Notes
Reminder that this vessel is not crewed by die hard zealots of the empire. the crew may be all imperial navy personnel but they are defenseless. Having this ship's crew abandon ship via escape pods upon the ship taking severe damage risking cargo detonation is the proper choice. Having the Captain or another crew stay behind to be a [dead] hero and attempt to ram it into an enemy vessel is ill advised.
If you are set on it; my advice is to treat it like a really big proton torpedo, piloting check for "gaining the advantage" is a good start for ramming accuracy and the game system's rules for ramming. If the ship's cargo detonates [assuming fuel or explosives] maybe go with Damage 10 (if full) with breach 2 to all ships within engaged range of it. and if ramming target was bigger ship, it takes double damage. to give player ships an out if they are trying to stop its ram or set it off early, let them make a hard piloting check with adversary 1 or 2 if it does go off, and advantages can reduce damage while success allows them to break off in time to not be in engaged range. want to still punish them a bit even though they succeeded on that but got threats? have their ship take system strain equal to threat & give them the knocked off course critical hit and have the check they make be upgraded once or twice like the initial one.