Throwing blades

[Gary]

Looking for some advice on what to do about throwing blades off my props for a couple years now. They last about 10-15 two way passes. I use stainless now and they last longer but still happens. Boat is a PT 45 spinning a Prather S235 prop at about 45,000 -46,000 rpm. They are modded but not thinned to keep the strength of the blade. Can they be heat treated by someone?

When she runs she runs well and smooth...no prop hop or chatter so to speak.
Thanks.https://www.youtube.com/watch?v=fkKNLOkGXVE

[grsboats]

At those rpm's is common to lost blades....yes I heat treat my props but they still break in my saw boats.......my solution as a retired dentist was start making my own props from CoCr something not cheap but that can be done to support those impacts.Gill

[Fluid]

Joerg was spinning his self-designed stainless prop past 60,000 rpm on his record runs, but each pass didn't last long. Not certain of the metallurgy or heat treatment, but most NAMBA SAW racers spinning high rpm (not that high) will lose blades from time to time. Most use BeCu props heat treated, but the treatment varies depending on the metallurgy. Many have softened their treatment to allow the occasional bent blade, which is better than tossing a blade.


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[RaceMechaniX]

For SAW runs blade failures are just going to happen. I have thrown my fair share of blades, but recently I have no issues with props even BeCu props. Recently i have been running the ABC props with the correct heat treatment and no issues. This includes blowing the tail at very high RPM and not so much as a bent blade.

Dental stainless and CoCr will work with thinner blades, but often I see the fillet and root of the blade are too thin which lead to cracks and thrown blades.

[Gary]

OK good to know I am not alone. My biggest problem after a thrown blade is getting a perfect copy of the same blade. Boat 5 out of 10 times does some funny things until I fine tune the prop. That's where I am now...boat hops a little on start and is 5 mph slower. Will take a few trips to the lake to get it perfect and than wait for the next blade to pop!!! LOL !