Cavataion ring on propeller (1999 johnson 40hp)

[omc_10]

My propeller is missing the cavatation ring... what exactly does it do? and is it important?

 

[galamb]

If I'm understanding what you are asking about it's like a small (spacer - also called an exhaust ring) that to goes on the back of the prop so that there is no "gap" between the gearcase and the prop itself when it's fastened to the prop shaft.

Most props extend slightly into the gearcase so there is no disruption to the water flow going to the blades.

A number of aftermarket props may fit different makes/models so a ring is needed to "customize" that prop to the particular motor it's going on.

And yes, it's important for both performance and can possibly prevent engine damage if you experienced severe cavitation at high rpms.

 

[TP.]

If you are talking about the ring on the outside rear of the prop you need it so you do not get cavitation-feels as if you are spinning your wheels when accelerating and when running it keeps air from gettin around your blades and loosing some of the "bite" your prop has on the water. Running without it may also cause pitting in the propellor over time. Good news is you can replace it.

 

[Jackspeedmarine]

Hi, The cavitation ring is a hydrodynamic device which fits periferally around your propellor and guides / ducts the water past your propellor blades to provide your with the maximum thrust that is available from the design designation of your propellor ie diameter / pitch.