Yacht stabiliser maintenance
Written by Michael Henson | With thanks to
Most vessels will have some form of stabiliser on board, whether it’s fin or gyroscopic (gyro), this is because nowadays these stabiliser systems have reduced in size enough to be practicable for boats as small as 10 metres. But what is involved to keep a set of mechanical stabilisers operational?
The majority of mechanical stabilisers use fins to create forces opposite to the direction of roll, thereby damping it - this is known as roll dampening.
Mechanical stabilisers have lots of moving parts that need maintenance. The fins and cylinders move endlessly to keep the hull level, directed by a vast range of sensors such as motion, speed and position, which in turn are all linked together through a digital control box.
In general, stabilisers require very little daily maintenance and don’t tend to take up much of a yacht engineer’s time. This is because the maintenance checks mimic a lot of what they would already be doing as part of their yacht engine maintenance, i.e. fluid levels and pressure checks, greasing, checking seals for leaks, oil filter replacements etc... However, occasionally more complex services are necessary, some requiring the boat to be hauled.
What maintenance to carry out
Create a maintenance schedule
Firstly look at the maintenance schedule included in the stabilisers operating manual and compare it with your yachts maintenance logs. Manufacturers generally provide both service hours and real-time intervals for each part. So simply work out what part needs maintenance when. Regular maintenance is the key to making any mechanical part last.
Healthy oilHealthy hydraulic oil should be honey coloured. If it’s overheated it will turn darker, if the oil is black then it’s been polluted, maybe by a leak from a bad seal; check this immediately as this is a clear warning sign that something is broken.
Overheated or contaminated oil must be changed, ideally by pouring the fresh oil through a paper strainer in a clean funnel. Change the oil filter element, too. It typically takes a couple of changes to get all the contaminated oil out of a system.
Even if the oil looks fine, most manufacturers recommend having a sample analysed yearly for contaminants, just like you do with your engine and generator lube oils. Excess wear in the hydraulic pump can lead to metal particles being present in the oil, indicating it’s time for a replacement.
System hosesSystem’s hoses need changing every five years, but inspect them yearly. It’s not expensive, but if one was to blow, the cost of the damage would be. Overheated oil can degrade the hoses more quickly, so they will need replacement before the scheduled interval (again more reason to ensure the oil is as healthy as possible)
When replacing the hoses, it is recommended to research suppliers of higher quality hoses than the one included with the stabiliser system initially. Some manufacturers provide weaker hoses as standard, with better ones as an upgrade. Always use the best hoses available.
Hydraulic oil cooling unitsThe hydraulic oil cooling units on stabilisers use heat exchangers, which with regular maintenance should keep the system operation at optimal efficiency. Steps to ensure the cooling system is working appropriately are needed. Change the raw-water impellers on schedule and check the zincs. Again treat the stabiliser system heat exchangers like the ones on the yacht engines and check the oil temperature regularly.
The surprising thing is, for such a mechanically complex system, stabilisers are relatively trouble free/easy to maintain.
Even though stabilisers are sophisticated systems, their designs make them extremely reliable.