Bay of Plenty Regional Council's Harbourmaster team has had its busiest winter in recent memory assisting with the salvage of a number of boats in Tauranga Harbour.

The last week in July alone saw four vessels needing assistance from the Harbourmaster team after heavy rain and strong winds.

One vessel was partly submerged needing water to be pumped out and the boat removed from the Harbour, while another sunk to the seafloor.

The Harbourmaster team is currently working with this boat's owner on a salvage plan. Two other vessels broke free from their mooring and anchor.

Deputy Harbourmaster Daniel Rapson says the salvage operations are a stark reminder for boat owners to check their vessels on moorings.

'We have had numerous reports of boats sitting lower in the water from taking on rain this winter and three boats that have sunk at their moorings over the months of June and July.”

He says with cloudy days, vessels relying on solar should also be checking battery levels to ensure automatic bilge pumps are operating.

It's essential that boat owners check on their vessels regularly to catch any issues early.

The recent incidents were caused by a mooring line chafing/wearing on a sharp edge, and boats slowly taking on rainwater and the bilge pump failing.

These could have been easily prevented with some regular maintenance checks.

Salvaging a boat that has sunk on its mooring can be a costly exercise for the owner with the bill coming in between $10-$15,000 per day for a commercial dive team and suitable barge.

The boat owner is liable for these costs and dependent on the size of the boat and how long it takes to get it out of the water it can cost much more.

In some cases the boat may be disposed of and destroyed by the Regional Council under the authority of the Maritime Transport Act 1994 with the boat owner liable for all costs incurred.