Just did a touch of digging, and no actually, sea mines generally should not explode if directly dropped onto a vessel. Nearly all the mines in the game that I know of are hydrostatically armed and have a 30-90s arming delay once at that depth, which means that they don’t become active until they have sat there for a hot moment. Sure, they’ll still do some major damage from the kinetic energy alone, but they generally shouldn’t detonate.
The rest are still valid, air-dropped contact mine can be adjusted accordingly.