How many of us have dreamed of earning enough money under way to offset the cost of cruising? I’ve always said that one of the best ways to make cruising pay was to become skilled in repairing air conditioning systems, then just head down island with the right tools and a locker full of refrigerant.

Monty and Sara Lewis, authors of the Explorer Chartbooks of the Bahamas, have my fridge technician idea beat hands down.
This cruising couple from Maryland earns a paycheck in the most organic way imaginable. For the past 17 years, they have been supplying fellow cruisers with essential intelligence, gathered aboard their 1978 Mainship 34 Saranade.

The Lewises publish three tabloid-size books with Bahamas charts and essential guide information for sailors and trawler people. Along the way, the books became so successful (with more than 80,000 sold to date) that Jeppessen incorporated the Lewis soundings data into its C-Map electronic charts and has licensed that data for PC charting software by MaxSea and Nobeltec. Garmin, too, bought in to Explorer data for its electronic charts. In fact, among the big players only Navionics does not use Explorer material and, for a time, was conducting its own surveys so it too could offer electronic charts based on something other than decades-old information.

Monty Lewis, a retired Maryland State Police sergeant, says he and Sara began their chart work in 1994 with the Exuma Cays. Until then cruisers were making the annual trek to George Town on Great Exuma with charts that had not been updated in decades, even centuries. “We did it because there wasn’t any really good information. Everything was very sketchy when we started cruising in the Bahamas,” Lewis says. “We used our trawler as a survey boat and gathered information using plotting sheets.”

Rather than charts, the Lewises used British-made topographical maps for their original plotting sheets. “The land masses were pretty accurate, except for a few places that were anywhere from a quarter mile to two miles off of correct geo-referencing. Of course, there was no hydrographic data at all,” Sara Lewis recalls. “These became our original plotting sheets. Before GPS at all, and then during ‘selective availability,’ we started making our notations using a hand-bearing compass for verifying our position. Once selective availability was out, our soundings and notations became extremely accurate.”

“Selective availability” is a reference to the days when the U.S. government deliberately prevented GPS satellites from broadcasting at full accuracy. Of course, when selective availability was turned off and GPS receivers themselves became better, these improvements were reflected in the Lewis books, which are updated regularly based on Saranade’s winter cruising. After the Exumas and Ragged Islands Chartbook, the Lewises went on to release books for the Near Bahamas and then Far Bahamas. For 2011, the 5th edition of the Far Bahamas book includes the Turks and Caicos for the first time.

This year was also a milestone for Explorer Charts because of the decision by sister companies MaxSea and Nobeltec to include Explorer charts in raster form in their catalogs. Raster is cartography talk for what amounts to a photograph of the chart in question, rather than a pure electronic rendering of the data, which is called a vector chart.

Using their “TimeZero” chart engine, both Nobeltec and MaxSea allow the skipper to render an Explorer raster chart in 3D, a mode that can improve situational awareness under way. Another enhancement blends the Explorer chart with satellite imagery, which is particularly effective in rendering the shallow waters of the Bahamas banks.

“The raster charts look really good by themselves, but when you overlay the high resolution satellite pictures on top of them, it becomes incredible,” says Iker Pryszo at Furuno USA. “These charts look really good because they are the strict copy of the Explorer paper chartbook. Of course, since they are raster charts, you see some ‘patchwork effect’ (common to any raster charts) when the original paper charts change scale.” (Furuno, which makes marine electronics hardware, is a part owner of MaxSea, and MaxSea provides the cartography for Furuno NavNet multi-function displays.)

Electronic charting companies usually get their data from government sources, but Monty and Sara proved themselves gifted amateurs, according to Jeppesen executive Ken Cirillo. “The truth of the matter is that the Lewises were a world ahead of whatever else was available. The British Admiralty had not done a survey of the Bahamas for decades. Those charts, obsolete to begin with, were being removed from the market,” Cirillo says.

Although the gin-clear waters of the Bahamas would lend themselves to airborne bathymetric surveying called LIDAR, Cirillo says the business model for selling charts and chart data to recreational boaters would not support the cost. Nothing could beat the dedicated husband-and-wife team cruising on a 33-year-old trawler with off-the-shelf Garmin chartplotters and depth sounder.

