Remember water has a refractive index of 1.33!
Frankly, I don't even know how you did the boat one.
You're way ahead of me!
Here we go!
This shot was taken between 8:42 and 9:33 am
(assumes November 15th).
I used Snell's Law of refraction of light passing through an interface of two media. The salty water nudges the refractive index up a little: n = 1.34
I superimposed a Google Earth image of the planet just to get a set of lat long lines for comparison to the ribbing on the underwater float. It is somewhat crude especially considering the sea surface may not be very flat. I think the shadow line on the float lies between latitudes 24 to 32 degrees. Using those estimates and Snell's law I get incidence angles from 33 to 45 degrees from sea surface normal. The Solar altitude is 90 minus that giving 45 to 57 degrees. Solar altitude gives the time of day (we know it's AM so the PM case is removed).