My poor boat was on the receiving end of birds roosting on the spreaders for a few weeks until I could get up there to replace the lines.
I flushed the worst of it off the boom-bag and dodger, but what remained still looked pretty awful, so I brought the boom-bag home for a proper clean-up.

First I tried a mix of bleach and soap as per Sunbrella's website: useless. Next was two goes of saturating the stains with cleaning vinegar, leaving it for 1/2 hour or so then brushing and flushing off: mostly useless. Ditto with 85% phosphoric acid. Then I used the garden hose narrow spray nozzle and a brush, which moved some more but was very hard slow work for an incomplete result.

I finally hit paydirt by soaking it in the half-full bath for about 2 hours, in warm water with about 1/2 container of Vanish dissolved in it: perfect!

I have no idea what all this has done to whatever vestiges of water-proofing that may have remained in the fabric after about 7 years of service. The scrubbing had to be done very carefully to avoid damaging parts of the stitching that was looking UV-affected.
Next is to do the same to the dodger.

Cheers, Graeme

Dunno what it is that these seabirds eat, but it's bloody hard to get off! I had nets all over the boat, and they managed to get inside them. Totally crapped out the cockpit and the fore deck. Have now gone to bright orange windsocks and some shiny flappy things hanging from the boom. Won't know if they're really working until nesting time.

Bird **** is uric acid. There is plenty of stuff online on how to clean. Metal Gleam won't help here!

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Ramona said..
There is plenty of stuff online on how to clean.

And much of it is rubbish, hence my post to save others wasting time like I did.

Cheers, Graeme