Had another go on the scrubber , and must have new brushes on as the boat is alot cleaner now. I think if you have a clean hull and keep getting it scrubbed on a regular basis then it will make a difference. The operators are also more experienced in cleaning ribs as they showed me how they now clean ribs different to last time. I am going to sign up for the year and see how it goes not much to lose and you get unlimited scrubs so once a week for me I think.
My last post on this subject was negative and after being persuaded to give it another go , I have to admit I was wrong if the boat hull is clean and you keep it that way then I think it will make a difference so long as you use it on a regular basis the big saving I am looking for is fuel so will let you know how it goes.