1983 Mercury 50HP 2-Strok Outboard – S/N: 6307834 – Propeller Question

by Bob
(Lenexa, Kansas)

I’m trying to replace the propeller on my Mercury outboard. I purchased a 24-foot Sun Tracker Party Barge pontoon used. The Mercury outboard had a 48-87818-9, 3-blade, 13 tooth, aluminum propeller. I’m on my second new aluminum propeller and I don’t seem to be able to get the correct size. The new purchased propellers will not achieve the correct WOT rpm (5,000 to 5,500). With the second new propeller, a 3 blade, 12 ¼ diameter, 9 pitch, aluminum and with this propeller the outboard idle at 1,000 rpm and the WOT is 3,000 rpm at 12mph. I realize the pontoon is heavy, but the WOT rpm seems way too low. Any advice will be truly appreciated!

Bob
Lenexa, KS
kansasasbell@hotmail.com