GL: Moisture resistance with no pressure discussion

[Ken Bloomfield]

Just to offer another possible solution to condensate water in your fuel over winter, I would like to make the following offering, as it works for me.  I am one of those who is fortunate enough to have electric power on my boat over the winter.  I thought long and hard about the issue of condensing water into my tanks as they breath.  I like the idea of the rubber balloon and the dessicant, but it was not so easy on my 50' MT.  So, the thought occurred to me that condensate only ever happens when a volume of air containing some Relative Humidity (RH) meets a surface with a temperature below the "dew point" of that atmosphere.  So, if one can keep the surfaces of their tank and the fuel itself (since it is also a potential condensate surface) above the dew point.  A little further research showed that this is not very hard to do in my boat.  Basically, what I do is throw a very small amount of heat (with heat lamps) onto my tanks, and in fact I do the same with my engine.  The
  issue
 that happens is that after a night, when the ambient temperature outside increases, the thermal mass of the tank/fuel is slow, and thus the tank/fuel surfaces "fall behind" the outside ambient.  The slight additional heat that I give them, keeps both the engine and the tanks bone dry inside (in moisture terms) and I don't worry about adding or deleting fuel.  This of course is only possible with the ability to have power available, but the needed wattage is very low.  

This solution has worked for me for 7 years, without a drop of water in the tanks, and eliminated the problem for me.  As CCC says, YRMV.  And, best of all, no need to get into PV discussions.

Cheers,
Ken Bloomfield
MTOA2062
AGLCA3529
MT50 Tellico Lady