[jimmyswimmy]

There are a number of conformal coatings that can be used to keep a circuit board dry at fish tank pressures. Parylene is my favorite as it isn't too harsh on the board materials and coats even underneath the surface mount components. Doesn't usually stick to the board though so it's more of a perfectly sealed bag around the board. It's good for basically forever.

If you unplug the connectors you rip a hole in the "bag" though and the connectors will corrode. The way around that is to use expensive hermetically sealed connectors that are designed to operate underwater. Each side of those will cost a few hundred USD for boring round connectors. I have never tried to run e.g. HDMI through a bulkhead but such a connector would probably be impressively expensive.

Anyway the best thing about Parylene is you have to send your equipment out to have it applied, no do it yourself here. The spray on coatings are usually sticky, messy, and not that great overall in comparison.

[krasin]

>The way around that is to use expensive hermetically sealed connectors that are designed to operate underwater. Each side of those will cost a few hundred USD for boring round connectors.

In this respect, I highly recommend Cobalt series of connectors from Blue Trail Engineering: https://www.bluetrailengineering.com/professional-products - they cost "just" tens of dollars each and are very good (I used them); quite popular with ROV community.

[montag]

What does ROV stand for?

[krasin]

> What does ROV stand for?

My apologies for an acronym. It's Remote operated underwater vehicle: https://en.wikipedia.org/wiki/Remotely_operated_underwater_v... (a small submarine, usually, with a long thin tether)

[jvanderbot]

I'm guessing remote operated vehicle - e.g., remote controlled submarines.

[Cyclical]

As a small note, IP67 sealed connectors vary greatly in price, with excellent high pin count options like the Ecomate Aquarius line being in the low tens of dollars. The Deutsch/Amphenol AT automotive connectors are also very cheap yet provide a watertight seal.

[jvanderbot]

I've seen some fairly generic looking many-pin connectors that are water tight. Is it just best practice to route everything through the 40+ pins and break out on the other side? Even power?

[alchemist1e9]

> Anyway the best thing about Parylene is you have to send your equipment out to have it applied

Could you share some vendors and pricing since it sounds like this is something you are experienced at?