Gene Kearns wrote:
On 13 Jan 2006 20:28:01 -0800 in rec.boats,
penned the following thoughts:
Wayne.B wrote:
On 13 Jan 2006 10:10:18 -0800, "
wrote:
What is your opinion about positioning fishfinder/GPS near a compass or
a VHF radio?
The VHF radio will have a magnet in the speaker and should be kept
well away from the compass if possible. The fish finder is probably
less critical but you should test it before mounting by placing it
near the compass and watching to see if the compass heading changes.
Thanks for explaining the reason why I need to keep the radio away from
the compass. You are right; the magnet inside the speaker of the radio
will likely cause problem to the compass. On the other hand, the
fishfinder and the GPS device should not have any magnet inside.
Therefore, I have a feeling that I should be able to mount them near
the compass. Great! Now, I don't need to worry about how to mount
those devices in my boat.
Not so fast! Any devices that are attached to wires will have a
magnetic field associated with them. Just because you do not have a
permanent magnet in every onboard device does not mean that each and
every one can be located, with impunity, adjacent to the compass.
I suggest you *not* permanently mount any of these systems until you
wire them and test them under load..... especially the VHF on
transmit!
Remember, shielded wires are your friend.
I assume the "wires" that you are talking about are something like
these:
- The wire connecting a fishfinder to its transducer.
- The wires connecting a device to a 12-volt battery.
- The wire connecting a GPS device to a GPS antenna.
If this is true, I will have to be careful about positioning the
fishfinder and the GPS device on the dash near the compass. I didn't
know that the little compass can be so troublesome. Unfortunately, the
dash is only 2-ft wide and 1-ft deep, and I need to have a compass, a
fishfinder, and a GPS all fit in that 2-sq-ft space.
Yes, I will mount all the device temporarily on a piece of wood that
will be tied on the console and test all of them before mounting them
permanently. And yes, I will test everything during a VHF
transmission. In fact, I have already ordered the fix-mounted VHF
radio _AND_ a handheld VHF radio. I will use the handheld radio not
only as a backup, but also as a way to test the radio transmission
during installation and before each boat launch.
OK, I will get very well shielded wires to connect everything.
Hopefully, this will not only reduce the voltage-drop, but also reduce
interference. Thanks for the tip.
Jay Chan