320 Re-prop

[dpvandy01]

Thinking about re-propping my 2003 320 with Twin 6.2L Close Cooled Inboards. Currently they have 3 blade NiBrAl and looking to go with 4 blades. Has anyone done this on this boat? Thoughts?

 

[dpmulvey]

A properly tuned three a blade should perform as well as a four blade. What are your P/S WOT?

 

[Vince_nj1]

I ran aground Memorial day weekend back in 2013 and slightly damaged on of my 3 blade props. Rather then pull the boat and wait 4 weeks for the prop to be repaired I opted to buy new 4 blades so I could be back in the water the same day. My plan is go back to the 3 blades and sell the 4 blades when I sell the boat. Anyway. I have the same set up as you. I used Atlantis Propeller. Ray is the owner. (856)231-0106 or 856 389 5275. I bought a set of ACME 4 blades. They were about $2200. My OEM were 3 blades , 18 x18.5x3.55 cupped RH and 18x19x3.55LH I gave him my HP and transmission ratio and he came back with a set of 17 inch 4 blades. Unfortunately I don't remember the pitch, but I think it went up a little to offset the smaller diameter. I am very happy with the 4 blades. I have slightly more lift at lower RPMs but may have lost 1/2 knot lower speed at plane. With a clean bottom in salt water (more buoyant), no wind or tide I run just under 25 knots at 4000 rpms. But the biggest difference I found was how smooth they are. I would send my 3 blades out every year to be balanced so I know they were in spec. The 3 blades would vibrate slightly when getting on plane. The 4 blades are as smooth as sewing machine regardless of RPM.s Overall I am very happy the 4 blades.

 

[dpvandy01]

Thank you for that post. I have had my 3 blades tuned and scanned every season as well as checking my shaft alignment and I am just not happy with the vibrations. That is what is driving the research and eventual replacement.

 

[dpvandy01]

A properly tuned three a blade should perform as well as a four blade. What are your P/S WOT?

Props scanned and tuned every season. Shafts scoped as well. I'm right at my spec for WOT.