Orange Roughy Pt 8
  |  First Published: March 2012

Just while the final touches are being made to the Orange Roughy, I thought it worthwhile just to re-visit the whole trailer issue after a few calls and some surprises I found when getting the trailer registered.

Those who build their own trailers, and not just boat trailers, should be aware that the regulations in Australia have changed when it comes to standards with springs, brakes, lights and coupling chains.


All new trailers (including imported trailers), not exceeding 4500kg Aggregate Trailer Mass (ATM), presented for registration in Tasmania must comply with requirements of the National Code of Practice for Building Small Trailers – Vehicle Standards Bulletin (VSB)1 – as published by the Commonwealth Department of Infrastructure, Transport, Regional Development and Local Government.

Vehicle or Trailer Identification Plate

All new trailers must have a vehicle identification plate (compliance plate) fitted securely with pop rivets or the like.

The person who built or assembled the trailer must fit a vehicle plate to the trailer in a prominent position. In Tasmania these plates are available from Service Tasmania for a minimal cost.


Trailers wider than 2.1m are required to have side marker lights or clearance lights fitted that must NOT show red to the front or white light to the rear. I have fitted small lights on the guards of my trailer that show red to the rear and amber to the front. My trailer is 2.4m wide, still 100mm under the maximum allowable width.


Single-axle trailers with a Gross Trailer Mass (GTM) not over 750kg do not require brakes. Gross trailer mass means the weight of the trailer fully loaded with the boat, engine and so on.

Trailers with a GTM over 750kg up to 2000kg GTM must have brakes operating on at least one axle which can be an ‘over-run’ braking system. Most boat trailers with twin axles will have braking of one form or another on the front axle. Mostly these days this is a disc brake set up, but some still prefer the drum brake arrangement.

Trailers over 2000kg GTM must have brakes operating on all wheels, which must be a ‘break-away’ braking system where the trailer brakes are activated if the trailer detaches from the towing vehicle. This is for really big boats and often this is done with electric activated brakes and is pretty much beyond the expertise of the average back yard trailer builder.

For those who love technical definitions, Gross Trailer Mass (GTM) is the mass transmitted to the ground by the tyres of the trailer when coupled to a towing vehicle and carrying the maximum load recommended by the manufacturer approximately uniformly distributed over the load bearing area.

Tow Coupling Attachments

Tow couplings are pretty easily sorted these days – if you buy your coupling from a reputable retailer it will conform to the specifications.

The key thing to remember is to fit it according to the manufacturers specification, which will be on the coupling.

Just make sure that if it is a bolt on coupling that you do not weld it on. If you do it won’t be registered and you will have wasted a lot of money and time.

It is easier and stronger in the long run to simply bolt it on with high tensile bolts.

Before you get too far down the track with bolting it on, just make sure the coupling will be at the right height for the tow vehicle to ensure that your trailer is level.

Safety Chains

The old days of welding on any old sort of chain as a safety chain are long gone for new trailers. I can remember with other trailers I have made that we just used whatever was lying around the shed at the time.

These days the chain must be stamped as being certified and fitted/welded into the right place.

Just about every one I have spoken to recommends that two safety chains be fitted, even if it is just a small trailer. This is because it allows you to cross over the chains when you shackle them to the tow vehicle. If the coupling fails then the drawbar is caught by the crossed over chains and you can stop relatively easily.

I have had a trailer come of the tow ball at 100kmh (some clown thought it was funny to disengage the safety clip at the boat ramp), and while it made a bit of a racket and scared the pants off all of us, the drawbar never touched the road and we stopped safely.

Rather than bore you to tears with the specifications, just ask at the retailer you buy the chain from. Tell them what it is for and the rating of your trailer.

Make sure the chain is stamped on at least every fourth link, and if in doubt, ask.

As a minimum I’d suggest 8mm chain for any trailer, that way you know it won’t break.


The trailer safety chains must be attached to the tow vehicle with certified rating shackles. Again, make sure you buy the ones that are strong enough and if in doubt, get the bigger ones! My understanding is that all trailers irrespective of age must have certified shackles used.

Stainless Steel shackles aren’t allowed due to the materials’ general low resistance to bending stresses.


Springs aren’t regulated as such, but my philosophy is always to err on the side of caution. The Orange Roughy probably only needed five leaf slipper style springs, but I opted to fit six leaf load sharing springs and axles – it will probably never break and the load sharing set up, while considerably more expensive, is also better for the boat and will never wear out with proper maintenance.

basic dimensions

The maximum trailer dimensions that are allowable on Tasmanian roads, (and this is the case everywhere else in Australia) are a maximum width of 2m, and a maximum drawbar length of 8.5m. The drawbar length is measured from the middle of the dual axle (the centre pivot of the load sharing axle set up) to the centre of the tow ball.

The width is measured from the outside of each guard, and tyres must not protrude past the edge of the guard.

The rear overhang, measured from the centre of the load sharing axle set up and to the rear is the lesser of either the same distance as the forward load space (to the bow of the boat or the front of the deck on a trailer) or 3.7m, which ever is the lesser.

So there are some basic regulations to bear in mind if you decide to build your own. I really enjoy building things, not just trailers, and I gain a lot of satisfaction from doing things my self. I am sure others also do.

If in doubt, consult with your local roads and traffic authority and if in doubt ask some one.


National Code of Practice for Building Small Trailers – Vehicle Standards Bulletin (VSB)1 – as published by the Commonwealth Department of Infrastructure, Transport, Regional Development and Local Government.

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