This isnt just WA most states have something similar. I think Adelaide was something like 500kg unbraked when I was there.

Most boat trailers going over that weight come with some sort of suitable brake set up normally as it might fall back on them if it didnt as they should be suited and rated for the weight being carried.

Insurance could be another issue if you exceed those figures and if you exceed the fitted towbar weight as well.

** Rockingham Offshore Fishing Club **

 Here you are, copied from the DPI website

5.5 Regulations for Your Trailer or Caravan

You must not drive a vehicle with an insecure load.

Your trailer or caravan must have:

n the correct coupling;

two safety chains for vehicles between 2.5 and 4.5 tonnes GVM. The chains must be

cross-hitched so that the trailer or caravan will still be secure if the coupling breaks;

n rear lights and reflectors;

n a light that illuminates the rear registration plate;

n side lights – if the vehicle is more than 2.1 metres wide; and

kg and two tonnes and a breakaway braking system if the trailer or caravan is over two

tonnes aggregate mass.

A brake is not required to be fitted if the trailer, caravan or plant trailer has a gross

trailer mass less than 750 kg.

Ensure your car is fitted with good exterior mirrors so you can clearly see behind you

when towing a trailer or caravan.

No one is allowed to ride in a semi-trailer, trailer or caravan while it is being towed, unless

the trailer has been approved and licensed for the carriage of passengers and is being

driven in accordance with any conditions imposed.

Towing Limits

Towing limits for vehicles are determined by the Road Traffic (Vehicle Standards)

Regulations 2002.

Simply stated, the regulations mean that:

The loaded mass of the trailer you are towing must not exceed whichever is the

lesser of:

manufacturer); or

by the vehicle manufacturer).

102

Where manufacturer’s specifications of the vehicle are not known, then the maximum

weight that can be towed is either 1.5 times the loaded mass of the vehicle (if the

trailer has brakes) or, if the trailer has no brakes, the weight is limited to the unloaded

mass of the vehicle.

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No Orange Hats Allowed

V8 twin turbo diesel....Ohh what a feeling!

OK,
In reality what size boat and trailer meet the 750Kg un braked trailer requirements?

I think there are alot of us out there towing illegal loads
and God forbid in the case of an accident wouldn't be covered by our insurance.

another rule is that the vertical load on to the tow ball/bar must not exceed 10 % of the obbject ie; boat, caravan being towed for example if your boat wiehged 1500KG then the two ball's vertical and horizontal load must not excceed 150KG.

an example is when i purchased a criuser years ago to tow my caravan the two bar was only good for 1200 kg so i had to purchase a two bar capable of towing 2100 kg which was ok as the vehicle was rated to two 2500kg and hayman reese made a tow bar to suit this application

you will most likely find that hayman reese or a WA eqiuvalent sells a tow bar to suit your vehicles maximun capacity and then you can have it fitted knowing it is covered both legally and for insurance unless you buy a boat that exceeds those capacities

"personal experience"

hope this helps  

fish hard work less

Most boats under 15/16ft wont exceed 750kg

eg: quintrex dont supply a trailer with brakes until the 490 range, 16ft in old money  

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No Orange Hats Allowed

V8 twin turbo diesel....Ohh what a feeling!

That info is pointing me in the right direction