Broken Prop

[davidhand]

I was motorsailing along when a sudden noisy vibration occured. After getting towed back and diving the boat I found that my two bladed prop was now a one bladed one. There was no indication a the time that I had hit anything, is it common for a prop to just come appart? I assume it is the orriginal prop that came with the boat, that makes it about 17 years old. Could it be dezincification? does bronze have zinc in it? I thought bronze was an alloy of copper and tin. Comments welcome.

 

[oldsaltoz]

G'day David,
This sounds more like you have dropped a blade from a folding prop, not uncommon at that age with no checks.

The pivot pins wear, and under load will break releasing the blade, have seen a few over the years.

The problem may be getting a replacement that will balance with the existing blade, but a bit of grinding will fix that.

Good luck

Old Salt Oz____/forums/images/icons/cool.gif

 

[dickh]

I have a folding prop in the garage which needs a new home, but have just noticed you are in San Fransisco so not economical to post!
Yes, folding props can come apart as previous poster says, proper bronze should not de-zinctify, but if it is Manganese Bronze it will. Best is Silicon Bronze or an Admiralty Gunmetal.

dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[davidhand]

No, actually it was a two bladed fixed prop which is why I was so surprised. Thanks for your comments (and also to the guy from Oz) but I am working on getting another, if its metric (boats a Beneteau) it may be a bit of a problem, but if so I'll try and pick one up when I am in England in a couple of weeks.
Cheers
Dave.