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Improved Radio Compass for Marine Service N IMPROVED type of radio A compass in now available for use in conjunction with the Western Blectric marine radio_ telephone. The radio compass indicates’ the bearing of the distant radio station in relation to the direction in which the vessel is headed. The most com- mon application is the determination of the ship’s position by obtaining cross bearings of two or more radio stations whose locations are known. In addition, the radio compass may be used as a “homing’’ device. There are many other uses. Even the direction of radio static can be determined and may often be of help in indicating the location of storm centers and their paths. Bearings to within 1 degree ac- Improved Type of Marine Radio Com- pass on the Trawler Thomas Whalen curacy can be obtained even at distances of 200 miles and more from the radio station under favorable circumstances. One feature of the compass is simplified procedure. A visual in- dicator is employed which enables the navigator to determine very ac- curately the correct ‘‘lubber-line’’ bearing. This method gives much more definite results than the older one which requires that the nay- igator listen on head phones for a minimum signal. Another feature is freedom from the possiblity of obtaining bearings which are in error by 180 degrees. The ‘‘sense’’ of any bearing is indi- cated positively and directly during the simple procedure of turning the loop wheel in the natural direction to bring the needle to mid-scale of the indicating meter. The compass consists of a radio receiver and a loop assembly. The loop, housed in a weatherproof cast- ing, is normally installed on top of the pilot house. The loop is turned by means of a shaft extending down into the pilot house to the end of which a small hand-wheel is t- tached. Operation is simplified to the fol- lowing two adjustments: 1. Tune in the desired beacon signal by operat- ing the tuning control on _ the receiver. 2. Rotate the loop hand- wheel in the direction which causes the indicator needle to follow in the same direction as the hand-wheel until the needle reaches (center-line) of the meter. Ship Hold Ventilator OR use especially in ship building and dry dock work a new ventilating unit has been de- veloped by the Coppus Engineering Corp., Worcester, Mass. It is designed to give a large volume of air, and still the complete unit can be lowered through a 14 inch diameter opening. As the total weight, including electric motor, is only 80 pounds it is readily portable and can be quickly set up and put into operation by one man. The unique feature of this ship hold ventilator is, that it can be placed in a vertical position, resting on a ring of the ventilator inlet, so that the air can be removed from the very bottom of ship holds and other closed compartments. Portable Ventilator for Shipboard Flexible tubing of 8-inch diameter may be used to carry off a volume of 1500 cubic feet per minute of fumes and foul air. This ventilator can also be used in a horizontal position, shown below. fe mid-scale Adjustable Plug Piston Of New Design HE NEW Bodenlos adjustable T plug piston, recently developed and introduced by the American Ship Building Co., Cleveland, is probably one of the most outstanding improvements for reciprocating en- gines in many years. The plug pis- ton is generally recognized as the sat- est from the point of view of injury to the cylinder. Also, friction, which means power, is at a minimum with this type and frequent boring of cylinders and repairs to piston and rings are avoided. There are in- stances where, in high pressure cylin- ders, plug pistons have run for 20 years and are still good. They have, however, had one serious fault and that is the leakage and consequent fuel loss. No matter how nice a fit is made to the bore of the cylinder, when the tool marks are worn off in a few trips there is a slight leak which in time becomes greater, With this new plug piston which can be adjusted to the minimum clearance at any time, very conven- iently and in a few minutes, without removal from the cylinaer, leakage is avoided without losing the other advantages enumerated for this type of piston. Time and expense is in- volved in removing and old type pis- ton from the engine, There are many times when they should be removed because they are worn down so much that they are inefficient but because of the expense nothing is done, In using the new piston the oper- ating engineer can keep the adjust- ment perfect at all times. Where this type has been fitted improved results have been noticed at once in tightness and increased revolutions of the engine, The movement of the ring for ex- pansion and contraction is by means of a right and left hand spiral thread and can be adjusted to a fraction of one-thousandth of an inch. It is, therefore, a true diameter at any point which has not been the case in other methods of expansion rings. The West Kentucky Coal Co., Pa- ducah, Ky., it is reported, has award- ed a contract to the Marietta Mfg. Co., Point Pleasant, W. Va., for the con- struction of 10 standard steel river barges for coal carrying, each barge is to be 175-x 26 x 41 feet, Ship Hold Ventilator of Portable Type with Flexible Tubing MARINE REVIEW—January, 1935 29