Deciphering Prop Numbers

thegammas · Post by **thegammas** » Thu Jan 18, 2007 7:32 am

Greetings all -

Does anyone know how to decipher the numbers on a prop? I am looking to score a back up prop for my 63 Merc 1000 (which eventually will power my Thompson). I find alot on e-bay and such, but cant really determine (other than Spline Counts) what would fit and what the differences are.

For instance - I am looking at two quick silver props; one with the numbers 48-29660-15 and the another with 48-34402-A1-11.

Any help would be appreciated.

Shaun E. · Post by **Shaun E.** » Thu Jan 18, 2007 6:24 pm

merc parts break like this- 48 means propeller group-34402 is the part-A1 is the revision number- and the last number is the pitch. If there is no "
A" number, it has not been revised. You will need a parts book to find out the specific prop numbers for that motor. I wish I still worked for a outboard dealer. Hope this helps you. Shaun

thegammas · Post by **thegammas** » Sun Jan 21, 2007 6:12 pm

Excellent - thanks for the break down - this helps a lot as I am looking at a spare prop and it has the same group and pitch as the one on the motor now.

Shaun E. · Post by **Shaun E.** » Sun Jan 21, 2007 6:45 pm

if the pitch number and the spline count are the same then it will work. They used to change those numbers all the time when they updated parts so it can get a little confusing. Glad I could help.

thegammas · Post by **thegammas** » Wed Jan 24, 2007 7:24 pm

Well then, one more question - I found a nearly new prop, same pitch, but three blade vs two. Am I even close to say that a two blade prop is best for higher top speed /engine RPM, where a three blade is best for more pulling power, but a lower top speed/engine RPM?

Shaun E. · Post by **Shaun E.** » Thu Jan 25, 2007 7:20 am

ok i will try to make this simple. The lower number of blades the more efficent the prop is. A one bladed prop would be the most efficent but it would vibrate like crazy. The higher number of blades the better the balance is. That is the reason they make props in 3,4,and five blades now. You also have to factor in the fact that props nowadays have cupping when they didnt have that years ago. A prop with cupping will act like a prop that has more pitch simply because it is more effective at moving water. So to answer your question the 2 blade will probably be a touch faster but the 3 will be more user frendly when it comes to planing and rise and torque steer. Hope this helps.

thegammas · Post by **thegammas** » Thu Jan 25, 2007 7:19 pm

this does help - thanks!