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Old 10-03-2016, 15:51   #31
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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Originally Posted by Pete7 View Post
In the past I have used a wire cup wheel in an angle grinder to clean any old paint of the prop which gives a good clean surface. The two coats of International Primocon followed by a couple or more thin coats of what ever the hull antifoul is. After a season most of it is still on and in good condition.
I've always done similar, sanding the prop and priming with PA10, then several thin coats of antifoul. Seems to hold up ok over a season. I do get some detachment, maybe 15-25% at the end of a year in the water.

The best primer I ever used was a bit of the propspeed stuff a pro had left over from a nearby job. It was two pack and going off just as I had prepped my prop for PA10. He had a tiny bit left in his tin, and I slapped it on as an experiment and then overcoated with my normal antifouling. Stuck real well, almost no detachment for two years.

I often smear a coat of lanocoat over the dried antifouling as an extra layer. Don't know if it helps, but it seems right.
My anodes don't seem to work hard. I get a year or two out of them easily.
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Old 10-03-2016, 16:08   #32
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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I'll bite, from an efficiency perspective what prop is more efficient than an Autoprop, and why?

BTW, I think his haul rate is peanuts from his local club there, compared to customary cost for a boat of that size.
It's far from a full test, but there is the one included herein Performance Differences Between MaxProp Sizes and Pitches

Otherwise found at Test Results - Flexofold folding Propellers

I'm sure that there are others, but it's time for me to move on to other pursuits.
That, & especially as, I can't much see spending more energy on this thread, when my original questions still await fielding by the OP.

And, yes, the original problem does seem odd, & vexing. As with the various props I've had, the zinc's have all lasted for several years.
Makes me wonder why the makers of the prop in question chose the alloys that they did. Particularly when there are some which are all but immune to corrosion, even sans anodes. As I'm sure Autoprops aren't cheap, so it's not as if they Need to make $ on proprietary zincs.

Big PITA, much like many aspects of Saildrives, if you ask me.
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Old 10-03-2016, 16:42   #33
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Re: Effect of Prop Antifouling on Prop Anode Wear?

I first polish the prop, then spray it with cold zinc spray or that zinc barnacle barrier stuff, which is the same product. Works pretty good when you sail instead of motor
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Old 11-03-2016, 05:38   #34
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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A few questions & thoughts:

- Why on earth do you need to haul out in order to change out your zinc? That has to be crazy expensive, given how often your doing it, coupled with your boat's size. Non?
It costs 150 pounds ($225) to haul my boat at Cowes, pressure wash, hold in slings for an hour for anodes etc., relaunch.

But I also dry out at the RAF Yacht Club sometimes -- free, but scary, time consuming and laborious.

I wouldn't haul out just to change the prop anode -- the one time when I needed that done without anything else, a pal of mine dove in a drysuit and did it. I suppose I could do it in a wetsuit and snorkel myself if I really needed to.

It's timed to correspond with washing the hull -- every two months in the summer and every four months in the winter.


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- Fiscally, it only makes sense to switch to a prop where the above isn't the case. Especially as there are more efficient propellers out there.
Because between; not needing to haul in order to change zincs, not needing to change zincs so frequently, & getting better prop performance (under sail AND power), it only make sense to change to another brand/type.
I mean the new prop would pay for itself in under a year, even without selling the old one. Which is obviously possible, & advisable.
"Efficient" in what sense? The Autoprop is the only variable pitch prop available for this size plant. From 150 hp you can have the magnificent Hudested, which is what I want on my next boat. Bollard pull is not the only, and certainly not the most important measure of efficiency. Efficiency at cruising speed is the most important thing, and here the Autoprop is the king.

Besides that, variable pitch is the absolute t*ts for motorsailing, and in general loads the engine much better than a fixed pitch prop. I have been using Autoprops since 1995, and I would never go back to having a fixed pitch prop on a sailboat. The Autoprop has some weaknesses, especially cost (most expensive prop you can buy in this size), also maintenance, high sailing drag, and weak full power pull, but altogether it's the best possible compromise of the various factors for my tastes, and I would definitely do it again unless the plant in the next boat is big enough for a Hundested, which is what I plan.

