That's the message from Maritime NZ, concerned that too many people are taking a risk on the weather when they go out, or sometimes not even checking it at all.
New Zealand weather is so varied, from hour to hour, and all over the country. A change in expected weather, or a turn for the worse, could make all the difference between a lovely day out and an emergency situation.
Marine weather forecasts state what the weather is expected to do. Land and general forecasts do not take into account win speed over water (which is double that over land) or the waves or swell.
If a land forecast does give wind speed, it is in km/hr rather than knots, which is a good indicator that you are listening to the wrong forecast.
To get the latest marine forecast:
To get forecasts when you're out:
Seek local knowledge from those who live in or are familiar with the area - harbour-masters are an excellent source of local information.
While marine forecasts are almost always accurate when predicting major weather events, such as gales, they can be less accurate when predicting local changes of conditions, so you should always be prepared for the unexpected.
The weather can change quickly and without warning. At the first sight of deteriorating conditions, head for shelter.
Look ahead If you're planning ahead or intend to be away for a day or two, get a long-range weather forecast. The outlook will tell you what weather is predicted up to 5 days ahead.
Having information in advance leaves plenty of time to alter plans ro decide to wait for better conditions.
Prepare for the unexpected Remember that the weather can change suddenly and without warning. Keep an eye on the weather while you’re out, listen to the Maritime Radio and NowCasts in your area so you get a warning of increasing winds before they arrive, and head for shelter at the first sight of worsening weather. When the wind starts to blow, the water becomes very rough, very quickly, especially on lakes and rivers.
Remember that forecasts are only the best prediction available at any given time.
If in doubt, don't go out! A large proportion of accidents involving small vessels are weather related. Bad weather makes the environment onboard a vessel extremely hazardous. It also places a lot of strain on the vessel’s structure and equipment and the people on board.
It is important to respect the weather at sea. Skippers should make sure they understand the different parts of a weather forecast and the best way to find up-to-date local information.
It is incredibly important to not just check the weather forecast, but to understand what you're seeing when you do.
Forecasts usually give a direction (such as 'north-west') as the direction the wind is expected to come from.
In a coastal or marine forecast, this wind speed will be given in knots, where 1 knot is approximately 2km/hr. This is an average speed, so always expect that gusts may be 50% higher.
Also allow for funneling between headlands, causing the wind speed to double.
On maps like the one opposite from the MetService website, the arrows show the direction of the wind, where the key below indicates the severity of the measure (wave height, for example).
'Sea' is a description of the waves formed by the local wind.
A 'swell' comes from either a distance disturbance, such as a cyclone or depression, or develops from wind waves that have been blowing from the same direction for a length of time. Swells increase in height and get steeper when they reach shallow water.
The measures used for swells are:
The average visibility in New Zealand is about 15 nautical miles.
This information is typically given when visibility is expected to be less than 6 miles (10km).
The visibility distances are:
All marine forecasts are for up to 48 hours, with the outlook for a further 3 days.
The MetService website has the option of a 3-day forecast or a 5-day forecast, where you can play a video to watch the progression of rainfall across New Zealand, and keep an eye on changes in wind speed.
This refers to the size of of significant waves that are generated by the wind in the area.
The approximate wind wave height measures used are:
Most boating areas are covered by the recreational marine forecast.
A situation is a description of the position and movements of highs, lows and frontal systems expected to affect the New Zealand coast within the next 36 hours. It also names those areas affected by warnings.
These are issued for gales, storms or squalls anywhere on the New Zealand coast. A strong wind advisory is issued in recreational areas if the wind is expected to be over 25 knots (about 40km/hr).
If the winds are associated with a cyclone from the tropics this will be mentioned in the warning, but tropical cyclone warnings are not issued in New Zealand.
Winds can be reported as:
Wind and tide
When the wind is opposing the tide, expect a much rougher sea.
When the wind is with the tide, expect a calmer sea.