Anodes, zinc

Anodes, zinc alloy.

Anodes for a Moonraker will typically be like this: Two anodes each 2-4kg placed on the hull, two shaft anodes, two small anodes placed on trim tabs. They will normally last for 2 years.

All metal parts, trim tabs, bathing ladder, rudder, shaft, engine, can instead be connected with heavy cables to two 4kg hull anodes, which will last 2-3 years. This solution more than halves the anode expenses per year. Build 305 has had this arrangement since 1999 and it works all right.

To connect the parts is used 25 mm² cables, which are equipped with soldered eyes at each end. The photo at left shows cables partly from the bathing ladder (1), partly from starboard trim plane (2), which are taken to one of the three bolts, which the cylinder is fastened with (3). The bolt is taken through the hull, and the hole thing is tightened with a cable on the inside, which is lead to the starboard anode. The port side is made similarly, though only connected to the trim plane, as the bathing ladder already is connected via starboard side. Port side is connected to the port anode.

As the propellers and the shafts are connected to the gearboxes via a flexible coupling, which allows no electrical circuit to pass, you'll have to provide this possibility to avoid galvanic corrosion. This can be done in several ways, and here is top right shown a cable loop outside the coupling, below middle an inside loop. This last require that the coupling is demounted, but the advantage is that it is safe, as it can't catch anything while revolving. Engines, rudders et cetera are also connected inside to the anodes.

When the whole thing is carried out, it has to be checked whether the needed connection has been established between the metal parts and the anodes. This is done by means of a ammeter adjusted to measuring resistance.

Before every launch the connections are routinely controlled.

2005