The cost of anodes and changing them is a rounding error in the total cost of operating the boat.

Also, you can't sell an Autoprop, because they are specifically made for your boat.

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- How cold can the water be?
I mean I regularly swim in tne N. Sea when I'm over in Scotland. Ditto in Puget Sound, where water temp. is 40 - 45 deg. F (5-8 deg. C).
Without a drysuit or wetsuit, in the dead of Winter, out near the Pacific Coast (Ocean proper).


Also, there are no shortage of divers in the PNW; recreational, & commercial, who only wear wetsuits. So I can't see water temp being that big an issue, regardless.
I mean guys even dive though the ice, sans heated wetsuits. Which are what professional divers wear when working in very cold waters for extended periods.
I am thinking about using divers for hull cleaning because I'm having trouble scrubbing my antifoul off. I just got a quote for 240 pounds ($360) for a "racing wipe" -- not cleaning. It's very expensive here, apparently, because of regulations. I've never heard of "heated wetsuits" (does such a thing exist?); they use drysuits around here. This time of year the water is 4 or 5C, and it is considerably more trouble, more discomfort, and more risk to dive in water of that temperature, than in Florida (say).

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Originally Posted by UNCIVILIZED View Post
- Why not switch to a bigger zinc? Even if it means either; having some oversized zincs custom machined, the prop. machined, or both?

- Has anyone done a current survey in your marina, like your insurer for example? As if there's stray current in there, I'm SURE that they'd take a STRONG interest in it.

- Have you tried hanging a zinc fish which is directly connected to your shaft?

- There are other options as well, in order to literally stop such problems. But they're a bit exotic, & Far too expensive for this application.


PS: The part about more efficient propellers has been covered extensively on here before; including a posting of the test in the May '09 Yachting Monthly magazine. Plus, of course, there's lots of info on same via an online search.
I'm not usually in a marina. I'm usually moving around, at anchor, on my Hamble River mooring (no shore power). I installed an isolation transformer the first year when I saw the high rate of anode wear, but it made no difference. Also made no difference being in a marina or at anchor or on my mooring. The prop anodes last exactly 4 months in all cases. It's definitely not stray current.


So in summary -- prop anode wear is not some kind of big problem which I am desperate to solve. I'm just curious whether painting the prop would slow it down.

In Florida, everyone painted his prop. Here no one does. I don't really understand why, and that has made me curious.
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Old 11-03-2016, 05:52   #35
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Re: Effect of Prop Antifouling on Prop Anode Wear?

I think quite a few "cruisers" paint their props. Perhaps the "round the cans on Sunday morning lot" prefer a polished prop and are willing to dry out or lift more often to deal with weed and barnacles etc. Also if you have a performance yacht you probably have a folding / fethering prop to match, which brings a hole difference set of A/F problems. The ma and pa out cruising for a week are more likely to have a fixed prop, so slapping on a coat of A/F in the spring will see them through the worst of the fouling during the summer.

Luke my chandler only uses Propshield because he is worried about the build up of paint jamming the blade gears and if the gears aren't protected then the barnacles will certainly jam them. He admits its at least a twice a summer job to replace the propshield (Lanolyn).

If you are lifting or drying out every couple of months, perhaps Prop Shield is the short term solution. How about a fixed winter prop and the Auto prop for Spring to end of autumn?

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Old 11-03-2016, 06:12   #36
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Re: Effect of Prop Antifouling on Prop Anode Wear?

Quote:
Originally Posted by UNCIVILIZED View Post
A few questions & thoughts:

- Why on earth do you need to haul out in order to change out your zinc? That has to be crazy expensive, given how often your doing it, coupled with your boat's size. Non?



