Effect of Prop Antifouling on Prop Anode Wear?

[GordMay]

Originally Posted by a64pilot

Some really tough people can actually become acclimatized to water temps that will kill us wimps.
There is this one long distance swimmer female I'm thinking about, I think she regularly swims for hours in water temps that would kill most people in minutes? ...

For 0ver 40 years, Lynne Cox has been the best cold water, long distance swimmer the world has ever seen.
➥ https://www.lynnecox.org/MapsNB.html

➥ Hell In High Waters: The Lynne Cox story - ESPN

➥ ISHOF.org | LYNNE COX

[a64pilot]

Yes, she was the one I talked about earlier.
However I believe she is significantly different physically from an average person, from the amount of blood at or near the skin, her seemingly ability to reduce this flow and I believe the amount and maybe even the type of fat she has, I've read she is more similar to a seal than an average person.
I believe she swims comfortably in water that would kill an average person in a short time, or so I have read.

I assume she was born with a lot of this ability, and it has been enhanced further by training

[deblen]

Originally Posted by Dockhead

Right. Duh . . .

Edit -- no, wait a minute -- it IS electrically connected to the shaft. They are bonded together. Both connected to the hull anode; the shaft via a kind of brush contact.

Hull anodes mounted to the GRP hull & wired to various pieces of "hardware" seems to be a UK/EU thing. I may be wrong here,but I don't think it is common practice in the "colonys"-at least it isn't locally.

I was involved in a thread re-grounding/earthing/etc. on here (CF) about 6mos. ago. I stupidly proposed a flex ground cable from an electrically floating SS rudder stock top to a brush on the shaft. I had measured appr. 2+ vdc by putting one meter lead on rudder stock & one on shaft of a boat that was experiencing prop pitting plus shaft pitting between inside stuffing box & trans. coupling-making a 2v salt water battery.
I was thinking that if I electrically connected the "floating" rudder to the shaft/prop,it would drive the vdc diff. to zero & no current would flow thru the water between them.
I was soundly reminded by several competent & experienced posters in the grounding "business" that I had just "closed a ckt." & current could now flow.
Perhaps it is not a good idea to connect more than one underwater item to the same hull anode? Don't know-just a thot.

Cheers/ Len

[Dockhead]

Originally Posted by deblen

Hull anodes mounted to the GRP hull & wired to various pieces of "hardware" seems to be a UK/EU thing. I may be wrong here,but I don't think it is common practice in the "colonys"-at least it isn't locally.

I was involved in a thread re-grounding/earthing/etc. on here (CF) about 6mos. ago. I stupidly proposed a flex ground cable from an electrically floating SS rudder stock top to a brush on the shaft. I had measured appr. 2+ vdc by putting one meter lead on rudder stock & one on shaft of a boat that was experiencing prop pitting plus shaft pitting between inside stuffing box & trans. coupling-making a 2v salt water battery.
I was thinking that if I electrically connected the "floating" rudder to the shaft/prop,it would drive the vdc diff. to zero & no current would flow thru the water between them.
I was soundly reminded by several competent & experienced posters in the grounding "business" that I had just "closed a ckt." & current could now flow.
Perhaps it is not a good idea to connect more than one underwater item to the same hull anode? Don't know-just a thot.

Cheers/ Len

Hmm, well, that all sounds logical enough. I wonder what knowledgeable others have to say about it?

I have a lot of faith in the designers of my electrical system, which is the best I've ever seen on any boat, but -- you never know.

[Ribbit]

Originally Posted by a64pilot

I believe an average person, diving into 5 or so C water may well drown, the gasp reflex of hitting water that cold will have them inhale water, or so I have always been told.

There was a time I used to be in a swimming pool pretty much every day (if not, swimming in the sea). Swam for the school, the City, Life Saving, you name it.

One early Saturday morning in the middle of winter, I hit the springboard at about 7:00 am straight into the deep end. That water was just above freezing.

