Auckland harbour master John Lee-Richards is urging boaties to learn the rules before heading out on the water, after six crashes over the past six weeks.
The collisions are being blamed on an increasing number of vessels using the harbour and a lack of knowledge among some newer boaties.
Mr Lee-Richards says he believes many of the crashes have been caused by inexperienced boaties.
He says the number of boats using the harbour is also increasing, with more than 160,000 recreational boats in Auckland.
Mr Lee-Richards says a number of training courses are available and those who are new to boating need to learn the rules before venturing out on the harbour.