Prop cavitation

[MikeY]

I've noticed while motoring along at 1/2 throttle or above (have H23 with Honda 8hp 4-str) that there is a lot of air (?) at the prop - is this cavitation ? Can I go to a larger prop ? Not sure what's on it.

 

[R. Palaia]

I had honda 8hp with 23 boat

The honda 8hp for a 23 boat is very big. On my boat I realized I was actually going faster if I backed off of full throttle. Any more power and the prop was just spinning (cavitation) and not giving any thrust. Next time you go out, inch the throttle up and see at which point you will actually start loosing speed. The hull will only go so fast, and the honda 8 hp puts out more than the boat needs. You don't even need a knot meter (I didn't)just look at the landscape going by and you will notice an increase or decrease in speed.Roc

 

[Jon Bastien]

Where is the exhaust?

Mikey, I know that the exhaust on my Nissan 5HP was through the propeller. Could this be the cause of your air bubbles?--Jon BastienH23 '2 Sheets to the Wind'

 

[Mike Epp]

fin foil

I put one of those fin type foils on the cavitation plates of my Honda 5 horse. It reduces cavitation, increases thrust and prevents the rudder from striking the prop!

 

[Rick Webb]

fin

I put one on my 6HP Mercury for all of the same reasons and found that it made it quieter as well.

 

[MikeY]

Bigger prop ?

Why not go with the next larger prop ?Yes, it does cav at about 1/2 throttle...and yes, the prop tried to eat the rudder for luch one day but now I have a bungee, from the storage lock to the tiller. It also doubles as an autopilot if I run it from the lock, around the tiller 2-3 times, then hook on underside of star side rear seat/gas storage.

 

[Jim Kolstoe]

Self-steering

Mike Y,  There is a more elegant self-steering approach, if you have an adjustable tiller extension ( which you should). Adjust the extension so it touches the seat back with teh tiller centered, then run a bungee from the tiller to jib sheet cleat on the same side. The bungee holds extension in place. The extension keeps the tiller from moving to that side. As for your prop, I've seen whole books on the topic - I'll leave it to an expert.Jim Kolstoe, h23 Kara's Boo