Boat trailer maintenance

Editor Grant Dixon has done more than his share of boat towing, and survived plenty of ‘incidents’, so is in a good position to offer advice on the subject.

Don't become a trailer failure

I’ve had it happen to me and seen plenty of ‘trailer failures’ parked on the side of the road: you set off for a simple day’s fishing or on holiday with the boat in tow, but fail to make your destination.

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There you are, in the heat of the day – or even worse, the dark of night – on the side of the road with ‘trailer issues’, your family or mates looking on forlornly. You might also be a long way from help, out of cellphone range to call AA, and perhaps your mechanical knowledge and the tools to fix the job are limited.

While your trailer issue might be as simple as all the air having rushed to the top of the tyre, it could be something much worse: a failed wheel bearing, broken stub axle, locked brakes, or even a disintegrating trailer frame or towbar.

At the very least the above scenarios may occasion a few choice expletives, but failure to maintain your trailer can have dire consequences. On average, seven people are killed and 45 seriously injured each year in New Zealand as a result of crashes involving a light vehicle towing a trailer, according to the NZ Transport Agency (NZTA).

Along with poor maintenance, among the leading causes of trailer-related accidents are ineffective or poorly fitted tow bars, overloading, and poor weight distribution.

The summer season will bring more vehicles on the road towing a trailer than at any other time of year, but drivers can do much to minimise the dangers with proper preparation and by following a few simple safety steps.

Before heading off with the trailer or caravan in tow, first check the tow bar to ensure all the bolts attaching it to the vehicle are tight, that there is no corrosion present, no cracking in the welds or structure, and that the tow ball is secured properly to the tongue. Also, make sure the tow ball is correctly matched to the trailer coupling – there are two main sizes of tow ball used in New Zealand, 1 7/8-inch and 50mm. A couple of manufacturers (such as Best Bars) have a quick-change convert-a-ball accessory that accommodates both sizes, which is very handy when renting a trailer or swapping between trailers.

A safety chain must also be used between the towing vehicle and lighter trailer/caravan, with double chains required if the weight of what’s being towed is more than 2,000kg and there is no independent braking system fitted.

When packing the trailer for the trip, make sure that the load on the tow-ball tongue does not exceed the recommended tongue weight (stated on the label). Too much weight can cause stability problems when driving and put undue load on the tow bar and connection to the vehicle chassis.

Incorrect loading has been identified as a factor in 27 crashes a year on New Zealand roads, and it’s probably one of the most difficult things to get right (that terrifying experience of a vehicle and trailer ‘snaking’ or swaying on the open road indicates a failure to get the balance correct).

Best Bars recommend a load leveler. This device fits onto the trailer’s draw bar trailer and connects to the towing vehicle’s tow bar to help redress the balance, transferring the load so it’s further forward.

By now many trailer boats will have had their first outing for the new season. This is the first chance many owners get to inspect their trailer unencumbered by the boat. Here, all those rust patches hidden by the hull will be plainly evident, as will any obvious deficiencies in the suspension or brake systems.

Another problem boaties face involves the trailer bearings. Trailer boats are often driven some distance to the ramp, which sees the hubs and bearings heat up. Then, once at the ramp, little time is wasted backing the boat, trailer and its still-hot wheel assemblies into the tide. Contact with cold water sees the hubs cool quickly, the air in the bearing housing contracts, pulling water through the seals and into the bearings with disastrous long-term effects.

Wheel bearing issues are not that easy to spot. You will need to raise the wheel off the ground and give it a spin. It should rotate easily and with minimal ‘rumble’. Saltwater and bearings are not a great mix, so minimise the risk by using plenty of grease and ‘Bearing Buddies’ (specially designed end caps that prevent water accessing the bearings).

Tyres, and in particular correct pressure, should be checked frequently.

Voyager Trailer’s Steve Williams says tyre pressure is a big factor in towing safety. Most trailers have 8-ply light truck tyres so pressure should be around 60psi. The right pressure is normally stamped on the tyre or the VIN plate.

