Prop problem

[billyfish]

Hi guys. The boatyard moved the anode from the prop shaft , as it was going through 2 a season, if it stayed on, to a proper job , but I don't think it is connected to the shaft properly , does this colour look right to you ? Been in the water 2 years and I've just wire brushed it and it's looking a bit pink , is it knackered?

 

[Tranona]

Where was the anode fitted? Normally that arrangement would have either a hull anode connected via the prop shaft in the boat or an anode on a special nut. Latter is rather small but should last a season.

The prop looks pinky and a bit of pitting. however nothing crumbling off the ends of the blades. It should ring clear with a tap from a hammer. If dull thud then it is dezincifying.

 

[Paul1962]

In a word - Yes - sorry to sound trite but if the anode was getting eaten then if you remove it, the galvanics will only eat something else.

Your prop has been de-zinced hence the pink

 

[billyfish]

It's now a hull anode connected to the engine and gearbox, but I think they snipped the wire on the prop shaft. See photo, you can see the wire connection at the bottom I think it should connect the bolt running through the rubber block to the shaft , the prop shaft was removed for something else . I tried to add a video of hammer on prop but it's too big. If it's a new prop is the boatyard liable

 

[sv_telemachus]

It's now a hull anode connected to the engine and gearbox, but I think they snipped the wire on the prop shaft. See photo, you can see the wire connection at the bottom I think it should connect the bolt running through the rubber block to the shaft , the prop shaft was removed for something else . I tried to add a video of hammer on prop but it's too big. If it's a new prop is the boatyard liable

I had a similar incident where the yard forgot/decided not to replace the prop shaft anode - thankfully the manganese bronze nut took the hit instead of the prop. In addition to whatever the yard's terms and conditions say, the Consumer Rights Act 2015 requires services to be performed with reasonable care and skill, it would arguably be reasonable for a professional yard to check the prop and shaft is galvanically protected before removing an anode.

This would have been my argument - in the end, a polite email explaining the issue was sufficient for the yard to agree to a new bronze nut. YMMV.

 

[vyv_cox]

Dezincification is a surface effect, so the pinkness you see is probably microns thick, nowhere near enough to cause failure. I suggest you.paint it to reduce the cathode area and improve anode effectiveness.

 

[Pye_End]

It's now a hull anode connected to the engine and gearbox, but I think they snipped the wire on the prop shaft. See photo, you can see the wire connection at the bottom I think it should connect the bolt running through the rubber block to the shaft , the prop shaft was removed for something else . I tried to add a video of hammer on prop but it's too big. If it's a new prop is the boatyard liable

If that is a Bullflex coupling or similar then you need to bridge the centre with a wire, assuming a hull anode is connected to the engine block. I had several goes at this before found something substantial/flexible enough not to snap due to the rotating shaft - I wonder if this has happened to you.

Alternatively, go for an 'electro eliminator' direct onto the shaft to the a hull anode.

 

[shortjohnsilver]

Dezincification is a surface effect, so the pinkness you see is probably microns thick, nowhere near enough to cause failure. I suggest you.paint it to reduce the cathode area and improve anode effectiveness.

Vyv, what would be your recommendation as regards ‘paint’ suitable for providing increased protection?

The OP’s ‘images’ (prop condition) are consistent with my 3 bladed bronze prop. Beneteau style with anode prop nut.

The last three years I haven’t treated it at all, other than scraping and wire brushing back to smooth and then slathering Vaseline all over it, but maybe painting it will help?

 

[vyv_cox]

Vyv, what would be your recommendation as regards ‘paint’ suitable for providing increased protection?

The OP’s ‘images’ (prop condition) are consistent with my 3 bladed bronze prop. Beneteau style with anode prop nut.

The last three years I haven’t treated it at all, other than scraping and wire brushing back to smooth and then slathering Vaseline all over it, but maybe painting it will help?

My standard is Hammerite special.metals primer, a superb etch primer that works well on copper and aluminium alloys. I then use Velox antifouling in Greece but this may not be optimum in other areas.
My prop anode used to last one year and shaft anode two. Since this treatment the prop anode easily two years and shaft anode was changed after four, although still probably 50% left.

 

[billyfish]

I've never painted props as it's gone in no time, the wire Bridge is missing. Boats coming out of the water again this winter same yard see what they say. Lesson learnt...if you want something doing properly do it yourself.

 

[vyv_cox]

I've never painted props as it's gone in no time, the wire Bridge is missing. Boats coming out of the water again this winter same yard see what they say. Lesson learnt...if you want something doing properly do it yourself.

Not with the combination I gave above. I have used it for 10 years, prop looks as good when it comes out as when it went in.

 

[billyfish]

So . In conclusion. We don't think it's going to break up and fall of anytime soon, but might need replacing

 

[shortjohnsilver]

So . In conclusion. We don't think it's going to break up and fall of anytime soon, but might need replacing

That’s the way I look at it.
There are no dinks dents or deformities across the blades and although it may not ‘sound’ as it should, it’s intact, so, just clean up and re-launch.
I’ll scrub off maybe three times through the year so able to keep an eye on the prop anode and general condition of the prop.
It’s surprising how long the Vaseline manages to hang on, but I think I’ll follow the ‘paint’ treatment provided by Vyv so as to extend the life of the prop as much as possible and replace when I have to.

 

[Tranona]

Did it ring OK with the hammer? Painting in the way Vyv describes will certainly help. Normal aF does wash off but the primer does adhere well if you abrade with 180 grit. Velox if you can get it is a good AF for props. Painting reduces the area of the yellow metal exposed to seawater.

The yard should be able to bridge the Bullflex with a stainless wire link with eyes to locate on a fastening each side of the coupling

 

[billyfish]

It seam to ring ok with a hammer, but don't have anything to compare it to

 

[Tranona]

Thud indicating the zinc has gone and just copper left is quite distinctive. Often it starts with breaking away at the edges and there is no sign of that.

TBH most props don't need an anode. The prop in the photo of my boat had been there for at least 20 years since the engine was installed and no anode. However alloys vary and it is almost impossible to predict the exact composition so it is sensible to fit one just in case. It will likely slowly wear and make you feel better because it is "doing something".