It is not just Coastguard's emergency work that is being hampered — fishermen are also hitting trouble with the excessive silt, particularly at low tide.
A number of boat owners have run into difficulties trying to launch when good fishing days have coincided with early morning spring low tides.
Commercial fisherman Murray Watson said the tides had made life difficult for him.
"It has been really bad in the early mornings and if I don't get out then it pretty much ruins the day.
"I need to be out there for 10 to 12 hours and the way it has been lately I can only stay for two or three and that's a no go."
Whanganui District Council port manager, Phil McBride said recent weather conditions had resulted in an increased amount of silt being deposited near the ramp.
"The buildup of silt at the boat ramp and the channel alongside No 2 and 3 wharves is very evident when the tide is out and this means launching or recovering boats can be quite difficult," he said.
"The deteriorating structure of the wharves and changes to health and safety requirements mean we cannot continue the use of a land-based digger to dredge this area, so we've been exploring options to dredge the channel and widen and deepen it to allow low tide access.
"The council wants to get on top of the dredging needs at the Wharf Street ramp to offer a higher level of service, which does come at quite a cost."
He said a modern cutter suction dredge had been ordered to undertake a thorough dredging job, and he was hopeful it would "provide the results we need".
"Unfortunately, the cutter suction dredge is still about five weeks away."
Until the dredge arrived, he advised boaties to check the daily tide tables before launching at the ramp.
Mr McBride was confident the dredge would fix the problem, adding there were alternative boat launching facilities available at the Putiki slipway if necessary.
