Best practices for marine and boat use require terminals to be galvanically compatible with the wiring you are using, insulated terminals, and the crimp method of securing. Insulation must be used, and can be either standard or the Heat Shrink type. Lug terminals are very useful in making connections, however, only those with a raised tab should be used fo prevent them from falling off should the connection become loose. Although Crimp Caps are permissible, they are my least favorite, and I rarely use them. Finally, friction-fit terminals, such as bullet connectors, should only be used in circuits under 20Amps.
Examples of terminals not appropriate for boats are Wire-Nuts of the style that are used in residential wiring, non-insulated terminals and barrel connectors (although Heat Shrink could be applied after crimping), and non-captive lugs.
Alternate terminal configuration include so-called Euro Terminals, where the wire is held in place by a set screw. However, a set screw pressure plate must be employed to prevent direct bearing of the set screw onto the wire.
Sealing connector ends. Occasionally you may have the need to leave a pigtail hainging, either temporary or permanenetly. Or perhaps you are needing to use a fish tape to pull cabling through the boat. While this is done with almost no forethought, there is actually a useful technique. As in the other examples, begin with cutting each wire a different length, then begin wrapping the cable with tape.
Continue with the tape wrap until you go one full tape-width beyond the end of the wire. Then flatten the tape by pinching off the tape end. Finally, fold the tape end over onto the end of the wire.
Next, continue with the wrap on the wire. This time you are going back on the wire in the opposite direction. After a loop or two, cut the tape from the roll so that you don't use too much tape or get it tangled.
When you are finished, you have a nice taped-off job as shown. Hint: if this is a temporary taping, such as feeding the wire end through the boat, bend the end of the tape over onto itself to create a "pull-tab". This - along with the taping technique shown here will make the tape much easier to remove.
When splicing RF coax, the only acceptable method is to use RF connectors such as PL-259 or BNC. It is never acceptable to use crimp type barrel connectors or lugs of the type typically used for AC and DC wiring.
There is one last topic that should be discussed, pulling (or fishing) wires through the boat. This is an essential skill for getting cabling into radar arches or other restricted areas. We'll discuss this next.