Dezinced Propellor and New Propellor

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BlowingOldBoots
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Dezinced Propellor and New Propellor

Postby BlowingOldBoots » Sat Mar 28, 2020 9:45 pm

Last summer I had a 10 year survey which identified that the propellor had dezinced. You can see from the pictures the pink surface after scraping the bronze material. It also rung quite dull, but still had a shallow ring, additionally the blade tip just crumbled away after a light tap with a small hammer. Fast forward to this winter and I bought a new propellor from T Norris Marine. The difference in ring is significant, a sharp, clear ring. I painted the propellor with an anti-foul starting by abrading with 80 grit according to instructions, primmer and 3 coats of the anti-foul.

I looked at various folding options and feathering propellors. The folders would have been good but extra expense, the feathering all required a shaft brake, additional expense and annual maintenance, which I don't want.

ImageUntitled by Rival Sailor, on Flickr

ImageUntitled by Rival Sailor, on Flickr

ImageUntitled by Rival Sailor, on Flickr

ImageUntitled by Rival Sailor, on Flickr

ImageUntitled by Rival Sailor, on Flickr

ImageUntitled by Rival Sailor, on Flickr

ImageUntitled by Rival Sailor, on Flickr
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mm5aho
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Re: Dezinced Propellor and New Propellor

Postby mm5aho » Mon Mar 30, 2020 10:52 am

I notice you have a hull anode nearby the prop.
My R32 originally had no anodes, and the prop did about 40 years like that, but eventually it too went the way of yours. I changed it a year back and did one summer, but I made an anode to fit the shaft just between the cutless and prop bush. I didn't put locktite on the fixing bolts though and the anode must have fallen off during the year. Just made a new one last Saturday (but can't fit it without access). Your anode appears to have a little wear. What's it connected to inside the hull?
My engine has the insulated VP gearbox, so propshaft is insulated from engine and electrics.
Geoff.
"Contender" Rival 32: Roseneath in winter, Mooring off Gourock in summer.

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BlowingOldBoots
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Re: Dezinced Propellor and New Propellor

Postby BlowingOldBoots » Mon Mar 30, 2020 1:06 pm

This year I have bought an Electro Eliminator and will fit that to a floor just beside the stern gland. I will connect the electro eliminator to the anode. The yacht has an Aquadrive CV coupling, fitted 10 years ago, which is not electrically bridged by me. I don't know whether the CV joint is internally electrically bridged. About 10 years ago, the propellor did ring brightly and the anode was connected to all the skin fittings.

Regarding the anode. As said, it was connected to all the skin fittings but this was removed as I came to the conclusion that this was not doing anything at all. It is currently connected to the engine block and gearbox block as well as the rudder shaft.

This is what it will end up like https://www.youtube.com/watch?v=LIVq18khHIs My plan is to connect the electro eliminator to the propellor side of the CV coupling and then to the anode and renew the engine block and and gearbox connections. I am not minded to connect the seacocks as they are all old Blakes Seacocks, unless advice has changed.
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Re: Dezinced Propellor and New Propellor

Postby SteveN » Fri Apr 03, 2020 8:49 am

I had a similar arrangement with shaft brushes outboard of the Aquadrive and linked to the same hull anode as in your picture. It seemed to work well enough and I didn't see any deterioration of the prop over the 16 years that I had the boat. The brushes were very prone to squealing though, hence the contact grease that you see in the picture at the link below. Although less than ideal this did stop the squealing with only a tiny increase in resistance.

The 13 no. Blakes seacocks weren't connected to the anode and were in good shape after 36 years. Like yours, only the engine block, rudder tube and shaft brushes were connected to the anode.

