An increase in Dublin Bay's pleasure craft numbers and Dublin Port's concern over the influx of inexperienced sailors into Ireland's biggest sailing centre have created a debate over navigation on Dublin Bay.

Worries voiced in the wake of last weekend's yachting tragedy may force port authorities to consider a small craft channel as a means of separating commercial shipping from yachts and pleasure boats at the busy port entrance.

But members of Dublin Bay's sailing community - numbed since the collision between the yacht Debonair and an inbound coaster that claimed the lives of four sailors at the mouth of the port - are saying little over the need to signal any new measures that limit the use of an estimated 1,500 boat pleasure fleet on Dublin Bay.

Although sailors and the port authority traditionally enjoy a good working relationship, there is concern that safety standards can be put in jeopardy.

This could be an effect of the rise in boating numbers due to the economic boom. The rise is nowhere more noticeable than in Dublin Bay and nearby coastal waters.

The trend looks set to continue with first-time boaters having the pick of the newest berthing facilities in a necklace of marinas around the country.

Dublin city moorings - 25 berths - located in the heart of the Liffey at Custom House quay have become a fashionable stopping off point.

It has led directly to more pleasure traffic entering the Liffey.

On June 8th, for example, the Dublin Docklands Authority hosts its spectacular 1720 sportsboat challenge, a yacht race for the 1720 class in the confines of the river walls and in the shadow of Liberty Hall. Also in the city centre is the thriving Poolbeg Yacht and Boat Club that has a fleet of sail and power craft on the sea-side of the East Link toll bridge.

On the southern shores of the bay, Dun Laoghaire boasts a new marina that will hold 700 pleasure craft. Currently, boats intending to enter the river from the sea must call Dublin Port Radio by VHF radio and proceed up the edge of the fairway channel under power (not sail) keeping clear of commercial traffic and maintaining a continuous listening watch.

The rise in the boating stock, though currently nothing like the volume of pleasure craft traffic in the UK, may necessitate port authorities looking at alternative measures to combat the dangerous crisis-crossing of commercial and leisure craft.

This is a special problem when shipping has difficulty manoeuvring in confined spaces - such as in the entrance to Dublin port, that narrows to a few hundred feet between the North Bull and Poolbeg lighthouses.

Numerous UK harbours and yachting fleets have experienced similar growing pains. It is one of the main reasons behind innovative decisions by numerous UK ports to adopt "yacht tracks" that attempt to stem pleasure craft sailing under the bows of big ships.

According to Mike Balmforth, consulting editor of MacMillan's Almanac, the two most commonly applied methods in the UK to deal with this situation are a small craft channel or - as in the case of some naval ports - the use of police launches that also act as safety vessels to accompany all ship movements.

In Dublin port, pilot vessels accompany ship movements. A recommended yacht route is a passive measure that may prevent a repeat of last weekend's sailing tragedy, the worst in Irish sailing history.

At Harwich, on the coast of East Anglia and the UK's busiest port, yachtsmen must follow a recommended yacht track that operates in the margins of the navigable shipping fairway.

The salvage operation to raise the wreck of Debonair last Monday was focused on a position close to Dublin Port's Number four buoy that marks the commercial fairway. The small craft channel system uses its own lighting and buoyage and works for both incoming and outgoing craft.

It is the same in Ramsgate, another UK port, which has a similar commercial traffic volume to Dublin, but with a much higher volume of pleasure traffic.

THE harbourmaster at Portsmouth, another UK port, has - possibly because of its narrow entrance (which has similarities to Dublin) - gone a stage further in efforts to separate both vessel types and made it a mandatory requirement on entering or leaving harbour.

Although the practicalities of such a measure in Dublin would require consultation with small boat users, it is acknowledged that there is scope for a second channel to run alongside existing shipping channels that cater for 16,000 ship movements per year.

Boats come from both the north and south shores of the bay so at some stage yachts will have to cross the lane.

In Harwich, yachts are required to stay in a track until they reach a marker that allows them to cross the shipping channel if they so wish, but then only at an angle as near as practicable to a right angle, the shortest possible distance from one side of the commercial shipping channel to the other.

Experienced Dun Laoghaire and Howth yachtsmen, however, point to the rules of the sea and the International Collision Regulations as adequate regulation. And some bay yachtsmen point to a long safety record and say there is no need for any further measures to control their movement.

However, a Dublin Port spokesman said all measures will be considered in the wake of two separate investigations into the accident.

David O'Brien is Sailing Correspondent of The Irish Times