Can you get or is there any recommendations for some devices that would give you depth and or water speed readouts? Any other devices out there that are useful?

I am a guage junkie. If I can't race against someone, I have to guage (pun intended) my progress somehow.

Would they be too fragile for a h14? ie the probes getting trashed by rocks etc?

I sail in a resevoir that has a few rocky shoals here and there and I have no idea of the location of all the shoals as I am the only sailboat around.

Well if you really want all the bits and pieces for this boat i do have a suggestion. Dont sail it. I dont know of many guages which are water proof and if your going to race well i dont think its race legal to have one on. Dont see why but all of this is true.