How do you keep these rats of the air from fouling your boat? If, like me, you keep your pride and joy on a mooring, you will have found it a continual battle. Swinging buckets, tattered plastic bags, dangling soft drink bottles - I've tried them all. Gulls become used to them very quickly. I've seen gulls roosting quite unconcerned beneath the moaning ‘bird scaring’ tape sold by chandlers.
I (and others) have resorted in the past to covering the topsides with netting. This is very effective and with a bit of luck you may snare some of the blighters. However, it takes a very long time to fit and remove, probably longer than scrubbing the guano off the decks.
I think I may have found a simpler solution. Two years after I have adopted it, gulls are still largely avoiding Harbinger. I saw the clue in Sydney, at Fort Denison (Pinchgut), formerly a seagull haven. Protruding at intervals above the battlements were feather dusters, which the ranger informed me, were placed to deter the gulls. I now dangle a feather duster from the end of the main boom when I leave Harbinger and the seagulls stay away. Why? Perhaps the fluttering feathers look like a possible predator, or, perhaps, like us, seagulls don't like to be reminded of their mortality.
The duster on the chart table is also a bit of one-upmanship over visitors in terms of implied standards of yacht care.