Location: Lake Saint Louis, MO | Steve,
Following up on my prop thread from last May... I'm hoping you can help me do better on propping my boat. The boat is a Lund 1875 Impact, with a Merc 115 four stroke. The factory mounted the motor on the middle hole, so the cavitation plate is about 1/2" above the bottom of the keel. The rig came from the factory with a 4 blade Merc aluminum prop, 13x17 pitch. This prop actually gives me the best performance of anything else I've tried so far, but the tach hits the rev limiter (6100 RPM) with some left in the throttle. Hole shot is good, cornering is good, and top speed is 38 (GPS).
I thought I could get better performance with a steel prop, so I've tried a Mercury Vengance 3 blade stainless steel in 13 1/8" x 16 pitch. The hole shot is fine, but I hit the rev limiter (6100 RPM) with a lot of throttle left. The top speed with two guys, 1/2 tank of fuel a regular load of muskie gear is only 34 (GPS) and the steel prop seems to lose grip if I trim it as high as the 4 blade aluminum. I thought this rig would break 40 MPH with the steel prop, but actually my top speed dropped 4 MPH.
I also tried the rig with a Mercury 13 1/4" X 17 pitch Black Diamond aluminum. Hole shot was fine, and top speed was about 36. Again, it felt like there was a lot of throttle left when I hit the limited 6100 PRM. That prop did not corner as well as the 4 blade aluminum.
I'm not necessarily trying to optimize top speed, but I would like to find a steel prop that give me the best all-around performance. I'm not a big fan of operating outboards at WOT all of the time and would like to maximize fuel economy when I'm on big water and making long runs, keeping the RPM in the 4000 to 5,000 range for cruising.
Recommendations? Thanks!
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