There are no railways, waterways, ports or harbours on the island. Loading jetties are located at Kingston and Cascade, but ships cannot get close to either of them. When a supply ship arrives, it is emptied by whaleboats towed by launches, five tonnes at a time. Which jetty is used depends on <answer>the prevailing weather on the day</answer>. The jetty on the leeward side of the island is often used. If the wind changes significantly during unloading/loading, the ship will move around to the other side. Visitors often gather to watch the activity when a supply ship arrives.
What determines the jetty that's used by supply ships to Norfolk Island?
the prevailing weather on the day