Propeller decoder?

[55Trucker]

Hi everyone. My propeller has the stamp "1918P21". Is there a decoder for these stamps? I am guessing that the P21 is pitch. What is the "1918", and is there a place where I can look this stuff up? So far I have been unsuccessful. Thank you.

 

[Lazy Daze]

You'll have to try and find the manufacturer. It's not Mercruiser. Hopefully there is more info somewhere else on the prop - maybe on the back side.

However, the other dimension you're missing is the diameter - which you can physically measure.

But, 21" pitch is about right for that boat. Are you have problems? Are you able to reach close to max RPM when WOT with a light load and trimmed properly?

 

[55Trucker]

I just measured it: it is about 7 1/8" in radius, so about 14.25 in diameter.

One problem I have is that the gauges are either unreliable or don't work, so I was flying blind since I bought the boat mid-summer. Fixing all of that is one of my winter projects. The boat "seems" fast at open throttle, with 3 or 4 adults in it, but it takes a few seconds to get to whatever its top speed is. As I read about pitch I am guessing that a lower pitch will provide more "torque" and get me to a lower top speed faster?

Two things prompted my question about the prop: 1) a neighbor has the identical boat but one year older, and his prop is 13.75" diameter with a pitch of 17. He claims this was the factory prop size. He said he also has a 4 blade prop that he uses to pull skiers. 2) On my maiden voyage in my boat with my grandchildren, I scraped a rock with my prop. The damage is enough to make me think about getting a new one, and I want to make sure I get the right one.

 

[play dough]

The Sea Ray prop chart indicates a 14.25 x 23" aluminum prop was standard for your boat. Max WOT target is 4600 rpm. That's your rpm goal with normal load. Each inch of pitch is worth about 200 rpm. Stainless vs aluminum also has an effect on rpm.

 

[Lazy Daze]

No, a 17" wouldn't have been standard. Are you sure he has a 180BR? '98 was the first year for the 180 - the 175 was the predecessor. Although I still don't think 17" would have been standard. I don't ever recall that being the case. But all that is a moot point.

Sea Ray hopped around a little between 21" and 23" for your boat. I had a 23" on my 180 (new from SR), but I feel 21" is the best overall prop. But sure, you could drop down in pitch for different performance. I wouldn't go SS, though - it's too heavy and there no real performane gain on this model.

VERY basically... lower pitch equals better hole shot, but sacrificing top end speed. You have to watch you don't over-rev the engine, though.

 

[55Trucker]

The load capacity sticker says 175, as does my neighbor's. Mine's a 1998, his is a 1996. All of the documentation I have on mine says it was purchased in June 1998, hull #SERR20631798, and the description on the paperwork says Sea Ray 175 Bowrider Sport. The prop that is on there is a Quicksilver, but after 24 years I doubt it is original. The 1998 Sea Ray prop matrix does not show the 175 (as shown in the excerpt posted earlier). However, the 1997 matrix does, and it lists 14.25" x 21P. Looks like my boat was a 1997 1/2 or something, model year crossover.

 

[Pirate Lady]

Decoder?..

 

[Lazy Daze]

The load capacity sticker says 175, as does my neighbor's. Mine's a 1998, his is a 1996. All of the documentation I have on mine says it was purchased in June 1998, hull #SERR20631798, and the description on the paperwork says Sea Ray 175 Bowrider Sport. The prop that is on there is a Quicksilver, but after 24 years I doubt it is original. The 1998 Sea Ray prop matrix does not show the 175 (as shown in the excerpt posted earlier). However, the 1997 matrix does, and it lists 14.25" x 21P. Looks like my boat was a 1997 1/2 or something, model year crossover.

Yes, you probably have one of the last 175's, then. I was basing my comments on your signature that shows you have a 180BR. Post a picture or two (sig pic is too small) and I can tell you in a couple of seconds which one it is.

Or... look on the aft, stbd corner under the rubrail. You'll see your HIN. Underneath that will be your model.

 

[55Trucker]

I just corrected the boat model number, it should be shown as 175 going forward. As I was going through the Sea Ray document packet that came with the boat, I just noticed that the boat manual says 175, and the IO manual 180. And you wonder why I am confused