Hmm. Interesting sub in the Moss Keg. The wording doesn’t specify that the Sargasso can’t be placed such that it touches another ship, so I’m assuming you could use this to place a Sargasso under an enemy, as long as it was still in contact with the Moss Keg.
Actually, looking again, outside of her ability, she doesn’t seem all that impressive. Still, I’d try to find a way to exploit her ability as much as possible.