Attaching sacrificial anodes to copper-sheathed and copper-clad boats
When attaching anodes to copper-sheathed and copper-clad boats, we recommend following the same instructions as for boats with GRP hulls. However, there are a number of additional instructions, which are as follows:
- The copper must be cut back to 20mm clear of the anode fixing stud collars.
- A pad of 6mm marine plywood should be fitted between the rubberised anode backing sheet and the copper sheathing. The pad must be painted with an epoxy resin paint system or similar and should be well bedded with marine-grade sealant.
- The pad should extend at least 15mm clear of the anode and over the area where the copper has been cut back clear of the studs.
- The copper must not be allowed to be in contact with any metal work that is being cathodically protected.
- The copper must be cut back from the outer end of the stern tube and any other metal fittings that are bonded into the cathodic protection system e.g. shaft brackets, rudder bearings and glands, if these are to be protected.
- We recommend checking that the cathodic protection system is isolated from the copper using a suitable multi-meter.
- Where the copper has been cut back, areas of exposed hull, in particular wooden hulls, should be well painted with an appropriate epoxy resin paint system or similar.
- Metallic-based anti-fouling must not be used on the plywood pad or on the areas where the copper has been cut back.
- When choosing this anode, we recommend that you refer to the instructions on boats with GRP hulls in salt water on our cathodic protection page, and select the anode which is a size larger than that suggested for conventional GRP-hulled vessels of the appropriate class.