Bristol 27

Rudder

• The rudder should be well aft, it must be strong and have a reliable bearing and linkage system, and it must also project well below the water so it remains effective at all angles of heel….it must be symmetrical; even a small flat area on one side will cause the boat to be balanced on one tack, but unbalanced on the other (You can check for symmetry using straight edges or by making cardboard templates.)…the hydrodynamic issues concern balance, directional stability, and control effectiveness  (Desirable and Undesirable Characteristics of Offshore Yachts, p. 92 – 3)
• Tremendous forces are constantly at work against your rudder, under way and even at anchor or at the dock.  (Upgrading the Cruising Sailboat, p. 51)
• A skeg certainly can help to block out weeds or lines from lobster and crab pots. It can also be a good place to mount a propeller aperture leading from a short, unsupported shaft. Skeg construction can be tricky. If it is going to contribute its share of support for the rudder load, it should be molded to the hull rather than simply tacked on. Further, the construction of the lower end must be carefully thought out if you want to allow for removal of the rudder….the skeg-mounted rudder will turn less quickly, but will have camber – which keeps it from stalling at sharp angles of attack.  (Desirable and Undesirable Characteristics of Offshore Yachts, p. 93)
• Vertical rudder stocks should enter the hull either through a glass or stainless steel tube bolted through a substantial block of wood….It wouldn’t hurt to strengthen the hull here, either by glassing in a heavier piece of plywood against the hull, adding extra layers of mat and woven roving in the area, or glassing in a few beams, between which the backing block can be glassed. Additionally, the stock should be supported higher up, where it passes into the cockpit or wherever else it emerges above deck. There should be a strong collar to support the stock and a bearing plate for firmly supported by structural members glassed to the hull….This reinforcement will protet the hull against normal loads and, in the sad event of a grounding, will even help prevent the rudder from being shoved up through the hull. Losing the rudder is one thing, losing the whole boat is a catasrophe.  (Upgrading the Cruising Sailboat, p. 51)
• The stuffing box on the stock of an inboard rudder should be tightened until it does not drip at all. Some water penetration helps to lubricate a spinning prop shaft, but an oscillating rudderstock doesn’t need any additional lubrication. The constant motion does, however, result in wear, and the exposure of rudders always places them at risk of being damaged.  (This Old Boat, p. 165)