There are a couple options that don't leave you stuck with fresh water only if you are away from your marina.
On my last 2 Catalinas the head and head sink drains were close by so I plumbed in a valved connection from the head sink drain to the head pump intake to grab fresh water from the sink drain. Picture an H with the left side being the head sink drain, the right side being the head input, and the horizontal being my connection with a valve/switch in the middle. Depending on your existing plumbing it can be simple and switchable using the 'wet bowl' setting on your head and proper settings of the thru-hulls.
Another option that can be used with most boats that have the shower head within reach of the head is to simply use the shower faucet to flush with..... which actually cleans the bowl much better than the normal head flow. My current boat has a separate shower but at the sink it has a second shower faucet which I use to flush with using the 'dry bowl' setting on the head.
Wickford/Narragansett Bay RI
Last edited by christyleigh; 06-24-2010 at 06:36 AM.