Boat compass: how to use it for sailing?
→ Installing and using your boat compass
Understanding how a boat compass works, so you can install and adjust it properly, is essential for any sailor. To install your , it's essential to choose a suitable location.
Make sure it's away from sources of disturbance such as loudspeakers, fire extinguishers, screens and electronic equipment, and that theaxis of the boat compass is perfectly parallel to the longitudinal axis of the boat (paying particular attention if the compass is installed on a sloping surface).
To install a built-in navigational compass, you'll usually find a drilling template included in the product packaging: simply fix it in the desired location, drill the mounting holes (remember to include the power cable feedthroughs for lighting), then cut out the center section using a hole saw.
Finally, don't forget to use non-magnetic screws (which are not attracted by magnets) to hold your boat compass securely in place.
→ Navigation compass: mandatory on board
A magnetic boat compass is essential when sailing more than 2 nautical miles from a shelter. Beyond its mandatory nature, it's essential to understand how a boat compass works in order to choose the model best suited to your type of craft.
For this, please consult our guide to . Whether it's a or a compass for powerboats, the magnetic compass is a crucial safety element, whether for the helmsman or to ensure that the autopilot functions correctly.
→ Boat compass mounting, several possibilities
Below, a list of the different ways to consider mounting your boat compass on board your boat:
➡️ Horizontally mounted
This extra-flat version, ideal for a in particular, provides excellent visibility of the rose and minimizes vibrations by absorbing them. On a motorboat, this version is installed on the flybridge, upper deck or center console. On a sailboat, the boat compass is recessed into the sides of the deck or mounted on a barrel.
➡️ Flush-mounted on a vertical or inclined plane
Also known as a "bulkhead compass" or "dashboard compass", a bulkhead compass is generally installed on the cabin bulkhead, on the cockpit side, so that it can be easily seen from the cockpit. On powerboats, it's the ideal type of mounting for a vertical dashboard or center console.
➡️ Bracket mounting
Very popular on motorboats, this type of mounting is quick and easy to install in any location, especially on surfaces with corners. Generally removable, it can be safely stowed away, a highly appreciated advantage on powerboats without cabins.
➡️ Mini-barrel mounting
Extremely flat and compact type of mounting, requiring no hole for installation. The boat compass is removable for safe storage.
➡️ Barrel-mounted
For wheel steering columns: for sailboats fitted with wheel steering.
➡️ Mast-mounted
If space is at a premium, mounting the boat compass on the mast may be the solution. It's easy to do, thanks to a special mounting bracket.
➡️ Bracket mounting
Often multi-functional, this type of boat compass is also removable.
Boat compasses: adjustment and compensation
Most boat compasses are supplied with compensation, or can be fitted with it as an option. Adjusting a boat compass for compensation involves changing the position of the two magnets close to the boat compass in order to influence the horizontal component of the rose, by modifying the North/South and East/West deviation.
As compensation is a delicate operation, we recommend that you call in a specialist to ensure that your boat compass works properly.
→ Compensating a boat compass
To compensate for a navigation compass, a second, disturbance-free boat compass is used as a reference. A is most often recommended for this operation.
▪️ Sail north on the reference compass
▪️ Adjust your course compass by turning the North and South screws in either direction so that it is also North.
▪️ Proceed in the same way, heading East
▪️ Sail south this time and reduce deviation by half
▪️ Then, heading west, reduce deviation by half again
Please note: once compensation is complete, a new deviation curve is required.
→ How to use your navigation compass?
To use a navigation compass, it's crucial to install it in the longitudinal axis of the vessel, away from any source of magnetic disturbance, such as electrical equipment or metal masses.
Before setting sail, you plot your intended course on the chart, taking into account magnetic declination (the difference between true north and magnetic north) and compass deviation (errors due to the compass' immediate environment). As you navigate, you adjust the helm so that the compass' true line indicates the desired course, while regularly monitoring the bearings to correct any deviations.
Understanding how to use a navigational compass also involves knowing how to interpret landmark bearings (fixed points visible at sea) to determine its position. By taking successive bearings from several landmarks and plotting them on the chart, you can triangulate to pinpoint the ship's position.
This method is particularly useful in coastal navigation or when electronic systems are unavailable. So, despite the advent of modern technology, mastering a remains a fundamental skill for any navigator.
→ Maintaining your boat compass
Once installed, your boat compass requires no special maintenance. Simply clean it regularly with soapy water and protect it with a boat compass cover, such as the Plastimo Contest 130 compass cover. This will prevent premature wear of your boat compass due to sea salt and UV rays.
