Thank you all for your responses to date.
1. I had no idea about the torque plate for the bow thruster but Oliver's explanation totally makes sense. I am hauling out in two weeks and will fit the kit at that time. I need to remove the BT anyway to replace the neoprene seals and change the oil.
2. The black composite plate (pics 5 & 6). I will check the water tank inspection plate. Thanks Bill.
3. Pic 4 is an aluminium disc, so not a zinc.
4. Pic 3 is some sort of stainless backing plate.
7. Pic 7 is some sort of plastic/teflon/composite?
As an aside, the primary reason I am hauling out is to repair rust spots on the iron keel ballast that suddenly appeared. I immediately checked the bonding strap in the bilge, and sure enough, it had corroded through. I had not long checked that strap and I suspect that the time frame between the strap failing, and the rust spots appearing was less than 3 months. A timely reminder for other owners to check theirs, and maybe even preemptively replace it before it fails if this has never been done on their SM. I have obtained 2 straps so that our awesome friends on Salagou can replace theirs before it fails.
Rob.
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Rob & Dee
SV Jaygo.
SM#224
Brisbane, Australia