Caveman Charlie
Chief Petty Officer
- Joined
- Oct 31, 2007
- Messages
- 545
I have a 3 blade aluminum prop with the fallowing numbers on it. On the hub is stamped 48-58422 And then there is a symbol. I can't tell what the symbol is. Lets say the other numbers should be read with the prop on the boat. If so then horizontally there are numbers in large print that read: 586(9) vertically above them it says 1 and then 3. Around the other side of the prop in horizontal small numbers it says: 48-58422A4 and then is says 19P. What does all this mean? Is 19p a 19 pitch prop?
The prop came on my 2500 pound boat powered by a stern drive Mercrusier 140. I won't be able to get the boat in the water until next summer. And, I did not get it running right yet this last summer after I bought it. But, it seemed to me to only go about 4000 RPM. The book recommends 4200-4500 RPM for a 140. But, the engine is old. Maybe it's only making 120 Hp instead of 140. The book that came with the boat recommends about a 15 inch diameter 23 pitch prop. So why did this boat have this prop on it. It came with ski ropes. Was he trying to get a better hole shot?
Also, it seems like the motor likes to run best about 2800-3200 RPM. if you get it over 35 she seems to really be working hard. So, why can't I get a prop that performs best at 2800-3200 RPM and then be careful not to over speed it above 4200? Why spin it out to 42 -45 and waste gas and make the engine work harder? It will mostly be used as a fishing boat. If I occasionally want to pull a skier why can't I just put my present prop back on?
Lots of questions I know. I hope some of you can help me to understand prop design and selection better.
Thank you for any answers you can give
Have a nice Day. Caveman Charlie
The prop came on my 2500 pound boat powered by a stern drive Mercrusier 140. I won't be able to get the boat in the water until next summer. And, I did not get it running right yet this last summer after I bought it. But, it seemed to me to only go about 4000 RPM. The book recommends 4200-4500 RPM for a 140. But, the engine is old. Maybe it's only making 120 Hp instead of 140. The book that came with the boat recommends about a 15 inch diameter 23 pitch prop. So why did this boat have this prop on it. It came with ski ropes. Was he trying to get a better hole shot?
Also, it seems like the motor likes to run best about 2800-3200 RPM. if you get it over 35 she seems to really be working hard. So, why can't I get a prop that performs best at 2800-3200 RPM and then be careful not to over speed it above 4200? Why spin it out to 42 -45 and waste gas and make the engine work harder? It will mostly be used as a fishing boat. If I occasionally want to pull a skier why can't I just put my present prop back on?
Lots of questions I know. I hope some of you can help me to understand prop design and selection better.
Thank you for any answers you can give
Have a nice Day. Caveman Charlie