Features August 1, 2001 Issue

Steering Compasses: Show Me the Way to Go Home

Aboard the Norseman 447, the skipper had at his command every electronic gadget known to man...

In the testing and evaluation, Ritchie had
three of the top five models. The five, left to
right, are the top-ranked Ritchie Globemaster,
the smaller Ritchie Navigator, the Ritchie
Voyager, the 4-1/2" Danforth Constellation
and the Plath Venus.

In a brisk southerly, headed west out of Mackinaw City, the sloop slipped from Lake Huron into Lake Michigan, bound for Beaver Island—which has a marvelous history involving a maniac named Strang who crowned himself King James, ruled libidinously and was assassinated.

As the boat passed under the Mackinaw Bridge, the skipper declared that he had the previous evening programmed everything, including the autopilot.

An hour or so down the track, the sun didn’t appear right. The binoculars showed a couple of small islands, named Hog and Garden, too much to the south. Comparing a loose sight over the big binnacle compass with a sneak peek at the chart suggested some intervention.

Because those who navigate electronically tend to suspect mutiny in even a casual glance at the nav station, the question was gently put to the skipper.

"Shouldn’t those islands be more on the nose?"

There ensued some activity at the nav station, followed by, "Belay the autopilot, man the helm, harden up to 225 degrees." Later there was a brief mention of calculations gone awry; the course had been off about 30°.

It demonstrated that navigating a boat still requires some seat-of-the-pants feeling for where you are... and a plain vanilla steering compass, programmed only by the earth’s magnetic field. The magnetic field has plenty of anomalies (localized or even moving), but they are known. Einstein called Earth’s big, two-pole bar magnet one of physic’s last great unsolved mysteries.

Along with inexpensive fluxgate compasses, electronic instrumentation has made navigation easier.

However, the high-tech stuff never will obsolete a good, carefully-adjusted magnetic compass which when coupled with common sense will get you safely from here to most anywhere.

The Collection
For this review, Practical Sailor collected, from the hundreds available, 18 steering compasses. Included are binnacle, bulkhead and bracket models, plus several interesting ones shown only in photos. Except for the bronze Telltale compass shown on page 7, all have 12V lighting and gimbal systems.

Ritchie and Rule rule the roost in the United States. Rule owns both Danforth, which has some "classic" models, and Aqua Meter, which because of reasonable prices and an excellent damping system, are said by Rule to be the most popular compasses in the world.

Suunto of Finland makes some high-style compasses. If you can afford to sail a Swan, a Suunto compass is standard.

Sweden markets the Brunton/Nexus line, which are known in other countries as Silva.

Plastimo, the French manufacturer, is owned by Air Guide, widely known for automobile compasses. Plastimo makes an amazing variety of compasses, including so-called tactical models and the widely-known Iris "hockey puck" hand-bearing compass. (The Plastimo catalog is good reading for fans of compasses.)

And, of course, there is C. Plath, of Germany, the only compass maker left that sticks with the very expensive spherical glass domes. The very strong glass domes defy ultraviolet degradation and are vastly superior to any plastic material. Plath guarantees them forever.

Nexus has a five-year warranty; all others are three-year guarantees.

The price range in steering compasses is startling, which may seem strange considering that a compass is a relatively simple device, a magnetized needle or disk that lines up with Einstein’s big magnet. What’s difficult, and expensive, is making it (1) turn freely but settle down quickly, (2) easy to read, (3) last a long time in a fairly hostile environment, (4) adjustable to allow for quirks that prevent it from behaving exactly the same on every boat.

The first is accomplished by making the "card," pivot point, and other internal parts extremely light in weight. If kept feather-light, the moving parts turn quickly and are easier to stop in the proper position. The single bearing point is usually a jewel (as in a watch). Fluid is used both to float the moving parts (giving them almost neutral buoyancy) and to dampen or smooth out the movement. Vanes are sometimes added to accentuate the damping.

The readability of a compass is important because conditions often are not ideal for discerning instantly what can be very important. Individuals with less than perfect eyesight prefer big numbers and marks; they go for cards with 5° marks, rather than the more cluttered-appearing 2° marks or even 1° (which require a large diameter compass just to print them). Traditionalists like at least some cardinal and inter-cardinal points, maybe just eight of the 32. Most of these compasses have card size and color options.

The housing for the working parts depends on the innards. Big "flat card" externally-gimbaled compasses are rarely seen on small boats (other than those with steel hulls). Full globe or semi-globular housings, whether binnacle, bulkhead, bracket or recessed, facilitate either rear-reading flat cards or front-reading domed cards—or both.

