Posted: Fri Apr 22, 2005 8:15 pm
Darren, let me address some of your comments about a chartplotting GPS at the helm, with my experiences doing it both ways, using paper at the helm before the chartplotter. Keep in mind, they're in an open boat with no cabin or windshield, typical cruising speed of 20 knots with a top speed of 30 knots... probably not as fast or as stable as your powerboat.
Weatherability: Our Garmin is mounted right next to our Whaler's starboard gunwale about two feet off the water. As a few will point out, I've never experienced the Mac cockpit, but some here make it sound pretty wet. However, I doubt it's any wetter than a 15' Whaler being run too fast in 3-5' seas, and our 178C has held up to that. It's IPX 7 and the worst we've put it through is probably IPX 5 or 6. If we turtle the boat, that'll be IPX 7. The display is relatively steady... not flapping around in the wind like the chart in the waterproof protector that needs a tether to keep it from blowing out. Not very easy to read. Is the Mac cockpit any less windy, especially when under power?
Speed of Use: I've found little need to use menus when underway, mostly using the dedicated Zoom In/Out buttons. With the faster screen redraws of modern processors, that's a lot quicker than panning with the joystick button. Very occasionally, I use the Page buttons to switch from chart display to something else, but most of the needed info, including the fishfinder's depth value, I can display on the chart. In fact, I put some different data fields on different pages, so they aren't all on the chart page... some on the compass page, some on the highway page, some on the fishfinder page, and some on the split screen page. And since the unit automatically switches charts depending on zoom level, it's a heck of a lot speedier than putting away one scale paper chart and pulling out another. BTDT, real PITA. There are a total of 40-something charts, including harbor charts, in the island area we boat in. 39 of them are in a non-waterproof chart book that would have to be laminated page by page for use at the helm.
Data entry: Yes, it sucks scrolling up and down through all the alphanumeric characters for each character entered. Fortunately for us, most of that's done either on the PC and transferred in, or when anchored. I'm sure you're probably quick enough to jump down in the cabin, and plot and label a fix on a paper chart on the table, and be back at the helm before I could label a waypoint on the GPS while underway. But my problem is I probably couldn't remember the coordinates by the time I got to the table. OTOH, you can't do this even with autopilot if the sea state isn't safe enough to leave the helm, and it would definitely be a challenge doing it on paper at the helm. When establishing a waypoint while underway in less than ideal conditions, I just take the default crpytic name. If I don't think I can remember what it is, I have Barb jot down the cryptic name and what it is in a small notebook. I agree this is definitely an area for improvement on electronic chartplotters, and a tablet-PC-like display you could hand write notes on would be great.
Detail: If you're talking about screen resolution, some displays are now at the threshold of normal human acuity at 2' viewing distance (150 lpi) but ours is just close. On a windless day on glass smooth water in our little boat, higher resolution might be an advantage. But with any waves or wind, it's hard enough to hold a paper chart still enough to resolve fine detail (300-600 dpi printing at 6"-12" viewing distance) in an open boat. Now if you're talking about the granularity of a vector drawing compared to a raster or paper image, I can understand, because at any given scale chart, the vector sacrifices at least something. But keep in mind that when zooming in areas where you need the detail most, you're probably automatically switching from a 80,000:1 or 40,000:1 chart to a much more detailed larger scale, maybe 10,000:1 or even 5,000:1. With any given paper chart, especially one folded or cut down for cockpit use, you're always compromising between detail and area covered.
Richard (divecoz), the links you posted are well worth reading... and not just for the notoriously poor Bahamas charts, but for any area that experiences hurricanes. I bought the Gulf Coast charts when we got the GPS, and I noted one particular area just inside the Pensacola pass was charted almost as it was when I was a kid. But from personally being there, I knew it had changed several times since as a result of hurricanes and what was a navigable waterway was now a huge sandbar even at high tide. What's hilarious is when viewing the aerial photos after Ivan, that area is now back very close to the way it was 30-something years ago, and the GPS chart is now very close to correct again! The big question is, whether paper charts would have been any more current?
The point in Richard's links is that there's also no substitute for local knowledge, whether it's from a very CURRENT cruising guide, or from others' CURRENT experience, or from what you discover yourself, using the GPS when you don't need it in good weather, which some might consider playing with a toy. You'll be glad you did it when fog rolls in. That's one thing we've done in the Islands of Lake Erie area. Daymarks appear to correspond closely to their locations on the GPS charts, but bouys can be all over the place... on the wrong side of a hazard, or rarely but actually, missing. And that varies from year to year. The things that don't move are the hazards they mark and we have a better idea of where we are with respect to them with a real-time location on the chartplotter.
I definitely don't disagree, that in unfamiliar areas, or especially when out of sight of land, it's essential to keep a track on a paper chart with periodic fixes. Electrics and electronics fail occasionally. USPS recommends one every hour and one at each course or speed change. There's no debate over whether using GPS fixes to do this are more accurate than using paddlewheel speeds in winds and currents, and the USPS guidelines are reasonable when trying to save battery power.
Where the debate, at least here, may be, is whether having a backup battery-powered handheld GPS/Chartplotter with the same cartography as the fixed unit, is a substitute for plotting on paper. This is just my humble opinion, but in the light of what's being done with GPS accuracy for national security, I don't think so... and said that in a previous thread.
