Marine Electrictian- Hamble

[olly_love]

Looking for a decent marine election in Hamble ( not one that's just install)
We have an issue with our anodes dissolving very quickly that needs to be addressed ( not other boats or our AC as we don't have it)

 

[Alex_Blackwood]

Looking for a decent marine election in Hamble ( not one that's just install)
We have an issue with our anodes dissolving very quickly that needs to be addressed ( not other boats or our AC as we don't have it)

You may be better talking to some one like these people.
Cathodic Protection

 

[superheat6k]

I'm happy to have a look, but is the boat out of the water. I live in Hamble. PM sent

 

[superheat6k]

To follow up I made a visit yesterday to Olly's boat ...

I observed a small folding two blade prop mounted onto a sail drive leg, completely isolated from the leg with two button anodes, one of each side of the prop.

These are corroding at an amazing rate, but only when the boat is underway. Apparently one disappeared entirely on a voyage from Hamble to Dartmouth. The blades were renewed quite recently due to pitting, so possibly a slightly longer term underlying problem here, no focused on fast dissolving zincs (I expect that once these have gone the pitting would likely resume).

So I made a few checks, but would like further opinions on this ...

1 The prop is electrically isolated from the drive leg anode.

2 The various parts of the prop all show a notable resistance between the parts in the range 3 to 8 ohms.

3 The ring anode behind the prop on the sail drive itself is also showing some wear and pitting, but has only been on a couple of months / trips.

So I wonder if the electrical isolation breaks down when the prop is spinning !

4 There is a general layering of hard fouling / calcium type build up on some of the components. Grease from last assembly is stil present on the simple gear teeth of the blades, this is clear.

5 No notable changes to the engine and drive set up have occurred. This is a simple installation with a Yanmar diesel, which is grounded to the -VE of the engine battery. There are very few other electrics, and nothing unusual connects to the drive. The steel wire cored cooling water supply hose is original and pre-dates the problem.

For now I have suggested the prop be removed, stripped to its component parts and dipped in HCL based brick cleaner to clean off any calcium deposits, making sure none of the metals react or fizz. But I wasn't too sure what grease to use - clearly nothing with graphite and would be concerned to use a lithium based grease, so suggested contacting the manufacturers, or consider silicon grease or possibly vaseline.

I have suggested all the parts once re-assembled should have localised resistances between any connected parts < 0.3 ohms. Once this is achieved suck it and see.

I did note the construction seems to be a mix of stainless steel swivel pins and securing cap head bolts, with bronze blades and hub sections. There is also what looks like a nylon bump stop to cushion the blades as they spin open in use.

Any further ideas on this one please ?

 

[Tranona]

That sounds like a Flexofold. If it is surprised the anodes disappear so quickly. The method of construction is quite normal and the mix of metals is why it has anodes. Earlier versions like the one I had did not have any anodes at all because the alloy used is very corrosion resistant. It was 10 years old when I sold it. Good advice to clean it (no problems with brick cleaner), and would suggest then painting with Velox to minimise the amount of metal exposed to the seawater.

 

[Alex_Blackwood]

To follow up I made a visit yesterday to Olly's boat ...

I observed a small folding two blade prop mounted onto a sail drive leg, completely isolated from the leg with two button anodes, one of each side of the prop.

These are corroding at an amazing rate, but only when the boat is underway. Apparently one disappeared entirely on a voyage from Hamble to Dartmouth. The blades were renewed quite recently due to pitting, so possibly a slightly longer term underlying problem here, no focused on fast dissolving zincs (I expect that once these have gone the pitting would likely resume).

So I made a few checks, but would like further opinions on this ...

1 The prop is electrically isolated from the drive leg anode.

2 The various parts of the prop all show a notable resistance between the parts in the range 3 to 8 ohms.

3 The ring anode behind the prop on the sail drive itself is also showing some wear and pitting, but has only been on a couple of months / trips.

So I wonder if the electrical isolation breaks down when the prop is spinning !

4 There is a general layering of hard fouling / calcium type build up on some of the components. Grease from last assembly is stil present on the simple gear teeth of the blades, this is clear.

5 No notable changes to the engine and drive set up have occurred. This is a simple installation with a Yanmar diesel, which is grounded to the -VE of the engine battery. There are very few other electrics, and nothing unusual connects to the drive. The steel wire cored cooling water supply hose is original and pre-dates the problem.

For now I have suggested the prop be removed, stripped to its component parts and dipped in HCL based brick cleaner to clean off any calcium deposits, making sure none of the metals react or fizz. But I wasn't too sure what grease to use - clearly nothing with graphite and would be concerned to use a lithium based grease, so suggested contacting the manufacturers, or consider silicon grease or possibly vaseline.

I have suggested all the parts once re-assembled should have localised resistances between any connected parts < 0.3 ohms. Once this is achieved suck it and see.

