Buying a second hand Navik self steering system

Navik Self steering systems

Navik self steering was discontinued by Plastimo in 2007. Mister Vee took over spare parts manufacturing and delivery shortly after.

The design shows details that are only possible when you have access to manufacturing on a scale like plastimo has.

Because the relatively small demand for spare parts the ones from Mister Vee are not made the original way but have been redesigned to suite alternative manufacturing methods.
Mister Vee primarily focus on the parts that are not made from metal and that can easily be lost or broken, or wear out over time.

As part of the business of supplying parts I often receive pictures of second hand systems, with the request to see if anything is missing or seems wrong.

Here is a list of things that can be wrong with a Navik self steering system:

- Mounting brackets are missing
People often take the system of the boat but leave the brackets on. Then sell the boat with the brackets still attached. The mounting brackets are the only metal parts that Mister Vee provide.

- Dislocated end fitting on the pushrod
The ball connectors at the end of the connecting rod are attached to a threaded insert which occasionally works itself loose. These can be glued in as a repair but one side has a rotating bolt in it. If glue gets in this joint then the windvane can no longer be rotated to set the course.

- The wind driven bits have had their weight or balance altered
If the repair of the connecting rod goes wrong, or the rod goes missing, some people make their own replacement. If this replacement has a different weight than the original, this may affect performance. 
The weight of the connecting rod is counteracted by part of the counter weight for the windvane. The weight of the counterweight and the connecting rod together offset the weight of the windvane above the axis of rotation.

Some people paint their windvane, as part of maintenance, or as a design feature, for instance by adding a flag. This may affect the balance of the windvane and if the windvane becomes top heavy, the steering will become unstable, resulting in a zig-zag course.
If the imbalance of the connecting rod and the counter weight becomes too big, it will become hard to set the course correctly, the system will have the tendency to steer away to a particular side.

Mister Vee offer a replacement connecting rod who's weight is matched exactly to an original connecting rod.
For other systems people sometimes make their own larger light weight blade. This can also affect the balance of the windvane-counterweight combination. If the centre of gravity ends up lower than it was with the standard blade, the light air performance my actually be reduced, despite the larger size as the wind now also has to lift the counter weight, instead of just moving it.

- Broken windvane
The windvane is made from a rather brittle resin. This can break but is repairable. Check the weight beforehand and try to get the weight and balance the same after the repair.

- Broken turret
The turret is what holds up the axis around which the windvane rotates. his is made of plastic and it can break. To repair it, do not trust glue alone, use a mechanical connection too.

- Turret parts get loose or go missing
The turret can rotate inside the stainless steel mast. There is a short piece of glass fiber tube connected to the bottom of the turret that slides inside the mast. There are two sleeves around this tube that act as a spacer between the outside wall of the glass fiber tube and the inside of the stainless mast.
The glue connecting the tube to the turret and the sleeves to the spacers can work itself free over time. The sleeves and the tube often fall inside the mast and can be recovered from the bottom of the mast to then be reglued. I'd prefer polyurethane glue like sikaflex for this, but if none is available, polyurethane wood glue also works.

- Broken or missing jointed connector
Mister Vee offer a replacement.

- Connections from the jointed connector down are loose or have been welded
- The trim tab has been welded or otherwise repaired.
The connections from the jointed connector down are what I considder the achiles heel of Navik systems. They use tiny mechnical connections, which if you are unlucky fail in a hard to fix way. Whatever you do, do not be tempted to weld them!
If the small "tiller" at the top of the trim tab shaft gets loose, I can make a replacement

- The paddle is broken
This is usually because of being hit by another boat rather than during general use.
The paddle is made from the same or similar material as the windvane and thus can be glued. However, there is a stainless tube inside that can be bent as part of the damage. It is hard to bend this back to ist original straightness without damaging more of the blade.
It also happens sometimes that one of the hinges for the trim tab break free from the trailing edge of the blade. If you still have the hinge, it can sometimes be sculpted back in with epoxy putty, if you do, make sure to keep the alignment of the axis for the trim tab straight!

- The pendulum rudder shaft is bent
The bottom of the rudder shaft is 15 mm rod welded to a much larger diameter tube. The 15 mm rod can be bent in extreme cisrcumstances. Bending it back is more about getting feedback on the amount of bend than anything else. If you can support the the tube on vee blocks you can easily check for straightness of the 15 mm rod by rotating the rudder shaft on the vee blocks. If the 15 mm shaft is propperly aligned with the rest of the rudder shaft, there will be no visible wobble in the 15 mm rod. It will probably be hard to get zero wobble but little wobble will likely be fine.

- The wooden quadrant is broken
Apply some wood working skills.

- Parts get misaligned or poorly adjusted
-- Mister Vee tiller
The Mister Vee tiller for the top of the trim tab shaft has no locating feature like the original does. This means that it can be mounted at an angle which it should not be.
The same goes for DIY repairs, which sometimes also gives a poorly aligned tiller.

- The cradle (aluminium) is cracked
If this happens to you, welding is the only option besides finding a replacement in the second hand market.

All of this leads to general maintenance:

• All joints should be slightly loose. If the are stiff, light air performance will suffer.
• Never use grease or oil on any of the bearings, this will gum up leading to stiff bearings and poor light air performance.
• Salt crystals can build up inside the bearings, increasing friction. Rinse with luke warm fresh water.
• Bearings can wear out over time. At some point you may want to replace them, Mister Vee offer spares.
• Stainless steel will often corrode at sea. You can use a new green scouring pad for the kitchen to rub most off, and use a 4% citric acid solution to try and neutralise the oxidation.
• If you want to use sandpaper, use new and unused, if you use other tools, beware that if those tools have been used on normal steel the tool can introduce iron to the stainless steel, giving a starting point for corrosion.
• Never, ever use a steel-wire brush on stainless steel! Use brass or stainless steel-wire instead.