--
Moe (watching JAG and Numbers while typing this)
Weatherability: Our Garmin is mounted right next to our Whaler's starboard gunwale about two feet off the water. As a few will point out, I've never experienced the Mac cockpit, but some here make it sound pretty wet. However, I doubt it's any wetter than a 15' Whaler being run too fast in 3-5' seas, and our 178C has held up to that. It's IPX 7 and the worst we've put it through is probably IPX 5 or 6. If we turtle the boat, that'll be IPX 7. The display is relatively steady... not flapping around in the wind like the chart in the waterproof protector that needs a tether to keep it from blowing out. Not very easy to read. Is the Mac cockpit any less windy, especially when under power?
Speed of Use: I've found little need to use menus when underway, mostly using the dedicated Zoom In/Out buttons. With the faster screen redraws of modern processors, that's a lot quicker than panning with the joystick button. Very occasionally, I use the Page buttons to switch from chart display to something else, but most of the needed info, including the fishfinder's depth value, I can display on the chart. In fact, I put some different data fields on different pages, so they aren't all on the chart page... some on the compass page, some on the highway page, some on the fishfinder page, and some on the split screen page. And since the unit automatically switches charts depending on zoom level, it's a heck of a lot speedier than putting away one scale paper chart and pulling out another. BTDT, real PITA. There are a total of 40-something charts, including harbor charts, in the island area we boat in. 39 of them are in a non-waterproof chart book that would have to be laminated page by page for use at the helm.
Data entry: Yes, it sucks scrolling up and down through all the alphanumeric characters for each character entered. Fortunately for us, most of that's done either on the PC and transferred in, or when anchored. I'm sure you're probably quick enough to jump down in the cabin, and plot and label a fix on a paper chart on the table, and be back at the helm before I could label a waypoint on the GPS while underway. But my problem is I probably couldn't remember the coordinates by the time I got to the table. OTOH, you can't do this even with autopilot if the sea state isn't safe enough to leave the helm, and it would definitely be a challenge doing it on paper at the helm. When establishing a waypoint while underway in less than ideal conditions, I just take the default crpytic name. If I don't think I can remember what it is, I have Barb jot down the cryptic name and what it is in a small notebook. I agree this is definitely an area for improvement on electronic chartplotters, and a tablet-PC-like display you could hand write notes on would be great.
Detail: If you're talking about screen resolution, some displays are now at the threshold of normal human acuity at 2' viewing distance (150 lpi) but ours is just close. On a windless day on glass smooth water in our little boat, higher resolution might be an advantage. But with any waves or wind, it's hard enough to hold a paper chart still enough to resolve fine detail (300-600 dpi printing at 6"-12" viewing distance) in an open boat. Now if you're talking about the granularity of a vector drawing compared to a raster or paper image, I can understand, because at any given scale chart, the vector sacrifices at least something. But keep in mind that when zooming in areas where you need the detail most, you're probably automatically switching from a 80,000:1 or 40,000:1 chart to a much more detailed larger scale, maybe 10,000:1 or even 5,000:1. With any given paper chart, especially one folded or cut down for cockpit use, you're always compromising between detail and area covered.
Richard (divecoz), the links you posted are well worth reading... and not just for the notoriously poor Bahamas charts, but for any area that experiences hurricanes. I bought the Gulf Coast charts when we got the GPS, and I noted one particular area just inside the Pensacola pass was charted almost as it was when I was a kid. But from personally being there, I knew it had changed several times since as a result of hurricanes and what was a navigable waterway was now a huge sandbar even at high tide. What's hilarious is when viewing the aerial photos after Ivan, that area is now back very close to the way it was 30-something years ago, and the GPS chart is now very close to correct again! The big question is, whether paper charts would have been any more current?
The point in Richard's links is that there's also no substitute for local knowledge, whether it's from a very CURRENT cruising guide, or from others' CURRENT experience, or from what you discover yourself, using the GPS when you don't need it in good weather, which some might consider playing with a toy. You'll be glad you did it when fog rolls in. That's one thing we've done in the Islands of Lake Erie area. Daymarks appear to correspond closely to their locations on the GPS charts, but bouys can be all over the place... on the wrong side of a hazard, or rarely but actually, missing. And that varies from year to year. The things that don't move are the hazards they mark and we have a better idea of where we are with respect to them with a real-time location on the chartplotter.
I definitely don't disagree, that in unfamiliar areas, or especially when out of sight of land, it's essential to keep a track on a paper chart with periodic fixes. Electrics and electronics fail occasionally. USPS recommends one every hour and one at each course or speed change. There's no debate over whether using GPS fixes to do this are more accurate than using paddlewheel speeds in winds and currents, and the USPS guidelines are reasonable when trying to save battery power.
Where the debate, at least here, may be, is whether having a backup battery-powered handheld GPS/Chartplotter with the same cartography as the fixed unit, is a substitute for plotting on paper. This is just my humble opinion, but in the light of what's being done with GPS accuracy for national security, I don't think so... and said that in a previous thread.
--
Moe (watching JAG and Numbers while typing this)