- How cold can the water be?
I mean I regularly swim in tne N. Sea when I'm over in Scotland. Ditto in Puget Sound, where water temp. is 40 - 45 deg. F (5-8 deg. C).
Without a drysuit or wetsuit, in the dead of Winter, out near the Pacific Coast (Ocean proper).

Also, there are no shortage of divers in the PNW; recreational, & commercial, who only wear wetsuits. So I can't see water temp being that big an issue, regardless.
I mean guys even dive though the ice, sans heated wetsuits. Which are what professional divers wear when working in very cold waters for extended periods.
Are you serious???? I have lived all my life surrounded by 32F/0C-45F/7C salt water. No human swims in that (without at least a wetsuit) for more than 15min. After that,they are unconcious, & shortly after,drowned!
We haul or ground out,(or hire a diver for a rope in the prop) for under water work.
Crikey!! I'm blue just from the memory of falling overboard a few times-need to go mix a hot toddy-Brrrr
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Old 11-03-2016, 06:13   #37
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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I think quite a few "cruisers" paint their props. Perhaps the "round the cans on Sunday morning lot" prefer a polished prop and are willing to dry out or lift more often to deal with weed and barnacles etc. Also if you have a performance yacht you probably have a folding / fethering prop to match, which brings a hole difference set of A/F problems. The ma and pa out cruising for a week are more likely to have a fixed prop, so slapping on a coat of A/F in the spring will see them through the worst of the fouling during the summer.

Luke my chandler only uses Propshield because he is worried about the build up of paint jamming the blade gears and if the gears aren't protected then the barnacles will certainly jam them. He admits its at least a twice a summer job to replace the propshield (Lanolyn).

If you are lifting or drying out every couple of months, perhaps Prop Shield is the short term solution. How about a fixed winter prop and the Auto prop for Spring to end of autumn?

Pete
Hmmm.

It's coming back to me that we were always worried about barnacles on the prop in Florida. Maybe the growth is just different.

In these waters, I don't get any growth on my prop other than the very rare, isolated barnacle, and some odd calcification which I have to wire brush off. I have no idea what that is, but it does not have a noticeable effect on the prop's work.

I do have a spare fixed prop, but that's quite a job to pull off one prop and set a new one. Certainly not worth just saving some anode wear.

If painting the prop is as much hassle as it sounds like, I think I'll probably pass on it and just keep changing anodes.

Maybe I should buy one of those adapters which will let me put a bigger one on.


P.S. -- Thanks again for that time when you dove and changed my prop anode! That was very kind of you. Eventually, maybe this fall, I'm going to get over to Andark and develop that capability myself.
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Old 11-03-2016, 06:17   #38
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Re: Effect of Prop Antifouling on Prop Anode Wear?

From the feathering props Autoprop is the most efficient I believe because it's the only one I am aware of with the "proper" blade shape, the others, Maxprop for example are flat blades and those are inefficient, efficiency being how much thrust do you get per unit of fuel being burned.
I'm not real familiar with folders, I can see how you could have an efficient airfoil on a folder.

Almost all wet suits for Commercial divers are heated by pumping warm water in a hose and into the suit, there are a few dry suit heaters that are essentially the same as the heated vests for motorcycles except of course you have to have a battery.
I know of a cave diver who thought he was going to be smart and use a few of those shake up hand warmer packets in his dry suit. They apparently work by iron oxidizing and giving off heat? Anyway put them in a dry suit and use your Nitrox mix your breathing to fill your suit and they get very hot, hot enough to burn you cause the O2 content is higher than air and I assume the higher pressure too. He came out of the cave pretty quick
Course if you use Argon as many do in the cold, then they don't do anything.

Lots of crazy people ice dive in dry suits, so I have to assume they keep warm, for me 68 F in a North Fl cave is freezing cold water, I'm a wimp.


