LIFE BOAT

Condensation will occur whenever the dew point of the air is higher than a (colder) surface. Pull out a handy dandy psychrometric chart to follow this simple discussion:

In your case, we can envisage several mechanisms that will result in high moisture content (ie high dew point) in the air inside the life boat.

1. The dew point temperature of the outside air surrounding the life boat is higher than the temeprature of the life boat (due to cold water temperatures), and outside air is introduced to the lifeboat by the ventilation system, open hatches etc..

2. If occupied, then people will be adding moisture to the air inside the boat.

We can also envisage several conditions where the internal surfaces of the lifeboat are colder than the dew point of the air:

1. The inside surfaces of the life boat are cold due to cold temperatures due to ambient conditions and temperature swings.

2. The inside surfaces of the boat are cold due to contqact with the water.

So now there are several options to prevent condensation:

1. Dehumidify the air inside the boat to lower the dew point temperature to below that of the cold boat surfaces. Mechanical coooling (air conditioning) can reduce the moisture content of the air, but to prevent over-cooling, air must be reheated to maintain comfort conditions - and the lowest practical dew point temperature achievable is in the order of a few degrees aabove freezing. OK in tropical waters, not adequate in extremely cold water. Alternatively, various means of desicant drying are possible, but again, not necessarily practical in a life boat. Both means are possible and practical to prevent condensation while the life boat is not in use. See Munters website for static applications of active desicant drying. See Dectron (dry-o-tron) site for mechanical drying.

b) warm up the interior surfaces to above the dew point of the air.

c) reduce the introduction of moisture into the boat via open hatches, etc. (Not practical to reduce occupants!)

Note that simply ventilating more will not reduce condensation, in fact, adding moist air where dew point temperature is higher than the boat surface temperatures will actually make things worse!

I would seal it and have dessicants control the inside. There are indicators available to show it is dry without opening the hatch. Using this thing is probably a one time thing, so it must be in optimum condition when needed. After use, it can be refilled with dessicant and resealed.

As above: dehumidify the air inside it.