Size of plug for Wind Transducer - Raymarine ST60

[cpedw]

I want to fit a cap over the masthead plug of the ST60 wind for the winter. What size is it? Is there an official stopper for it and can I get hold of one?

 

[vic008]

23mm id. I beleive its genuine Raymarine. Haven't fitted it yet

 

[cpedw]

Thanks for that.