The towers are often knocked off for various reasons. Spotting the low lying disc is pretty well impossible with any swell. This is a common problem on Caernarfon bar.
I saw it on Tues on our approach (our new mooring is by the castle)
It seems to be made of two flat round shape fins in an 'x' (like those foldable dayshapes) rather than being a round big ball/sphere shape and red/white
The water was very flat though but we could clearly see it in the daytime
(the older ball shaped fairway is on the quaysidde car park)