Strange spare prop

[Nos4r2]

I bought this cheap on ebay the other day as an emergency spare. It was described as a plastic prop but when it arrived it seems harder than any other plastic props I've seen and it's pressed together in sections with separate blades.

Has anyone seen one before? If so is it actually plastic or is it some kind of composite?

[alexm]

It looks a bit like a piranha prop to me which are made from Verton... but they usually have the name on them.

[Nos4r2]

I did wonder about that.

Just had another look at it and it appears to be a piranha without badges-it says RCOB on the back and googling "RCOB Propeller" comes up with Piranha rear hub types.

Are they any good? I've never used one.

[Nasher]

Matt

I also have one as a spare prop, although mine is a 4 blade jobbie.

Yes they are made by Piranha, and appear to work very well.
Although I've only tried it briefly and it is the same pitch as my Stainless one.

My reasoning was that it was lighter to carry around as a spare than another Stainless or Ali one. If you are carrying a spare make sure you also have a spare Washer, split pin and nut with you of course.

Oh and it was less than £40 on ebay with two spare blades. It was advertised as an old Johnson one, and with JWs help I knew I could put it in my lathe and take 5mm off the back of the outer lip to make it fit my Suzi.

Nasher.

[Nos4r2]

Cheers Nasher,
I might well try using it as a main prop. I'm running a 17" at the moment and it's hitting the redline with solo use.Going up to 19" might add a bit of top speed and save some fuel when cruising.

[jwalker]

Nos, what are the white teethy bits?

[Nos4r2]

Originally Posted by jwalker

Nos, what are the white teethy bits?

They are just part of the removable blade.That's not a very good picture-it's been taken with the camera so close that you can't see all the way through it.

[wavelength]

I did a product test on a pirahna prop years ago ( must be 15- years plus back) when I wrote for boat fisherman magazine. The problem I found with it was that we went up one size pitch (cos they wanted us to as they said they were more efficient). The motor was fine with the ally prop at the lower pitch but when we put this prop on we found the bottom end was poor cos we were now overpropped but at the top end the top speed was way down and the engine over-revving and my conclusion was that it was due to the blades flexing under load. Changed the blades down in pitch and bottom end was ok but the over revving was of course even worse. Its still in the garage somewhere in its cardboard box. However I think that afterwards they may have stiffened the blades up a bit. In the true spirit of editorial freedom balanced with the need to keep advertisers revenue that particular article probably didnt make it to print

[Nos4r2]

Thanks Dave-it's appreciated. £21 for an emergency prop is a pretty good deal anyway-if it doesn't work well I can dump it in the console but forewarned/forearmed etc

[Jizm]

I bought one of those a while back. Found it was crap so put it back on there and made a wee profit by advertising properly. Can't go wrong for £20!