Re: CORRECTION: ROV site

[Dave Everett <deverett@idx.com.au>]

At 21:40 28-09-98 EDT, you wrote:
>In a message dated 9/28/98 2:39:01 PM Eastern Daylight Time,
>Ray.Keefer@eng.Sun.COM writes:
>
><< My only concern is that the wall between the dry and wet parts be strong
> enough to handle the pressure differential at depth. >>
>
>Valid concern.  That presents a problem because the thicker the wall between
>the dry and wet parts, the less effective the coupling because magnetic
fields
>decrease by the square of the distance, I think.  I'm wondering what's
>available "off the shelf"?
>
I've made magnetic couplings using neodynium iron-boron magnets, these are
incredibly powerful. I was driving a leadscrew through 3mm stainless steel,
the coupling should be fine at least to 10mm. The only problems I can see
are 1) steel becomes magnetive and may diminish the coupling strength 2)
strong magnets play havoc with compasses.