and one thing lead to another and I replaced the 15 year old reinforced 2 ply water pipe between the seacock and the sea water stainer as I thought a failure in that critical two feet of piping would be a bit difficult for a quick fix. Up that that point I had not carried with me any significant piping supplies.
I somewhere read that the suction up from the seacock into the strainer is a more difficult issue of old pipe than outward pressure. I don't know if this is true.