Although braking systems for boats have come a long way in recent years (especially with regard to protection from the harsh environment they must endure), they still require plenty of TLC. Any wear on the brake shoes or disc pads is obvious, but it is the other moving parts – such as the arms and rotors – that need to be checked and protected. Also, if you use electric override brakes, care needs to be taken when beach launching to avoid immersing the units in water.

LED lights have done much to improve the trailer boatie’s lot, but often cheap wiring lets them down. Electricity and salt are a deadly combination and will damage wiring looms quickly if joins and connections are not properly sealed and protected.

The multi-pin plugs need looking after, too. I have yet to come across properly watertight plugs, so plenty of Inox/CRC or a similar product will help keep the connections working effectively. Sealing where the cable goes into the back of them with silicone or binding with electrical tape is worth the effort.

Prevention is better than a cure. We have mainly had Voyager trailers under our various magazine project boats. While this product comes highly recommended and we have happily towed our boats for thousands of kilometres on them, like all trailers they do need to be maintained. If you are not a mechanical DIYer, get the manufacturer or their agent, or your trusted local garage, to give your trailer a once over at the start of the season.

While some of the following may be obvious, the points make a good guide when planning that longer towing journey.

Plan your trip. Go at a time when there is less likely to be heavy traffic on the road.
Watch your following distance – especially important if the road is wet.
Is your vehicle up to it? You may invalidate vehicle and boat insurances if you attempt a tow for which the vehicle is not rated.
Check WoF and rego, along with lights, before leaving.
Be courteous. If you are not maintaining the average speed of the traffic, pull over and let faster vehicles pass.
Take your time. Towing a heavy load can be stressful, so take regular breaks on long hauls.
Check tyre pressures. Lower than normal pressures can affect the handling of both trailer and vehicle, as well as fuel economy.
Load carefully. Make sure that extra fuel, bait, ice and camping equipment carried in the boat is not too far forward or too far back.

On the road

Uses for the spare brake fluid, wheel nuts and prop flag are obvious, as is the torch. The blocks of wood – in various sizes – are used when jacking up the boat or for preventing it moving if no longer hitched to the vehicle. A large boat needs a jack with a decent capacity – most car jacks won’t cut it. Wheel nuts are often ‘frozen’ due to rust, hence the Inox/CRC and a substantial wheel brace to which you can apply plenty of leverage to work the nuts free (and do them up again).
Should the winch rope break, the extra tie-down can be used to pull the boat onto the trailer and, when in place, keep it there.

D-shackles are always going missing from the safety chain, as are winch handles – there are some miserable bastards around who have no scruples about removing someone else’s shackles and trailer-winch handles. Similarly, a high tensile Abus chain and padlock guard against trailer theft.
Inox/CRC can be applied to wheel studs when you remove a flat tyre to make it easier to undo the nuts next time. After tightening, smear some grease around the nut for added rust protection.
Voyager recommend doing the nuts up with a torque wrench to 72ft lb, and then check them again after doing 50km or so. Excessive tightening can stretch the stud, so don’t overdo it.

An old towel comes in handy for wiping your mitts at the end of the repair. You can also lie down on it if you need to get under the trailer.
Tow ropes never go amiss.

This kit has helped me and a number of others get back on the road quickly with a minimum of frustration. It is perhaps a bit ‘OTT’ (Over the Top), but, trust me, the kit has proven its worth over the years.

Spare brake fluid
A decent wheel cross-brace
Blocks of wood
Eight-tonne bottle jack
Wheel nuts
Tow rope
Prop flag
Winch handle
Waterproof axle grease
Old towel
Chain and padlock
Dolphin torch
Tyre pressure gauge.

Whenever I have the boat on behind, the ‘Get Out of Jail’ kit is always with me in the back of the Ford Ranger. This fish bin contains:

Get out of jail kit:

Boat trailer maintenance


January - 2015 - Grant Dixon

New Zealand Fishing News Magazine.
Copyright: NZ Fishing Media Ltd.
Re-publishing elsewhere is prohibited

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