I went there, but I didn't see anything about Valley hatches. Which post was it?
What I don't understand about rubber hatch covers is why they don't all have robust lift tabs on them. On my boat, only one hatch cover has a lift tab. I learned not to use the tether tab as a lift tab on the others.
My next boat, which is being built for me right now, shouldn't have any such issues, due to the type of hatch covers they use.