First bit of advice is get yourself a custom flush mount for your lid from ZZ Tops Canopies in Strand. ( See pic above,..designed for Stealth Kayaks but if your ski has a similar lid then 💪)
If you chose rather to use the bracket your Fish Finder came with. Make sure you remove the unit from its bracket when surf launching.(You can only expect so much of any unit if it gets smashed by a wave)
Submerging a unit is never a good idea even though it is “waterproof” to 1m
Try as best u can, not to get salt water in the terminals(They are costly to replace) If u do rinse them with distilled water and vinigar 50/50 mix as soon as possible and dry. (Point is, look after the unit like it was not made to be in water)
If u wipe the dried salt on your screen you will scratch it!!. Either splash water on before and wipe gently.
Use sim-24 to keep terminal 100%, can get from Seaport or general boating or sailing shop.
Get yourself some corrosion block and spray all connectors after every clean. It’s a sticky oil that protects all connectors and corrodible bits. Works a charm.
Do yourself a favor and try be kind on the unit and it will serve you many years.