No wonder Judy is confused.
All I can say is this must be a Royal Navy only term. A couple of lengths of wire secured by a Senhouse slip serving as a guard rail (just called 'railings' on merchant ships) would not pass muster on a merchant ship.
Senhouse slips need to be under constant tension to work properly, so if the wire guard rail becam slack for any then the slip might open, et voila no more guard rail. About the only place you will find a Senhouse slip in use today on a merchant vessel will be to secure lifeboats and life-rafts.
Just for Judy here is a piccy of a Senhouse slip.
Newt:
I think in the American Merchant Marine (and perhaps in the US Navy too) they are known as Pelican clips, but I am not at all sure.
[ 09. August 2003, 10:42 AM: Message edited by: corydoras ]