A tragic boating accident that killed three people has served as a stark reminder of the many dangers that come with crossing a breakwater into open ocean.

Two Marine Rescue NSW volunteers died attempting a failed mission to save a stricken yachtsman near the South Ballina breakwall, in the state's north on Monday, prompting experts to warn that century-old infrastructure cannot protect sailors from harsh conditions.

The volunteers, aged 78 and 62, have been remembered as heroes for their efforts to save the man in his 50s who had been aboard the yacht when it hit the breakwater.

Construction on the Ballina breakwaters began in 1889 to create a safer entrance to the Richmond River by reducing the number of breaking waves but little had changed in their design or construction in the 137 years since, coastal engineer Angus Gordon told AAP.

While the northern wall has been made accessible for foot traffic and activities such as fishing, the more remote southern end is suffering significant challenges.

"The last 50 to 80 metres of the head of the southern wall has been severely damaged, in fact, it's below sea level now," said Mr Gordon, who is an experienced sailor.

"Approaching from the south, you have to be extra careful because the breakwater extends under water well past where you can see it."

Ballina was not known as one of the most treacherous crossings, Mr Gordon said but in bad conditions, such as those faced during the tragedy on Monday night, it could be extremely dangerous.

The rescue vessel that set off to help the stricken yacht soon capsized while battling the 2.5-metre swell and strong winds.

Ballina Shire Council Mayor Sharon Cadwallader said improving the safety of the bar through dredging had been a priority of her community for a very long time.

"It's quite a graveyard of six sunken wrecks on the Ballina Bar," she told AAP.

Dredging sand to increase the depth of the water in the passage and reduce the chance of dangerous breaking waves is undertaken regularly by the state government up and down the coast.

Transport for NSW is undertaking 12 dredging projects but are not operating at Ballina.

Nevertheless, Mr Gordon said the long-term viability of dredging could be questionable.

"The problem with the dredging is that almost as soon as you do it, everything fills again," he said.

"There's so much sand out there that dredging will only last a relatively short time."

All survivors of Monday's accident are expected to make full recoveries but one of the volunteers suffered four broken ribs and a broken leg.

Two others were hospitalised with more minor injuries.