating friends are now using SS as well, rarely damaging a prop and never a lower unit or outdrive. Just allot of bucks. U might try to find a good rebuilt SS prop at maybe half the cost of a new one. Rick