By the way I thought that getting antifouling paint on the anode was a cardinal sin, but I'm not sure if that's backed up by good science.

https://drive.google.com/open?id=1XH0aa ... wWntBxMxM4

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claymore
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Re: Dezinced Propellor and New Propellor

Postby claymore » Fri Apr 03, 2020 5:20 pm

We had a folding prop on our previous boat (Hunter Delta) which is just a big Sonata really and sailed well. I was always a little uncertain that it would engage if I went into reverse - it always did but I always worried.
We had a new drive train installed in 1997 after I'd manage to sail over fishing net, stall the engine and bend the shaft plus damage the gearbox. I toyed with the idea then of a folding prop but the perceived wisdom at the time was that it would be a waste of money with a long keeled motorsailer so we didn't. Of course, prop technology might well have advanced since then but I doubt fitting a folder would turn Claymore into an Ocean Greyhound.
On the subject of the ring from the prop - I have a couple of old ones and I'm wondering whether we couldn't form a band - the Nautical Propanologists is, I think quite catchy and if we work on it - we may be able to play at the Edinburgh festival in '21...
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BlowingOldBoots
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Re: Dezinced Propellor and New Propellor

Postby BlowingOldBoots » Sat Apr 04, 2020 10:16 am

claymore wrote: ....... On the subject of the ring from the prop - I have a couple of old ones and I'm wondering whether we couldn't form a band - the Nautical Propanologists is, I think quite catchy and if we work on it - we may be able to play at the Edinburgh festival in '21...


I will consider giving up the day job.
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cpedw
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Re: Dezinced Propellor and New Propellor

Postby cpedw » Sat Apr 04, 2020 2:12 pm

claymore wrote:- the Nautical Propanologists
Are they the people who have an unusual attraction to red Calor bottles?

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claymore
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Re: Dezinced Propellor and New Propellor

Postby claymore » Sat Apr 04, 2020 5:00 pm

cpedw wrote:
claymore wrote:- the Nautical Propanologists
Are they the people who have an unusual attraction to red Calor bottles?


Well - I was attempting a subtle play on words and having once read that a campanologist was someone who rang bells rather than acting in a rather gay or effeminate manner, I thought ringing propeller bells might somehow squeeze past the more eagle-eyed of you. I hadn't thought of propane at all - me being a butane type of person
Regards
Claymore
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cpedw
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Re: Dezinced Propellor and New Propellor

Postby cpedw » Sat Apr 04, 2020 6:35 pm

claymore wrote:Well - I was attempting a subtle play on words and having once read that a campanologist was someone who rang bells

Then you need the Latin for propeller - Campanology from Late Latin campana, "bell" according to Wikipedia.

claymore wrote:- me being a butane type of person

Is that a euphemism for "all p*ss and wind"?

In case you're wondering, it's the Coronavirus dividend.

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Re: Dezinced Propellor and New Propellor

Postby DaveS » Sun Apr 05, 2020 6:15 pm

I fitted a feathering Kiwiprop to Avilion and was very happy with it. I tried some experimentation over a number of years with the blade angles to try to get max revs from the engine, but concluded that the manufacturer's original settings were optimal. A bad passage in a gale off Skye made the point. It was less efficient compared to a conventional prop, perhaps using 5% more fuel while motoring, but the huge gain was the lack of drag while sailing, so I sailed more and motored less.

I forgot the important bit: the Kiwi is made of stainless steel and plastic so no corrosion issues.
Image

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sahona
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Re: Dezinced Propellor and New Propellor

Postby sahona » Fri Jul 31, 2020 7:48 pm

Going back to the OP and electrolysis - I am about to be thrust into the world of common grounds and (possibly?) linked anodes/hull fixings. My existing engine is totally insulated from the negative battery circuit and is about to be replaced by a modern chassis-ground type I fear. This could possibly change my whole outlook on boat electrics and involve more than engineroom work. Since 1978 (as far as I am aware) everything has survived without being interconnected and the single anode is tied to the stuffing box. When my new engine arrives and is subsequently attached to the battery what can I expect? The plan is, once the young fit person has finished installing my engine, to measure everything for stray currents and then short-circuit to eliminate, but the disconcerting thing is -there doesn't seem to be a definite solution that meets the bottom line for everyone. I don't really want to use the prop (or anything else) as a litmus device, but on the other hand, I will probably be long gone before the results of my misjudgement come home to roost...
Précis : Changing from isolated Perkins 4108 to grounded block Beta, what are the electrolysis implications? Experiences anyone?
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