1984 alpha one/ merc 228 sear ray 270da

yellowbelly

Petty Officer 2nd Class
Joined
Jul 11, 2008
Messages
153
back to step one with this boat, pulled the boat last fall to find out this boat came with 1.98 gears with 305's in her..with 23p props i was over reving the motors if i got on her...this spring i throw on a pair of 27p 4 blades and wot was at 4100 rpms with a gps speed of 42mph, ran great for 15 hours and one of the drives gave out.. replacing both drives with the correct gears (1.47) will i spin the 23p or should i go lower..thanks
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
My calculation indicates about 20% slip with the 27" at 4100.
Run the 23s and go from there.
 

yellowbelly

Petty Officer 2nd Class
Joined
Jul 11, 2008
Messages
153
new drives(1.48) and 19p 4 blade alum props are running 4000 rpms wot at 39 mph. looks like 17p is gonna be the ticket
 
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