Underwater warp tension meter

A self-contained electronic solid-state instrument capable of measuring the tension between the different parts of a trawl net in operation, has been designed and developed for the measurement in the range 0 to 300 kg with an accuracy of ± 2 kg. The instrument is useful for measuring the resistance to motion of various accessories of a trawl net. It consists of an inductive type underwater tension transducer and an electronic indicating meter kept on board the vessel, both the units being connected by electric cable.

Wadge Bank trawl fishery studies. Pt. 2. The effect of trawling on the catch per hour from 1945 to 1960

The object of this series of papers has been given in Part 1 (see Additional informations for details) which deals with the first known commercial fishery on the Wadge Bank from 1928 to 1935. There is no recorded trawling on the Bank between 1936 and 1944. This paper deals with the changes in the total catch (i.e. all species combined) per hour of trawling in relation to the changes in fishing intensity from 1945, when the present trawling activities started, to 1960. The effect of trawling on individual categories or varieties will be presented later.

Portable electronic warp load meter

A portable type warp load meter has been developed for the use in fishing trawlers. The instrument enables to monitor the warp load in fishing trawlers accurately and easily without disturbing the routine fishing operations. The instrument can be used in several other places like cranes, bollard tests for marine engines, dry docks etc. especially when the operation has to be conducted easily without disturbing the load system. The information displayed in micro ammeter in the range 0 to 1000 kg can be fed to continuous recorders for detailed analysis and permanent records.

In situ temperature and salinity meter

Development of a portable self-contained electronic meter for on the spot determination of temperature and salinity is described. Instant and remote measurements of temperature and salinity of sea and estuarine waters in the range of 25-30°C and 30-35°C for temperature with an accuracy ± 0.05°C and 0-37‰ and 31-37‰ for salinity with an accuracy of ± 0.2‰ and ± 0.05‰ respectively are possible with the instrument. The temperature compensations of the salinity measurements are done manually with the help of temperature charts. The temperature and salinity measurements can be fed to continuous recorders.

Development of a torque meter for fishing vessels

The paper describes the development of an electronic instrument to measure the torque developed on the propeller shaft of fishing vessels at various speeds of the propeller. By measuring the torque, it is possible to determine the actual power transmitted from the engine gear-box unit to the propeller so that propeller efficiency can be evaluated and the optimum size of the propeller for a specific engine and vessel can be determined.