392 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
the verge of the danger line where the slackening of the vessel’s speed or other 
unexpected occurrence might result in kinking it, capsizing the trawl, or fouling the 
net. The dredge rope is to the beam trawl what the string is to the kite. Hence tlie 
necessity for keeping a continuous strain on it while it is going down; otherwise it 
will lose its balance and ftnally capsize, as would the kite with a slackened string. 
The horizontal drag resulting from tension on tlie dredge rope and the mean track 
of the trawl from surface to bottom is shown by the following data from Table 1 (p. 391 ), 
where the depth is 3,000 fathoms and length of ro])e 4,000 fathoms. The time occupied 
in paying it ont is 2 hours and 32 minutes, or 152 minutes, during wiiich the ship 
moved through the water 6,375 fathoms, at a mean speed of 2.55 knots iier hour, or 
42 fathoms per minute. The rope was paid out at the mean rate of 20.3 fathoms per 
minute, with a resultant drag of 2,386 fathoms, a mean of 15.7 fathoms per minute 
had the trawl remained on the surface, but it sank at the mean rate of 19.7 fathoms 
per minute, increasing the drag 1,414 fathoms, or 9.3 fathoms per minute. Thus the 
total horizontal drag was 3,800 fathoms, or a mean of 25 fathoms per minute. 
The margin between the speed of ship and rate of veering rope grows broader as 
greater depths are reached and the length of rope increases, for the weight of the 
latter accelerates the forward movement of the trawl and assists in steadying it. 
A beam wind is most favorable for lowering and dragging it, as the vessel will 
then drift well clear of the dredge rope and the speed is easily regulated, either with 
the engines or by the use of sail. Hauls have been made in deep wmter under sail 
alone when the conditions were favorable, thus economizing fuel and saving wmar and 
tear of machinery. 
If the vessel will not steer with the lee engine, as may happen under low speed, 
drag of trawl, and unused i)ropeller, it should be stopped and the weather one used 
instead, as the drag will in a measure counteract the inclination of the vessel to fall 
oft’. The weather engine would be used habitually only for the possibility of the rope 
being caught in the propeller. 
The requisite speed for lowering the trawl will be readily attained w'ith the engines, 
but with fair wind and current the lowest speed might be too great for dragging after 
the trawl is landed on the bottom. In this case the engine may be stopped and the 
vessel allowed to drift, the rate being increased, if desirable, by the use of sail. 
It has been found necessary in exceptional cases to slowly back an engine to retard 
the drift, and with an adverse wind and current it may be advisable to use both 
engines turning slowly rather than drive one at high speed. 
The angle of dredge rope and the strain on it, shown by the accumulator scale, 
are watched very carefully after the trawl is landed, and increasing strain is noted. 
Should the increase be gradual and not excessive, it is an indication that the trawl is 
performing its function normally; but a sudden accession of 2,000 or 3,000 pounds 
signifies that the trawl has either encountered some obstruction, or buried itself in 
the soft ooze of the ocean bed. 
Instant relief is afforded in either case, first from the dredging engine, which, 
having its friction clutch properly adjusted, allows the drum to reverse and the rope 
to run out until the strain is brought within the limit of safety, the vessel’s headway 
being stopped in the meantime. 
The roiie is then hove short, the ship backing or steaming ahead slowly to relieve 
the strain, and in this manner she is placed directly over the trawl. If the trouble is 
due to its having caught on a ledge of rocks, or other ordinary obstruction, it can 
