Low tides mean boats are unable to get into the Wharf St boat ramp at times. Photo/ Supplied
Spring tides are again making the Wharf St boat ramp inaccessible at times.
Several boats were unable to get back and had to wait for the water to rise.
Wanganui Coastguard president Garry Hawkins said the low tides were "exceptionally low" and were expected to be that way for at least another next week.
Even the Coastguard's boat has been affected.
"At the weekend we sort of struggled to get back in because of the low tide. We had to winch it."
Hawkins advised boaties to plan trips around high tide and to aim to return two hours before low tide.
Whanganui District Council ports manager Phil McBride said he was aware of the problem and a long-term strategy for dredging parts of the port, including the area adjacent to the Wharf St boat ramp, would form part of the Whanganui Port Revitalisation Project.
Council recently trialled a cutter-suction dredge to remove silt and maintain a channel to the boat ramp area.
"The dredge has widened and deepened the channel alongside the wharf and around the boat ramp, however, the area immediately adjacent to the boat ramp is always going to be very shallow during spring low tides," McBride said.
"This area of the port is also particularly susceptible to siltation, particularly after any significant weather event."
McBride said dredging was costly.
"In order to maintain continuous access in all tidal conditions would require near-continuous operation, which would not be cost effective."
The council have had discussions with Coastguard and a purpose-built davit further downstream is being considered.
But Hawkins said the Coastguard boat wasn't set up for that.
McBride said alternative boat ramps are available if the Wharf St boat ramp is not suitable.
Riders and spectators in Whanganui are anticipating the start of the last race.