Hi JP. I would like to have that setup, but I have two issues:
On Kristy (SM243) the anchor wash pump is supplied with SW from a thru-hull inboard of the forward head (in the "hallway" between the head and hanging locker). That would mean running a new hose from the FW tank through the bulkhead.
If that's not daunting enough, I have the 60 l/h watermaker, so I don't have enough capacity to justify washing the boat and chain with FW.
Too bad, here in the ABCs...there is constant accumulation of dust from the dry islands and has been a plume of dust from the Sahara adding to the problem since I arrived. It has only sprinkled a few times in a month which turns the dust to mud. I've been washing down w SW every few days to keep the cockpit and down below as dirt free as possible. Even if I had the FW wash down I don't think I'd like to make water in the bay as there are no pump out facilities and I regularly smell black water being dumped.
If my Watermaker dies I will seriously consider replacing it with the duo.
We improved Eleuthera by removing the SW pump and connecting directly to the FW network. But... you need a good water maker.
Eleuthera, SM 007