Plugs are something for the experienced fisherman.
They are more difficult to fish than spinners, can't be used as universally and
last not least they are a quite a bit more expensive, so loosing them really
hurts and usually the beginner does lose more lures. But of course they also
have a few advantages over other lures: they can imitate forage fish much better (only
some soft baits can keep up with them in this discipline). Swimming and
suspending models can be fished very slowly and shallow at the same. Others can
be fished very fast and deep. There swimming-diving action covers a lot of
presentations that can't be done with other lures. Apart from that, the diving
lip gives them an own special action which often seems to be, just what the fish
want to see. The best application for Plugs is
trolling: they stay very constantly
at a certain depth, swimming models will surface when you stop or in very sharp
curves rather than snagging the bottom. In Combination with a fish finder it is
possible to troll practically without
a snag. The diving depth of a plug is determined mainly by the length and
diameter of the fishing line ( and of course the shape of the plug itself). The
speed is much less important, except if you troll or retrieve so slow, that the
buoyancy or weight come to take effect. Very fast speeds tend to make plugs run
The form of the diving lip makes a plug go deep or shallow: if
it stands almost vertical the plug will run shallow and wiggle with a high
frequency. If is almost horizontal the plug will dive deep and will move slower
and with greater amplitude, it will also create a considerably larger resistance.
A bigger lip will also swim deeper as well as an eye attached farther back from
the tip. It is important that the plug keeps it's vertical position even if you
pull it through the water quite quickly. Each model has got a maximum speed up
to which it can still maintain the desired action. If you pull it to fast it
will spin miserably and won't dive any more. Some plugs are not designed for
faster retrieves and some are just plain bad. The diving lip and the body of the
plug together determine the way it will move: will it be a more tilting motion
from side to side like you tend to get from shallow divers and flat sided lures or
will be more of turning, tail wagging action like you see in the Rapala Taildancer
and other deep divers.
Plugs are, with the exception of special surface lures, the only lures which are normally lighter than water, swimming at rest and diving on the retrieve. Except for theses swimming models there are also sinking ones and for some years now suspenders. A very high buoyancy is not usually desired, because the lure will shoot to the surface like a kork when you pause the retrieve. A suspender can be twitched in front of the nose of a predator much more subtly. Buoyancy on the other hand can be plus when you want to swim over a snag and will help create a more lively action. Sinking models are more suited for deep calm water where you can count them down to just above the bottom. In the current you can switch to sinking model when the swimming variant seems to go a bit to shallow.
Plugs exist in all sizes up to true monsters over 20cm in length (I believe that the 40cm Turrus Ukko is the biggest readily available model). As with most other lures the rule is: the bigger the deeper. Roughly you could say that the diving depth is proportional to the size, meaning that a plug twice as long of the same make will go twice as deep.
Plugs are "more three dimensional" than some other lures and come in a lot of different shapes. Roughly you can divide them into the slimmer fish like models (called minnows in America) and the plumper, roundish ones (Am: crankbaits). Of course you will find everything in between these extremes, round or flat cross-sections, straight or banana shaped bodies. Not to forget the lipless ones like the Rattlin Rap. You will want the shape of the lure to imitate the forage your quarry is feeding on but also it should create the right action (together with lip).
Another specialty of plugs, which can be important are the rattles inside the body of some models. Often these consist of one or more internal chambers filled with metal balls. Again you will find countless variations mainly differentiated by the size of the Balls. Few large balls (e. g. Fat Rap) make a more knocking sound while a lot of small balls (e. g. Husky Jerk) give a higher pitched rattling sound. Sometimes a rattling plug is far superior to quite one, at other times the rattling seems to frighten the fish. I think it differs with species and location, maybe it depends on the currently preferred prey.
The choice of colours in plugs is immensely high, but it can be reduced to a few basic patterns: silver/white, yellow/gold, green/perch, blue/silver, red/orange/brown, black (rare). Then there are of course some special combinations like the classic red head. In general natural patterns with close resemblance to the forage are very successful. A curiosity I have noticed is, that an orange belly can be a key to success but also to complete failure. So be sure to always try both: orange and neutral bellies. Sometimes it doesn't matter so much though.
Plugs can be presented in a lot of different ways. Short jerks preventing the lure to find its regular wobble let it shoot and dart like a disoriented baitfish. Longer pulls make it look like a fish on the run or in search of food. A constant slow retrieve is also possible although it is usually not the most effective style.