Is the hull pear shaped anode still required!

[seafox67]

I'm slowly refitting my boat (in stages) and this winter will see all my seacocks replaced with Tru-design composite (plastic). I currently have a large prop shaft anode and a pear shaped hull anode!

I have tried to read and understand the corrosion process and I believe the pear shaped hull was only required to stop the seacock corrosion!

Have I got this wrong?

Many thanks for any advice.

 

[PaulRainbow]

If it was only connected to the through hulls, it's no longer needed, in fact, it was never needed.

But, if it can be electrically connected to the shaft/prop it will act as an additional anode for those parts. If you have a solid shaft coupling you can connect it to the gearbox. If it's a flexible coupling still connect it to the gearbox, but you'll need a bridging wire on the coupling. The anode would also serve as a grounding point for any a shore power Earth connection (subject to a suitable Galvanic isolator or isolation transformer), or an Earth connection for an inverter. Under these conditions it should last for several years.

 

[seafox67]

If it was only connected to the through hulls, it's no longer needed, in fact, it was never needed.

But, if it can be electrically connected to the shaft/prop it will act as an additional anode for those parts. If you have a solid shaft coupling you can connect it to the gearbox. If it's a flexible coupling still connect it to the gearbox, but you'll need a bridging wire on the coupling. The anode would also serve as a grounding point for any a shore power Earth connection (subject to a suitable Galvanic isolator or isolation transformer, or an Earth connection for an inverter. Under these conditions it should last for several years.

Thanks for your reply Paul...

I've also been clearing out old wiring and removed the old household earth wire that was attached to the anode! but can't remember where that wire went to! (done last winter).

I might as well keep the anode installed to the hull so would I be best to just connect it up to my gearbox? That's only a few feet away from the anode terminals.

Cheers
Paul

 

[Alex_Blackwood]

Thanks for your reply Paul...

I've also been clearing out old wiring and removed the old household earth wire that was attached to the anode! but can't remember where that wire went to! (done last winter).

I might as well keep the anode installed to the hull so would I be best to just connect it up to my gearbox? That's only a few feet away from the anode terminals.

Cheers
Paul

Not sure what you mean by "Household" Earth wire . However, I would strongly advise that you find out where it came from and what it was connected to. Was it for shore power, an anode bonding connection or What? You don't say what other equipment you have. As Paul pointed out the anode could serve as an Earth (Grounding ) point for an inverter or shore supply via a GI or Isolating Transformer. Any chance it was used for this purpose in the past?

 

[seafox67]

Not sure what you mean by "Household" Earth wire . However, I would strongly advise that you find out where it came from and what it was connected to. Was it for shore power, an anode bonding connection or What? You don't say what other equipment you have. As Paul pointed out the anode could serve as an Earth (Grounding ) point for an inverter or shore supply via a GI or Isolating Transformer. Any chance it was used for this purpose in the past?

It was just that green wire stuff that you find used in houses behind dry walls... it was very corroded!... Thanks for the feedback, I'm over at the boat tomorrow so will have another proper look around the shore power etc.

Cheers

 

[Tranona]

If you can get a good contact through to the prop shaft - via the gearbox casing and the coupling then you could do away with the shaft anode. If the shaft anode does not go too quickly do away with the hull anode. If you had both the shaft anode would wear first (because it is closer to the prop and then the hull anode would take over.

 

[pvb]

If the shaft anode does not go too quickly do away with the hull anode.

As he already has the holes in the hull, he might as well keep the hull anode.

 

[Tranona]

Even if it does not do anything? Not too difficult to fill the holes.

 

[pvb]

Even if it does not do anything? Not too difficult to fill the holes.

It's an extra anode, so it's unlikely to not do anything. Anyway, why make work?

 

[Alex_Blackwood]

It's an extra anode, so it's unlikely to not do anything. Anyway, why make work?

As I suggested earlier. Sort out why it is there in the first place!