stolight3
05-30-2001, 02:03 PM
We have renovated a 1983 Galaxie 18'shallow "V" boat. We installed a 95 Mercury 2.5 150efi motor to a CMC Hydraulic jackplate. Our 1st test run was with a 21 pitch High Five prop. The jackplate was all the way up and trim almost all the way down The acceration was way to cool but we ran out of top end.We tacked easily over 6000 rpm (I was afraid of hurting the engine)so we kept it at 6100. (speedometer showing 61-63
We next put on a 21 laserII prop. We had a problem getting it to not cavitate out of hole unless we brought the jackplate down. We were also getting to the 6000 rpm range too quickly maybe mid 6000 before cavitation. We were flirting with mid to high 60's.
The boat (hull) performed well, never once chimewalked.
Question
(1 We want to go faster (we love speed). Do we get a High Five 23 or 25 or any suggestions?
(2 what is a safe maximum rpm (getting different suggestions)
(3 Any and all help would be greatly appreciated.
P.S. our boating days go back to the fifties when my dad would build 14' boats with 45 or 50 hps motors on them going 45+ mph.race all day on the river with guys who would do the same. We are reliving those days now and with alot more hp.
We next put on a 21 laserII prop. We had a problem getting it to not cavitate out of hole unless we brought the jackplate down. We were also getting to the 6000 rpm range too quickly maybe mid 6000 before cavitation. We were flirting with mid to high 60's.
The boat (hull) performed well, never once chimewalked.
Question
(1 We want to go faster (we love speed). Do we get a High Five 23 or 25 or any suggestions?
(2 what is a safe maximum rpm (getting different suggestions)
(3 Any and all help would be greatly appreciated.
P.S. our boating days go back to the fifties when my dad would build 14' boats with 45 or 50 hps motors on them going 45+ mph.race all day on the river with guys who would do the same. We are reliving those days now and with alot more hp.