Ressurection with another prop test. Trying to reach a new speed record (for me) Conditions were OK, 65 degrees, clear day with nearly no wind. The boat likes a little chop. Tried a 25 Tempest, semi-old school with the large square ventilation holes. I mention the large holes because the boat was a pig out of the hole with this prop. Throwing the hammer down from idle the motor would instantly ventilate the prop spinning the motor to 5800 and the boat speed was not enough to get on plane. I had to keep the throttle pinned for what seemed like forever (six seconds)until it finally nosed over. Once on plane things got back to normal. Max RPM with negative trim was 4800RPM running a flat 43 mph. Trim it to neutral and the speed climbed to 48MPH at 5000 RPM. Add a little positive trim and I saw 50 MPH turning the same 5000 RPM. Tried 4000 RPM and I got 40 MPH. Trimmed it out WOT and saw 61MPH (ie. Trimmed it to the end of the trim stroke with a little bit of trim tab) and it would only turn 5600 RPM throwing a huge rooster tail. Conclusions, Too much strain on the motor to get on plane and I know the motor was working harder/using more fuel cruising around. Prop slip is thru the roof. I found a prop the Merc can't easily handle and I could never live with the time to plane. Now I am done, until the next hair-brained idea that is.
02-22-2011, 02:14 PM
Hybrid Mode
