Don’t make simple inch/millimetre conversions – 25mm is not exactly the same as 1in. Propshaft diameter A vernier gauge is useful here.Some seals must be ordered for your exact shaft size and stern tube size, while others have some adjustment and fit a range of sizes.īefore you order a new dripless stern gland, you’ll need to know the following:
Most require a pressurised water feed to keep the seal lubricated and cool. Lip seals are similar in appearance but seal via a lip, or sometimes two, which bear upon the shaft itself. Both types use an articulated rubber sleeve to keep the water out, but face seals use a collar, clamped to the shaft, that bears upon a surface on the end of the articulated hose. Seals can be divided into two main groups – face seals and lip seals. Other types and makes can be found in use – some, like the Halyard oil-filled seal, are no longer manufactured but are still giving sterling service. There are five main makes available in Britain – Tides Marine, Volvo, PSS, ManeCraft/Deep Sea Seals and Vetus – offering what are known as ‘dripless’ shaft seals, claimed to be completely waterproof for leisure craft. Nowadays there’s a much wider choice when it comes to stopping the water coming in via the stern tube. Many boat owners want their bilge to be as dry as the rest of the boat. That was fine back in the day when boats were built with deep bilges and tended to leak at the seams anyway – but modern, leak-free boats with shallow bilges are different. But even a well-adjusted stuffing box should drip into the bilge around once per minute. The once-ubiquitous stuffing-box stern gland still has much in its favour – it’s simple, tried-and-tested and easy to repair and service.
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