I have one piece 3/16" SS backing plates behind my cleats. It would have to ripe out part of the
deck to brake them loose. 1 mm (.040") thick is not much better then
fender washers. It wouldn't pull out EZ but would loosen up under heavy stress. Once loose it would continue to wear away at the holes.
As for
anchoring, there are special
anchor cleats (clamps) for that. You'll want your anchor to come off a
bridle or straight out your roller unless you need to heave-to, so to say, in a strong
wind at anchor for ease of motion reasons.
Cleats should be strong but not your main source for extreme
weather holding.
e.g. Sea anchors need a very strong attachment(s) that will withstand hours and hours of constant abuse. For this many build in special eyelets for attachments. But if you plan
anchoring in heavy
weather anchorages I hope you yourself can hold up to the stress. As well, you'll most likely want to put in a spring line or add a kellet to reduce stress on the attachments.
As for what you have, I
would beef it up with thicker
single plates.
Here's an article that'll give you more info on anchoring....................._/)
Anchor Catenary