Toilet sinking the boat.
All, The E31 head platform is such that at least when normally installed, a Groco K-H toilet bowl rim is almost at the boat's waterline. This could be similar on other Ericson's as well with other brands of toilet too, I don't know. It was sooo close for me (the top of the bowl is 1/4" above the outside water line with the boat on flat water in our slip) that I was scared to death I'd sink my boat one day if I forgot to close the raw water intake seacock before going sailing. It so happens that E31 hull #33 had the same toilet model as mine but in that case, the outside water line was 1/4" ABOVE the toilet bowl and on two occasions within two weeks, the former owner forgot to close the seacock after use and upon returning 30 minutes later from a quick trip to West Marine both times (honestly), he found the cabin sole awash. He decided to call me for a solution by either adding an anti-siphon valve as I have in my head or by not shopping at West Marine any more, he chose to add the anti-siphon. It's the Groco 3/4" bronze model that I've mounted on the forward bulkhead to the left of the toilet. It's almost on the center line of the boat at about chest height and when not in use, is hidden by a hanging towel. To flush my toilet, one has to place a left finger over the vent hole to allow raw water to be pulled past the valve as one pumps the handle with the other hand, opposite from the intended use of such a valve. The theory is that raw water cannot siphon that high and certainly not with the vent open, thereby saving one from sinking their boat. By removing a finger from the vent when exiting the head, that insures that the vacuum has been broken. Actually you can hear and see water in the intake hose return to the outside water level as you remove your finger. Is it unsightly? That's relative when compared to risking the loss of my boat, so my answer would have to be no. Anyhow, like I said, the thing is covered by a bath towel on a hook over it. In a conversation with Tim, the service guy at Groco years ago, I mentioned my installation and he admitted to me that he has recommended the same method for the same reason for the last decade or more. Regards, Glyn Judson, E31 hull #55, Marina del Rey, CA