Boat Forum / Electronics / December 2003

From the originator of the recent "laptop trivet" thread, another post
on using laptops aboard.  I have a good secure place for the laptop,
with decent visibility for the screen, but getting to the keyboard is
awkward.  A remote keyboard has the same problems as a typical mouse,

Rate it.

  I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.
  How do you calculate distance between two points using lat/long? If

I have just bought a couple of Delphi Freedom marine deep cycle batteries
for my service bank. Is there a recommended minimum voltage below which one
should not discharge? Also, if the nominal capacity is (say) 100Ah, is that
measured between standard voltages or is it measured from ...

Both Charles Wing and Nigel Calder allude to connecting the neutral
and ground wire of AC generators at the generator.  Both authors also
show alternator generators with a centre tap at 0v and the other two
conductors at +60/120v and -60/120v (giving 120 and 240v

I am considering the GPSMAP 182 but also see the Raymarine 435 looks like a
good option too.  They use different chart packs.  If anyone has good
knowledge about these units & electronic charts I would appreciate their
insight.

Folks,
I'm looking for a strobe circuit that will
1) run from 12 Volts
2) drive a high-power flash

Alden Electronics 406 EPIRB. Model 1015.   Mgf. date 4/95.  
     406/121 Mhz output.
    With intergral strobe and mounting bracket. Owner's manual included.
    New condition; was never mounted on a boat.

I want to use the two stereo speakers of my boats AM/FM/Cassette Player for
my VHF radio. I wired both radios to a Double Pole Double Throw switch. The
AM/FM/Cassette Player works, but the VHF radio volume is so low I can barely
hear it.

Does anyone know of a source for the electric motor in the autohelm
3000. I contacted raymarine and they no longer supply parts.
                                Tony

  Considering buying a radar, so I have a few questions:
1. On a sailboat, where do you put the display? I rarely steer from behind the
wheel, mainly by sitting on one of the gunwales beside the wheel, or sometimes
by Otto while hiding from the rain under the dodger (hence the name ...

I am considering buying a Garmin GPSMAP 162 but am undecided as
whether to get the internal version or the external version. My boat
is fiberglass sloop and I think the GPS would work inside the cabin.
However I would like to mount it outside in good weather. In other

www.taiyomusen.co.jp/EnewHome0307/DG%20Compass.html
This uses a GPS to get ship postion and uses a LF ADF to get a fast response
bearing line on a shore beacon. Wonder how well it works in real practice???
Touted as a coastal alternative to a gyro.

I've checked through the archives and found a few on this subject but
none that clearly state if there is any real advantage of running a
24V system.
    Obviously the current draw for a given load will be less but I've

Looking to make up a spare GPS-laptop cable - don't want to pay the
$30-35 that the official factory cable with connector and pigtails
costs just for a backup spare. Furuno says it's proprietary and no
other sources.