The men were all rescued safely and did not require medical treatment.
A Coastguard spokeswoman said it was always "fairly" dangerous crossing the Kaituna Bar, but conditions were especially dangerous at the moment.
She said the men had not done anything wrong, but it sometimes "happened" boats struck a sandbar.
It had been a busy 24 hours for Coastguard crews after two elderly men were also caught on the bar and their vessel capsized yesterday at 1.30pm.
Initially, the two men were trapped under their boat and it took "a while" for them to get out, the Coastguard spokeswoman said.
One of the men took in a lot of seawater and was assessed by paramedics but not taken to hospital, a St John spokeswoman said.
The Kaituna Bar crossing is a well-known hazard for boaties.
People launching boats in the river estuary near Maketu need to cross the bar to head out to sea.
Coastguard Maketu has made a video showing how to cross the bar safely.
The groups says that, because of the shallower water and changing conditions, bar crossings can be extremely dangerous, even for experienced boaties.
It advises boaties to seek local advice on where the sandbars and channels are, check the conditions are safe, make sure everybody is wearing lifejackets and ensure the boat has at least two forms of communication to call for help.
Coastguard's Maketu unit is one of 62 units across the country that relies on volunteers to help provide about 300,000 hours of their time each year and contribute to about 2000 search and rescue operations.