The shock didn't result in a 'suck', it resulted in a 'blow' that lasted until I surfaced and hit the exit ladder on my way to the hot showers.

Heated Pools work really well if somebody remembers to turn the heating on.

Fascinating thread by the way.

[UNCIVILIZED]

- Have a professional electrical current survey done of the boat. Even to include when some of the major systems are both off, & powered up. Ditto on anything which makes power (testing with it both off, & on, that is).

- Add extra, & larger zincs to your shaft.
Also: Check their purity/compliance to standards too. So that you're getting the least noble ones which you can find/make.

- Consider a zinc fish, which is connected directly from your shaft, to the fish in the water.

- Consider coating your prop with Zinc, as several posters have suggested.

- Find out what alloy you shaft is made of (& let us know).

- Try putting some bottom paint onto your P-bracket. At worst, you'll simply have to remove it, a few haul outs down the road.

- Look at the propeller efficiency test again, & note the efficiencies of some of the others. As there are a few on there, which outclass the Maxprop, Autoprop, & others.

Then give a few of them a call, & see if they're willing to backup their efficency claims with a live, money back, test. Or one which, where if the numbers they claim don't come to pass, then there's a small re-stocking fee.

And Please. When you ask us for input on, & or solutions to a problem:
~ Tell us the Whole story at the outset.
~ Answer our diagnostic questions directly.
~ Be both willing to listen to the advice given, as well as to try it.

For if you're not willing to try out the direct results of the wisdoms for which you're inquiring, is there any point in asking for such?

[Ribbit]

Uncivilised, I think it was you that recently linked a folding/feathering prop comparison test somewhere, and I was intrigued by one that wasn't included in the test results. A two bladed folder that I really fancy trying.

eliche_radice_folding_propellers

[UNCIVILIZED]

PS: FWIW, if you haven't tried any new propeller types, or even considered digging into the; literature, test, & user reviews of what's out there now. Then you cannot know, or even begin to know, what you may or may not be missing.

And given the advances in everything else in 20+ years... As an example KIWI Prop - Cruising Anarchy - Sailing Anarchy Forums

Not to mention, that there are even firms which allow you to try out different prop types on your boat. If your boat is of the sort to which they cater.

[a64pilot]

I don't think you "get" the whole prop thing, it is not which makes us the most efficient motorboat, I can tell you the answer to that is a fixed two or maybe three blade, and a whole LOT cheaper too. Efficiency in that regard is sort of irrelevant to me, and I think Dockhead as well.
The idea is to have a variable pitch prop, one that will provide thrust at low engine RPM, even if the boat is making way under sail.
You can't do that with ANY fixed pitch prop unless your way over propped when not under sail, reason is today I am pure motoring, tomorrow I may be sailing at three kts, but wish to go faster, then I can crank the engine and run it at 1000 RPM and make seven kts.
With a fixed pitch prop it would take probably 1400 RPM to make any significant thrust, and 1800 to put me at seven Kts, this isn't theory, that is the way it was on my boat, before the Autoprop, and I was over propped.
Ideally I'd like a controllable pitch prop that I was in charge of setting pitch, I' d install a pyrometer and set prop pitch by exhaust temp, but alas that doesn't exist for a 40 HP engine, or if it does, I don't know of one.
So I settled with an auto pitching prop, which as all things are, is a compromise.
Autoprop is expensive, complicated and does not give much thrust when the boat speed is zero, but like I said in 6 kts of apparent wind on a reach, I can motor sail at seven kts, with the engine at 1000 RPM, which I like, fuel burn is low, but to me more importantly, engine noise is a lot less. 1000 RPM isn't nearly as obnoxious as 1800.


