Allow SSM tubes to satisfy destroyer requirements

[Enderminion]

Given the severely limited topside space of a destroyer the requirement to have a single above water torpedo tube is a bit excessive, it can't be a corvette because those are smaller (too small for MSAM). Thus allow SSM tubes to satisfy the requirements for destroyers to have torpedoes.

[christian]

i agree, having the option to replace torpedo tubes with missiles would be nice.

[williammiller]

I like that idea, thanks.