Anode type for portishead marina?

[contessaman]

Hi, just moved the boat over from Cardiff bay. Had aluminium anodes there as a compromise for freshwater mooring and saltwater cruising.
remember when I had a boat years ago in portishead, it had a leak. At first I thought it was my potable water tank because I tasted the water in the bilge and it wasn’t seawater. Turned out I did have a leak and somebody told me afterwards the water in the marina was brackish . I guess there’s a lot of fresh water flows down the river Severn and also rainwater flows into the marina.
anyway, proof is in the pudding, so my question, what anodes do you guys use in portishead marina? Is it salty enough for zinc to work? Thanks

 

[TwoHooter]

Ask Alan Stafford, Mobile Marine Engineers - SOS Boat Services, Tewkesbury. He will have a view of the current position because of the boats he looks after in the marina. When we kept our boat there the zincs seemed to erode OK but that was some time ago and things might have changed.

 

[VicS]

Hi, just moved the boat over from Cardiff bay. Had aluminium anodes there as a compromise for freshwater mooring and saltwater cruising.
remember when I had a boat years ago in portishead, it had a leak. At first I thought it was my potable water tank because I tasted the water in the bilge and it wasn’t seawater. Turned out I did have a leak and somebody told me afterwards the water in the marina was brackish . I guess there’s a lot of fresh water flows down the river Severn and also rainwater flows into the marina.
anyway, proof is in the pudding, so my question, what anodes do you guys use in portishead marina? Is it salty enough for zinc to work? Thanks

Why not continue to use aluminium anodes?

They are suitable for both salt water and brackish water

 

[rgsmg53]

I'm currently a berth holder at Portishead and have been for a number years. I've always used zinc without problem.

I also bought a boat which had been berthed in Cardiff Bay. Turned out it had magnesium anodes which no one spotted - and I didn't think to ask. I found out when when corrosion products blocked the grille-type raw water intake ( yes, really). Luckily found it soon enough to prevent more serious damage. Fitted zinc and never had problems since.

Whilst there is a small stream (I think) that empties into the town end of the marina, it is tiny compared to rivers emptying into Cardiff Bay so I doubt Portishead counts as 'brackish'. I've never tasted the water in the marina basin - don't think I want to.

Willing to be corrected but zinc works for me.

 

[Sneds]

We are in Portishead and use aluminium
Suitable for both salt and fresh

Try searching Macduff anodes for more info

 

[PeterBoater]

I believe that aluminium is suitable for salt and brackish, not fresh; magnesium is for fresh.

 

[Sneds]

You’re right, I stand corrected

 

[bitbaltic]

It’s all witchcraft. We had mag anodes when in Cardiff Bay and they were always nearly gone after a season. When we took the boat to the fully marine conditions of Milford Haven, we changed to Zinc and after 2 years in the water most of the anode was intact; the yard suggested giving it a go for a third year but I demurred. Principally because the anode is on a saildrive and protects the leg (hugely expensive to replace if damaged). I might be more sanguine about a hull anode.

 

[TwoHooter]

Perhaps it is worth mentioning that the water is not the only thing that affects erosion of anodes. An important factor is stray current corrosion, which is the principal cause of damage to sub-surface metals. If your own boat is protected with a galvanic isolator then the biggest cause of concern is being in enclosed waters with a lot of iron around (particularly sheet piling or steel boats) and the risk that there are stray currents in the water from boats who don't have galvanic isolation, or from faults in mains supplies, "leaky" shore power leads dangling in the water, etc. It's most likely that this is the cause of anodes eroding more quickly in some places than others. A really well protected vessel will often be protecting its less well protected neighbours.

 

[contessaman]

Cheers for the replies I think I will stick with aluminium anodes for now then. The boat is pretty self sufficient with inverters and renewable energy so I don’t tend to leave shore power connected when afloat.