21..20.. 23.. 22?.. pitch it to me!!
212rowboat
Member Posts: 2,591 ✭✭✭✭✭
I started out (purchased boat) with a wounded 21p 14.25" 3 blade.. eh.. it was wounded, so its hard to say much, but the boat seemed to struggle..
I dropped to a 14" 20p 4 blade (alum).. it hit the rev limiter, but I really liked it jumping on plane and holding plane @ 16~17mph, but over 3400rpm..
I jacked that prop up, guys, and I've no clue what I hit.. something hard, but zero damage to the skag, and I didn't fell anything at all.. didn't even notice it until it was out of the water, which tells me it happened at the ramp... And, I was sober as a cat (as always while playing capt).. I MUST have hit something dang hard as it was coming up the trailer.. anyway..
I just slapped on a 14" 23p 4 blade.. it was cheap for a new prop, alum, and brand new.. hey, I'm still experimenting, anyway... Guess what? I like it a lot!!! I can come out of the shot at around 7~8 seconds or so, hit 45mph with a four people and loaded down nowhere near rated wot (i hit 4kish rpm, limit window is 4400-4800).. I held nice plane, trimmed right, with spray right under the helm, and 25mphish, 3200rpm.. I really dig that.. what I don't dig is idle speed maneuvering, where it moves quite a bit quicker than the 20p.. I reckon I could get used to that, though.. one strange thing this four blade does, the other didn't: the stern really pushes higher, and changes the boats attitude in the water below plane speeds.. almost like the nose dives..
I have a three blade stainless 22p 14.5" sitting on my workbench.. I've been staring at it... You fellers with experience on such matters: would you rec a stainless THAT much more than aluminum?? The only reason I'm not bolting it on right now is because I'm really surprised the 23p wasn't too much, and more so because I don't wanna beat it on whatever it was that took out the 20p before I figure out what that was....
I dropped to a 14" 20p 4 blade (alum).. it hit the rev limiter, but I really liked it jumping on plane and holding plane @ 16~17mph, but over 3400rpm..
I jacked that prop up, guys, and I've no clue what I hit.. something hard, but zero damage to the skag, and I didn't fell anything at all.. didn't even notice it until it was out of the water, which tells me it happened at the ramp... And, I was sober as a cat (as always while playing capt).. I MUST have hit something dang hard as it was coming up the trailer.. anyway..
I just slapped on a 14" 23p 4 blade.. it was cheap for a new prop, alum, and brand new.. hey, I'm still experimenting, anyway... Guess what? I like it a lot!!! I can come out of the shot at around 7~8 seconds or so, hit 45mph with a four people and loaded down nowhere near rated wot (i hit 4kish rpm, limit window is 4400-4800).. I held nice plane, trimmed right, with spray right under the helm, and 25mphish, 3200rpm.. I really dig that.. what I don't dig is idle speed maneuvering, where it moves quite a bit quicker than the 20p.. I reckon I could get used to that, though.. one strange thing this four blade does, the other didn't: the stern really pushes higher, and changes the boats attitude in the water below plane speeds.. almost like the nose dives..
I have a three blade stainless 22p 14.5" sitting on my workbench.. I've been staring at it... You fellers with experience on such matters: would you rec a stainless THAT much more than aluminum?? The only reason I'm not bolting it on right now is because I'm really surprised the 23p wasn't too much, and more so because I don't wanna beat it on whatever it was that took out the 20p before I figure out what that was....
Comments
Am I reading your comments right? 4,000 RPM WOT with the 23"? If so, the engine is lugging WAY too much. Have you had a look at the pitch calculator I posted recently? Now that you have real world data, you can fine tune my spreadsheet so that it can reasonably predict your theoretical performance numbers for your rig.
Mark
2019 MTX20 Extreme
I found what I hit this morning.. it was at the ramp.. some **** tossed a street sign in the drink at the base of the ramp, with the metal pole laying at roughly 45* angle and pressed against the sea wall... Another boater was mad as all get out wrestling with it.. he hit it with his outboard, while loading up.. what makes people do things like that I'll never understand, but it has teenager prank written all over it.... I winder how many other people fouled props before this was discovered?
Mark, I did use your calculator from the other thread.. and I appreciate it greatly.. I was right on the line, mathematically, of having too steep a prop.. but it seems to like it... I can still plop on the 22p ss prop just to see... It's almost perfect because it not only drops a pitch, but it picks up diameter- it should almost be a 'push' so far as the engine is concerned.. except, I don't know how much difference the ss will make over the aluminum as far as flex and weight (which is what I assume affects the rpms, right?)..
Oh, ok Drew. I agree that the 22" will probably be bang on. Flex, or lack thereof, of the ss prop will have a greater effect than rotational mass. Cupping will also make a big difference.
BTW, what drive package are we talking about here?
Mark
2019 MTX20 Extreme
OK then. Gut instinct tells me the ss 22" will be perfect and most efficient for cruising. It will be interesting to see your WOT data with it.
Mark
2019 MTX20 Extreme
I feel a lot better about what happened to the 20p prop, even though I'm still tweaked about it.. I reckon I can consider myself lucky there was not an expensive ss on there during that encounter.. at the least I'd be fixing that prop.. it could be I'd be buying a new one and a new lower unit, too.. who would do that and why is beyond me.. it was just plain mean..