Irvine’s harbour was once situated close to Seagate Castle. Much of Irvine Burgh’s importance and prosperity was because it had a functioning harbour from which coal and other goods from Glasgow, carried by pack horses, could be sent off to Ireland.
As the ships arrived at Irvine, the seamen blew a horn alerting the waiting the people that it was time to load the cargo and a train of pack horses laden with goods, set off for the dock. On their return to Glasgow they would be laden with goods which had been imported, such as grain and butter from Ireland; timber from Memel in Germany, and grain and timber from America.
A military report prepared by an English official sometime between 1563 and 1566, along with the writings of others, reveal that the harbour was so choked with sandbanks that it struggled to maintain a shipping trade. Collections were taken at the church doors and taxes were levied on local ale or goods entering or leaving the harbour to raise money for repeatedly dredging the harbour.
The Town Council soon found that the money raised from its customs duties was not enough to meet the cost of re-dredging the harbour. In 1587 the magistrates of Irvine obtained an Act of Parliament to enable them to appoint a reasonable stent (allotted portion) and taxation to support the harbour. In 1665 the Town Council took the decision to cut through the lands of the Marres to construct a new harbour. In 1759 the Clyde was deepened, enabling ships to land at Glasgow, and by 1760 Irvine ranked as Scotland’s third port. By 1820 large vessels preferred to use Ardrossan Harbour, instead of Irvine, where they could load their cargoes with less trouble without the danger of the harbour not having a sufficient depth of water.