Nigel Calder Answers Question - Ask Sail Page 2

THE EXPERTSNigel Calder is an expert on boat systems and diesel engines. Don Casey has written many books and articles on marine maintenance and repair. Tim Bartlett is a former Royal Navy officer who is an expert in radar and electronics systems. Gordon West is a communications expert and a specialist in radio communications.DIRTY GROUND
Author:
Publish date:
saip_0909_05_z+answers_question+tim

COMPASS TRUISM

Is it all right to use magnetic headings on my chartplotter to adjust a new compass?

KARL WESTMAN, OCEAN CITY, NEW JERSEY

TIM BARTLETT REPLIES:

In theory, definitely not. But in practice I'd have to give you a very guarded "maybe." The problem, of course, is that your heading is the direction your boat is pointing in. Your chartplotter/GPS unit cannot know this. It only knows the direction the boat is moving, known as your "track" or "course over ground."

saip_0909_06_z+answers_question+bearings

And there can be a big difference. For example, if you are doing 6 knots with a 3-knot current on your beam, there's a difference of almost 30 degrees between your heading and your track. But if you should be lucky enough to have a perfectly calm day and there is no tide or current to affect the boat's course over the ground, the track shown by your chartplotter should be the same as your compass heading if the compass is adjusted properly.

A good way to check your compass is to aim your boat at a fixed landmark or buoy, and then take the magnetic bearing of the landmark by placing your chartplotter's cursor on it. Then compare that bearing with the compass heading. As long as the landmark is more than a mile or so away, the bearing shown by the chartplotter should be the same as the compass heading, give or take a degree.

CLEAR CHANNELI'm thinking about getting a satellite radio receiver so I can download all the marine weather products that are available these days. But I'm curious: Will I have to mount one of those softball-sized antennas above my deck?

HENRY MEYER, CHICAGO, ILLINOIS

saip_0909_04_z+answers_question+gordon

GORDON WEST REPLIES:

Before you do anything about mounting the antenna, first check with your marine electronics specialist and make sure that the satellite radio weather products you plan to receive will be compatible with the charting program you have or plan to use. Navico's Northstar, for example, includes the Sirius weather module with Shakespeare's Galaxy softball-sized antenna system, and this antenna can pull signals in through fiberglass. Even so, if you have a deck with a teak overlay and it is covered with seawater, chances are good that reception of satellite signals will likely be blocked.

Related

catstory

Cruising: Sailing With a Young Family

The dark is alive when you are surrounded by water. Black is tinted blue and silver, and sky meets surf with electricity and the lapping sounds of silence. Inside our 36ft catamaran, moored off Cooper Island in the BVI, the raw nature outside, just now settling down from a late ...read more

IslandPacket349

Boat Review: Island Packet 349

After years of quiescence in the wake of the Great Recession, iconic Island Packet is back with its new 349, a re-boot of the old Estero that not only looks great, but takes the Island Packet style of sailing performance to a new level. Design & Construction First among the many ...read more

190219NEEL51

Video Tour: Neel 51 Trimaran

At this past fall’s Annapolis Boat Show, SAIL magazine had a chance to corner Neel Trimarans founder Eric Bruneel and have him give us a tour of the accommodations aboard the new Neel 51, winner of the “Multihull over 50ft” category in the 2019 Best Boats contest. For a complete ...read more

IMG_0173

Electronic “Flares” for Cruisers

The United States Coast Guard requires that all boats operating in coastal waters or on the high seas carry a selection of visual distress signals. Almost invariably, such signals include the pyrotechnic type, either handheld or fired from a flare pistol, but surely there are ...read more

M2-HOOK-TOP-AND-CHAIN-1

Gear: M2 Chain Hook from Mantus

Stay Hooked Chain hooks on anchor snubber lines tend to fall off when you least want them to. Not so this latest example from Mantus. The M2 Chain Hook is secured to the chain by a simple elastic strap, so it won’t come off when the snubber loosens. Made from corrosion-resistant ...read more