Know your Nautical Terminology
slip
1. To let go a rope at a precise moment, such as when releasing the last attachment to a buoy, when getting under way.
2. To slip an anchor: to let go the anchor cable, abandoning the anchor so as to get under way in an emergency, rather than spend time hauling in the cable to raise the anchor in the normal way. The released anchor cable is usually buoyed to aid recovery later.
3. The difference between the theoretical distance traveled per revolution of a vessel's propeller and the actual advance of the vessel.
4. A mooring area for boats enclosed on three sides vice a dock which is open on three sides.
5. In marine engineering, the motion of the center of resistance of the float of a paddle wheel or the blade of an oar through the water horizontally.
6. In marine engineering, the difference between a vessel's actual speed and the speed it would have if the propelling instrument acted upon a solid.
7. In marine engineering, the velocity of the backward current of water produced by the propeller relative to still water.
8. In marine insurance, a memorandum of the particulars of a risk for which a policy is to be executed, usually bearing the broker's name and initialled by the underwriters.
Propeller slip (#3) 
Floating boat slips (#4) 
WWG1WGA
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(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)