Houseboats, Boat Trailers and the Murray at Mildura

This guide is for anyone who tows a boat to the Murray around Mildura, Merbein, Buronga or Wentworth, and for owners of houseboats and larger boats with 12V systems. It covers trailer lights and plugs, the tow vehicle's wiring, onboard batteries and charging, and which state's boating rules apply on the river.

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The river at Mildura

The Murray is the reason Mildura exists. The town grew from an irrigation colony, and river boats carried its early produce to market. Today the river is about recreation as much as water. At Lock 11, the lock and the weir are separated by Lock Island, and boats pass through several times a day. Downstream, Lock 10 sits near the junction of the Murray and Darling at Wentworth.

Houseboats are a big part of the river's tourism, and many locals own boats ranging from small tinnies to ski boats and cruisers. Whether you tow a boat to the ramp every weekend or keep a houseboat moored, the river is hard on electrical systems, just in different ways.

Whose rules apply on the river

This catches out plenty of people. The Murray along this stretch is NSW water, and NSW boating rules generally apply on the river, even if you launch from the Victorian bank at Mildura or Merbein. Licence and registration rules for boats and personal watercraft differ between NSW and Victoria, and there are arrangements for interstate vessels and licence holders.

Transport for NSW explains how interstate vessels can be used in NSW, and says interstate licence holders need a NSW licence to keep using NSW waterways after three months. The rules for Murray River border residents can be different, so check the current rules with Transport for NSW before you head out.

Boat trailer lights and plugs

The Murray is fresh water, which is kinder to trailers than salt. But trailer lights still fail often. The usual pattern is a hot light being backed into cool water. The sudden temperature change can crack the lens or break the seal, and water gets in. Once inside, it corrodes the globe contacts and wiring.

Here's how to keep boat trailer lights working:

• Fit sealed LED lights designed for boat trailers.
• Unplug the trailer before reversing down the ramp, so the lights are off and have time to cool.
• Run wiring inside the trailer frame or in conduit where you can, to protect it from damage.
• Use a good earth wire back to the plug, rather than relying on the trailer frame.
• Rinse the trailer after each trip and let the lights dry.
• Clean the plug pins and use dielectric grease to keep moisture out.

The tow vehicle

The trailer plug on the car is just as important as the one on the trailer. It's exposed to road spray and dust, and it often gets dunked on the ramp. A corroded socket can cause dim or flickering lights, or lights that don't work at all. Check it regularly. Our guide on how to wire a 7-pin trailer plug helps if you need to replace one.

Heavier boats may need trailer brakes. Transport for NSW's page on towing a trailer or caravan says trailers over 750 kg gross trailer mass need brakes on at least one axle, and trailers over 2,000 kg need brakes on all wheels and a breakaway system. These requirements come from national standards, but check the current rules in both states before you tow.

Houseboat and cruiser 12V systems

Houseboats and larger boats often run a house battery bank for lights, pumps, fridges and electronics, separate from the engine's starting battery. These are charged by the engine, a generator, shore power or solar. Common problems include house batteries going flat, charging systems not working properly, and corroded connections in damp areas.

The basics are similar to a caravan. Keep the starting battery separate from the house batteries. Size cables correctly and fuse every circuit close to the battery. Our guide on what size cable you need for 12V explains how to choose.

Marine electrical work has its own standards and products. Use marine-grade cable and connectors, and get a specialist marine electrician for anything beyond simple jobs. Any fixed 240V wiring, including shore power and generator connections, is for licensed professionals only.

Small boats: starting batteries, bilge pumps and nav lights

On a tinnie or ski boat, the electrical system is usually simple: a starting battery, a bilge pump, navigation lights and perhaps a sounder or radio. Simple doesn't mean trouble-free. A boat that sits on its trailer in a Mildura backyard through a hot summer can come back to a flat battery, a seized bilge pump switch or nav lights with green, corroded contacts.

Before the first trip of the season, charge the battery fully and have it tested, run the bilge pump, and switch on every light. Fit a battery isolator switch so nothing drains the battery while the boat is parked. Make sure every circuit has a fuse sized for its cable. Our guide on where to put the fuse when wiring an accessory explains why the fuse belongs close to the battery.

If you head out early or come back after sunset, your navigation lights must work and meet the rules. Check the current requirements with Transport for NSW, as NSW rules generally apply on the river.

High water and storage

The Murray at Mildura reached moderate flood levels in late 2022. Boats, trailers and vehicles stored near the river can be affected by rising water. If a trailer or vehicle has been in floodwater, check the wiring, plugs and lights carefully, and don't start a car that's been flooded until it has been inspected.

If you store a boat between seasons, disconnect or isolate the batteries, or use a battery maintainer. Check for rodent damage before using it again.

Before you launch

A quick check at home saves trouble at the ramp. Our guide on why trailer lights aren't working helps if something's wrong. Local help is listed on our Merbein and Wentworth pages.

Parts for this job

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Get it done: get a quoteDo it yourself: shop submersible trailer lights

Get it done: get a quoteDo it yourself: shop 7-pin trailer plugs

Get it done: get a quoteDo it yourself: shop marine cables

Get it done: get a quoteDo it yourself: shop battery isolator switches

Questions Mildura drivers ask

Do NSW or Victorian boating rules apply on the Murray at Mildura?

The Murray along this stretch is NSW water, so NSW boating rules generally apply, even if you launch from the Victorian side. There are special arrangements for interstate vessels and licences, and these can change. Check the current rules with Transport for NSW before you go out on the river.

Why do my boat trailer lights keep failing?

The most common cause is water getting into the lights. Backing hot lights into cool water can crack lenses or break seals. Use sealed LED lights designed for boat trailers, unplug the trailer before launching, and rinse and dry the trailer after each trip. Check the earth connection too.

Can an auto electrician work on my houseboat?

Some auto electricians handle 12V systems on boats, such as batteries, charging and lighting. Marine work has its own standards, so a marine electrician may be better for some jobs. Any fixed 240V wiring, including shore power and generators, must be done by a licensed professional.

Need an auto electrician in Mildura?

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