have adopted Diesel engines are powered so that those under 50 tons have 

 about 2.5 HP per ton, those of around 100 tons have 2 HP per ton, and those 

 in the 180 ton class have about 1.3 HP per ton. The object is to maintain 

 speeds of around 10 knots. 



3, The problem of bait tanks 



Bait tanks are the most characteristic feature of skipjack boats. 

 Their capacity is related to the number of operations which the boat can 

 carrj out on the fishing grounds, and by extension to the amount of the 

 catch. It sometimes happens that boats encounter large schools of skip- 

 jack which they have gone to much trouble to find, and then are unable to 

 operate because they arc out of bait. Indeed, bait is life and death to 

 the skipjack fishery. 



(1) The bait tanVs are supposed to hold the bait fish in a healthy condi- 

 tion without lowering their vitality or causing ther to die until the time 

 'ihen they are to be used on the fishin{_: grounds. In order to accomplish 

 this the following requirements must be met. 



(a) The bait fish must be kept as quiet as possible to prevent any needless 

 waste of their energy. For this reason the tanks are located amidships 



on the center line of the boat where motion is at a minimum and where 

 they are convenient for use. (See Figure 13) 



(b) In order to maintain the vitality of the bait fish there must be a 

 thorough circulation of water. This factor has a bearing on the amount 

 of bait which can be kept Vidthin a given space. Water exchange is either 

 natural or powered, and in some cases both systems are used. In the 

 natural water exchange s;;-3tem openings are provided in the hull '^/ithin 

 the bait tanks so that the water will circulate naturally. With a powered 

 system a water pump is installed in the engine-room to provide a constant 

 circulation of water. Ordinarily the pump keeps the tank constantly filled 

 and makes th.e water circulate within the tank; the overflow runs off 



from the hatch-coaming on deck through a pipe which leads to t^e side of 

 the boat. This nethod provides approximately 30% more water than the 

 natural system and as a resiilt the amount of bait which can be heir' is 

 greatly increased. A completely water-tight electric light provides 

 illumination within the bait tank. This greatly increases the viability 

 of the bait and lowers the death rate. 



(2) I/icreasing the holding capacity of the bait tanks 



By increasing the capacity of the bait tanks it is possible to lengthen 

 the operating time on the fishing grounds and increase the catch. This 

 increased capacity can be attained by installing more tanks, building larger 

 tanks, and by using a powered system to exchange the water in the tanks. 

 However, the balance of the vessel as a whole must be considered in adopt- 

 ing these measures, 



4., Sto'-'age of the catch and ice capacity 



A2 



