Yachting fans want developers to pull the plug on £100 million plans they claim will ruin the true purpose of Brighton Marina.
Parkridge Developments wants to transform the marina with new leisure outlets including bars, restaurants, shops and extra housing.
But boat owners are considering moving from the marina, saying over-
development and disruption are spoiling their enjoyment.
Members of the Brighton Marina Yacht Club have even suggested barricading the entrance to the marina as a protest.
Club president John Duffy said that would only be a last resort. He believed the yachting facilities were being sacrificed for profits.
The club is based in a temporary building at the North Wall, its fifth temporary premises in 25 years. The club has spent more than £100,000 on converting premises.
Members thought they had agreement for a permanent base at the West Quay but that has now been earmarked for development by Parkridge.
The marina opened as a 2,200-berth yachting harbour after the 1968 Brighton Marina Act emphasised the importance of yachting, cruising and boating.
Subsequent residential and commercial development meant the number of berths was significantly reduced. There are now 1,200 berths, with about 1,000 of them regularly used.
Mr Duffy, of Perrymount Road, Haywards Heath, said the marina already had grossly inadequate parking facilities for the number of residences. Those would come under more pressure from people visiting new shops and restaurants and the existing Asda superstore, drive-through McDonald's, cinema, casino and bowling alley.
Boat owners have to park in the multi-storey car park almost half a mile away from their boats.
When Mr Duffy became the club's membership chairman in 1988 there were more than 800 members. There are now just 450.
He said: "Eight years of disruption while the development takes place will drive the regular boat users out of the marina and the attraction of the waterside will gradually die.
"Proposals for improved berthing facilities at Newhaven will become increasingly attractive."
Work has almost finished on the Waterfront building, which will house discount outlet shops, ten bars and restaurants and a boutique hotel.
Philip O'Callaghan, Parkridge's managing director, said: "Providing a much wider range of choice in terms of shops, restaurants and bars can only be good for people using the marina, especially the boat-owners.
"International visitors are much more likely to stop off at Brighton Marina, with better facilities than in Hastings or Eastbourne."
A refurbishment of the multi-storey car park will bring into use another 1,000 spaces. A car park management team starts next weekend to give visitors better guidance to spaces.
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