Works planned around the lunar cycle

Hull City Council commissioned KWL to complete much-needed works on the Hull Marina lock-gates.

Initially installed in the 1970s, the lock gates withstand massive pressure and with opening and closing many times each day, the rubber seals wear-out and need to be replaced every 10 years or so.

Tides on the River Humber are semidiurnal, meaning high waters usually occur twice a day. Therefore, the team had a fixed window in which the work could be completed – carefully planned to take place when the tide would be at its lowest.

Thursday 15 October was the day before the new moon, which falls into the last quarter of the lunar phase – the point at which the tide would be at a minimum.

At midday between the two high tides, the water level was estimated to be as low as 0.8m – an ideal opportunity for the large rubber seals to be removed and replaced.

The team used a crane and cage to lower our engineer, James Rust into the cavity next to the open gates.

Supervisor, Alan Bourne explains:

“We get involved in all sorts of different works at KWL but this was a new one for me and the team. We started work as the tide was drawing out, the water level dropped down completely and our engineer worked quickly to remove the old seals and replace with new, lifting him in and out four times.”

“It’s been interesting learning about the lunar tides, we take it for granted but when it comes to working in the water, we have to be guided by the moon.”

“After some fast work in bitter winds, the gates were restored and will now operate more efficiently, to keep the water in, where it should be.”

“We are pleased to play a part in the upkeep of Hull and its history through projects like these.”