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Jack. A machine for raising or moving heavy weights. It commonly consists of one or more screws, turned by a lever or ratchet and working in a case, which rests upon the floor or ground.

Jack. Small flag of a ship, especially the national flag which was flown at the bow on a jack-staff. The Union Jack, properly the Union Flag was always flown in this position. The earliest reference to the use of the word jack as a flag dates from 1633, when it meant a small flag on the bowsprit.

Jack, Hydraulic. A machine for raising or moving heavy weights in which the power is exerted by means of the pressure of some liquid acting against a piston or plunger.

Jack Rod. A term applied to a pipe or a rod to which the edges of awnings or weather cloths are secured.

Jack, Sand. A rectangular cast iron box filled with sand and having a side outlet near the bottom which can he closed with a plug. The box is filled with sand to about one inch from the top on which a block is placed as a support for keel blocks or cribbing. They are placed under the cribbing and keel blocks so that when a vessel is ready for launching it may be lowered on to the cradle by removing the side outlet plugs in the jacks allowing the sand to run out.

Jack, Screw. A device in which the screw is used to overcome great resistances, lift heavy weights, etc. It consists of a cast cylindrical body, internally threaded, with a broad base worked at one end. A large screw turned by a bar or lever and carrying on its outer end a flat palm works into the threaded body.

Jackass. A conical shaped canvas bag stored with oakum and fitted with a lanyard at apex and base, used for closing the hawse pipes around the chains to prevent shipping water through the pipes; also called a hawse bag. P.S.

Jack staff. A term applied to a flag pole erected in the bow of a vessel.

Jackstay. A rope, rod or pipe rove through eyebolts fitted on a yard or mast for the purpose of attaching sails to the yard or mast. The term is also applied to the outer or boundary rope of a netting or awning.

Jacob’s Ladder. A ladder having either wire or fiber rope sides with wood or metal rungs attached at regular intervals. One end is usually fitted with sister hooks or shackles for hooking on.

Jaw, Boom or Gaff. The semi-circular end fitted to a boom or gaff for the purpose of making a loose attachment to the mast.

Jet Condenser. See Condenser, Jet.

Jetsam. Goods or cargo thrown overboard from a vessel in order to lighten her when in danger of sinking.

Jewel Block. See Block, Jewel.

Jew’s-Harp. The odd shaped shackle fitted directly to the shank of the old-fashioned anchor.

Jib. A triangular sail bent to a foremast stay.

Jib-Boom. A spar placed on top and projecting forward of the bowsprit for the purpose of holding the end of the outer jib.

Jib-Boom, Flying. A spar placed on top and projecting forward of the jib-boom for the purpose of holding the end of the flying jib.

Jib-Boom Stay. A stay running from the forward end of the jib-boom to the martingale.

Jib Crane. See Crane, Jib.

Jigger. A term usually applied to the after mast in a ship having four or more masts.

Jiggers. Light tackles generally rove as luffs used for miscellaneous work on deck. They are also termed watch tackles and in some cases Handy-Billy tackles.

Joggled. A term applied where a frame or plate is offset in the way of a lapped joint. The object of the joggle is to dispense with the necessity of fitting a liner.

Joggled Frame. A frame in which offsets are worked in the way of the laps of the shell plating. By joggling or offsetting the frames at a lap both plates fit snug against the frame.

Joggling Machine. A machine in which two short power driven rolls are used for joggling, or crimping, or offsetting plates. The rolls are offset in such a way that a plate is joggled, or crimped by passing through the machine. These machines are generally operated by an electric motor.

Joiner Door. See Door, Joiner.

Joiner Plans. Arrangement plans of quarters and living spaces showing the location and arrangement of a vessel’s furniture, toilet articles, etc.

Joiners. Wood workers who make and set up all the wood work requiring considerable skill such as panels, doors, sashes, built in furniture, etc.

joint, Butt. A term applied where a connection between two pieces of material is made by bringing their ends or edges together and by fastening the same by a strip or strap that overlaps both pieces. Holes for bolts or rivets are drilled or punched in the straps and pieces to be connected.

Joint, Lapped. A term applied where a connection between two pieces of material is made by overlapping the end or edge of one over the end or edge of the other and by fastening the same by bolts or rivets.

Joint, Strapped. See Joint, Butt..

Jointer. A type of wood planing machine used for planning the edges of lumber. The table and cutters are usually similar to a planer and a vertical fence is provided for use as a guide while dressing the edge of a plank or other piece of work.

Jolly Boat. A pulling boat of small size.

Journal. That portion of a shaft or other revolving member which transmits weight directly to and is in immediate contact with the bearing in which it turns.

Journeyman. Originally a workman who had completed his service as an apprentice. It was early practice to bind out apprentices for a term of years. Upon completion of apprenticeship, the workman was given a certificate testifying to his qualifications in his craft, and he could then journey where he would and ply his trade. Hence the name journeyman, meaning a workman skilled in his craft or trade.

Jump. To make a flush joint between two planks or plates of iron or other metal. To join by a butt weld in smith work.

Jury Mast. See Mast, Jury.

Jury Rudder. A term applied to any temporary or makeshift appliance that is used to steer a boat when the regular rudder is out of commission.

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