Windjammer wrote:

On eBay, there are at least two types of touch-screen monitors being sold -
7" and 8" size both with VGA input as well as A/V.

Has anyone tried using these as displays for marine navigation?

In particular, wondering about the resolution and how the touch-screen could
be used with popular nav software like Fugawi?

The ones I saw did resolutions of 640 x 480 (4:3 for computer display)
and 1600 x 1200 (16:9 for movies) and were rated for brightness at 400
nits.

In use, 640 x 480 is a pretty small desktop for a computer but adequate
for displaying one application (like fugawi, for example).

If you want to use them out in daylight or in bright sun, the "nits"
value is an important number. A LCD display of 400 nits (like the ones
on eBay) is considered daylight viewable but you probably won't find it
useful in direct sunlight. You may be able to use it if you shade the
display or are under cover with sunlight not striking the screen.

A good quality marine display would be rated at 1600 nits for brightness
and is basically 4 times as bright as the 400 nits one and easy to read
in direct sunlight. But those extra 1200 nits don't come cheap. Build
it into a NMEA4 "sealed from salt spray mist" enclosure and the price
goes up again. The touchscreen is usually optional and the price goes
up again. And in some cases the touch screen layer renders some of the
nits less effective and the reduces the viewing angles.

It looks to me like good and cheap are mutually exclusive on displays
suitable for daylight use in marine settings.

More on the resolution. If you set your desktop display to 640 x 480
and run Fugawi, you can see the amount of info that would be displayed
on the smaller monitor at that resolution. It will be physically
smaller on the small monitor but the same amount data is seen. To most
people 640 x 480 looks better on a small monitor than it does on a large
monitor.

If you cut a 7" diagonal 4:3 hole in a piece of cardboard, held that at
the distance you intend to mount the monitor, then backed off until
your computer display is visible through the hole, you can get a feel
for what you will see with the monitor mounted. This is an
approximation, you have to sort of mentally visualize that the display
is at the same distance as the cardboard.

On the touch screen software, your finger tip on the screen should cause
the same things to happen as does your mouse cursor. If a cursor-over
pops up a menu then a touch should do that. Taps and double taps will
do things like click and double clicks. It should work much like a
typical kiosk or the touch pads found on many laptops. But you are at
the mercy of the intentions of the programmers and the amount of
flexibility programmed in.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)