Brackish/Seawater anodes

[Tamer11]

Good evening

My boat is kept on the river at the moment, but I am changing her mooring to a salt water one. How quickly should I change the anodes from Brakish. The hull is GRP, so just protecting the Engines.

Thank's

 

[CLB]

The hull anodes are protecting the props, shafts, unless it is an outdrive boat, in which case the drive anodes are protecting the drive. The engine may have some pencil anodes, which protect the engine, but these can be changed quickly and easily straight away.

If the hull/drive anodes are magnesium, I would change them pretty quickly (within a few weeks). If they are aluminium, they will be fine to be left. If they are zinc, they may have become passive in the freshwater and will also need changing/checking quickly.

 

[Momac]

What type of metal are your present anodes?
If Aluminium they should be suitable for brackish or salt water .

 

[rafiki_]

Good evening

My boat is kept on the river at the moment, but I am changing her mooring to a salt water one. How quickly should I change the anodes from Brakish. The hull is GRP, so just protecting the Engines.

Thank's

If magnesium, then immediately. they will fizz away merrily. If aluminum, you have a bit more time, but you need zinc for sea water.

 

[pondfish]

My boat is kept in Cardiff bay it's fresh water so I use magnesium I go into salt water about 250/400 hours a year and the anodes work fine,
I renew every year and there is still magnesium left on the anode so they don't fizz away in a few days as everybody keeps saying.

 

[rafiki_]

My boat is kept in Cardiff bay it's fresh water so I use magnesium I go into salt water about 250/400 hours a year and the anodes work fine,
I renew every year and there is still magnesium left on the anode so they don't fizz away in a few days as everybody keeps saying.

Yes, but your anodes are nicely washed by fresh water every time you return to the Bay. A friend keeps his boat at Penarth, and he could almost see the anodes dissolve when in Portishead. You may be better off with aluminium if you do a lot of sea water excursions?

 

[MrB]

Nothing to add but A.S.A.P have 20% off MG Duff Anodes at the moment. (no connection, just got an email from them this morning)

 

[pondfish]

I see you use the word almost,
I have stayed at portishead for almost a week also was traped in WATCHET for over 7 days seen no fizzing at all.
I have tried ally and after 12 months I wiped them with wet glove when lifted out and they were like brand new so they didn't work for my boat but they were crusted over.

 

[Lulla-Belle]

If your boat is in Cardiff Bay you need to meter your boat out!

I had magnesium fitted and as you, go out to sea reg and when I got lifted noticed so much wear on my legs it was crazy.

After replacing, servicing and triluxing them before refitting had a local renown electrical gentleman to meter me out and when we compared the reading to the sacrificial chart we needed to put ZINC on, against everyone elses opinion in the marina I did and this year when lifted legs show no erosion but noticeable wear on my leg anoids.

I did try aluminium but Volvo dont recommend them! When checked they just calcified up and didnt work.

This area of engineering is a total science and esp in Cardiff Bay, just ask McDuff!! they didnt want to quote?? My experience get metered out and be sure its an expensive mistake to guess!!

 

[pondfish]

If your boat is in Cardiff Bay you need to meter your boat out!

I had magnesium fitted and as you, go out to sea reg and when I got lifted noticed so much wear on my legs it was crazy.

After replacing, servicing and triluxing them before refitting had a local renown electrical gentleman to meter me out and when we compared the reading to the sacrificial chart we needed to put ZINC on, against everyone elses opinion in the marina I did and this year when lifted legs show no erosion but noticeable wear on my leg anoids.

I did try aluminium but Volvo dont recommend them! When checked they just calcified up and didnt work.

This area of engineering is a total science and esp in Cardiff Bay, just ask McDuff!! they didnt want to quote?? My experience get metered out and be sure its an expensive mistake to guess!!

Zinc will not work in Cardiff bay,
Zinc is only for salt water if used in fresh they will crust over then they won't work when in salt water,
What I found out by being in Cardiff bay for the last 7 years is if your boat uses a shaft you need magnesium anodes, if you got legs you need aluminium anodes.

 

[Lulla-Belle]

I would have agreed with you until last year !

Have your boat metered out you may be surprised?

I even have a hanging anode fitted now to save my leg thruster and transom shield anoids!

I'm more than happy to keep mine on zinc having seen the evidence and proved it with science.

Aluminium on legs esp Volvo DPH is a disaster!

Sorry if you disagree but thats science for you?

I

 

[Tamer11]

Thank's for the responses. They are Zinc anodes. She is now going onto the River Dart so I guess these will be good.

 

[pondfish]

Had my boat lifted this weekend to check and this is the state of my magnesium anodes so they are working going to replace in the next month or so these went on in march 2017.

 

[GrahamHR]

I even have a hanging anode fitted now to save my leg thruster and transom shield anoids!

I'm more than happy to keep mine on zinc having seen the evidence and proved it with science.

Aluminium on legs esp Volvo DPH is a disaster!

Sorry if you disagree but thats science for you?

I

Science ? I see no scientific evidence from you.

i don't use hanging anodes ( no need to).

I've used aluminium anodes on my DPH drive for 3 years in salt water; no drive corrosion whatsoever. I do have the Volco ACP system though.

Scientifically, if the anodes are no in direct electrical contact with what they are meant to protect, they provide no protection at all. Whether they are zinc/ aluminium or magnesium.