John Tideswell

Walking around Wickes like you do and came across this. Measures 65mm diameter and once you cut a ring from the rest of the connector it fits perfectly into the screw lid. Cheap at £2.

Thanks guys for all the suggestions. The last time out I got some water on the receiver and the rudder servo stopped working. Assumed it was a receiver issue yet it turned out the servo was dead. Having done a bit of googling it turns out that water across the servo plug can actually short the insides of the servo out.

Looking for the foam or rubber material that fits inside the screw pot lid to create a better seal. I have seen some blue type material being used but don't know the spec or where to buy it from. Thanks