12 volt fuses for anchor and bowtruster controls.

If you check voltage at the switch and also at the relay and bow thruster you will probably find  it is either  low or non existent.  If it is low then measure voltage when switch is operated and it may drop to be very low. That is what happens when the cables are corroded internally.

That corrosion was so bad on my 2007/2008 model 400 that I have had to replace wiring for bow lights, anchor winch control, and vee-berth  reading lights right back to the electrical board. That was a very time intensive job involving destruction of some interior panels due the the way these boats were built.

Cheers

DJ

As you found, it is very difficult to actually remove the existing wiring which runs towards the bow from the main electrical board.

Unfortunately Hanse has used tight cable clips, screwd to the hull itself, prior to fitting the lining, making the wires trapped. I don't understand why the did that instead of installing conduits, like they have elsewhere in the boat to enable  maintenance of the electrical system especially as they used un-tinned copper cable which is mote sensitive to corrosion. Many other manufacturers use conduits everywhere.

I cut the free ends off the corroded cables so nobody is tempted to use them in the future.   I cut small access squares in the lining to enable new cables to be run through next to original cables, all in colour coded mesh cable protection sleeves. All the cables are labelled both ends. Then I fitted a couple of small junction boxes in the space where the bow thruster is sometimes fitted. I also ran additional cables to provide a 12V power outlet in the anchor locker for future use of an anchor wash pump.

Where I cut the access holes I refitted the removed pieces with backing flanges, as shown in attached pic. Not pretty but the options were limited.