I'm pretty much in the same situation; no room for any more wiring. In my case, I think I'm going to upgrade to the larger diameter tubes for the pedestal guard. I'd like to have something that angles back for a larger instrument like a chartplotter. Not inexpensive as you also have to get the pedestal plate with larger holes, but everything is available from Edson, so should fit.

[url]http://www.edsonmarine.com/marinestore/index.php?main_page=index&cPath=8...

JZ
Does the 541s has a small card slot door that is held shut with a magnet?
If so the magnet will interfer with your compass if it is placed to close to the compass. This can be checked out by passing the GPS close to the compass and watching to see if the compass moves.

[QUOTE=caprice 1050;13383]JZ
Does the 541s has a small card slot door that is held shut with a magnet?
If so the magnet will interfere with your compass if it is placed to close to the compass. This can be checked out by passing the GPS close to the compass and watching to see if the compass moves.[/QUOTE]

Indeed, JZ, the cabling may be the least of your obstacles here.
On page 10 of the Garmin 541 installation manual, it indicates that it must be installed at least 30 inches from a compass.
I bought a different Garmin chartplotter last year and had to return it to the store for this very reason (because of the magnet door on the card slot). Stupid design flaw on an otherwise nice product.

I have the small diameter tubes on my pedestal and was able to put all the wiring for a Garmin 4212, Garmin GMI 10, Raymarine auto pilot, and Garmin radar with all the power cables and connectors through the tubes. I had to remove the tubes and cut 3/4 by 1 1/4 inch slots in both tubes where the Navipod would mount. I won't say it was easy but it can be done and I think I could get one or two extra small cables through there if something came up and I needed to do it.
I have had no adverse effects on the compass though the units are a lot closer that 30 inches. I pre-tested the powered up unit before I installed it and saw no deviations on the compass. A hand held compass finds no ill effects held fairly close to the 4212 in different positions and distances. I talked to Garmin about this and 30 inches is mentioned in an abundance of caution. Having installed a lot of electronics in aircraft I have to say that I would worry a lot more about the power cables than that little magnetic door. In any event, with everything turned on and installed, unless there are really big problems, then it should be possable to "swing" the compass to compensate for a new installation. I am pretty sure that you can find instructions on how to do this somewhere on this website.
Anyway, every installation is different and where it works fine on my 36, the same installation may not work on another boat.

I pulled two runs of 9 conductor wire for a Standard Horizon RAM mike and chartplotter/AIS through the port tube on our pedestal, there was nothing in it at all and in fact it had never been drilled through the floor. Finding the tube from below was the hardest part since it was blind. Everything on our boat that was already there was in the stbd tube.

More or less the same experience for me installing the GX2100 RAM mic and Lowrance chartplotter last month. Found strbd tube mostly full, with only one wire in port tube...

[QUOTE=Chachere;13387]Indeed, JZ, the cabling may be the least of your obstacles here.
On page 10 of the Garmin 541 installation manual, it indicates that it must be installed at least 30 inches from a compass.
I bought a different Garmin chartplotter last year and had to return it to the store for this very reason (because of the magnet door on the card slot). Stupid design flaw on an otherwise nice product.[/QUOTE]

Course this predicates that:

#1 The compass has been professionally swung by a compass adjuster and two deviation cards are on-board one for electronics turned on and one for electronics turned off.

#2 The owner actually knows how to use a compass.;) Considering that approx 98% of the boats I work on do not have a deviation card, or a professionally swung compass, my guess is that even if the owner does know how to use a compass it is going to be very inaccurate. In some areas that does not matter but here in the land of pea soup and granite accuracy matters..

BTW it is not just Garmin with magnets in doors Raymarine, Lowrance also have them....

This is my latest design for a pedestal mounted plotter (without a pod). Neat, clean, inexpensive and looks more factory made than many of the commercially mounts out there.

Raymarine e7D (which is bigger than a 541 and close to a 740)
[IMG]http://www.pbase.com/mainecruising/image/142617922.jpg[/IMG]
[IMG]http://www.pbase.com/mainecruising/image/142617926.jpg[/IMG]
[IMG]http://www.pbase.com/mainecruising/image/142617929.jpg[/IMG]

[QUOTE=neilroach;13390]
I have had no adverse effects on the compass though the units are a lot closer that 30 inches. I pre-tested the powered up unit before I installed it and saw no deviations on the compass. A hand held compass finds no ill effects held fairly close to the 4212 in different positions and distances. I talked to Garmin about this and 30 inches is mentioned in an abundance of caution. Having installed a lot of electronics in aircraft I have to say that I would worry a lot more about the power cables than that little magnetic door. [/QUOTE]

I'm just saying, its worth checking first -- your mileage may vary, as they say. The Garmin unit I had bought was the 740, and when I positioned it at the pedestal I was seeing something like a 10 degree swing on the compass. I ended up installing an earlier Garmin plotter which didn't have this effect on the compass -- apparently its more of an issue with the later Garmins.

