Technical article by Brian Greer (reprint) Part 3 of 3

Copyright NZ H28 Yacht Owners' Association.

SOME SOLUTIONS Continued

CORRECTION OF SWAY AND YAW

The remedies outlined above may have controlled the motions of pitch and surge but we are still faced with the basic cause of anchor dragging; the swing induced by the imbalance of forces when anchored in the conventional way.

The obvious way to overcome the imbalance of bow anchoring is to anchor by the stern. Wind and wave forces now act behind the CLR and the vessel becomes self stabilising (see Fig 4). The bridle should be brought aboard abeam the propellor line, protected against chafe, secured to the nearest stanchion and taken round the mast or bollard.

Traditionalists will immediately point to problems of wind and weather from a direction never envisaged by the designer. Provided the rudder is secured amidships, however, the H28, with her soft waterlines aft and overhanging stern, will ride stern seas comfortably and lie more quietly and safely than when yawing and swinging to a bow anchor. The main difficulty arising from stern-to anchoring comes from the need to protect the companionway from draught and rain. Moreover, should a wind change in the night turn the anchorage into a lee shore, the skipper will have the added task of having to turn his boat before getting underway

Increasing the scope will not correct swing; it may even accentuate it. Nor is fore and aft anchoring appropriate, unless the swing is induced by strong tides or changing currents. Notwithstanding, for those who favour more conventional methods, there are several other ways to minimise swing, all of which take advantage of the principle of elastic resistance rather than physically limiting the range of movement, thereby perhaps placing dangerous loads on the ground tackle.

1. Rig a Staysail If the wind is not too strong, hank a storm jib to the backstay and sheet it tight amidships. (see Fig. 5)
2. Rig a Sea Anchor If you have searoom astern, deploy a small sea anchor, or an old tyre casing from the stern on a long nylon line. If there is any sea running, aim to have this drag about half a wavelength astern, so the maximum drag will occur when the yacht is in the trough and most likely to sheer away.

This method, of course, suffers from the disadvantages of multiple anchoring mentioned earlier, and if the wind shifts, you are back to one anchor.

Of the three types of motion discussed above, swinging is without doubt the most serious. Fortunately, it is also the most easily prevented. If fact, suppression of swing is the key to emergency storm anchoring - and it makes life a lot more comfortable for ordinary anchoring as well. As can be seen, successful anchoring does not involve massive ground tackle and multiple anchors, but rather the application of simple logic and the use of modern technology.

c. Rig a Forward Bridle A bridle on the bow rode, brought aboard just forward of the mast, may provide a restoring torque, and at the same time, allow the bow to rise more easily to steep seas.

d. Set a Second Bow Anchor This is a favourite remedy in nautical books, particularly for strong winds in shallow anchorages. The anchors should be set 45^o apart and centred on the wind direction, (see Fig. 6).