Fishing and Gear Technology

Unit 7 - Floats and sinkers

7.3.Special Floats

Trawl plane float: As the size of the vessel increases, there is a tendency to tow the gear at a speed more than 3 knots. While towing in faster speed all the ordinary spherical floats have a tendency to go downwards thus reducing the mouth opening of the trawl. The trawl plane floats have low resistance and more lifting at speed before 3 knots. These types of floats are suitable for midwater trawling.

Siamese twin float: is made by joining two spherical aluminum floats with a curved collar.

Hydro foil floats/Upthrust floats: It is also a spherical float, but the difference is it has a collar around one third of the lower portion known as stabilizer. In experiment it is proved that when towed at 5knots, the lift of the float is equal to that of 10 floats and drag is of only 3 floats.

Inflatable floats: Used in pelagic trawls. They are becoming popular for all floatation as storage is not a problem due to their inflatable nature.

Hydrodynamic floats: Hydrodynamic float has a streamlined top, and V shaped bottom .They are very efficient.