Alain,
My response is provisional based on some unknowns. First off, what is the source of the in port image of LCI-84 and 87 and LCA's? Color images are almost always tricky to determine "true" colors. The source of the digital image is important to know. If a direct scan of an original transparency or of a print copy and how many generations from the original, impacts the colors seen. Plus, way too often whoever posts color images, may well "play with" the colors to make them "prettier". But based on the third LCI (LCI-497), painted in what looks like Ms 22, the lighter color should be 5-H, and the darker blue shade is reasonable for 5-N.
I found another image on Navsource taken at the same time of the same ships, taken a different aspect and credited to being a USCG photo ...
https://www.navsource.org/archives/10/15/1015008406.jpg ... has colors quite a bit darker than of the one you posted which is also posted on Navsource ...
https://www.navsource.org/archives/10/15/1015008702.jpg ... These two images illustrate how ships painted the same and having photos taken even at the same time can appear with completely different levels of "darkness".
But, based on LCI-84 and 87 being USN manned/operated (not sure about the LCA's, but I believe they are RN/RCN), the darker blue is likely 5-N. The LCA's are a question mark for me. Since they are RN (or RCN), I assume the blue is a RN color. Which one I don't know.
Rick