[QUOTE=Chachere;13453]I'm just saying, its worth checking first -- your mileage may vary, as they say. The Garmin unit I had bought was the 740, and when I positioned it at the pedestal I was seeing something like a 10 degree swing on the compass. I ended up installing an earlier Garmin plotter which didn't have this effect on the compass -- apparently its more of an issue with the later Garmins.[/QUOTE]

Guys,

A "proximity test" is totally inconclusive of what the actual compass error may be. The only way to know the actual effect is to get a compass adjuster out there with a "magic box". I have yet to see any magnet door plotter not throw a monkey wrench into the mix with a compass when properly swung. Until all the cardinals and intercardinals have been tested you have NO WAY to know the effect..

Some of these installations simply make swinging the compass impossible. On the boat pictured the compass was swung with the plotter removed. It was wired that way for easy removal so if the need came up that the compass was the only option it was a "known" quantity with the plotter removed..

The "proximity test" showed next to nothing for error but when swinging it did show errors bad enough that the compass adjuster was "not comfortable" signing off on a deviation card for that installation. Owner also has three more compasses on-board so the decision to helm mount was made...

[QUOTE=Maine Sail;13458]Guys,

A "proximity test" is totally inconclusive of what the actual compass error may be. ...[/QUOTE]

I am not in any manner qualified to assert otherwise -- nor do I. Sure, probably only a competent compass technician can evaluate and adequately compensate for the impact of wiring currents and the like (certainly beyond my present skill set). My only point was that if as a dumb consumer I did a proximity test with the Garmin 740 and the thing is already showing a fairly egregious impact on the binnacle compass (and, by the way, from reviewing my notes from last year, it was actually 20 degrees!), it struck me that it was perhaps not exactly the best choice of chart plotter for that particular installation -- or at least it might be better to look at some alternatives.

In fact, my analysis was "influenced", as it were, by several threads discussing this on Sailnet. Including this one -
[url]www.sailnet.com/forums/electronics/68153-garmin-740-radar-question.html[... - in which Maine Sail wrote 2 years ago regarding the Garmin 740:
[INDENT]"[The Garmin] 740 ... has a STRONG magnet for the chart door which requires it to be about 3 feet from the nearest compass (read REALLY, REALLY DUMB). I think you'd be much better off with an older 3206 as they are still available on the net for about HALF the cost of the 740, networkable and they have the great old Garmin user interface... I just had to replace my plotter about four weeks ago and considered the 740 until I began researching.. Doh'!! Went with another 3200 series.. " [/INDENT]
See also [url]www.sailnet.com/forums/electrical-systems/65905-gps-compass.html[/url] and [url]www.sailnet.com/forums/electronics/72909-chart-plotter-interferes-compas...
This may be a dumb question, but can a compass be adequately compensated for a piece of equipment that shows that much interference?

A bit off topic, but related.

It's clear to me that the engineer or product designers for a number of products do not actually use them, or understand the environment where they'll be used. The magnet on the door of a product that's going to be used near a compass is a good example. Has the designer ever been on a boat???

Going back to my 1st boat in the late 80's, it came with an Autohelm self contained tiller pilot. It worked fine until I got caught in a thunderstorm. The little red status LED stuck up through an unsealed hole in the top of the case; water went in and destroyed it. :mad: The ads for the thing have pictures of people crossing oceans, yet the thing can't survive a thunderstorm? Autohelm sold me a new one for cost (to their credit) and it had a clear lense over the LED. Well duh...!!!

And why would Autohelm/Raytheon put an "Offset" button on the depth sounder? How many times to you set the keel offset? Er, uh, once?!? :confused: But when I want to change the depth alarm, which I do all the time, I have to hold 2 buttons for 2 seconds, another to go into calibrate mode, then push up/down buttons, hold 2 buttons for 2 seconds.... Are you kidding me???? :confused: How about having a [I]menu[/I] item for keel offset and give me a button to adjust the depth alarm quickly? Like my ancient Datamarine sounder from the 80's did, via a little switch.

Most of these products work quite well, but have irritating flaws that probably wouldn't be there if the designers knew more about where/how the products were going to be used.
Rant over (sorry). ;)

You are sooooo very right.

JZ - I have the Garmin 740 (and the magnet issue). I did my install with a heavy duty Ram Mount attached to one side of the pedestal. Ran the wiring through a water proof cable fitting that was already next to the port pedestal tube and tie wrapped the wiring to the pedestal post. Not nearly as clean as through the tube but fewer issues and less time. I use my chart plotter on my fishing boat as well so the ram mount lets me easily move it there and back. I also remove it when not at the boat due to theft issues at my marina.