Offshore, weather is not background. It sets what can happen on any given day, and getting the forecast wrong is measured either in vessel day rates or, worse, in near-misses.

Why a general forecast is not enough

A public marine forecast covers a wide area at low resolution. It tells you roughly what the region will do. Offshore construction needs something different: what will happen at this site, at turbine-hub height, at sea-surface level, in the specific window when a lift or a transfer is planned.

Wind speed at 10 metres is not wind speed at 150 metres. Significant wave height across a forecast zone is not the sea state at one foundation. The gap between the general and the specific is where plans go wrong.

The parameters that actually gate work

Different activities have different limits, and each has to be forecast against its own threshold:

Crew transfer is limited by significant wave height at the point of transfer. A CTV pushing on a boat landing has a hard ceiling, often around 1.5 metres, above which transfer stops.

Lifts are limited by wind speed at hub height and by the motion of the vessel doing the lifting. A jack-up is more tolerant than a floating crane, but both have limits set by the load and the rigging.

Cable operations are limited by sea state and current, which affect both the lay vessel and the touchdown point on the seabed.

Forecasting is a decision tool, not a weather report

The value is not in knowing the weather. It is in the decisions the forecast enables: whether to mobilise a vessel that costs tens of thousands a day, whether to start a lift that cannot be paused halfway, whether to send people offshore when the window to bring them back might close.

A good forecast, delivered early enough, turns those into planned decisions rather than reactions.

Measurement alongside prediction

Forecasts are models, and models are wrong sometimes. Deployed wave rider buoys give measured sea state at the site, so a coordinator can see what the water is actually doing alongside what it was predicted to do. When the two diverge, that divergence is itself information.

In a region like the Taiwan Strait, where the monsoon and typhoon seasons dominate the calendar, this combination of forecast and measurement is not a luxury. It is how a season's worth of work gets done in the windows available.