As TFJ says, don't use undercoat or primer and if it's weathered plastic you don't need to sand it down. just clean it.
Use short flick/flick/flick strokes across the pipe for best coverage and least brush marks. Long strokes up and down give poor opacity and brush marks which don't flow out.
I shall print out Lakeys replies, issue them to nominated worker and supervise from ground level, I might have to translate them into Estonian though.
Any way bugger off up to Scotland, just two tips when the sounder goes into double figures it is not faulty, the water is that deep, and your normal method of touch and go navigation doesn't work as it's granite not mud you're dealing with.