Once you have installed a proper, dual switchable fuel filter assembly with a vacuum gauge in your engine room, you can be sure that you have covered your bases in terms of delivering fuel to your engine(s) that is clean and free of water. All you need do on a regular basis is to monitor the vacuum gauge on the filter assembly, noting the degree of vacuum present between the fuel tank and the selected primary filter. As long as the needle remains out of the red zone, you need not worry about the status of your fuel delivered to your propulsion engine(s). That is very comforting as you cruise unfamiliar waters.
(I tagged this post for power only. However, if I owned a large sailboat with a 110hp diesel and sufficient tankage to motor long distance, I would most assuredly do this on my sailboat as well. If any boat is large enough to warrant dual switchable fuel filters, I consider this a no-brainer. The value to a Monk 36 or Hallberg-Rassy 46 is the same.)
About the only thing slicker than this setup is when you have a second, duplicate vacuum gauge remotely mounted at your helm, where you can keep an eye on the filters when running the boat, without needing to go down into the engine space. This is a pretty great addition to your helm, and it is easier than you might imagine.
It is pretty straight forward to add a vacuum gauge, as long as the gauge is not too far away from the fuel filter assembly. In fact, Racor recommends you keep the hose that runs between your remote helm gauge and the filter assembly under 14 feet in length. As long as you can keep the hose under that length, you should have no trouble installing a remote vacuum gauge.
So here is how you do it. Leave the original vacuum gauge already installed at your fuel filters, but put a T in the system for an additional hose (the T fitting is below the original gauge in the photo below). Using regular Type A fuel hose, run a length of hose from this T up to your helm, where it is attached to your second vacuum gauge at your helm. There is no need to do anything special with this hose. As long as there are no air leaks, it will register any vacuum pressure between the selected fuel tank and the selected fuel filter, just like the original vacuum gauge.
Racor and other manufacturers make vacuum gauges with their connection on the back of the gauge, rather than at the bottom as you see on your filter assembly. This on-back connection simplifies the hose connection underneath a helm console, making it an easy set up, again as long as you stay under the maximum hose run.
Once you have completed this installation, you can keep an eye on your fuel filter's operating situation from the control and general situational awareness of your helm, and eliminate the guesswork associated with out-of-sight instrumentation that requires you to go into the engine space to monitor status.
Have a great week. Planning to visit some interesting boat repair work this week. Should make an interesting story or two...