Boat trailer maintenance

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Paul Walker
21 July 2017

Many people stow away their boat over winter, however proper care and inspection is essential to ensure springtime doesn’t become an expensive repair exercise.

When winter is now well and truly with us, a reminder of the damage that can be done over this period by the lack of basic preventive maintenance seems appropriate. This applies to your pride and joy: the boat, the outboard, the trailer and all the electrical gadgets that go with it.

There is a big investment here so it seems foolhardy to let it deteriorate and rot over winter when a small amount of effort on your part could head off a lot of trouble keeping your boat in good nick.

I work in a tackle and boat sales business and have seen what salt-water corrosion can do and know the high costs of repair – yep, big money!


In this issue we will cover boat trailers, as they are the most vulnerable to corrosion in the boating package. Next issue I will look at the boat and outboard in the next issue as getting the trailer up to scratch may keep you busy for a while unless you’re one of the lucky ones that has a new or near new trailer.

The frame

These days most boat trailers seem to be made of galvanised box section steel. Every time the boat is launched salt water fills this box section. As the trailer dries in the car park the salt remains to do its nasty work by getting into little pinholes in the galvanising.

Step 1: Having removed the wheel proceed to  remove the U bolt and plate.

Over a period of time rust and corrosion will eat your trailer from within unless washed thoroughly (with out fail) every time you launch the boat in salt water. Thorough washing may not stop corrosion but it will slow it down and there are some products that will help effectively combat the corrosion. Products such as Salt Away or Mac’s Salt-Enz are salt killing solutions with have their own dispensers. They attach to your garden hose allowing you to spray deep into the box sections. Spray from both the front and rear of the trailer to penetrate the areas where salt can settle.

Step 2: Remove eye bolt.

If you haven’t previously used this type of product give serious consideration to using it in the future. Spend some time washing down the trailer getting into all the little nooks and crannies as a little extra time spent here could save a lot of money in the long run. A mid-sized trailer is about $3000 or more to replace

Step 3: After removing U bolts and eye bolt, slide spring backwards to remove and replace with new springs.


Modern trailers with multi rollers, sometimes known as wobble rollers, pretty much look after themselves and need very little maintenance. Every now and then after launching the boat spend five minuets checking all the rollers for cracks and wear.

Should one need replacing this is a very easy process. Just pull out the split pin, slip off the washer and old roller and replace with a new one. Pop the washer and split pin back on - job done.

Step 4: Springs can now be replaced, proceed to reconstruct in the reverse order until complete.

Occasionally it might pay to spray some lube like Inox, into the joint of the pivot bar that holds the rollers. That’s about all that is needed with multi-roller trailers.

Older styled trailers will need a bit more work. Keel rollers or any rollers that have a tighter fitting centre pin will require you to dump the boat (maybe on the lawn) while you draw out each pin one at a time. Grease each pin, then replace.

Hand winch, jockey wheel and tow coupling

The winch is a fairly basic machine and really only needs grease on the cogs and oil on the moving shafts a couple of times over the season (including winter). Pull out all the winch rope and check to see if it needs replacing. Grease both internal sides of the rope drum while the rope is unwound as a lot of salt water comes in on the rope, which then lies against the drum causing it to rust.

Step 1: Punch out the old cones from the hub.

With the amount of winch handle thefts that take place at boat parks each year try drilling a small hole at the end of the handle shaft which can take a small removable lock pin. This allows you to take off the handle after use and lock it in the car boot.

Step 2: Have your new bearings ready to insert.

The jockey wheel is similar; make sure the main shaft and the mechanism it pivots on is always greased. Oil the handle knob and check the tyre for cracks where the shaft goes through (apply some grease to the shaft as well). If the tyre is an inflatable type keep it inflated. Many jockey wheel tyres come in to our workshop flat and absolutely stuffed (another avoidable expense).

Next time you’re fuelling up the boat take an extra ten minuets to check the trailer tyres and jockey wheel for pressure.

Step 3: Make sure you purchase exactly the same bearings to replace the old ones.

Tow couplings are pretty important so make sure all is in proper working order. Grease and oil all moving parts but before you do have a quick look up inside the coupling for any wear that might stop it locking down on the tow ball.

