Z302 prop question??
 

Ok, so my Z302 now has 12hrs on the new 502 mag mpi and am really confused with my prop selection for the Bravo Three. Here are the details.

RPM: 4000 at WOT ( I know very low but that is all I can get with the 26p props that came with the boat)
Speed at WOT per speedo: 40 mph
Weight: 5 adults, 4 kids approx 800lbs
Fuel: 1/2 tank
Conditions: 1'-2' slight chop
Air Temp: 90 degrees
Boat condition: Painted bottom (wish it wasn't but it does stay in the water)

Mercury web prop calculator states that I need a set of 22P props but with all the pictures I have of Z302's and Z300's that are running 502's in them are running the same 26p props.

Anybody any ideas?

Re: Z302 prop question??
 

I also have a chance to buy a set of 22P (cupped) for a really good price and may just go ahead and buy them but really think that they may just really over rev the engine at WOT.

Re: Z302 prop question??
 

I dont know a lot about Bravo 3 drives/props but with a 4" drop in pitch you will add about 800rpms at WOT. If you can get the 22's at a great price it might be worth a try & if its too much you can always sell them on to someone else & settle with 24's.

Re: Z302 prop question??
 

I have a 215 Talari with the 5.7 L bravo 3 running the same 26p's. My rpms are low and hole shot sluggish. I am going to go to22ps but the cost isnt fun. I have talked to a couple of places where I can trade in my props and for about $250 and get refurb props. If I were you I would reprop as I am not sure who pushed these 26ps on all of us, was Merc having a sale???? LOL.

Re: Z302 prop question??
 

I have an older Z model with a 502/Bravo 1 setup. Motor is carbureted, very mild cam, and puts out maybe 400HP. We went to a 22 pitch 4 blade and love it. 12 seconds to 50MPH and a top speed a little over 60. The prop is a powertech MS275 OFS4R 22pitch. I'm told the 4 blade props take a lot of torque to make them work well, fortunately the big blocks can make some.

We moved from the cupped 3 blade factory speed prop to the 4 blade and it was like adding all wheel drive to the boat....lots of traction especially out of the hole. It also flattened the wake making the boat much nicer to ski behind. The trade off is top end, but this prop only cost us 2-3 MPH at the top.

Re: Z302 prop question??
 

I too have a Z302 with a 502 MAG MPI (270 hrs) and bravo 3 with a set of 26 pitch props. It also has a rough antifouling bottom. With a full tank of gas (119 gal) it has a WOT of 4700 RPM and a speed of 51 mph. However when new it would do 57 mph at 4800 rpm. This is about the advertised speed (55 to 62 mph). My performance degradation may be due to rougher bottom and a slight hook starting 30 inches in front of the transom. I have no data with people aboard but it does make a large difference. You might compare with just you in the boat. I guess you have checked your spark knock sensor and oil pressure sensor to make sure the rpm limiter hasn't kicked in or the knock sensor set back your spark advance. Also if you have sat in the water and collected any barnacles on your prop your RPM will stay low with a fully manned boat. Attached are the performance curves from my boat over the last 9 years, all with just me, a full tank and a clean prop. Chart 2 has the curves and sheet 1 has the numbers.