Thanks for the prompt response, you all scored very highly, and confirmed my suspicions in most cases, but also put me right in others. And now that we have some keen experts suitably engaged please could you help further?
1. Is indeed the back of the manual bilge pump that is located on the bulkhead in the heads. My ‘real’ question is slightly more complex…It probably pumps out from the shower tray which has a standard looking plug hole in the corner near the door. But is this a ‘standalone’ bilge or is it in anyway connected to the main bilge under the cabin sole?
2. Seawater strainer looks as if it can be serviced? Do I just twist off the top and peer inside looking for weed or barnacles etc, or is there any other trick to keep it behaving itself?
3. Fuel filter looks straightforward, is it just twist off and replace like a car oil filter? Are they readily available, can you recommend a brand to use or even avoid?
4. Again, as suspected, this is a manual bilge pump (the pic preview only loaded half the image, click on it to open the file), but what do we think it actually drains?