water in gas tank

[Viper]

If you're talking about installing a clear bowl filter assembly like the Racors used in diesel applications, those are not allowed in gasoline inboard and sterndrive applications for safety reasons. An assembly that has a drain plug is good for checking and draining off water that may be in the assembly. As an early warning system for water in the fuel, there are filter assemblies with water sensors that alert the operator when water is present in the filter.

[Phrancus]

Ah, so there is a difference between inboards and outboards (I found one for outboard use). Outside the vapors would be less of a danger than inside obviously.

More comfortable to have a warning in a dashboard, I don't have that for my diesels so i need to open the hatch and climb in to drain the separators.

[Viper]

If you have Racor filter assemblies which are pretty popular as primary filters, some of their models have ports for installing water sensors. Wiring in a new install for an alarm and warning light at the helm is pretty straight forward.

[Phrancus]

Good tip, I do have Racor and it has a port to add a heating element. Logically this could be used for a water sensor (don't know about difference in conductivity between diesel and water at this moment).
You don't want to see my racor's at the moment: one lump of bacteria-pulp up to half the glass.... don't dare to push power and thus flow...
I plan to add a Racor so the flow will be: tank - 10 micron racor - 2 micron racor - engine's filter - injector.
Should the 10 micron not get dirty any more ( I will clean the tank of course) than it was not a necessary thing to add but when not it will save the finer filter for clogging up.
With two I might get to adding a water sensor like you mention. A heater is pointless: when it's that cold I will not be going anywhere anyway (my engines are even a variant without pre-heaters (glow things, what's that in english)

However interesting and exciting to get to the job of improving all, at the moment I'm keeping my fingers crossed that the boat will come out of the winter weeks (sudden snow and frost here) afloat and engine(s) startable. The plas was to get her inside in November.... bit of delay and got a surprise pack of snow and -10 C out of the blue.

I did emergency winterize but also the power fell out at the marina (my backup was a small heater) and I fear a water-lock due to the quick anti-freeze procedure I could have done better.