[h2ofamily]

WoodNfish,

I went through some of the same questions recently with my 17 Logic. I bought a shop manual and read these posts for info. My boat didn't have a tach when I bought it, so had one installed so I could check rpm at WOT.

The boat has a 2000 Johnson 70hp 2stroke and a SS prop when purchased. There are no markings on the prop for size, but the original prop is a 14" X 17 aluminum. After getting the tach installed I checked rpm at WOT and it was on the high side at 5800 RPM. Target for my engine is supposed to be about 5500. I was doing about 34-35 mph with three in boat and trimmed out as best I could. The SS prop was nicked and dinged from the original owner and I was trying to determine whether to refurb or replace.

We do a lot of slalom skiing with deep water single ski starts. I weigh about 185, so that takes some doing. The engine/prop combo pulls me up pretty well and I didn't want to tinker with a bunch of prop sizes trying to find one better. At the end of the day I decided to refurb the SS prop and I installed one of the fins from Bob's machine as recommended by putershark, htp://www.bobsmachine.com/Products/transom_stabilizer.cfm.
I am very happy with the setup. I didn't know about the propulse prop.

With the fin the hole shot was markedly better, the boat stays on a flat plane at much lower speed (12 - 13 mph), and pulling me up from a deep water start is faster. One thing I didn't notice any improvement in was turning, it still skids just like before and needs some fancy throttle work to turn sharp enough for skiing.

I have not taken it back up to WOT with the refurbed prop yet, but at midrange throttle noticed about a 2 mph increase over previous speed at 4000 rpm, 25 mph v. 23 mph with dinged prop.

All in all, the guys who post here with specific answers to specific questions are pretty good and give good advice. I am a novice and have benefitted from them already. Us novices appreciate you experts sharing your hard earned experience.

Thanks.