By 1665 Seagate harbour was no longer accessible, due to a change in the flow of the River Irvine.
The new harbour was cut out of the lands of the Marres, bought by the Council in 1572. Under the terms of the common good, the men of Irvine were conscripted to dig out the harbour. The town was divided into quarters and the men from each quarter took a turn on different days. Anyone who refused was fined 12 shillings Scots for each day’s absence. Taxes were levied against ale, beer and malt to raise money to maintain and repair the harbour.
The first lighthouse was erected in 1669 and the causeway and a road leading to the harbour were built in 1677. The first official harbourmaster was appointed in 1731. John Webb opened the shipbuilding yard at ‘the Brae’ in 1759 and a row of warehouses were built in 1767. The flood of 1769 damaged the harbour which required major repairs.
Prior to the opening of Port Glasgow in 1668, Irvine and Greenock were the main harbours for goods coming into Glasgow, carried overland by pack horses. When the Clyde was dredged in 1773, Irvine lost most of its Glasgow business as ships were able to take their cargoes directly into the city, however Irvine continued to be busy, exporting coal from local mines and textiles and other goods from surrounding areas including Kilmarnock and Paisley.
The silting-up of the harbour, which had been such a problem at Seagate, continued to be a problem, as silt was carried down both the Irvine and Garnock rivers into the harbour. In 1826 Irvine Town Council sought parliamentary consent to enlarge, deepen and improve the harbour. In the same year it handed over control and maintenance of the harbour to the Irvine Harbour Trustees. Rather than deepen the harbour the Trustees simply maintained it. They did not foresee that as the new harbours at Ardrossan and Troon grew, Irvine would not be able to compete. Large ships over 100 tons preferred to dock at Ardrossan where the water was deeper and in 1840 Ardrossan Pier Railway Station opened, making it easier to receive and distribute cargo. In 1863 Troon Harbour’s status was raised to Head Port with Irvine ranked as a subsidiary. Troon was exporting 140,000 tons of coal annually whereas Irvine’s was only exporting 44,000 tons. In 1869 the Harbour Trustees deepened and developed the harbour, extending the wharf and purchasing six steam cranes. By 1899 Irvine was exporting 189,000 tons of coal annually. In comparison Ardrossan, Troon and Ayr were exporting around 400,000 tons of coal each. A new dredger was acquired in 1911 and the harbour master Martin Boyd installed the Pilot House. The harbour area were busy during both world wars, but then went into a slow decline. With the advent of the New Town, the harbour area was given a new lease of life. In 1965 the old Harbour Mission became the Harbour Arts Centre, the Magnum Leisure Centre opened in 1976 and Irvine Beach was redeveloped into the Beach Park. In 1985 the Scottish Maritime Museum opened, followed by the Big Idea in 2000.