I'm in Fl and my prop isn't painted, I just dive it and keep it polished off, actually have my Son do it. I will put prop speed on it, just didn't when it was new just in case I had to send it back, the adapter at least doubled the life of my zinc, as I believe there is probably three times as much zinc now

Dock, weigh one of your Autoprop zincs, then go weigh a "B" prop zinc if you have an H5 prop and see what the difference is, I don't have an Autoprop zinc or I would. If your Autoprop is an H6, then it would use the next bigger standard prop zinc
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Old 11-03-2016, 06:30   #39
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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From the feathering props Autoprop is the most efficient I believe because it's the only one I am aware of with the "proper" blade shape, the others, Maxprop for example are flat blades and those are inefficient, efficiency being how much thrust do you get per unit of fuel being burned. . .
That's right, and it's a useful clarification.

Autoprops are not the most "efficient" in terms of maximum bollard pull in ahead; Maxprop is slightly better (about 10%), according to the YM test. Yet the Autoprop produces a higher top speed than the Maxprop, less prop walk, etc.

But small differences in bollard pull interest me (and I daresay most cruisers) much less than fuel efficiency, and here the Autoprop is king -- besides the proper airfoil blade shape, you also have the effect of variable pitch -- it's like a continuously variable transmission with overdrive, versus a single speed fixed gear.

It saves a lot of fuel, I think up to 20% under some conditions. But maybe even more importantly than that, it saves your nerves, because it shifts up when less power is needed and allows the engine to run slower but better loaded up.

This is particularly important when motorsailing, and really makes motorsailing a great pleasure, because instead of having the engine churning away at the RPM which matches the speed, even though little power is needed, the Autoprop shifts up and lets you throttle way back.

I think of my Autoprop as my main "light air sail"

It has a few disadvantages, for sure, but after 20 years of using them, it's still what I would choose.

And now that I've taken it completely apart myself (just yesterday; see the other thread on this), I like it even more. It's beautifully made inside -- reminds me somewhat of a Lewmar winch -- and incredibly simple to take apart.


Autoprop is no good at all for racers, because one of its disadvantages is that it has the highest drag of all folding and feathering props. That's because it droops one blade when feathered by the nature of its operating principle.

Hundested (drool) doesn't have this disadvantage.
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Old 11-03-2016, 06:43   #40
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Re: Effect of Prop Antifouling on Prop Anode Wear?

For those that haven's seen an Autoprop here is a video. I'm 90% sure they way the work is by water flowing by increasing the pitch, so the faster the boat moves, the more induced flow, the more pitch. I believe that centripetal force flattens or de-pitches the blade, that is why when there is no boat movement and you add a bunch of RPM, it feels as though a clutch is slipping, but let her get a little speed, and the prop gets more "bite"

Also reverse in any normal prop is VERY inefficient as the trailing edge of the prop becomes the leading edge of course as the prop is spinning backwards, Autoprop is unusual in that it flips around so the leading edge is still the leading edge, even when the prop rotation is reversed.
I don't know this, but have been led to believe the design originated from WWII when it was of great importance to have a strong reverse in order to get a landing craft off of the beach

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Old 11-03-2016, 06:44   #41
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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If painting the prop is as much hassle as it sounds like, I think I'll probably pass on it and just keep changing anodes.
If the prop is off the boat Lanolyn (Propshield) it is then:

1. Warm prop in oven.
2. Warm lanolyn to runny custard consistency.
3. Slap it on the prop.
4. Fit prop.
5. Have a G&T

At least if you make a mess it's only animal grease to clean up not blue antifoul paint and dust all over the decks.

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Old 11-03-2016, 07:07   #42
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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Most people around here polish their props and leave them as bare metal. And I also do that. For some reason, the prop doesn't foul all that much.

But my prop anodes wear intensely, and are gone in 4 months, which is the limiting factor for me for a lift out.

For some reason, having a shaft anode on doesn't seem to make a lot of difference. I don't understand that.

I wonder if I were to paint my prop with antifoul, whether that would slow down anode wear by reducing contact with sea water?

