In torrential rain at Vicarage Road, neither side managed to overcome the treacherous conditions, meaning that Hammers have now gone eight matches without a win.
Chances at both ends were few and far between - the best of a scrappy first half fell to David Connolly - making a timely return from injury as Jermain Defoe began a five-game ban - who combined well with Michael Carrick but fired into the side-netting from a tight angle.
The Irish striker was then denied by a sliding block from Watford keeper Pidgeley, while Brian Deane saw a 20-yarder comfortably saved.
At the other end, Devlin's dipping shot was tipped over by James and the Hammers keeper had to be alert on the stroke of half-time to tip a Vernazza shot around the post.
The downpour continued throughout the second half but Hammers' control sadly didn't, as the hosts stepped up a gear.
Midfielder Webber wasted the best chance of the game in the 50th minute when he directed a point-blank header straight against Ian Peace, before sending a low effort just past James' right-hand upright just moments later.
The England number one had a lucky escape when he spilled an up-and-under, before both sides had penalty appeals turned down when Vernazza's strike appeared to hit Dailly on the arm and Connolly raced up the other end to be out-muscled by Gayle.
Substitute Richard Garcia saw an angled effort fly just wide in the 80th minute, before Dailly almost snatched the winner with a header that forced Pidgeley into a full-length save.
Hammers now drop to ninth after Ipswich and Cardiff both won to leapfrog above us and a victory against bottom team Wimbledon on Tuesday night is vital if Pardew's men are to get their promotion chase back on track.