Chart­ing con­tin­ued from page 49


Passage Maker - - @Rest -

route-check­ing func­tion that’s sim­i­lar to my sug­gested rou­tine, high­light­ing ar­eas of pos­si­ble con­cern and mak­ing it easy to zoom in to in­ves­ti­gate fur­ther. This can be done on elec­tronic raster charts, at least for the U.S. The soft­ware also has the abil­ity to “un­quilt” the raster charts such that a user can see all the other in­for­ma­tion printed on the orig­i­nal chart.

Re­gard­less of the level of so­phis­ti­ca­tion avail­able to me, I would al­ways per­form the fi­nal step of zoom­ing in to the most de­tailed data level avail­able and scrolling along the en­tire route to look for ad­ja­cent haz­ards. The soft­ware does not pro­vide this lat­eral vi­sion.

At sea, we use the au­topi­lot much of the time, but we never con­nect it to the chart­plot­ter. I ex­tract a bear­ing to the next way­point from the chart­plot­ter and plug this into the au­topi­lot. This way, the crew also has to stay alert and we im­me­di­ately be­come aware of cur­rents and other fac­tors set­ting us off the track and can de­cide what to do about it, as op­posed to hav­ing the au­topi­lot cor­rect for these fac­tors. We main­tain a writ­ten po­si­tion log at least once an hour so that if the elec­tronic charts crash we have a re­cent fix from which to be­gin a dead reck­on­ing plot on the paper chart. In­cluded on this log are the range and bear­ing to the way­point and the cross-track er­ror, which pro­vide the ne­c­es­sary in­for­ma­tion to de­ter­mine tidal and other in­flu­ences.

If it be­comes ne­c­es­sary to switch to paper charts, I have the skills to use par­al­lel rules and other con­ven­tional plot­ting de­vices. We rely heav­ily on vis­ual nav­i­ga­tion in nar­row chan­nels and when close to any haz­ards. We have hand-bear­ing com­passes and know how to fix po­si­tions with crossed bear­ings, tran­sits, and so on. Un­like us, many big ships no longer carry paper charts. For years it has been le­gal for them to rely on vec­tor-type elec­tronic charts, but they must be of­fi­cial elec­tronic nau­ti­cal charts (ENCs) is­sued by a na­tional hy­dro­graphic of­fice and dis­played on a type-ap­proved elec­tronic chart display and in­for­ma­tion sys­tem (ECDIS). The lat­ter, in par­tic­u­lar, has to com­ply with rig­or­ous stan­dards, one of which de­fines es­sen­tial data that must be dis­played at any zoom level, in­clud­ing shal­low wa­ter sound­ings and haz­ards. Ships must carry a fully func­tional and in­de­pen­dent backup sys­tem (which can be an­other ECDIS or tra­di­tional paper charts). This level of tech­nol­ogy re­moves many of the prob­lems with elec­tronic charts that I have iden­ti­fied but is pro­hib­i­tively ex­pen­sive for re­cre­ational boaters and re­quires a lot of real es­tate in the nav­i­ga­tion sta­tion.

An al­ter­na­tive, less rig­or­ous stan­dard to ECDIS has been de­vel­oped by the Ra­dio Tech­ni­cal Com­mis­sion for Mar­itime Ser­vices (RTCM). This de­fines op­er­a­tional and per­for­mance re­quire­ments for elec­tronic chart­ing sys­tems (ECS) other than ECDIS. It de­fines four cat­e­gories of equip­ment—A, B, C,

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