Anyone have any experience?
Zincs erode for a reason (to prevent more valuable equipment from doing do). Never do anything to stop or slow zinc erosion or they may not be able to do there job. Except to find the reason for excessive erosion if such exists. A qualified marine electrical technician should be able to measure the electrolytic potential between components of your boat to determine if there is an issue. Bronze alloys contain copper, the active biocide on anti-fouling paint. Antifouling paint should not be applied to metals as it will cause them to erode, if it creates a conductive path between metals.
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Old 11-03-2016, 07:29   #43
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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It costs 150 pounds ($225) to haul my boat at Cowes, pressure wash, hold in slings for an hour for anodes etc., relaunch.

But I also dry out at the RAF Yacht Club sometimes -- free, but scary, time consuming and laborious.

I wouldn't haul out just to change the prop anode -- the one time when I needed that done without anything else, a pal of mine dove in a drysuit and did it. I suppose I could do it in a wetsuit and snorkel myself if I really needed to.

It's timed to correspond with washing the hull -- every two months in the summer and every four months in the winter.

When you started this thread, you stated that:
"my prop anodes wear intensely, and are gone in 4 months, which is the limiting factor for me for a lift out."

Which I read as you saying that you have to haul 3x/year in order to change your anodes. Meaning that you haul that often for the expess purpose of changing your prop zinc. That's how you phrased it.
There was no mention then, of you hauling so that you could wash your antifouling. And that both jobs were transpiring at the same time. Nor that you Had to haul in order to clean your bottom, due to the regulations governing such.

"Efficient" in what sense? The Autoprop is the only variable pitch prop available for this size plant. From 150 hp you can have the magnificent Hudested, which is what I want on my next boat. Bollard pull is not the only, and certainly not the most important measure of efficiency. Efficiency at cruising speed is the most important thing, and here the Autoprop is the king.

My statement about "efficency" included the following about propeller performance:
- Max pulling power. Otherwise known as how much of the engine's power a propeller transfers to the water in order to move the boat.
- Top speed. Again, a measure of how much power is going into the water.
- Least drag.

If a prop is good at those things, then it's making best use of the fuel being burned when the engine's on. And most people motor near the upper end of their engine's power range. Say 80%+ of it's maximum RPM's.

So if a prop's giving you the best speed when the engine's burning that amount of fuel per unit of time, it's efficient.
And the less drag under sail the better. As if one's boat sails well, especially in light air, when every bit of eliminated drag helps, then you don't need to turn on the engine. Ergo (again) the prop's efficient.

Besides that, variable pitch is the absolute t*ts for motorsailing, and in general loads the engine much better than a fixed pitch prop. I have been using Autoprops since 1995, and I would never go back to having a fixed pitch prop on a sailboat. The Autoprop has some weaknesses, especially cost (most expensive prop you can buy in this size), also maintenance, high sailing drag, and weak full power pull, but altogether it's the best possible compromise of the various factors for my tastes, and I would definitely do it again unless the plant in the next boat is big enough for a Hundested, which is what I plan.

Me, I don't motor sail much. Or even motor much. So I want a prop which helps in those aspects. IE; It helps me to sail efficiently. Although, yeah, I'd love it if they made a variety of variable, controllable pitch props, for engines between 25hp - 100hp+.

When my engine's on, I want the best power transer to the water which I can get. So that I burn the least fuel per mile that I can. And or, that puts the max power into the water possible, so as to get me out of a sticky situation. Or to make the most way against a strong current, etc.
So, Max Power; for emergencies, & also to make headway against the elements opposing my progress. Plus giving the occasional tow.

The cost of anodes and changing them is a rounding error in the total cost of operating the boat.
Yeah, the cost of new anodes is part of the maint. costs. And generally such is done with the boat in the water. Unless it's time to renew the antifouling.

