jkimball
Petty Officer 1st Class
- Joined
- May 14, 2013
- Messages
- 220
So after about a year and a half of kicking the idea around I finally took the plunge and decided to try out a 4 blade prop. Before this I was running one of 2 props, a 17" SS (OMC/SST) and a 19" SS (Viper) both 3 blade, and I got decent performance out of both. I have a 17' Four Winns Horizon with a Johnny 115 OB. with the 17" at WOT I was at about 5,400 - 5,500 RPM & 41-42 MPH depending on load. With the 19" Viper, I was at 5,000 - 5,100 RPM & 44-45 MPH again, depending on load and conditions.
I wanted to try the 4 blade because I have learned that they give better holeshot, control, rough water handling, smoother ride etc. so I bought a 17" Solas Amita-4 Aluminum. I figured if I didn't like it, it was better to sink $100 in something than $300 +. Well, I put it on and splashed the boat Saturday. When I backed it off the trailer I could instantly tell a difference in low speed maneuverability, when I got out of the No Wake Zone and dropped the hammer, it jumped out of the water like a 747 taking off (maybe a little exaggerated) and planed almost instantly. It was much smoother, handled better and in the chop in the middle of the St. John's on a windy day (11-12 MPH winds) it kept the stern up and the bow planted allowing me to cut the chop and a MUCH better ride/ handling.
The weird thing though, and I don't know how to explain this, is that I actually gained RPMs... I've always heard that when adding a blade, drop an inch to account for RPM loss... I didn't want to go too small to a 15" (glad I didn't otherwise WOT RPM would be through the roof) so I stayed at 17". But with the 4 blade, aluminum 17 x 12.5" prop, I now am at 5,500 - 5,600 RPMs, @ ~ 38-40 MPH... I guess my question is, should I go for a 19" to keep from over revving, and maybe squeeze an extra MPH out of it? No, I don't normally ride around WOT so the extra top end is kind of insignificant to me, but the RPMs have me curious... thoughts or advice?
Could the extra RPMs come from the fact that though a little thicker and not as cupped, the aluminum is significantly lighter?
I wanted to try the 4 blade because I have learned that they give better holeshot, control, rough water handling, smoother ride etc. so I bought a 17" Solas Amita-4 Aluminum. I figured if I didn't like it, it was better to sink $100 in something than $300 +. Well, I put it on and splashed the boat Saturday. When I backed it off the trailer I could instantly tell a difference in low speed maneuverability, when I got out of the No Wake Zone and dropped the hammer, it jumped out of the water like a 747 taking off (maybe a little exaggerated) and planed almost instantly. It was much smoother, handled better and in the chop in the middle of the St. John's on a windy day (11-12 MPH winds) it kept the stern up and the bow planted allowing me to cut the chop and a MUCH better ride/ handling.
The weird thing though, and I don't know how to explain this, is that I actually gained RPMs... I've always heard that when adding a blade, drop an inch to account for RPM loss... I didn't want to go too small to a 15" (glad I didn't otherwise WOT RPM would be through the roof) so I stayed at 17". But with the 4 blade, aluminum 17 x 12.5" prop, I now am at 5,500 - 5,600 RPMs, @ ~ 38-40 MPH... I guess my question is, should I go for a 19" to keep from over revving, and maybe squeeze an extra MPH out of it? No, I don't normally ride around WOT so the extra top end is kind of insignificant to me, but the RPMs have me curious... thoughts or advice?
Could the extra RPMs come from the fact that though a little thicker and not as cupped, the aluminum is significantly lighter?