Landers
The term 'lander' is used to describe any platform that carries one or more instruments to the seabed and remains there until we are ready to recover it. The type of lander we use depends on a number of factors, including the number of instruments it has to carry, how deep in the ocean it needs to go, and how long it needs to stay there.
In shallow water, the lander may be lowered to the seabed from a ship and have a marker or recovery buoy on the surface. To recover the lander, it is lifted from the seabed. This may sound simple but in practice can be a very complex and potentially hazardous operation.
In deep water (and sometimes in shallow water) it is not practical or desirable to lower a lander on a wire. In such circumstances, the lander will be designed to fall freely and land on the seabed. This type of lander is usually in two sections: a buoyant upper section, which contains the instruments and sensors, and a heavy lower section. For the duration of the deployment the two sections are held together by a release mechanism and the weight of the lower section keeps the lander on the seabed.
When it is time for recovery, the release can be operated remotely and the instrument package floats to the surface, where it is picked up by ship. Some landers are designed to release a data capsule at a specific time and to send information back to the laboratory using a satellite telemetry system. The data capsule itself may be lost, but this eliminates the need to use a ship for data recovery, the cost of which may far outweigh the cost of replacing the lost equipment.
Listed here are some of the landers we use. Their basic function is described here, for more details please follow the links.
MYRTLE
(Multi-Year Return Tide Level Equipment) is a deep-water free-fall lander used mainly for measuring sea pressure (water depth). It has independently releasable data capsules and is designed to stay on the bed for five years. It holds the record for the longest continuous seabed pressure measurement. We are currently developing the next generation of MYRTLE (MYRTLE-X), which will be capable of a ten-year deployment.
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ADCP landers
The early versions of these landers were built principally to deploy ADCPs (Acoustic Doppler Current Profilers). Because scientists were interested in current measurements near to the sea bed, these landers had a low profile so that the ADCP could be mounted as low as possible. This low-profile design has continued with the later versions.
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Bottom pressure recorder
NOC Liverpool, has the longest established Deep Ocean Lander group in the UK. With over 40 years Bottom Pressure Recorder (BPR) design experience and over 240 deployments, mainly of one-year duration or longer.
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STABLE
(Sediment Transport and Boundary Layer Equipment) is a large lander designed for making measurements of suspended sediment near to the seabed. It can carry a variety of instruments. It is limited to 100 metres water depth and is lowered to the seabed. We also have a free-fall version with a 1,000-metre capability.
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RAPID lander
RAPIDLanders operate in the deepest parts of the ocean and have been designed to withstand the crushing pressures of depths up to 5km, the equivalent of 500 elephants.
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