176 ideal prop?

Tim as always, you are 100% correct, but that old prop needs some time with a couple of hammers and some heat, it is pretty "out of shapes."

I agree with the assessment of the 1442, but we thought it would be fun to throw it on their just for chits and giggles.

I know you're just busting chops, but I'll bite.

Taken out of context... I always recommend spinning the engine at max rated rpm (generally where it makes peak power) at a minimum, preferably exceeding it by 100-200rpm. For a 240hp PCM, the max recommended rpm is 4400, so 4400-4600 is the window, with 4500-4600 being the ultimate goal. You won't hurt anything spinning it at 4700-4800 but if there's a good prop out there that can knock the revs back to the range i just stated, you can gain a little bit of performance as well as some efficiency.

I say "spin it to win it" to those afraid to exceed max recommended rpm for fear of "breaking things" or some such nonsense. Over propping to keep revs below max rpm is detrimental to both performance AND reliability as putting a large prop that loads down the engine is harder on components than over revving (slightly).

That Navionics App is cool!

Not 100% sure the tach is correct. It was my fault we had to shut it down. I should not have gone along. I told him to drop me off and make some passes on his own, but he would having nothing of it. He'll get some better data on a flat inland lake and I won't be with him.

I also think that 14x16 is a VERY tired prop. I also offered up my 1442, we just have to get it off the Sport. AND I will give him one of my portable GPS's (which I forgot to take with us this trip).

Today Steve loaned me his 422 and I took her for a test run after timing it last night.

We got 4700 RPM at 43mph. That speed was measured on a cell phone app and I had to back the throttle down after a few seconds (rollers on Lake Michigan).

I think this is the sweet spot of the boat that Zach was referring to. I noticed a reduction in vibration and now I just have to ski it to check the hole shot.

I think I have to adjust the carb now after changing the timing, but I'll post more stats when I get them.

Cheers!

Chris

Gary! How dare you!

I have a 1996 Ski 176. I switched from a three blade to a four blade this summer. This is my first season with the boat. It seemed to me that top end is around 45.I can look at what prop is on the boat.      

I had to do official wedding things all Thursday and Friday.

Gotta make sure she's making full power. I was just up on lake Nagawika this weekend. I should have given you a heads up.

skutsch wrote: and trust me, it won't take much to take the head off with the headstart I have given it...

I am in no way laughing at your pain steve, but that's funny

Frankenotter wrote: Steve, are we still on for Thursday? EDIT

Sounds like you got a plan, my need was to just waste some time, you go take care of your stuff! I'd ride along with you, but the boss will have my head if she comes back from work and I am out playing with boats, and trust me, it won't take much to take the head off with the headstart I have given it...

Chris, what's on the boat now- a 3-blade or 4-blade? Confirm the dimensions on your spare- if be amazed if it only has 14" of pitch. $5 says it had 17", can't recall if it's 12" or 13" diam... But that would have been the original prop on a 176, not the 14x16- at least based on what I've been able to gather.

Wake should not change based on blade count, I'm not sure I buy a table/turbulence difference either. The latter can be impacted (along with rooster firmness) by props that run different rpm at a given speed (higher rpm = firmer/harsher), but blade count shouldn't factor in much. Props of different style (Oj vs acme, for instance) may cause changes to boat attitude depending on how much stern lift they generate (which in turn plants the nose, distributing the boats weight over a larger surface and makin the wake slightly smaller- at the expense of top end speed), but all of the acmes we are discussing are similar in design and shouldn't change the boats attitude in a measurable way.

Like I said above, there is no 3-blade equivalent to the 422 or 668, only ones that have (incrementally) less pitch. I would not choose a prop based on blade count unless all else were equal- in which case I generally prefer 3-blades on our lighter direct drives. Matching pitch to wot is a more important consideration though, IMHO.

Frankenotter wrote: I use it exclusively for slalom and barefoot.

And collecting oil and toxic waste out of the Milwaukee River...