|This has now happened twice, to two different boats, so it's time to flag the issue.
Some years ago, Kat's Paw found itself becalmed on the far side of Humber Bay, engine kaput. Fortunately another competitor towed her back to the club. The mechanics found around 12 liters of water in the 55-liter tank. The theory was that, when racing rail-down, the tank vent had siphoned masses of water back into the tank. The original vent was blocked and a new one installed on the transom.
I thought this was an isolated incident but I recently had the dubious pleasure of pumping the fuel out of my tank and replacing the Racor filter cartridge. About half of the fuel pumped out looked like emulsified oil, so clearly there was a lot of water in the tank. Vent to be moved toot sweet.
Your mileage may vary, as they say, but if you're in the habit of sailing rail-down as we are (Toronto harbour can be quite gusty), this inexpensive precaution might be in order.
C&C 27 Mk IV