Using a propeller shaft liner on your sailboat can greatly increase your boat's life expectancy. One major benefit of utilizing a propeller shaft liner is increased stability as well. The reason why it works so well for that is because the shape of the shaft actually allows the shaft to turn backwards and forwards. Therefore, it greatly reduces the amount of wake created by the bow of the sailboat.
One of the drawbacks of using the propeller shaft liner is the fact that the size of the opening to the bow is usually smaller than the opening at the stern. This means that the amount of vertical movement of the boat's hull is decreased. However, this small difference in the vertical movement of the hull does not have an impact on the way that the vessel handles during the sail. The difference in how the bow and stern handle the boat during a sail is due to the fact that the separation of the bow from the stern creates a greater moment of stability than that of the stern.
In order to get around the problem of propeller shaft liner loss, many sail manufactures have invented the CaE method which stands for Center of Equation. The C Ae method makes use of an optimized configuration of vanes to disperse noise. Basically, the C Ae method works to reduce the amount of time that each of the blades rotate. The result of this reduced rotation time is lessened amounts of wake created by the bow and consequently, less noise.
If you were to compare a dry propeller shaft liner with a dry propeller shaft liner, you would notice that the size of the opening to the bow is larger in relation to the size of the opening at the stern. The reason for this is due to the fact that the latter protrudes further outwards when the boat is afloat. If you were to look at the propeller assembly at the stern, you will notice that it is positioned inboard of the hull and has a number of fins. The position of these fins at the stern is important as it helps to distribute the bow vibration that occurs with the boat's hull throughout the whole length of the propeller shaft assembly.
There are a number of factors that need to be considered when choosing the right type of propeller shaft liner. A small propeller shaft is adequate for smaller boats that have a low level of hull. Larger boats that are more powerful or have a higher hull height require a more robust propeller shaft liner. The best type of liner for a high hull height boat is a tubular liner that spreads the vibration from the boat's hull and propeller shaft. In case you are using a conventional wet dry boat wash system, then it will be suitable for damp conditions. However, if your boat is in salt water, then using a conventional wet dry system may not be the best option.
When looking at the prop shaft bore, there are three different designs that you can use to minimize the amount of thrust that is transmitted through the bow - the round rod, the flat-ended spear and the tubular. The circular rod, spear and tubular liners spread the thrust throughout the length of the shaft to the flat-end and tubular designs just spread the thrust along the diameter of the propeller shaft. With the rounded rod, there is less of a transmission of energy to the propeller shaft. A good example of a round rod is the scroll trimmer. The flat-ended design spreads the thrust evenly across the entire circumference of the propeller shaft bore.