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334 tions call for a speed of 31 knots. Simplification of control proved to be a considerable engineering problem but was solved in such a manner that the units are not only compact in construction, but easy for the av- erage engineering staff to grasp in principle. Ship-Log Is Improved by Use of Connector Accurate determination of a _ ves- sel’s speed has always been of the utmost importance because of the use made of this knowledge as a check (and sometimes as the only means) in fixing the ship’s position. Dead reckoning may be excellent naviga- CONNECTOR—THE WIRE TO THE REGISTER AND THE LINE TO THE ROTATOR ARE CONNECTED TO THE SMALLER AND LARGER CHAMBERS RESPECTIVELY SHIP-LOG AERIAL tion with a good log and a carefully adjusted compass. One of the well known types of ships logs is a ro- tator attached to a line towed be- hind the vessel, the recording device fastened to the other end of the line being as a rule secured on the rail in the stern quarter. The speed of rotation of the rotator of course varies with the rapidity with which it is towed through the water, and by proper calibration, making due al- lowances, an accurate record of speed is obtained. The inconvenience of a location so far away from the bridge and the use of the log in the more or less broken water aft of the propellers has been overcome by Thomas Walker & Son, Ltd., ship instrument mak- ers, 58 Oxford street, Birmingham, England, in the perfection of a pat- ented connector for the _ ordinary ship log. The accompanying illustra- tions show the general appearance and method of installation. A boom 20 to 25 feet in length is located at any convenient place well forward, preferably under or near the MARINE REVIEW bridge and is made fast by a goose neck stepped in the rail, while the out- board end is supported by wire guys. Near the end of this boom the con- nector mounted on the regular type of shoe is properly secured and lashed. The revolutions of the rotator are transmitted through the connector to the log register on the bridge by a light aerial wire to which a spring is attached to ensure even tension. {n adjusting the length of the aerial there should be little tension but at the same time no slack for best opera- tion. It is important also to align the eye in the connector with the register spindle. The log register is usually mounted on a bracket fixed to the bridge at a level of the hand rail. For convenience in hauling in the rotator a tripping line is used with a bulls eye attached which rides on the log line. To use the log, attach the governor wheel with the big log line and ro- tator to the large eye in the connec- tor and the spring and hook of the aerial to the eye of the log register on the bridge. The other end of the aerial is lowered from the bridge and attached to the small eye of the con- nector. After this, the boom is swung out, the guys are made fast, the rotator is thrown well overboard and the line is paid out. In hous- ing the log it is important to avoid kinking the wire of the aerial when coiling it up, and care should be taken to keep the vanes of the rota- tor from damage due to striking the sides of the ship, so that the accuracy of the log may not be affected. Length of line depends upon the speed of the vessel and the height SHIP-LOG CONNECTOR INSTALLED ON THE END OF A BOOM AND HOOKED UP TO THE REGISTER AND TO THE ROTATOR of the boom above the water. The higher the speed the longer the line and the nearer the boom to the water, the shorter the line. Not September, 1925 less than 30 fathoms of line should be used for a ship that has a speed of 12 knots. If the rotator breaks the surface a greater length of line must be used or it can be LOG REGISTER, AT VIKING LOG ~ CONNECTORG GOVERNOR WHEEL 25 to 55 FM. LINE SMALL GRAPPLING IRON “CHERUB ROTATOR DIAGRAMMATIC PLAN SHOWING INSTAL- LATION OF SHIP-LOG WITH CON- NECTOR weighted by using a sinker. Some- times a copper cored line is used to ontain the same results. Oiling of the connector in a proper manner is essential for good opera- tion. A solidified oil should be used with occasionally a little ordinary ship log oil added from time to time. One filling of solidified oil ought to last for seven days or more. The dirty oil should be removed from time to time and the connector thoroughly cleaned to keep it in good working condition. A paraffin base oil should never be used. The ship log connector carried as described on the end of a boom near the bridge makes it possible to tow the rotator ahead and far removed from the propellers—along the side of the ship and the readings can be made directly by the officer on watch by simply looking at the register located on the bridge. He can do this while taking his land mark bear- ings without loss of time getting coin- cident readings. It is also possible for him to see at all times that the rotator is functioning properly and that it is not fouled. The rotator . 3 + : q ,. s