Sterndrive maintenance
The Surveyor* says spend a little money regularly to save you a bomb in the long runAfter 19 years of having a repair business on a slipway, I was amazed to hear the same response, time after time, from boat owners who had just been slugged with a major repair bill from the resident mechanic...
"But I hardly used the boat in the last 15 months."
Yeh, well, that says it all…
Sterndrives —or as I learnt after a recent US visit where they call them outdrives (and, of course, we sometimes call them just ‘legs’) — do need regular maintenance and a strict schedule should be followed.
With sterndrives, spending a little money regularly will definitely save you big money in the long term.
WHAT IS A STERNDRIVE?
A little knowledge on what makes sterndrive
A sterndrive resembles the lower unit of an outboard and has two halves.
The top half is connected through the transom to the power supply, that being the engine, via a gearbox. The lower unit has another gearbox.
Between the two gearboxes is a vertical drive shaft.
Both 90 degree gearboxes in the upper and lower halves do the job of transmitting engine power to the propeller shaft at the bottom end of the 'leg'.
Both Mercury's MerCruiser and Volvo Penta’s Aquamatic stendrives are an effective way of transferring high power output via the inboard engine to the outdrive and propeller for top performance.
The sterndrive itself pivots to create the steerage and propulsion unit in one, eliminating the need for rudders.
For boats moored in a saltwater environment, you can still have the great performance. It just means your sterndrive will require a stricter routine servicing arrangement than trailerable and/or freshwater rigs with ‘legs’.
Along with the “spend money to save money” saying comes the advice to “use it or lose it”.
EXPERT TIPS FOR STERNDRIVE MAINTENANCE
- Here are some tips and pointers to help you maximise your time on the water and save you on those hefty mechanical bills
- >> Service your sterndrive every six months. Change oils, anodes, gaskets, etc, which will require a haul-out or slipping.
- >> Replace bellows and clamps every 12 months. Ignoring this maintenance task is one of the traditional causes of expensive sterndrive failure.
- >> Re-apply the antifoul coating every 6 months. The antifouling used on the sterndrives does not contain copper due to sterndrives having a cast aluminium housing. Its performance is limited and do not expect it to perform as well as your hull coating.
- >> Inspect and replace the cathode and anodes on a regular basis. If you are going through them at a high rate, you may have other corrosion issues at play (covered in previous articles).
- >> Keep the sterndrive clean from marine growth. Using it regularly takes care of this, otherwise have a diver clean it down. (Take care when using a scraper in and around the rubber bellows).
- >> Never leave the sterndrive trimmed up in the water for an extended period of time. In this position, marine growth on the stainless ram can damage the seals to the ram cylinder.
- >> Maintain your propeller coatings and keep them clean. Not only does marine growth cause the propeller to become unbalanced and cause vibrations, this in turn reduces the life expectancy of the bottom seals, which can allow water into the casing and damage the gearing.
- >> Repair any damage to propellers. No matter how small the damage, as mentioned above, props become unbalanced and can damage the lower seals.
- >> Always use a qualified marine mechanic. This is essential for all sterndrive services and repairs.
But for all sterndrive owners, always freshwater flush the engine and drive after use. A good washdown is recommended to remove any excess salt water from the surface.
ED: It’s also worth investing in some added insurance by way of the
QL NeutraSalt or Saltaway flush system, both of which can be
installed aftermarket for <$1k. The QL system is often fitted to new boats here by the more experienced dealerships.
Volvo Penta's OceanX sterndrive has a specially developed titanium-ceramic coating and a drive monitoring sensor package (petrol only) to help guard against corrosion as well.
Finally, for my trailer friends, please trim the drive up before leaving the boat ramp!
I hope by following these simple tips you can maximise your time on the water and save you money as well.
Next we will look a t the exhaust system including risers and manifolds and their importance and overall well-being to your engine long-term.
*Gavin Clark is a contributor at boatsales.com.au and BoatPoint.com.au who writes under the pseudonym 'The Surveyor'. He is a shipwright and marine surveyor with a business called Slipstream Marine based in Sydney. Gavin has 28 years experience in the boating industry, is an avid boater and owner of a 33ft Sharpie (trawler). Gavin can be contacted at http://boatsurveying.com.au.
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