As you do not appear to be having much luck I will offer this general observation (I designed/ specified/ and inspected electrical
power systems for a lot of years, the latter years including a lot of surge supressors).
I don't think I have ever witnessed so many "snake oil
salesmen" as landed in my office after the computer/ surge supressor era arrived. In order to compete even the legitimate suppliers got pretty far over the line with their claims.
Considering that you are floating on one of the select anode materials, any device from a company "out of business" that is going to electrically connect to that anode probably belongs in the garbage can.
Without getting into the lightning protection/ anchor
power swamp, you need two protection modes. Normal mode surge protection ( think between the + & - 12 volt leads) and common mode protection (think everything connected to the engine/ aluminum
mast) at a voltage relative to the sea of say 20,000 volts. Most of the damage from surges is in the latter case, but not all (spike from anchor windlass
on/off probably normal mode). Typically to provide protection there must be an electrical
device connected between the +-12 volt wiring
(norman mode), and mast/ engine
to sea water
In your particular case proceed with caution!
PS I built my own, but for a FG yacht.
Common mode might be better thought of as between +12 volts and seawater hull