Why would you wish to fight a flooding tide, Alan?
We leave Oulton Broad and take the EBB to Gt Yarmouth to arrive there at LW + 1.30 (Slack Water, GY). So I leave OB about 3hrs30mins before that.That way I can set revs for about 4-5mph and have a ground-speed of 6mph (when allowed).
So, if LW GY is, say 15.00, I'd want to get to GY at 16.30; so I'd leave OB at 13.00.