A good cover is paramount if the compass is to resist the sun, which tends to yellow the white paint used on the cards, and to at least partially protect the compass from the impact of hard objects, especially booms. Compass repairmen say booms dropped by failed topping lifts or vangs are the biggest threat to binnacle compasses.

The adjustability of compasses is accomplished with magnets that can be moved to compensate for quirks involving their placement on boats. Luck and a skilled compass adjuster often can eliminate, for practical purposes, the need for a deviation table—a permanent record of the difference between what the compass reads and actual magnetic headings. If the differences can be worked down to a degree or two on any heading, that’s closer than most helmsmen can steer.

Test Procedures
The Practical Sailor damping test involved pulling the card 90° off with a small magnet, quickly releasing it and measuring the time it took for the card to turn back and settle.

In the accompanying chart (see below), the "Damping" column usually shows three figures. The first number is how many degrees the card initially swings past its original position. This is called the "period." The second figure is the amount it overswings in the opposite direction. This is called the "half period."

The third figure, the most important by far, is how long it takes for the card to become stationary. It might be called the "settle time." On a constantly moving boat, stationary usually is a relative term, but how much the compass jumps around determines how easy, or difficult, it is to steer a reasonably accurate course.

In other columns on the chart, the compasses were assessed for readability and appearance.

Readability is not subjective. Some cards can be read from six or even 10 feet, some from no more than two feet. The placement of the compass sometimes depends on its distance from where the helmsman sits, or how good the helmsman’s eyesight is. Remember, it must be readable in a rainstorm or, if you sail at night, with artificial lighting.

Appearance is, of course, subjective. For instance, although many sailors like the very modern appearance of, say, the Suunto compasses from Sweden, few sailors at a boat show can resist slowing down when passing the booth that displays, in its gleaming brass or chromed elegance, the Danforth 8" compass with the dramatic Skylight Head and a flatcard with 1° marks and all 32 cardinal points. It is a premier showpiece. (The photo on the opposite page shows its near cousin, the 6" card version with 2° marks.)

However, because it involves the beholder’s eye, appearance was given less weight in the final rankings than the other factors.

For the final ranking column on the chart, the period and half period were ignored in favor of the settling time, which was melded mathematically with evaluations of readability, appearance and the cover.

The Bottom Line
As sometimes happens in the Practical Sailor testing and evaluation, the compasses that worked their way to the top of the rankings were, with one exception, larger and more expensive models.

The top five were the Ritchie Globemaster (the SP-5 may be the most popular steering compass ever made); the Ritchie Navigator binnacle model (a smaller, less expensive version of the Globemaster); the new Danforth 4-1/2" dual-reading, flush or binnacle mount sailboat-powerboat model that has what the manufacturer claims is a "virtually-indestructible" Lexan dome; the flush-mount Ritchie Voyager (white RU 90s with blue cards often are found in pairs, port and starboard, but unfortunately have neither internal lighting nor compensation), and the magnificent (and magnificently-priced) Plath Venus, which comes closest of all to a "forever compass."

The second five were the big Nexus 150, the venerable and very popular Constellation binnacle mount, the Nexus 125, the Suunto B95 (an excellent bulkhead tactical compass) and the Plath Merkur.

In the third five were the Nexus Racing Elite, the Plastimo Olympic 135, the Plastimo Contest 101, the Plastimo Contest 130 and the Aqua Meter’s Saturn.

The data and comparative figures in the chart, along with the photos, are guides to whatever compass may fit your boat or suit your needs or preferences.

Contacts - Aqua Meter & Danforth, Rule Industries (ITT), Cape Ann Industrial Park, Gloucester, MA 01930, 978/281-0573; www.rule-industries.com. Nexus, Brunton Marine, 620 E. Monroe, Riverton, WY 82501, 307/857-5606; www.bruntonmarine.com. Plastimo, Marisafe, 1721 Independence, Sarasota, FL 34234, 866/383-1888; www.marisafe.com. Plath, Weems & Plath, 214 Eastern, Annapolis, MD 21403-3318, 410/263-6700; www.weems-plath.com. Ritchie, Ritchie Navigation, 234 Oak, Pembroke, MA 02359, 781/826-5131; www.ritchienavigation.com. Suunto, Suunto USA, 2151 Las Palmas, Carlsbad, CA 92009, 800/543-9124; www.suunto.fi. Telltale, A.G.A.Correa & Son., 11 River Wind Lane, Edgecomb, ME 04556, 800/341-0788.


Also With This Article
Click here to view the Steering Compass Value Guide.
Click here to view "Steering Skills."

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