But the way things were written, it sounded as if the boat was being pulled 3x/year, just to swap the anodes. And at $225 per haul, plus the cost of the anodes, that's $700+ per year, simply to swap one's zincs.
Which to me, is pretty outrageous. Thus my questions & confusion. As well as my commentary, that such fees, when added up over time, would pay for a different (more "efficient") prop., easily.
Given that premise, my math makes sense.

Also, you can't sell an Autoprop, because they are specifically made for your boat.
Sorry, not something I was aware of.
Although, there must be some market for them. As most boats have sisterships. And thee are other boats which have similar power plant & drag profiles. Which is what you ned to match when choosing a prop.

I am thinking about using divers for hull cleaning because I'm having trouble scrubbing my antifoul off. I just got a quote for 240 pounds ($360) for a "racing wipe" -- not cleaning. It's very expensive here, apparently, because of regulations. I've never heard of "heated wetsuits" (does such a thing exist?); they use drysuits around here. This time of year the water is 4 or 5C, and it is considerably more trouble, more discomfort, and more risk to dive in water of that temperature, than in Florida (say).
The diving which I was talking about explicitly, was in cold waters. And in temperatures akin to those which you state. Check my post.
The few degree difference between what you state, & that I mentioned aren't real significant. Yeah, one notices, slightly. But for things like survival time, & how long one can operate efficiently before the fog of hypothermia sets in... when the water's That Cold, it really doesn't matter all that much.

Heated wetsuits are more common for guys working in cold, deep water, for extended periods. It's really the only way for them to stay warm, when submerged for hours at a time.And such suits have been around for quite a while.
Also, if you're seriously working. As in commercially, & the like. A small tear in one's drysuit can be seriously Bad Juju. And there are plenty of sharp edges on things, where those guys work.

Drysuits will keep you warm in those kinds of waters, for a while. And are worn by some professional divers, if they're warranted for the application. But any system has it's limitations in such environments.

I'm not usually in a marina. I'm usually moving around, at anchor, on my Hamble River mooring (no shore power). I installed an isolation transformer the first year when I saw the high rate of anode wear, but it made no difference. Also made no difference being in a marina or at anchor or on my mooring. The prop anodes last exactly 4 months in all cases. It's definitely not stray current.


So in summary -- prop anode wear is not some kind of big problem which I am desperate to solve. I'm just curious whether painting the prop would slow it down.

In Florida, everyone painted his prop. Here no one does. I don't really understand why, and that has made me curious.
My understanding of water temps, & diving hardwear, etc. Comes not simply from the literature. But from friendships with more Commercial & Military divers than I have relatives.
Plus, in having spent more than a little bit of time in very cold water myself.
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Old 11-03-2016, 07:53   #44
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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Are you serious???? I have lived all my life surrounded by 32F/0C-45F/7C salt water. No human swims in that (without at least a wetsuit) for more than 15min. After that,they are unconcious, & shortly after,drowned!
We haul or ground out,(or hire a diver for a rope in the prop) for under water work.
Crikey!! I'm blue just from the memory of falling overboard a few times-need to go mix a hot toddy-Brrrr
I have no reason to BS you on this. It's something that I've done, many times over. As have a lot of other guys I know. Because sometimes it's just mandated by the job, & or circumstances.
I was Navy for many years, & sometimes the things you do/have to do are "interesting". Albeit I've been in 40 deg. water since then, too. For extended periods. And plenty of people can attest to as much. Although there seems little point in going into detail, given the response to my statements already.
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Old 11-03-2016, 08:17   #45
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Re: Effect of Prop Antifouling on Prop Anode Wear?

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?
I think her circulatory system has actually changed from an average person and maybe some other actual physical differences?

I cut this from Wikipedia

Cox is perhaps best known for swimming 2h 5 mins in the Bering Strait on 7 August 1987,[3] from the island of Little Diomede in Alaska to Big Diomede, then part of the Soviet Union, where the water temperature averaged around 43 to 44 °F (6 to 7 °C).
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