Need prop help

[Simper fi]

Hello all, I wanted to change props for the first time on my sea ray 180 br , it has a 3.0 merc, with alpha 1 drive, I have had the boat sinse new in 2001 and have put 60 hours on the boat, recently I talked to a guy that sold me a shiny stainless prop in 14.5 with 19 pitch, the stock prop that came on the boat was a 14.5 with 21 pitch, wife and I took boat off base to give her a spin and the engine was spinning up close to 7000 rpm, so immediately let off after it would not even plane out, came home thinking something was tore up , changed the prop out with the one that came on it took it back out and everything was normal 40 mph at 4750 rmp, so can anyone tell me what happened and why :wow:

 

[blaster]

Check the numbers stamped into that steel prop. It should operate within range if the numbers you posted are correct. I ran a 21 pitch stainless and was at 4700 rpm 43 mph lightly loaded and 4800 rpm 41mph with the 21 aluminum. I doubt you acctually hit 7000 rpm. I would check the ground wires on the back of the tach to be sure their tight. I ran tidal potomac with those numbers. At deep creek lake I ran a 19 aluminum and was at 4850 rpm and about 38 mph with the high altitude. When I ran the 21 it was a dog and wot was 4400 lightly loaded. I've heard a 4 blade 18 pitch aluminum runs good for hole shot on the 180 but it may over rev a little. I would think that a 19 ss prop would run sweet on that boat at just a little overspeed maybe 5000 max.

 

[Simper fi]

Check the numbers stamped into that steel prop. It should operate within range if the numbers you posted are correct. I ran a 21 pitch stainless and was at 4700 rpm 43 mph lightly loaded and 4800 rpm 41mph with the 21 aluminum. I doubt you acctually hit 7000 rpm. I would check the ground wires on the back of the tach to be sure their tight. I ran tidal potomac with those numbers. At deep creek lake I ran a 19 aluminum and was at 4850 rpm and about 38 mph with the high altitude. When I ran the 21 it was a dog and wot was 4400 lightly loaded. I've heard a 4 blade 18 pitch aluminum runs good for hole shot on the 180 but it may over rev a little. I would think that a 19 ss prop would run sweet on that boat at just a little overspeed maybe 5000 max.

Hello thanks for the input, the stock prop is alum is a 14.25 with a 21 pitch, they stainless is d3 by 13.25 by 19 pitch , I've listened to so many different motors run I really don't need the tach lol I'm not sure of the problem but it would not do anything right other than spin that little prop like crazy

 

[blaster]

Did the 19 plane off ok or is the hub slipping? Somethings up to be turning that fast. If you have gps try to get some speed numbers to compare to the other prop. Using speed rpm's and pitch you can calculate prop slip %. I ran a 14.5 x 19 aluminum on my 2001 180 br and didn't come close to over reving that much.

I just re read your first post and you stated you couldn't plane off. Sounds like a spun hub on that prop. Might want to confirm that and then have a word with the guy who sold you that prop.

 

[Simper fi]

Did the 19 plane off ok or is the hub slipping? Somethings up to be turning that fast. If you have gps try to get some speed numbers to compare to the other prop. Using speed rpm's and pitch you can calculate prop slip %. I ran a 14.5 x 19 aluminum on my 2001 180 br and didn't come close to over reving that much.

I just re read your first post and you stated you couldn't plane off. Sounds like a spun hub on that prop. Might want to confirm that and then have a word with the guy who sold you that prop.

Hello thanks for the help, took the prop by a different boat shop and told them the same story , they tested the hub and your right spun hub, so anyway I took the prop back to the guy who sold it to me and he is going to replace it, thanks for the help

 

[blaster]

Glad you got it figured out. Good luck with the next one.