Not as safe as one thinks. Yes; it is batty. (^^^) Of the three solutions, NAVOL is probably the easiest and safest to engineer, though not the most accessible to solve chemically (stored pressurized oxygen is.), but even it is insane once a gelled "slightly toxic" monopropellant (Otto fuel) becomes possible. RFNA is usually limited at 84% nitric acid with dinitrogen tetroxide (~12-13%) and 1-2 % water plus trace inhibiters to keep it from eating the stainless steel or aluminum storage tank and piping. There are too many stories of accidental venting and the service crew doing the Wiley Coyote and not making it (Soviet safety gear was not the best and also see underlined.) to discount the safety hazards involved. Italians knew how to use mines which for them were ASW weapons. They were good at transit analysis and laid ambush minefields accordingly. The Regia Marina gets a bad rep. They were quite an effective navy for what they had and the problems they faced. Some of their solutions were "novel".