Saranade, her profile reminiscent of a Downeast Maine lobsterboat, is powered by a single Cummins 220 diesel. Given that they conduct much of their research in the stormiest months, the Lewises find comfort in their ability to find shelter, thanks to Saranade’s shoal draft and a flybridge that provides a high vantage for “eyeball navigation,” or as the Lewises prefer to call it “visual piloting rules.” Both terms describe the way one must time the daylight and read the color of the water to navigate Bahamian shallows.

“We’re thought about upgrading our boat in recent years, but it’s very difficult to find a better boat for what we do,” says Monty Lewis. “We could get a larger boat but then we would be talking more draft. Our boat is pretty good for what we do it has less than three feet of draft and a protected propeller. And it’s pretty maneuverable. We can get into tight places.”

I personally appreciate the Explorer books for their treatment of obscure places in the Bahamas. The Lewises have completed three cruises along the remote Jumentos archipelago, all the way down to the tiny settlement of Duncan Town on Ragged Island. By doing so, the Lewises are mapping one of the paths that American cruisers will someday use en route to Cuba once we are permitted to go there. (See PMM January 2010, “An Even Greater Loop”). Duncan Town is a pretty ambitious destination for a small, single-screw powerboat, given that only 10 to 15 percent of the hundreds of North American boats in the Exumas each winter are power, even though the Exumas are closer to the U.S. and feature marinas and other amenities.

I’ve always been intrigued by a place in the Bahamas I have never been. Samana Cay is likely the actual first American landfall by Christopher Columbus, which happened on Oct. 12, 1492. Samana is about 10 miles long, and stands 20 nautical miles to the northeast of Crooked and Acklins islands (which are themselves remote and rarely visited). There is an anchorage on the south side of Samana, whose land mass and fringing reefs would offer protection during a passing norther, but entering the bay requires that a visiting boat navigate a dog-leg path through the reef or cross a field of potentially shallow coral heads.

The Lewises describe Samana Cay as “Nirvana for the nervy.” As it happens, they have not been to Samana either, nor have they been to some of the other remote Bahamian Out Islands, instead relying on trusted cruising associates to supply sailing directions. “We have people who have been cruising for 30 years who have stopped there while going back and forth in remote places such as Mayaguana and Great Inagua,” Sara Lewis says. “We supplied them with some worksheets to put things in our format. They gave us waypoints and soundings. Monty is able to verify quite a bit now with Google Earth.”

The Lewises are particularly proud of their efforts to ensure that the soundings on their charts have been reduced to the depth at mean low water. This is particularly important since so much of Bahamian cruising happens in depths of less than 12 feet; consequently a tidal range of up to 3.5 feet can be pretty significant. It can make the difference between being able to make a transit, having to wait or having to choose another route.

Monty Lewis says he spends a great deal of time calculating the state of the tide¾as much art as science in an island nation comprised of both shallow banks and deep ocean. “With the technology survey boats are using today, it’s easy to measure the depth at a location,” Lewis says. “Of course, to be accurate you need the state of the tide. You can have all sorts of computer programs, but it’s still going to be a judgment as to the state of the tide where you are.”

Including theTurks and Caicos in their Far Bahamas book was a departure for the Lewises. It was the first time they did not use their own boat for research. The Turks and Caicos, still a British territory, lie 200 miles beyond the most remote marina in the Bahamas, Flying Fish Marina on Long Island. Rather than slog upwind in their 34-footer, the Lewises flew down and conducted their research in a rented boat. Sara Lewis says she doesn’t see the Turks and Caicos as a destination per se¾except for divers¾but the island group lies along the small-boat route to the Caribbean and, as such, deserved their attention.

And before I forget, the Explorer books are not just charts. They include thousands of words of cruising guide text: practical advice, tide tables and detailed descriptions of points of interest at each island and anchorage. As I was writing this article, Sara and Monty Lewis and their daughter and executive editor Kate Fears were readying a new edition of the Near Bahamas. Explorer chartbooks can be purchased for $60 from www.explorercharts.com, or at Bluewater Books in Ft. Lauderdale and West Marine stores.