PACKING THE STERN GLAND
The role of the conventional stern gland is to keep water out whilst allowing the shaft to turn. Brass collar stern gland have a tacky rope like material inside which is squeezed by either a large nut or sleeve to stop leaks.
Packing The Stern Gland… Preparation Is Key!
It is common to tighten the stern gland if your narrow boat is taking in water; it is important that the stern gland is not over-tightened resulting in room for no further adjustment if another leak occurs. A small amount of leakage is to be expected, around a drip once or twice a minute is normal. Once you have about 12mm of adjustment left you will need to start thinking about re-packing the gland.
Repacking the stern gland is commonly executed whilst the narrow boat is in the water. The amount of wear to the front the gland will indicate how much water is likely to leak when the packing is removed. On minimal wear, using the greaser prior to removing the old packing may seal the shaft. Alternatively your bilge pump will cope with a greater volume of water.
The key is to have all your tools and materials to hand once you start this essential piece of narrowboat maintenance.
Packing Types & Sizes
Packing generally comes in 3 sizes; 6mm, 8mm and 10mm. Your narrowboat handbook/manual should detail the size required.
Packing comes in white and black varieties. Freshwater boats can use either type but sea-going vessels should only use the white packing which doesn’t contain graphite.
Preparing The Packing
Before you start to remove the old packing, which will inevitably result in an ingress of water, you will need to prepare your new packing. This will ensure you can remove and replace the packing as quickly as possible.
The new packing needs to be cut in to rings. Firstly wrap the packing around the shaft to ascertain the correct size and then using a very sharp knife either make a vertical cut or a 45 degree joint. The knife must be sharp to avoid fraying the ends.
Removing The Old Packing
It is not recommended to add more packing on top of the existing packing. The old packing will have lost it’s ‘body’ and is likely to be worn and hard. Best practise is to always remove and replace, unless you find yourself in an emergency situation.
Re-Packing The Stern Gland
Using a blunt instrument, such as a screw driver, push a piece of packing down the hole. Place the next packing ring in with the cut about 120 degrees from the first, and repeat until you have about 3mm space at the top. Any leaking should now hopefully have stopped. If the gland is still leaking, gradually tighten the nuts until the drips stop or happen once or twice every minute.
Packing The Stern Gland
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