Select Page

There are less maintenance tasks to carry out on a saildrive transmission than on a traditional inboard shaft drive system with its associated stern gear. For example, you don’t have to worry about engine alignment, cutless bearings and stern glands. I owned a boat for seven years that had a Volvo Penta saildrive transmission system and this caused no problems during my ownership. The same applies to Yanmar saildrive systems.

However, there are a few critical things that require maintenance. These are as recommended in detail by the engine manufacturers and should be adhered to.

Corrosion

  • Drive leg housings are made from aluminium and they must therefore be well protected from corrosion, requiring a special copper-free antifouling paint, plus undercoats. The housings also need dedicated sacrificial zinc anodes to prevent them from galvanic corrosion.
  • Carefully inspect the drive leg for any damage to the paintwork. Any exposed aluminium will quickly corrode in salt water. Look for any white corrosion beginning to form on places where paint may have been chipped off. If any such damage is found it will need to be ground back before the unit becomes seriously damaged.
  • Anodes are designed to protect saildrives from electric currents generated while in sea water.
  • The electrical system of the engine will need to be an isolated system and not one which is grounded to the battery negative.
  • When a non-aluminium propeller is fitted, additional anodes are required.

Oil change

  • Regular checks of saildrive transmission oil are important. Any signs of milky coloured oil indicate water has found its way into the system. This could occur because of a shaft seal failure or defective drain plug seal.
  • Manufacturers usually recommend that the transmission oil is changed annually, which can only be done ashore by draining the oil from the base of the leg. On some systems the oil can be removed using a hand pump operated from the engine bay. In order for the oil to drain completely, remove the filler cap on top to allow air in.
  • Always use the manufacturer’s recommend oil and be careful not to overfill the system.
  • Be aware that some manufacturers recommend a torque setting for the oil drain plug and also advise that the seal is replaced regularly, because if there is the smallest crack in the rubber seal it will leak.

seal saildrive maintenance

Rubber seal

  • The saildrive leg passes through a thick rubber seal that attaches to the base of the hull. Yanmar sail drives differ from Volvo Penta so it is worth checking with the manufacturer’s recommendations. Volvo recommending replacing seals after 7 years while Yanmar recommend replacing their sail drive seals every two years, which is quite a difference. Replacing sail drive seals is a fairly major job which has to be done ashore and entails lifting the engine. The part itself is pricey but significant additional cost needs to be factored in for the engine lift and labour involved.

Tidal heights and the rule of twelfths

For those skippers who need to make a quick calculation or don’t have access to specific tidal curves for their location, it is possible to make an approximation using a system called the Rule of Twelfths. This is a simple method used to estimate the height of tide at any given time during the tidal cycle. It is based on the idea that the rise and fall of the tide is not constant, but follows a predictable pattern than can be divided into twelve parts.

How to operate a winch

Winches are drum shaped mechanical devices used to handle halyards, sheets and control lines. One of the important crew...

Boat Engine Failure – what to check

Engine failure If your engine fails or is overheating there are a number of things to check immediately: • Air filter...

Hourly Checks when sailing or motoring

  Hourly Checks Get into the habit of carrying out these checks and both yourself, your crew and your boat will be...

Steel hull maintenance

A steel boat owner’s biggest enemy is corrosion. You don’t have to worry about osmosis or rotting timbers, instead rust is the number one issue that will keep you awake at night.

Essential Knots: Clove hitch

Essential Knots: Clove hitch Use: Tying a rope to posts, bollards, rings or a guardrail. Step 1. Make a turn around the object and lay...

Boat electrics

All boat owners should have a basic knowledge of electrics, both to avoid encountering electrical problems at sea and to stand a chance of solving them should they occur.

Boating emergency – how to broadcast a MAYDAY emergency call

How to broadcast a MAYDAY emergency call   How to broadcast a MAYDAY emergency call if a vessel or person is in grave...

Top 5 Reasons Why an Inflatable SUP Should Be Your Next Yacht Accessory

In this article, inflatable paddle board expert Jason Paul gives the top 5 reasons why an inflatable SUP should be your next...

Boat Improvements

My Boat - practical improvements Author - Mike Rossiter Most boat owners who have had their craft for any length of time will have made what they...

Boat batteries

Under-sized battery banks are one of the key factors behind power failure at sea, as well as the premature failure of batteries, so make sure that your boat battery measures up to the use you want to put it to.

An explanation of the IALA maritime buoyage systems – IALA A and IALA B

What are the differences between the two IALA buoyage systems, IALA Region A and IALA Region B, and where are they used?   As recently as the 1970s...

Essential Boat Safety Briefing

Skippers Responsibilities Skippers are obliged to give a safety briefing to the crew even if they are a regular crew. At...

Boat maintenance log

Keeping a boat maintenance log is an ideal way of reminding owners what needs to be done to a boat and when. Read on for some tips,...

Boatyard Health and Safety

Boat storage facilities are potentially hazardous environments and it is the responsibility of both boat owners and boatyards to ensure that the...

The Boatyard Book – a boat owner’s guide to yacht maintenance, repair and refitting

The Boatyard Book is a fully illustrated 224 page practical reference manual that provides advice for boat owners on planning and carrying out annual maintenance, repairs, upgrades and refits of sailing yachts and motorboats, up to 20 metres in length.

Care of boat batteries

Boat batteries need to be kept properly charged, which means never allowing the batteries to discharge below 50 per cent of their total charge. As well as the batteries themselves, keeping a boat’s charging systems in good shape will also help to keep batteries topped up to a higher level of charge.

How a propeller works

Have a look around any boatyard and you will notice quite a variety of propellers – some have two blades, some have three and others have four or more. While most propellers are completely rigid some have blades that fold.

Steel and Aluminium Hulls

The two metals used for hull construction are steel and aluminium. These are both very strong materials and will last a long time as long as they are cared for, which primarily means protecting steel boats from rust and aluminium boats from electrolytic action.

The VHF DSC Radio jargon buster

AIS - Automatic Identification System This system is used by shipping. It allows another vessel or coast station to use...

Understanding boat engines

Irrespective of what kind of engine a boat is equipped with and who does the work, the regular care and maintenance of a marine engine is essential. The most common cause of marine engine failure is widely known to be lack of maintenance.

Dag Pike’s Boat Survey

We're really pleased to be working with Dag Pike on some great new apps for iPhone & Android. Here'a a bit more about the first app: Dag Pike's...

Estimating and plotting your position at sea

This post covers how we go about estimating and plotting our position using traditional methods, when out of sight of land – covering Dead Reckoning, Estimated Position, Tidal Streams, Leeway and more…

Sterndrive maintenance

Sterndrives are a popular form of propulsion in the powerboat market, but require a fair amount of care and maintenance. The main factors to be aware of are salt water corrosion, lubrication and regular inspection of the bellows, the condition of which is vital to prevent water from entering into the hull.

Diesel engine winterisation

An inactive boat engine needs to be protected from corrosion during the winter, caused by the rising humidity levels through the cold months and the salty coastal air. This applies whether the boat is left afloat or hauled out over the winter. Read here about the two important stages of winterisaton for a diesel boat engine.