I did note the construction seems to be a mix of stainless steel swivel pins and securing cap head bolts, with bronze blades and hub sections. There is also what looks like a nylon bump stop to cushion the blades as they spin open in use.

Any further ideas on this one please ?

Not sure if this is the unit, Does this help? Note No Grease! I cannot comment on your readings . However I would suggest that as they were taken out of the water they could be misleading. I expect that Olly was grateful for your help!
https://25334245.fs1.hubspotusercon...28c3ba68|ae49d5dd-8b0c-40fe-9e64-1baaa3407536

 

[superheat6k]

Not sure if this is the unit, Does this help? Note No Grease! I cannot comment on your readings . However I would suggest that as they were taken out of the water they could be misleading. I expect that Olly was grateful for your help!
https://25334245.fs1.hubspotusercontent-eu1.net/hubfs/25334245/2-blade US SDz 2.1_2022-1.pdf?__hstc=130470800.b69a5600db6b60116219e06a41e3e076.1673174255254.1673174255254.1673174255254.1&__hssc=130470800.6.1673174255255&__hsfp=2689179221&hsCtaTracking=f07a673e-29c6-4233-b31f-807d28c3ba68|ae49d5dd-8b0c-40fe-9e64-1baaa3407536

I wonder if the grease was part of the problem, but would lithium affect the balance - can't remember where it sits on the nobility scale.

NB It would be considerably more difficult to take the resistance measurements in (under !) the water, and would certainly bugger up my multimeter !

 

[Alex_Blackwood]

I wonder if the grease was part of the problem, but would lithium affect the balance - can't remember where it sits on the nobility scale.
Could be, don't know about lithium. However, irrespective of whether my link is for that unit. I would stick with whatever manufacturers installation instructions are.

NB It would be considerably more difficult to take the resistance measurements in (under !) the water, and would certainly bugger up my multimeter !

You know what I mean I would think that voltage and current readings for Cathodic or Electrolytic action would be more appropriate in water.

 

[Alex_Blackwood]

To follow up I made a visit yesterday to Olly's boat ...

I observed a small folding two blade prop mounted onto a sail drive leg, completely isolated from the leg with two button anodes, one of each side of the prop.

These are corroding at an amazing rate, but only when the boat is underway. Apparently one disappeared entirely on a voyage from Hamble to Dartmouth. The blades were renewed quite recently due to pitting, so possibly a slightly longer term underlying problem here, no focused on fast dissolving zincs (I expect that once these have gone the pitting would likely resume).
Is this a long standing problem or a recent development. Is it Galvanic or Electrolytic? In either case there must be an electrical circuit. Has it only started after the installation or repair of a piece of equipment? How soon prior to departure and after arrival were the anodes inspected on the Dartmouth trip? what sort of mooring is the boat normally on? Is it happening under power , under sail or both? is it only happening happening when on board equipment is switched on?
So I made a few checks, but would like further opinions on this ...

1 The prop is electrically isolated from the drive leg anode.
Is this isolated from the drive shaft or just the leg?
2 The various parts of the prop all show a notable resistance between the parts in the range 3 to 8 ohms.
That could be due to grease or resistance between moving parts.

3 The ring anode behind the prop on the sail drive itself is also showing some wear and pitting, but has only been on a couple of months / trips.

So I wonder if the electrical isolation breaks down when the prop is spinning !
Is the prop spinning when folded when not in use?

4 There is a general layering of hard fouling / calcium type build up on some of the components. Grease from last assembly is stil present on the simple gear teeth of the blades, this is clear.

5 No notable changes to the engine and drive set up have occurred. This is a simple installation with a Yanmar diesel, which is grounded to the -VE of the engine battery. There are very few other electrics, and nothing unusual connects to the drive. The steel wire cored cooling water supply hose is original and pre-dates the problem.

For now I have suggested the prop be removed, stripped to its component parts and dipped in HCL based brick cleaner to clean off any calcium deposits, making sure none of the metals react or fizz. But I wasn't too sure what grease to use - clearly nothing with graphite and would be concerned to use a lithium based grease, so suggested contacting the manufacturers, or consider silicon grease or possibly vaseline.

I have suggested all the parts once re-assembled should have localised resistances between any connected parts < 0.3 ohms. Once this is achieved suck it and see.

I did note the construction seems to be a mix of stainless steel swivel pins and securing cap head bolts, with bronze blades and hub sections. There is also what looks like a nylon bump stop to cushion the blades as they spin open in use.

Any further ideas on this one please ?

Sorry don't have any other ideas, This sort of thing can be a bit specialised for diagnosis. However seems suspicious that it only appears to be happening when the boat is in use i.e. batteries and equipment switched on! Got this a bit muddled, Expand to read!

