A controlable pitch propeller (C.P.P.) on the fishing boat produces not only a reduction of the fuel consumption of the driving diesel engine but an increase of towing power compared with a fixed pitch propeller. However, an engine operated under inadequate C.P.P. management can not fully display the expected effects. Thus, experiments on the fuel consumption of main engine were conducted to evaluate the operation of C.P.P. blade angle.
The results showed that the minimum fuel consumption of main engine operated under the generating power greater than 50% were obtained by the blade angle at 21 deg. with the revolution control, and that under the generating power lower than 50% were obtained by setting the operation point of main engine at the right side of maximum propulsion efficiency curve on the performance chart which showed the output of main engine in abscissa and the number of shaft revolution in ordinate. From the results, it can be also concluded that a reduction of deposit which is produced by the reduction of thermal stress, by improvement in combustion, by the prevention of deterioration of the lubricating oil has good effects on maintenance and durability of main engine.
The studies were undertaken to accumulate fundamental data for artificial formation of seaweed beds in the
areas of decadent seashore condition. The investigation was firstly made of the role of repellence against abalone
Hal紡is discus hannaj of benthic animal using malic and citric acids and their carboxylates, and secondly was
Carried out in regards to the effect of these substances on the growth of Sargassum horneri. Among the repellence
effect of the substances for abalone, the effect of malic acid was largest at low concentraions, followed by
those of citric acid, malate and citrate. The substances were also confirmed to promote the growth of germlings
and fronds of S. horneri in the laboratory culture. Using malic and citric acids which elicited repellence effect at
low concentrations against abalone, the relationship between each of two substances and the growth of S. hoγneγi
was observed in the field. The method was carried out by setting up concrete blocks (tetrapod type, about 30 cm
in heicht) at 2 m under sea surface. The blocks were coated with synthetic resin (aminoethylated acrylic resin)
containing malic and citric acids and rolled twine attached with seedling of S. horneri. By the observations of
growth of S. horneri after 8 months, it was found that the growth was remarkable and many fronds survived on
the blocks in the case of using malic acid. The results showed that malic acid was nutrient element for growth of
S. hornerj and prevented to be disppeared by grazing of benthic animal for frond of one. As mentioned above, it is much expected that the use of malic acid practica11y produces beneficial effect in the formation of artificial seaweed beds.