I forgot to test the Pureseal plates at the start of Autumn so I did it mid month and am reporting it here. I continue to be impressed by this stuff but cannot get any information or an answer from the makers. 3 years and 3 months and it is still working. It is starting to get shell life attached to it now, it did in December too, but that was really small shell but a few of them, this time only one shell but a little bigger. It came off very easily though and the rest was just slime and algae. So by my reckoning it is still working. Seems to be getting patchy but still working. I would imagine that with constant motion the algae would be lessened but even so I wouldnt be complaining if this was on the boat. But unless I can get onto the manufacturer before launch, likely to be at least a year away the way things are going, it wont be going onto the boat, maybe on the dingy. I just cant risk it. I need to know how far a 3 litre can will cover and if I find 9 litres is not enough, how I can get some more. I doubt I will hear from them though so all of this testing, however encouraging it may look, will have been for nothing.