Pre-season prep for a Trailer

To enjoy the freedom of trailer-sailing, you must arrive at your destination safely, follow this guide to ensure you have a happy trailing experience! The concept o trailer-sailing begins with the word 'trail' because that is how the voyage starts. Logically, then we need to first look at the trailer when contemplating the first voyage of the year. To reach your sailing paradise quickly, the trail-sail boat moves over two mediums, tarmac and water. Boats are durable things, especially when they are only exposed to the destructive effects of a marine environment while being used, and are taken out of the water at the end of a holiday. Sadly the same is not true for trailers. While they are simple objects, the effect of time and trips to the seaside age them faster than the boats they carry so they need more inspection and maintenance if they are to perform safely. If the sailing is to be fun, the trailing should ideally be incident-free, so some of the following checks are for both pre-trailing and pre-season. Obviously, the trailer can be taken to a specialist to be serviced, but if a problem arises later it is better to know how a simple bit of kit works than to have to phone for expensive help at the roadside. You'll find advice from the Trail-Sail Association's website.

Trailer Body

A trailer-borne boat is hardly likely to suffer from 'polyestermites' or osmosis, but rust worms are always hungry to attack a steel trailer. They find the easiest parts to start eating are welds and hidden cavities, where water-retaining muck can gather. Even when the trailer has been hot-dip galvanized after assembly, welded joints may flex in use and crack the galvanized skin. This shows up as thin brown lines, and if not treated, rust will continue to eat away at the joints. If the trailer is painted, treatment means using a pot of chemical intended to stop rust on car bodies, followed by plenty of zinc-rich paint. It may not be a good idea to use passivating chemicals on galvanized metal, but on a dry day, after the crack's interior is washed dry with methylated spirit, sealing it with zinc-rich paint will be worthwhile. Lubricate any rollers. It may only be possible to work some grease in so do a proper job when the boat is off the trailer.


The life of a tyre is not infinite. According to the Tyre Safety Council a tyre lasts five to seven years after which, irrespective of whether it has more than the legal minimum 1.6mm tread depth, it should be replaced. If you are trailing aboard, your tyres need 2mm tread depth all over. The tyre's week of manufacture is shown on one of the sidewalls as a four digit code. The first two are the week number, the second pair the last two digits of the year. The sidewalls also state the maximum weight and tyre pressure. Much more information about tyres is available online from

Leaving the trailer standing all winter with the full weight of the boat on the tyres is unwise. If the trailer is fitted with tyres that need something like 70-80psi pressure, it may be easier to take them to a suitable pump before returning them to the trailers axle. Take care when inflating them to these sort of pressures - bear in mind that lorry tyres operated at such pressures are inflated in special safety cages. Before returning the tyres to the trailer, inspect the sidewalls for damage, like cuts or slight bulges. This is much easier to do when the wheels can be inspected without having to crawl under the boat. Use permanent marker to write correct tyre pressure on mud guards and make a note if left-hand threaded nuts are used.


The prudent owner will have left the trailer with the hand brake off, and with the brake cable slackened. These precautions allow for the fact that rust will grow on the inner faces of the break drums, and may bridge the tiny gap between the shoe drum, seizing them solid. If that happens, a significant expenditure of expletives and use of a big hammer may be needed to make the wheels turn in the spring. Modern trailer brakes are required to automatically disengaged when the trailer is reversed, so this maneuver may release winter seized brakes. Wipe a greasy cloth over the sliding parts of the auto back-run release system inside the brake drum to aid rust resistance. It is worth pointing out that these types of brakes are useless when reversing down a slipway. The mechanism does not know the difference between the wheels rotating backwards when pushed by the car, or when pulled backwards down a slope by gravity. Re-tightening the brake cable and checking that the handbrake works also confirms that the brakes should work properly when being towed. If the brake shoes need replacing, it may be better going to a specialist - some shoes are held in place by seriously strong springs. With the drum off check the cable linkage works freely. Lubricate the cable tension balancing pivot mechanism with grease.


The market for boat trailers is not huge in the grander scheme of things, so there are few items of kit like axles and hub assemblies specially made for submersion launching, complete with the 'double seals' needed to keep the grease in and water out. Instead there are two main types of bearings: tapered roller and cartridge type. Little can be done with the latter, other than make sure there is a rust-preventing film of grease where the seals contact the shaft. Accessing the brake shoes for inspection may mean removing a brake drum that is also the bearing housing. If the hub holds tapered rollers they'll need careful setting up on reassemble. If they are correct before the hub is removed, mark the compression nut so it can be re-tightened to the same place later. Taper bearings need lubrication. Filling the entire hub with grease leaving no space for water to enter, can make up for the lack of 'double seals' on submersion launching trailer. But if you copy this method, great care is needed to prevent the excess grease reaching the brake shoes. If water does not get past the seal, the small 'garter spring' that holds the seal's lip against the shaft can rust and fail. The bearing will then be none too happy if water can enter freely, nor the brake shoes work well if the grease escapes. Replacing taper bearings is not difficult. Their identification numbers are engraved on the side of the shells, and are recognized by bearing stockists. Keeping old bearings as spares is a good idea, as in an emergency they may be better than ne ones which have quietly rusted away while you were off sailing.

Wheel Nuts

Few people set off on a trip without first checking that the wheel nuts are tight. However, doing so with a spanner to make the nut squeak each time is bad practice. Each squeak stretches the stud a fraction, inducing a stress that will eventually make the stud suffer from fatigue failure. Always use a torque wrench if you want to keep the wheels on your trailer.

