Prop Selection on a "New to Me" Rig

[studlymandingo]

I've been reading over several of the threads on this forum for prop selection. Very helpful and interesting stuff. I just traded in my old 16' CC with a 75 Evinrude for a 1986 18' Winner Sea Quest Center console. The boat is equipped with a 150 Mariner that appears to run quite well. The boat had a dinged up, chunked out 14 X 70 aluminum prop on it. I put it in the water with this prop just to give it a quick trial run. I was given a 14 3/4 X 23 SS Yahama Prop by the guy I got the boat from. I immediately put the prop on, and headed out into Tampa Bay. The first thing I noticed was the sky, it quickly came into view when I pushed the throttle forward. It took longer than I wanted to plane off, and the RPM's at WOT were around 4800. I realized this was too much prop for my setup, and went to a local marine salvage shop to see what kind of trading I could get into. I traded the prop for a SS Rapture 14.25 X 21, and headed back out into the bay. The boat planed out faster, not as fast as I would have liked, and I was getting 51-5200 RPM at WOT. I had the 60 gallon tank full, and my 220 lb neighbor on board. After returning home, I read about the vent holes for hole-shot performance, and the Rapture already had holes, but there were plugs in them; I've taken them out, but a cold front has pushed in, and the water was really rough today. It was difficult to restrain myself from going out anyway, but somehow I managed. I'm hoping for improved hole-shot, but obviously the 5100 WOT is too low. Do I need to have the prop pitched down slightly, will a different brand work better, could the engine be in need of a good tune-up? These are all questions that I just don't have answers to yet. I'm hoping that some of you out there can help.

 

[WillyBWright]

Re: Prop Selection on a "New to Me" Rig

Pull your sparkplugs and see if you're running on all 6. If any are burning differently than the others, there may be a problem. I'd expect the 21 to do better.

 

[studlymandingo]

Re: Prop Selection on a "New to Me" Rig

The plugs all looked like I would expect to see in an outboard. I dumped a can of SeaFoam into the tank (approx 30 gals in a 60 gal tank). I took the vent plugs out of the prop. Ran the boat around Pinellas Point in Tampa Bay. I do get a better hole-shot, and the WOT is up to around 5400. The motor is running more smoothly, I really think there was some stale gas in the tank when I got the boat last week. After reading all of these posts regarding the motor height, I think I'm going to raise it a notch and give her a run to see any difference there may be. I'll keep the posts coming regarding my results.

 

[Ron G]

Re: Prop Selection on a "New to Me" Rig

You really need to stick to one thread,did ya do what they suggested on the other thread yet?