Ropes and knots

When I first started going on boats I literally couldn't tie one knot.
Since then I have learnt the proper way to attach a fender (clove hitch) and the proper knot for a loop on the end of a rope (Bowline).I have been known to do a cleat hitch too... The only trouble is I have to keep re-learning them every time I go on the boat as I forget so quickly. They will just not stick in my head.
I often just make my own ones up and hope no-one notices.