Depends on the operational environment.  A frigate might see the conditions you describe, but not an aircraft carrier.  MIL-STD-810 covers immersion, as well as blowing rain, and watertightness.

TTFN

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When sealing electronic gear, constant immersion is a lot easier to deal with than splashing. For instance, O rings work reasonably well at constant depth, but are lousy for things floating on the surface.

When you add in the strong probability that someone will hit your electronics with an anchor or a chain, designing stuff for deck use is a case of belt and braces.  

Cheers

Greg Locock

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You might find ANSI/IEC 60529 interesting.

Available in part for free here http://www.nema.org/stds/complimentary-docs/upload/ANSI_IEC%2060529.pdf

If the vessel falls under a class society then you might also try the ship rules, such as Lloyds, DNV, ABS etc.  If the rules provide no information you could contact the relevant society and ask for an interpretation.  

Also, if your item is particularly large, draws significant power from the vessel, air, hydraulics etc and is to be a permanent fixture then you may need to submit designs to the classification society for approval because it MAY affect the vessel class.

The rules do include information regarding greenwater on vessel decks.

Ussuri,

   It is a surveying device, and the ship probably will be fairly small.  The device is battery operated, but it will be tempting to connect it to the ship's electrical power.  

   My primary concern is with waves crashing over the ship and damaging or tearing loose our equipment.  NEMA 4 and IP66 both involve spraying with big hoses, and IP68 is submergment in still water.  We would need to keep the box attached and sealed.  There would be a safety hazard with any cables that dangle after a failure.

   Are people on ship religious about removing deck equipment and stowing it below?  If they are, there is another possible solution.  

   We are quoting on a job, and I want some idea of how messy and complicated this going to get.  I have an approach worked out, but sombody must have solved this.  This is not a good job for trial and error.

   I will look up your sources.  

               JHG

Might be worth having a look at the electronic speedometers we use on yachts masts - they are exposed to a fairly nasty environment, and seem to survive.  

Cheers

Greg Locock

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