Subject:	Both Dee & 3000psi are right
Author:	drdread
Date:	2/6/2002 10:09:05 AM
Message:

Grease is A-OK as long as you don't use too much. In the case of Ikelite housings, though, they frequently use compression O-rings, which need no grease at all. A compression O-ring is one which sits flat against a flange is gets compressed against the flange by a surface applying pressure parallel to the surface (parallel to the surface normal, that is).

Compare this to an O-ring that has to slide across another surface. For instance, the main o-ring on the back door of a Nikonos V camera sits in a little groove that runs around the inside of the door. When you hinge the door shut, the O-ring has to slide across the inner surface of the camera body itself.

In the case of "slide" o-rings, grease is necessary to allow the o-ring to slide without twisting or deforming. In the case of compression o-rings, no sliding action takes place, so no grease is required. That's not to say that grease is bad for the o-ring, but since grease can attract dust & dirt & hairs, why use it if you don't need it?

As for your housing, I'd have to see it to make sure, but I bet it uses compression O-rings because that's Ikelite's MO.
Truth is, I'd just do whatever the manual tells you to do. If it says "use grease," then go ahead. If it says "you don't need it, but you can use it if you want," I'd skip the grease. FWIW, my Ikelite N90s housing uses a compression O-ring, and I basically never grease it. Once a year or so, I grease the O-ring if I know I'm going to be storing the housing for a couple of months. But in daily use, I do not grease the O-ring.

About the batteries: 3kpsi is right. "NiCad Memory" is basically a thing of the past. I have written several articles about this on Rodales D2D board; you can find them with the search tool, probably. The upshot is this: partial charges are not bad, but overcharging is. The old "discharge completely" thing was simply because starting with an empty batter provides an easy baseline for how long the pack should stay on the charger before removing.

So go ahead & do partial charges to keep your pack topped off. If you have an Ikelite smart charger, you have no worries whatsoever (it will stop charging when the pack is full). If you have a 'dumb' trickle charger, Just check in on the pack every hour or half hour. If it feels warm to the touch, it has started overcharging; take it off the charger immediately and plan to charge it for shorter runs afterwards.

Dessicant: you can find the stuff locally at several places. Dive shops (especially ones that sell photo gear) are good places to start. Pro photo shops are good, too. Then I'd check these other places: mailboxes etc. and other shipping outfits, food service warehouses (food often ships with dessicant), and computer outlets (every hard drive I have ever purchased had a dessicant pack in the box with it).

Sea & Sea sells the stuff, as does Pioneer Research (aka SeaLife).

Good luck! I have a ton of it, but I can't figure how to get it down to Freeport in time to help you...

D

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