3 blade to 4 blade

[Sharphooks]

I’ve had 4-blades on my last three boats. This summer I hit a rock with my OFS4 16x17 PowerTech 4-blade. I probably could have kept using the wounded prop after cleaning it up a bit but I ended up swapping it out with a Suzuki 16 x17P 3-blade that I ‘be carried as a spare for the last 4 years. I had a 100 NM run ahead of me to get back to port and I didn’t want to take chances with a 4-blade prop that might not spin 100% true

First thing I noticed—-very similar boat behavior at low RPM cruise speeds— my sweet spot is 3,700 - 3,800 and I had no problem matching the planing characteristics of my 4-blade.

Next thing I noticed ——10% less fuel consumption with the benefit of 5% more speed for any given RPM!!!

Engine: DF300 Suzuki. Boat: 24 foot Skagit Orca

Not sure I’ll ever go back to that OSF4 4-blade after what I saw with the 16” diameter 3-blade. What I probably will do is step up for a 16 x18.5 Suzuki water-grip as that’s probably better matched for my boat. Let me know if you want to sell your RH one.

 

[David Hall]

I had the opportunity to upgrade my BIIIX to a 2015 BIIIXR, I kept my OEM 22p propset. Last September I decided to upgrade the props due to a couple small hairline cracks in one blade and they’re 15 years old, also I wasn’t getting peak rpm out of my yanmar 6LPA, I decided to go with Hill Marines signature 4X4 set in a 20” pitch. Got the rpms I wanted but that is more pitch related. I notice a stronger pull up to plane, and a slight increase in top end speed. So far I like them.

 

[Sangstercraft]

Do people ever use 4 blade props on smaller outboards, like my 135 Honda?

 

[David Hall]

My understanding is that fewer blades are more efficient in a single prop configuration.

 

[man*of*steel]

Do people ever use 4 blade props on smaller outboards, like my 135 Honda?

I have a 4blade stainless on my 20' Thunderjet. Totally changed the characteristics of the boat. See my propping story on the Fin for F50 thread.