Swim accessories can be helpful if they are used, not as a substitute for inefficiency, but to develop greater efficiency. I’ll limit this discussion for now to swim fins and hand paddles, elaborating on a column I wrote a year or two ago.

Paddles come in a variety of shapes and sizes as well as means of attachment to the hand. Their main purpose is to expand the surface area of the hand that the swimmer uses to manipulate water for propulsion.

There are two ways in which hand paddles can help a swimmer to improve.

For one, the increased surface area forces the swimmer to develop stronger arm and shoulder muscles to control both the paddle and the greater amount of water being pulled or pushed for propulsion.

It is hard in a gym situation to duplicate the exact angles at which the developed muscles will be used, so paddles can be helpful toward that end.

The other way a paddle can help involves how the swimmer manipulates the hand as it functions in the water. Just as the paddle exaggerates the surface area, it also exaggerates how the hand moves through the water.

If the swimmer’s wrist is not kept above the hand, the water can rip the paddle off. If the swimmer slides the hand through the water instead of pressing against it, this fault will be magnified, too.

In short, the paddle must be applied in an efficient manner, or it will be useless and negatively impact the swimmer’s stroke.

Swim fins, even more than paddles, come in a variety of shapes and lengths. The flexibility of long fins provides propulsion for snorkelers and SCUBA divers.

Long fins can also help pool swimmers to raise the body’s level on the surface, thus enabling the upper limbs to function more effectively. However, such fins slow the legs’ rhythm, which does not transfer to swimming without them.

Shorter fins can perform the same functions to a lesser degree, while duplicating the rhythm of swimming without them.

Additionally, using fins elongates the legs and widens the feet, thereby increasing the body’s waterline so that it moves faster, according to Froude’s Law. (First mentioned in my column last May, this concept indicates that, all other things being equal, the ship – or body – with the longest waterline travels the fastest.)

Swim fins and hand paddles are not a substitute or a crutch. They are indeed useful to the swimmer by developing strength and assisting to position the body and its parts for more efficient swimming.

Dr. Bob Colyer of Bluffton is an actively retired college professor, coach and author of “Swim Better: A Guide to Greater Efficiency for Swimmers & Ins