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Boat Trailer Parts

Ranjan Shandilya
Read on to know about maintenance of a boat trailer in detail.
This post is for all the boat enthusiasts in you. If you have a trailer which unfortunately is broken and needs replacement of a few parts, with the help of this write-up, you will be able to know about the maintenance basics of tires, axles and brakes.


While purchasing tires for your trailer, here are the inputs that you should consider:
  • A very important point to note is that passenger car or light truck tires should not be considered for a trailer as they are usually radial belted. As such these tires have flexible side walls and they could lead to trailer sway and loss of control.
  • Purchase tires that have double steel belts with full nylon plies. They are suitable for heavy-duty applications, and have a lengthy life.
  • Ensure that the thread design is such that it offers traction in both dry and wet conditions.
To maintain stability with the tires while on the road, ensure that the inflation pressure is always at the appropriate level. A major safety measure that you have to take care of is to maintain the correct 'lug torque'.
If the torque is inadequate, then the wheel may wobble and fall off. The torque should be checked and corrected very frequently. The ideal torque is recommended by the manufacturer, so be sure to confirm the same while purchasing the tires.


  • While measuring the length of the axle to support your boat, you need to consider the distance between the center of one tire to the center of the other tire, or more precisely, the distance between one hub face to the other.
  • While measuring the spring centers, measure the distance from the center of spring to the center of the other.
  • The load capacity of the axle should be such that it supports the maximum gross vehicle weight rating.
  • The overall length of the axle is measured as the distance from one extreme end of the axle's spindle to the other extreme end of the spindle.
  • Axles are available in many styles, and it is important to choose the compatible one for your trailer, that provides ample tire clearance and also supports your boat properly.
  • The different styles of axles available are straight axles, drop axles, and torsion axles.


The braking system in trailers can be either hydraulic or electric. Let us look at these systems in more detail.

Hydraulic Braking System

In this system, when the brakes of the tow vehicle are applied, the inertial differential pressure that is developed between the tow vehicle and the trailer is used to create a mechanical pressure, which is applied to the push rod of the master cylinder in a hydraulic surge brake coupler.
As the mechanical pressure generated is proportional to the difference in pressure between the two vehicles, the entire braking system is automatically regulated.

Electric Braking System

When the brakes of the tow vehicle are applied, a controller placed in the tow vehicle generates an electronic signal that is proportional to the rate at which the tow vehicle is slowing down.
The electric power unit in the trailer receives this signal and produces a hydraulic pressure that is again proportional to the strength of the signal. This pressure is finally distributed throughout the trailer brake system which slows or stops the trailer.
The electric braking system is very adaptable and supplies robust braking for a wide range of trailers. A 12 volt power supply is all that is needed to send the electronic signal from the tow vehicle to the trailer.
The weight of a fully loaded trailer should be considered while selecting the braking system and components. If your trailer has multiple axles, then you will need to consider the number of brakes that will be required. To gain maximum benefit from braking system, adequate care and maintenance as per the instructions and service manual is very important.
A boat is a very important investment. It is an investment that is made purely to suffice a passion that sometimes borders on obsession. It is for the sheer feeling of having the wind flying your hair while you maneuver your boat in the middle of the waters.
A trailer is an important utility to help transfer your dream boat from one shore to another. Hence it is an equally important investment and therefore use only the best spare parts available.