[Hakahura]

I partly agree with Canovaro's post.

But in my experience having the radio guy trained up helps in addition the hydro man. I find this especially noticable when your boat becomes equiped radar detection equipment. Seems to me a trained operator gives ealier warning of radar emisions and depending on your level of realism the emision plots on the map are more accurate.

The radio and hydro posts are the 2 I train and promote quickest.
Of course if you use SH3 Commander you can train your crew as quickly as you want and in whatever manner you see fit.