Hi Fred,

There were many creative replies on this thread ranging from dolphins to ghosts, but I think you're onto something relative to the varying thermal expansion/contraction rates of aluminium and steel. I suspected the sound was from the standing rigging as mentioned and this seems like the most plausible answer. I note your recommendation not to loosen the shrouds. I just hope the amount of movement isn't enough to damage anything such as chainplates or shroud-to-mast connector fittings. Thanks again.

By the way, SV Wings is a beauty. What model is she?

Best regards,

Dan