I run a Turning Point Express Mach4 19P stainless prop. Motor is still in the 2nd hole down (where it came from the factory). I can turn it 5800+ RPMs day long at 46 mph or so. Speed is via GPS on Humminbird and RPMs are via Vessel View mobile. I need to raise the motor another hole because while I can turn nearly 6k RPMs, I stop gaining speed around 5600 or so.
ok finally got my spitfire x7 17 pitch and ran today results 2 people and fishing gear 1/2 tank gas 5800 rpm 46 mph just me and same gear 6000 rpms 48 mph, i was able to run 3 mph faster with just me and 19 pitch and 5600 rpms, running with two with 19 pitch ran 5200 rpms and 44 mph, i think i will stay with the 17 because i will be fishing with someone most of time and it lets my motor run closer to top rpms
bump
Interesting stuff, I will be going out solo this weekend and will report back what I can do with the 19p up another hole. Never thought about the 17p might be the answer. 48 @6k sounds pretty good to me.
Originally Posted by BBW
Either remove weight or lower the pitch on your prop. Its simple physics.
2018 Ranger RT188 SC Black/115 hp Yamaha SHO 4-stroke; Garmin LVS34 - north
2018 Ranger RT188 DC Black/115 hp Merc Pro XS 4-stroke; Garmin LVS34 - south
14' Mirrorcraft tin boat (ancient) with a 9.9 Mercury 4-stroke, no electronics; catches fish anyway
I raised my engine up a hole and really didn't see any difference. I still can't turn any more than 5800 without the prop starting to slip pretty bad. The last bump will usually make the RPMs jump from ~5800 to well over 6000 but speed really doesn't change. I have to trim it down 3 or 4 bumps to get the prop hooked back up. The RPMs drop to about 5200 at that point and speed drops accordingly. I've never had that happen before...usually when the prop blows out I'd hit the limiter and a quick bump down would hook it back up quickly. I guess I either need to go up another hole, try a similar pitched 3 blade prop or go down to a 17P 4 blade...
Update to this thread....
Motor was raise another hole. #4 if I am remembering correctly (1 from top). This past weekend it ran 50 mph at 6100RPM's. Boat was light, not a ton of tackle and gear as it was the first trip out for the year.
0 porpoising
19P Spitfire x7
Glad moving it up worked for you. I wasn't impressed with mine but it could have been either the prop or the amount of crap I was hauling. I really thinned out what I carry and the boat performance went up just from that. I'm really looking to move to a bigger boat but might try raising the motor to see what happens.
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