Types of Boat Trailer Axles

There are three main types of boat trailer axles: straight axles, dropped axles and torsion axles. Within these axle styles the axle may be either square or round. The axle you choose may depend on the size and weight of your boat as well as the distance and type of roads you will be driving on with your trailer.

Straight Axles

• As its name suggests, a straight axle is a straight bar that looks very much like the typical axle found in everything from toy cars to full size cars and boat trailers. Because of its design, a straight axle is usually made from heavier metal, designed to carry a load without bowing under the weight.

Dropped Axles

• The two main differences between a straight axle and a dropped axle is price and height. The dropped axle is really a straight axle that has been lowered (or dropped) in the center. Because a boat sits lower on a dropped axle there is a slight increase in gas mileage when trailering a boat, but the bigger benefit is being able to launch a boat from a lower profile, meaning you will not have to back your vehicle quite as far down the boat launch ramp to get your boat off the trailer and into the water.

Torsion Axles

• The torsion axle is a more engineered axle that is designed to provide a smoother ride. Torsion axles work similar to an independent rear suspension in cars; with a torsion axle your trailer and its load will not bounce around quite as much while driving. Some believe torsion axles work best with a lighter load because of the lack of springs in a torsion axle system do not give it enough play with a heavier load.

Round Axles

• Round axles tend to be more universal and are not brand specific, making them easy to replace since they don't have specifically placed bolt holes like a square axle. However, round axles are usually not galvanized, which means they may corrode sooner than a square axle and for this reason should be avoided for saltwater boating.

Square Axles

• Square axles get their name from the rectangular metal they are crafted from, unlike the tubular metal of a round axle. Square axles are usually made of galvanized metal and therefore will last longer than round axles. However, square axles tend to be brand specific since each axle manufacturer adds bolt holes to their specific locations before the galvanization process. This is not really a problem until you need to replace a square axle -- make sure you get the same brand of axle as a replacement.