 

[olly_love]

Hi, So This only seems to happen, when the boat is moving under engine not sail,
No new kit installed recently except a VHF but this was installed on the same wireing and connections as before

i can try to test will all kit off then turn each piece on

Prop is folded and put into reverse

 

[Alex_Blackwood]

Hi, So This only seems to happen, when the boat is moving under engine not sail,
No new kit installed recently except a VHF but this was installed on the same wireing and connections as before

i can try to test will all kit off then turn each piece on

Prop is folded and put into reverse

OK. So when did you first notice it, recently or has it been long term? Was it evident before installation of new VHF? I suspect that is an Electrolytic action and not Galvanic, which means that you have a stray current flowing in the unit. I am afraid that is only a guess and impossible to diagnose on line. Perhaps Superheat can offer you a bit more assistance. Another stab in the dark. Have you checked the alternator wiring and connections? Just something peculiar to the engine being used. May be impossible to see but is there any chance you would notice any "Fizzing" at the anode with the engine running , in and/or out of gear?
Sorry clutching at straws a bit! You really need to think of everything and anything and not dismiss any possibility, no matter how remote.

 

[olly_love]

We had the new prop fitted in Aug 2021 ( had a wrap which caused the old one to come off) and the VHF was installed around the same time,
however the New VHF was installed on the same wireing as the old one? the antenna was installed on the same plug as before.

I will change all the wiring and check this, it was a brand new Icom so cant see this being an issue?

We have installed a new alternator last year as thought this may have been the issue.

 

[Tranona]

Don't think there is any connection between anything in your boats DC system and the propeller. Don't have an explanation for the anode wear but nothing seems wrong with your setup so suggest you paint the prop either with Trilux or Velox keeping the anodes clean and try again.

 

[Alex_Blackwood]

We had the new prop fitted in Aug 2021 ( had a wrap which caused the old one to come off) and the VHF was installed around the same time,
however the New VHF was installed on the same wireing as the old one? the antenna was installed on the same plug as before.

I will change all the wiring and check this, it was a brand new Icom so cant see this being an issue?

We have installed a new alternator last year as thought this may have been the issue.

I don't think you need to change wiring at this stage. just check through everything, thoroughly. If you never had this problem with the old prop. maybe worth talking to the manufacturer, another stab in the dark. Also try what Tranona suggested. Leave no stone unturned!! You don't by any chance have an inverter installed?

 

[ean_p]

What was the original VHF?

 

[olly_love]

A Simrad RD-67 so an older unit

 

[Tranona]

Go back to post#4. There is no continuity between the prop and the drive therefore no connection with any electrics in the boat either 12v or 240v. so changing the VHF or the alternator is irrelevant - just co incidence that they were changed at a similar time.

If it is a Flexofold worth talking to Darglow Engineering as they have many years' experience with these propellers.

 

[ean_p]

Go back to post#4. There is no continuity between the prop and the drive therefore no connection with any electrics in the boat either 12v or 240v. so changing the VHF or the alternator is irrelevant - just co incidence that they were changed at a similar time.

If it is a Flexofold worth talking to Darglow Engineering as they have many years' experience with these propellers.

The rapid loss is in the button anodes on the leg and is at such a rate so as to suggest electrolytic loss as opposed to galvanic. I would suggest that a little previous pitting on the prop may or may not be a factor in the present issue and if the prop is ( truly) isolated from the leg and the buttons then focusing on the prop is a bit of a red herring. All of course if I've got the drift of the previous posts, if not then I'm just jibbering so please ignore me...?
The enquiry about the previous VHF was that some brands ( icom being one) connect the RF ground to battery negative where as the more commercial brands tend not too and so a change in set can when active present a connection to battery negative to anything connected to the ariel ie masts ect.

 

[Alex_Blackwood]

Go back to post#4. There is no continuity between the prop and the drive therefore no connection with any electrics in the boat either 12v or 240v. so changing the VHF or the alternator is irrelevant - just co incidence that they were changed at a similar time.

If it is a Flexofold worth talking to Darglow Engineering as they have many years' experience with these propellers.

Are you sure? post #4 says "Isolated from the leg anode" in post #9 I do ask if it is isolated from the drive as well. Neither do we know what is, or isn't relevant. We just don't have the information to make definitive statements. not trying to be clever or knock your post just as I see it. As with many of these technical posts on site investigation is the only real answer. Good point about Darglow!

 

[Alex_Blackwood]

The rapid loss is in the button anodes on the leg and is at such a rate so as to suggest electrolytic loss as opposed to galvanic. I would suggest that a little previous pitting on the prop may or may not be a factor in the present issue and if the prop is ( truly) isolated from the leg and the buttons then focusing on the prop is a bit of a red herring. All of course if I've got the drift of the previous posts, if not then I'm just jibbering so please ignore me...?
The enquiry about the previous VHF was that some brands ( icom being one) connect the RF ground to battery negative where as the more commercial brands tend not too and so a change in set can when active present a connection to battery negative to anything connected to the ariel ie masts ect.

Just what I thought. See #11. Must be right then!!