Regular maintenance of See Blitz strobe light

[smr547]

refer #595

Annual servicing of the See Blitz as per the User Guide.

• Device installed new Jan 2022 by @pauljones17
• Next service due Nov 2023 at Boatworks

Device should be tested by each skipper as part of the safety brief -- update to skippers notes required?

@mrmrmartin @peterottesen will be interested

[smr547]

This is a routine maintenance issue -- we keep them closed until they fall due