Brandon Mason has joined Scottish Championship side Dundee United on loan.
The left-back will remain with the Tangerines for the remainder of the season as he looks to continue his development with regular first-team football.
Mason, 20, has been a regular in the Hornets Under-23 side and made four senior appearances for the club last season.
Under-23 teammate Harvey Bradbury has also moved on loan, but will remain much closer to home.
The 19-year-old has joined St Albans City, also until the end of the current campaign.
Connor Stevens has become the third young departure of the day, joining Oxford City again on loan for the rest of this term.