Which brakes for which trailer?
  |  First Published: November 2014

There is always confusion about what types of brakes are needed for what trailer. The majority of fishers will have a mechanical over-ride system fitted to their trailer. This is the most commonly used braking system. The problem is that the bigger and heavier the boat, the higher the rating your trailer needs to be.

There are a lot of factors that need to be considered when rating the capabilities of a trailer. The brakes are only one factor, however if you know the rating capability of your braking system you are able to know straight away whether you have the right one or not.


Not all trailers need brakes, if your trailer has an ATM of 750kg or less then by law you are not required to have a braking system on your trailer.

Just keep in mind that although your boat and trailer unloaded (no fuel, equipment, water, etc.) may weigh less than 750kg when you load it you may go over. Not a big deal right? WRONG. If you are involved in an accident and the trailer is taken away for weighing and comes in over its rating then you have a problem, not to mention the insurance company having an excuse not to pay up for repairs. And do we really need to give insurance companies another reason not to pay?


As I mentioned earlier, most fishing boat trailers will have a mechanical over-ride braking system fitted to them, however, there are 2 types of over-ride braking systems: one is mechanical and the other is hydraulic.

Both types have a maximum rating of 2000kg with a hand brake attached to the coupling. They both also work on inertia, meaning that when you apply the brakes on your car, the force of the boat and trailer push on the coupling shaft, which applies pressure to the handbrake leaver that will either pull on the cable (mechanical) or pushing fluid in a cylinder (hydraulic).

These systems require brake callipers fitted to one axle and both need the callipers serviced (usually when you have your bearings changed).

There are positives and negatives for both systems, for example hydraulic callipers don’t need to be adjusted like mechanical callipers do, but the brake lines do get rusty and can create cracks and leaks that allow air into the system causing the brakes to fail.

Overall, it really comes down to preference and practicality when choosing the right over-ride brakes for your trailer.


If you are lucky enough to have a boat that requires the trailer to have a rating of over 2000kg you have a lot more responsibility when it comes to the maintenance of your trailer. Your trailer will have a hydraulic over electric braking system fitted to it.

If you have a straight electric brake system fitted with drum brakes then I strongly suggest you change immediately – electricity and water don’t mix!

There are a lot of braking actuators out there that are capable of pulling up your boat and trailer; depending on your make of trailer will depend on what system you have. All work the same way and require you to have a brake control unit fitted into your car.

Your brake control unit is connected to your brake light switch on your brake pedal, so when you apply pressure to your car brakes, a signal is fed to your brake control unit. From there a signal travels through wiring to your car trailer plug and when the trailer is connected through to the trailers brake actuator. The actuator then pushes brake fluid to the brake callipers. The amount of pressure applied to the brakes depends on the settings on your brake control unit (refer to your owner’s manual when setting your brake control unit).

You will also have fitted to the front of your trailer a ‘break away switch’ and ‘break away battery’. These are required by law and the battery needs to be always charged enough to apply the brakes for a 15 minute period if the switch is deployed. Your car is also required to have a ‘battery charge indicator’ fitted, to show you whether your break away battery is charged or not.

The braking system is only one element when it comes to the rating of your trailer, you can’t change the rating of your trailer just by adding or removing a braking system, a lot more is involved, but at least you know the ins and outs of the different braking systems found on boat trailers. If you are unsure of whether your trailer needs brakes or if they are working, make sure you speak to an expert as safety is always #1.

• Christian Bold, also known as ‘The Trailer Guy’, is one of Australia’s leading trailer and caravan repair specialists. As the Director of Bold Trailers he is a licensed motor mechanic, auto electrician and automotive body builder. Christian is also an AUVIS and e-safety examiner for the RMS. You can contact Christian and the team at Bold Trailers for any information regarding trailer and caravan repairs, maintenance, modifications, legal requirements, imported trailers, parts and accessories and new and used trailers for sale. Their friendly technicians are always willing to help you to make your towing experience safe and enjoyable. For more great tips go to www.boldtrailers.com.au or Phone: (02) 8544-8114.

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