By 'helpful assistant' you mean my good lady wife who is happy to sit in boats as they sail along on a light summer breeze, but otherwise thinks they are dangerous toys only slightly safer than my motorcycles.

Success! I managed to knock it back into just the right place to withdraw the centreboard.

Thanks - it feels like there is a metal sleeve that is meant to sit in the centreboard but it has shifted to one side so it is now partly in the centreboard and just protruding enough to make it impossible to remove the board. I can feel it from the starboard side but not on the port. Attempts to drift it back haven't been successful.

Any clues how to remove the centreboard? I have removed the bolt but the centreboard seems to be still pivoting on the same point. If I stick a finger into the hole I can feel a metal tube. I'm wondering if this has moved to one side so it's still preventing the centreboard from lifting clear.

Thank you. If might go a bit quicker once I get rid of the large quantity of silicone sealant holding it together. Everything is covered in the stuff.