Both RiverRat and Must-ski have extensive show team experience. I would listen to them for a show team prop. It sounds like the four blade is a good prop. If you are looking for a little more rpm and low end I would be tempted to have the tip cup (or some of it) removed and leave the trailing edge cup alone. This would decrease the effective pitch a little and also decrease the effective rake. This should give you a little less bow rise, more static thrust, and more RPM. Opti's have rev limiters so you really can't over rev one. jim
Took off my merc 4 bladed 15"X18p prop last week and put on a standard 3 bladed merc aluminum 15"X17p prop. More testing to be done this week coming up but this is what I've discovered so far. The 3 bladed prop only runs the boat about 2 mph faster at the top end and the 3 bladed "blows out" almost every time coming out of the hole on tight turns. The 4 bladed prop seems to have more bite starting from a dead stop but I haven't tried a heavy pull yet. I will try and have some of the cup taken out of the 3 bladed prop this fall but so far I'd have to say I favour the 4 bladed prop for my applications. On a side note, in turns out that our 17.6 is much more versatile than I could have imagined. Not only does it do a nice job pulling skiing acts, but it also works well as a safety/pickup boat with the open bow (just more room to put skiers and skis). I only wish that the gas tank was up front. Airguide speedo goes in next week and a wedge installed this fall. Kevin
Maybe I should try the four blade. Is it a Merc aluminum prop? I had a bow rider many years ago and I was able to shoe horn a tank under the front bow seat. It was not a Dyne and there may not be room for one in your boat. Maybe two small tanks--one on each side. jim
If the prop is ventilating in turns, taking the cup out will probably make that situation worse. Props are black magic, so it might be worth a try. I have to really lay my boat on its side to make it ventilate, but it is a foot narrower than yours. Moving the tank to the front might make it ventilate worse also. jim
Hi Jim, I'm 99% sure my four bladed aluminum prop is a merc prop. I will double check when I get out to the lake tomorrow. I never had time to check the rpm / speed ratio's and will most likely wait until my airguide is installed. Cheers, Kevin
Jim, The four bladed prop I have IS a Merc Prop. It's an Alpha 4 aluminum 14.5"x18p prop and Mercury lists this prop as being designed for ski boats. Interesting to note that both the 3 bladed 15"x17p and the 4 bladed 14.5"x18p run the exact same numbers at 3500 rpm and 4500 rpm (on this boat). At 3500 rpm I do 29 mph and at 4500 rpm I do 37 mph with either prop. For moving the boat from one location to another, I have the kids run it at 3500 rpm as all the boat review stats I looked up for the 150 Optimax have 3500 rpm providing the best fuel economy. I would still like to try one of the high performance stainless steel 3 bladed props before the end of the summer. I'm wondering which one to try first. Kevin