Tow Hitch

On trailers fitted with brakes, the tow hitch has a mechanism that applies the brakes as the car slows down. Springs and dampers ensure that the brakes are applied progressively, not slammed on the moment your foot is lifted off the accelerator pad. Greasing the sliding parts ensures that they work freely, and operating the handbrake lever reveals which parts move and will thus benefit from being oiled properly. Smear grease inside the tow hitch cup - unless it has a friction grip stabilizer which requires the ball to be grease free. Check the gaiter for damage, and replace if damaged. A new gaiter will probably stretch enough to fit over the head of the tow hitch. Grease the hydraulic damper housing. If the trailer 'knocks' against the tow hitch when braking or accelerating, replace the damper as soon as possible. If the trailer ever breaks free from the car, perhaps because the tow ball breaks off - I have seen this happen on caravans in front of me - the break-away cable must be strong enough to apply the handbrake. But it must not be so strong as to damage the bit of car it is attached to before it breaks off. It is worth never looping the cable around the tow ball's neck, and always check that it will work as intended. If the trailer is small, a check-chain can be used to keep the trailer attached to the car if the primary tow hitch fails.


Stabilizers nearly always rely on friction to prevent a trailer from starting to sway from side to side - swaying that can build up to a wild, uncontrolled fish-tailing. Some stabilizers grip the tow ball with a passion equal to that of a miser holding a five pound or dollar note!! Others are attached to the car and have a pivoted arm attached to the trailer, via a joint that is reluctant to bend due to some kind of internal friction arrangement. Where there is friction there is wear, and if one of the wearing parts is steel, once the wear stops rust wants to attack the bright face. Thin rust rapidly wears away, but has more friction than bright steel, so it is better to remove it before checking that the stabilizers work properly. The friction pads also wear, and so need checking. One test to check that everything is OK before setting off is to use a vice to duplicate the cars mounting point, and then try to move the arm in the same manner as the trailer when it tries to 'snake'. Or simply mount it on the car and move the trailer like it would when it trying to wag out of control.


The trailer's lights need to be checked before setting off, and any deficiency such as a poor earth producing a dim bulb needs to be rectified. Dim bulbs may also be due to poor connections, or short circuits. It is worth checking that spare trailer bulbs are stowed in the car. Attach the lighting board to the car's socket, and check all the lights. Check the indicator repeater on the car's dashboard functions when the trailer is plugged in.


The trailer winch will be a lot easier to use if it is lubricated. Hub bearing-grease will protect gears and the ratchet spring from the elements. The bearings will benefit from oil. It is important to inspect the whole length of the strop, as UV light and mold can wreck it especially the top layers. Providing there is enough length left to cover the boat, it may be prudent to chop the end off and re-secure the hook to strong material.

All-Up Weight

Boat builders seem to understand the weight of trail-sail boats to make them appear more road friendly, and by the time the boat is ready for the sea it may have increased in weight by as much as 25%. It is best to tow the boat to a weigh bridge for guidance, you may need stronger axle, brakes and tyres. If you know a trailer is overweight you might be able to make a single cautious journey. But if you know it is, then something is bound to give and fail sooner or later, and trailers do not work well with an absent wheel!!

Other checks before hitting the road

Outboard engine

Ensure there is no petrol left in the tank from the previous year: using old petrol with new is a guaranteed formula to create problems with running and starting. Donate end of season petrol to your car, or if doped with 2-stroke oil, donate it to a car without a catalyst converter. Take the engine cover off and spray the engine with WD40 or a similar protective product. Check for white powder around water jacket gaskets - if it comes from internal corrosion then WD40 will not help. Some engines have brass thermostats that cause internal galvanic corrosion once the paint skin on their housing fails. You can replace the function of the paint skin with a thin, rigid plastic gasket cut to the same shape as the water jacket cover. Check the leg anode - if it is white from running in fresh water, use a stainless steel wire brush to remove the white film and expose fresh zinc, as the film can kill an anode's function in salt water. Think about the need to change the gear oil and impeller, plus any other annual service requirements. Check the propeller bag is still in a useable condition.


The trail-sail boat shipper can easily examine rigging, looking for any kinks that will fatigue fail, and feeling for broken strands. The most important part to examine is the top of the forestay if there is a roller-reefing foil, because the wire can be bent here during mast raising operations. Bottle screws are also easy to bend when raising a mast and bent stainless steel is an unreliable way of keeping a mast up. Each lurch of the boat fatigues the metal as it seeks to straighten out.


Air pumps at a garage forecourt create too much pressure, so it is safest to pump the fenders at home


Hopefully it was stored on a bench somewhere dry over winter, away from a cold concrete floor whose chill will limit the general circulation of the electrolyte as its density alters slightly. When checking the electrolyte level and its specific gravity, remember that battery acid burns skin and ruins clothes.

It is prudent to check both navigation lights work but also change UV damaged lenses. Even if there is no intention to sail at night, getting caught out at dusk is the wrong time to wish the lights were brighter. There is no need to raise the mast to check its lights if a multi meter is handy. Set at almost any Ohms scale, it will report if there is or is not a connection. Check for corrosion of the plug and socket, and be aware that copper wire may be rotten inside its PVC sheath if the strands are not tin plated.

Car tyres and Tow bar

Check the car's tyre pressure and condition. Also, check the state of the tow bar mountings, or ask for written confirmation that they are sound when the car passes its MOT.


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