Second hull anode on saildrive boat?

[vyv_cox]

Hi Vyv,

The prop has a boss which bolts onto the shaft. The shaft and retaining system butt up against this boss.

The boss has a resilient rubber bush which drives the prop hub. This electrically insulates the hub, hence blades, from the boss and shaft.

Best option is to look at the Boat Show. They are keen to talk about the products.
I suspect the boss and hub have some sort of drive spline system to carry the substantial torque loads involved. I imaging the, should the rubber be eroded, there would be metal to metal between the hub and boss.

As soon as I'm back, I'll look for drawings.

It is an amazing piece of kit from an engineering point of view.

Tony

The Autoprop website shows none of this, neither does the video, although all are specifically for saildrive units. They say the rubber is for shock absorption, not insulation.

 

[pvb]

What is the purpose of this "huge anode"? You say it is connected to the electrical ground but what underwater appendages are bonded to it for protection by it ?

If there's an electrically isolated saildrive, the anode may have been fitted by the boatbuilder in order to comply with CE requirements for earth bonding. My Bavaria has an isolated saildrive, and there's a hull anode fitted.

 

[VicS]

If there's an electrically isolated saildrive, the anode may have been fitted by the boatbuilder in order to comply with CE requirements for earth bonding. My Bavaria has an isolated saildrive, and there's a hull anode fitted.

For what is described as " the craft's external ground/earth or ground plate" then.

 

[Tranona]

If there's an electrically isolated saildrive, the anode may have been fitted by the boatbuilder in order to comply with CE requirements for earth bonding. My Bavaria has an isolated saildrive, and there's a hull anode fitted.

Have not followed the internal bonding, but pretty sure the extra anode is bonded to the rudder tube as recommended by Jefa. Whatever it is, it slowly erodes - about half its small bulk in the first year.