Also check the bolts and welds that hold the coupling to the trailer frame as well as the safety chain with its D-shackle.

Step 4: Replace the cones first.


Unscrew and take off both sets of lens covers looking for blown bulbs and corrosion on exposed wiring. Corrosion can be mostly removed by spraying with Inox. After a few hours give the wiring a scrub with an old stiff toothbrush. Rub a little Vaseline around the lens covers to seal them against water. If the lighting components are looking a bit sad consider replacing with new L.E.D lights. Note: before removing the old ones unscrew the top plate of the wiring connector plug and photograph it so you can remember where all the wires go.

Important: Heavily grease cup bearings before installing and putting everything back in place.

After removing the old lights use the existing wiring to pull the new stuff through the box section frame. Tape the ends of the old and new wires together and pull them out of the exit hole at the coupling end at the front of the trailer. Do this on both sides.

Now comes the tricky bit; with a blade or side cutters remove about twenty milimetres of plastic sleeving and expose the copper on all the coloured wires. Twist all of the same colours together making sure the copper is tightly twisted together. A small dab of solder may help here.

Following your photograph fit them into their correct slots and tighten the locking screw hard. Now replace the cover plate and plug it into your vehicle. Test the running lights, brake and indicator lights. Hopefully it all works, if not there’s always the local auto electrician.

Replacing springs

Quite often springs may look rusty but they often have a lot of meat left in the steel. A good clean up is all that is required. If it is time to replace them it’s actually not too difficult on most small to medium sized trailers to do it yourself.

It’s not necessary but you may find it easier to take the boat off the trailer before placing a jack under the axle. Remove the wheel, then lift the trailer to a comfortable height and place two safety stands at the front and rear of the trailer. Leave the jack to support the axle. See the photos for the following steps.

You should find two U bolts over the axle locking into a square steel plate - remove these.  Undo the eyebolt at the front of the spring that locks it to the trailer. As you pull this bolt out the spring should drop down.

The rear of the spring should be slipped into a u shaped saddle welded to the box section - slide the spring forward and remove. Take an old spring with you when you buy new ones. Check the U and eyebolts as well. Galvanized springs are better value.

Putting in new springs is a matter of doing the same procedure in reverse.

There should be a locating lug in the centre of the spring which should slip into a corresponding hole in the axle. Once this is done the U bolts can be locked back into the steel plate. Taking photos can help remember how it all goes together.

With the boat off the trailer check all the nuts and bolts replacing any one at a time so everything stays in place and the frame doesn’t disassemble itself. Any nuts that are too rusty to undo cut off with a small angle grinder. Try not to cut the galvanizing.

Wheel bearings

I personally believe this is a job for mechanics or people with good mechanical knowledge as it can be disastrous if you get it wrong. Take your time and take care.

You don’t have to remove the boat from the trailer. Use the same jacking procedure as above. Remove the dust cap or bearing buddy from the hub then dig out as much grease as you can. You will find a split pin through the stub axle with a large castle nut behind it. Remove both of these. Pull the hub toward you; hopefully it will slide off easily. See the photos for an illustration of the following procedure.

Wheel bearings are made up of two parts: cups and cones. The cups should pull out of the hubs with your fingers. There are two sets of bearings in the hub- front and rear.

The cones will require a hammer and punch to remove. Clean once removed (you will notice the rear ones are bigger than the front ones). They will also have coded numbers printed; take the old ones to a local bearing suppler and replace with the same ones.

When installing the new ones first pack the new bearings and inside hub with marine grease. Carefully punch the new cones down inside their respective sides of the hub until they reach the stopping lip. Place the rear-bearing cup into the hub and slide the whole unit back onto the stub axle. Once in, place the front cup into the hub and replace the castle nut and split pin.

This is a great time to throw away the old dust caps and replace with a set of bearing buddy’s. Use the old dust caps for sizing. With the new bearing buddy’s hammered in nice and tight get that grease gun and pack the hub with marine grease before replacing the wheel- give it a spin, job done!


All the products mentioned in this article should all be available at good service centres, chandlery stores, auto stores like repco or super cheap and bearing suppliers.

By getting your trailer up to or better than WoF standard over winter you won’t have any trouble over the fishing season, leaving you more time to fish.

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