Sent from my iPad Pro using Cruisers Sailing Forum

[Dockhead]

Originally Posted by a64pilot

I don't think you "get" the whole prop thing, it is not which makes us the most efficient motorboat, I can tell you the answer to that is a fixed two or maybe three blade, and a whole LOT cheaper too. Efficiency in that regard is sort of irrelevant to me, and I think Dockhead as well.
The idea is to have a variable pitch prop, one that will provide thrust at low engine RPM, even if the boat is making way under sail.
You can't do that with ANY fixed pitch prop unless your way over propped when not under sail, reason is today I am pure motoring, tomorrow I may be sailing at three kts, but wish to go faster, then I can crank the engine and run it at 1000 RPM and make seven kts.
With a fixed pitch prop it would take probably 1400 RPM to make any significant thrust, and 1800 to put me at seven Kts, this isn't theory, that is the way it was on my boat, before the Autoprop, and I was over propped.
Ideally I'd like a controllable pitch prop that I was in charge of setting pitch, I' d install a pyrometer and set prop pitch by exhaust temp, but alas that doesn't exist for a 40 HP engine, or if it does, I don't know of one.
So I settled with an auto pitching prop, which as all things are, is a compromise.
Autoprop is expensive, complicated and does not give much thrust when the boat speed is zero, but like I said in 6 kts of apparent wind on a reach, I can motor sail at seven kts, with the engine at 1000 RPM, which I like, fuel burn is low, but to me more importantly, engine noise is a lot less. 1000 RPM isn't nearly as obnoxious as 1800.


Sent from my iPad Pro using Cruisers Sailing Forum

Got it in one. Exactly.

Once you try a variable pitch prop, you never go back. I was certainly not asking for advice on changing props. That was not on the table.

[Dockhead]

Originally Posted by UNCIVILIZED

PS: FWIW, if you haven't tried any new propeller types, or even considered digging into the; literature, test, & user reviews of what's out there now. Then you cannot know, or even begin to know, what you may or may not be missing.

And given the advances in everything else in 20+ years... As an example KIWI Prop - Cruising Anarchy - Sailing Anarchy Forums

Not to mention, that there are even firms which allow you to try out different prop types on your boat. If your boat is of the sort to which they cater.

The prop I have cost about $8000, could not be sold (since it was made specially for my boat), and I'm happy with it. I was not asking for advice about this.

I know the Kiwi prop very well, and it is greatly inferior to what I already have, according to what I personally need from a prop.

[Dockhead]

Originally Posted by UNCIVILIZED

. . .
And Please. When you ask us for input on, & or solutions to a problem:
~ Tell us the Whole story at the outset.
~ Answer our diagnostic questions directly.
~ Be both willing to listen to the advice given, as well as to try it.

For if you're not willing to try out the direct results of the wisdoms for which you're inquiring, is there any point in asking for such?

I will try whatever seems sensible to me, after digesting different points of view. The point of asking for input, is to add to the thinking. Also to have a conversation which is interesting not only for me, but for all who participate, and even for people who might read these threads years later. The trying is already something completely different.

Please don't contribute to these threads, if you feel it is an imposition on your valuable time. They are intended to be interesting for everyone concerned, and not just for me. If you don't enjoy it, don't trouble yourself.

[savoir]

It isn't compulsory for stray current to be caused by the shore power connection. It is quite common for a boat's engine and/or gearbox to be used for earthing electric motors. Any current flowing in that direction will find its way out of the boat via the propeller shaft. Check for earth wires on the block which might be traceable back to the water pressure pump, bilge pump, head or some other electrical item.

That might be the culprit.

[Dockhead]

Originally Posted by savoir

It isn't compulsory for stray current to be caused by the shore power connection. It is quite common for a boat's engine and/or gearbox to be used for earthing electric motors. Any current flowing in that direction will find its way out of the boat via the propeller shaft. Check for earth wires on the block which might be traceable back to the water pressure pump, bilge pump, head or some other electrical item.

That might be the culprit.

That's interesting. But all the grounds on my boat are, by design, led to the hull anode, both AC and DC. It looks like this:

[s/v Jedi]

Surprised that nobody mentions the Gori 3-blade which has very little drag while sailing and has the "overdrive" setting for motorsailing; looks like a viable compromise between fixed, variable and feathering prop

I'm still happy with my Maxprop.