Grant Harrison returned in place of the injured Luke Snashall for his first league start of the season with Ben Dartnall also returning in place of Casey Ham who took his place on the bench.
On a glorious morning, it was Seaford who had the first chance of the match as Matt Hayward broke through the United defence, took the ball round Grant Young but his touch was too heavy as the ball ran out of play.
United pressed forward and looked threatening as Wes Tate and Jack Divall tested McDonnell in the visiting goal.
With 17 minutes played, Jason Taylor danced into the penalty area, beating three defenders before being adjudged to have been fouled and the referee awarded a penalty.
There were protests from the Seaford Town defence and after consultation with the assistant referee,the decision was overturned a corner awarded.
Five minutes later United took the lead as Dartnall played the ball to Tate who teed the ball up for Taylor to volley home past McDonnell.
The goal appeared to spur Seaford as Clive Snell was inches away from the top corner with a 30 yard effort before less than a minute later, Hayward saw his effort hit the bar and rebound off Young and away from danger.

United’s lead was extended moments after the half-time break when Tates’ corner was played to Adam Kneller who showed great composure to chest the ball and place a sidefoot volley in off the post.
Taylor, who was a constant threat to the visiting defence all match, won his side a penalty after his cross was hanballed by Sam Pout, giving Tate the chance to extend the lead but Tate saw his penalty well saved by McDonnell.
Dartnall could have put the game beyond doubt following a counter attack but he pulled his effort wide of the post when well placed.
United did make the game secure however when Tate met the perfectly timed run of Divall who calmly slotted past McDonnell.
Credit to Seaford Town, they never gave up and went close through Daniel Onipede and Reece Ayliffe, but there wasn’t to be any comeback as Linton Rogers completed the scoring with virtually the last kick off the match