Help me design my panel...

[exposure]

I am in the process of designing a new layout for my instrument panel. Here is the current layout so you have an idea of what I am working with...



The VHF on the lower right and the Autopilot in the lower middle are staying, as is the radar on the far right. I would prefer not to move any of these, but may. All of the 4-inch instruments are going to be replaced with the Navman series of instruments. There will be 3, 4-inch sized displays to install. The GPS is going to be replaced with a Garmin 188 GPS/Sounder. I also need to install a traditional compass, perhaps a bulkhead mount. Since so many holes need to be moved, I plan to install a new blank panel over the entire area and start cutting new holes to fit the new design.

For a new panel I was thinking of using a black acrylic/lexan sheet, screwed and bedded over the top of the whole panel area. This would be all cut and trimmed to look nice of course.

One of my big concerns is mounting the compass such that it won't have errors due to the surrounding electronics. Currently there is an electronic compass that has a remote fluxgate sensor forweard of the salon.

Any good ideas or words of wisdon are appreciated.

Woody

[CSY Man]

Can't view or open the picture.

[exposure]

It seems that the photo gallery here has decided to take a vacation.

[Alan Wheeler]

I would remove the old units, fit the blank panel and then layout the new units before cutting holes and see what takes your fancy. You can't really go wrong with only three. Your main concern is going to be compass. And the concerns won't come from the Navman uits, but from the VHF and Radar units. Can you retain the electronic compass? Otherwise, make sure you are some distance away from everything with the regular compass.
Wheels

[exposure]

Yes, I could keep the electronic compass, but I don't like it. It has a fixed "card" with north at the top and a dial that rotates around and points to the boat heading. I find it very confusing. I wish it had a fixed lubber line and a rotating card as a normal compass would.

I also don't lie relying on an electronic device as a primary navigation tool.

I may try a regular compass in the far left hole, farthest from the radar and the VHF, and see how it works. Of course there are plenty of wires behind the entire panel, including the main 12VDC bus about .5 meters below the row of instruments.

[Alan Wheeler]

OK I follow you with the Electronic compass.
With a mag compass, I would imagine your biggest enemy will be the radar screen. If it is CRT, it will have degausing coils and correcting magnets on the neck of the tube and so on. It will probably have a changing mag feild between operation and off.
The VHF may or may not be of influence. The only reason it will have an influence is if there is enough metal in it to have some sort of feild. TX'ing shouldn't introduce a changing feild stron enough, but it is easy to test that by placing the compass near it and TXing and see if the card moves. Just keep the antennae cable dressed away from the compass. Actually, keep all cables dressed away from it, but I doubt the new Navman units will be of any trouble.
Good choice on the Navman by the way. I have just brought an Autopilot and hopefuly the wind instrument will be next on the list when I can afford one.
Wheels

[exposure]

The more I think about it the harder it is to find a good place for a compass. The mast is on the left side of the photo. The VHF transmission line and the radar cable run across the back of the panel and up the mast. I think experimenting is the only way I'll find out if I can find a spot with minimal magnetic disturbance.

[Alan Wheeler]

The mast I imagine, would be alloy. No problems with magnetism there. The cables running up the mast will be sheilded and then the mast it's self will also act as a sheild. So you should be safe. As you said, experiment, but I don't think you will have an issue.
Be wary of winces close by. They are mostly SS and bronze, but you may have the odd internal shaft that could be slightly magnetic. Once again, just experiment. It is a matter of moving the compass slowly and carfully around, keeping the thing pointing in the same direction. If you see the card move slightly off that line, something has influenced it. Once you settle on a position, switch on and off everything you can think of and watch the card. Once again, if it stay's still, no problem. good luck,
Wheels

[exposure]

I'll follow your plan to check the compass. The mast you see is stepped on top of the roof and does not extend below it. There is a wood compression post underneath. All of the wires that run into the mast are unshielded, right behind the panel.

Thanks.

[kraker]

mount your compass either from the cabin overhead or over that windshield in front of the pilot.......

[exposure]

I was looking at that idea today. I think it's just too high. Unless there is a compass that can be easily read when it is pointing down I don't think it will work. The overheaad is 6'-5" off the deck, and my wife is 4'-11". Any other ideas?

[Wahoo Sails]

I haven't tried this myself ... but find it an interesting theory. There is engine room sound insulation available with a thin sheet of flexible lead in it ... you'll know it's the stuff I'm talking about as soon as you pick it up ... it weighs a ton. Anyway, the idea is to make a shield of sorts to come between the magnetic sources & the compass ... hey? It could work .... ?

L S/V Eva Luna
Bob

[captd]

the other
"magnetic sources" may not take well to the lead. be carefull, lead does not encouraged magnetic accuracy.

[David M]

Originally Posted by exposure

The more I think about it the harder it is to find a good place for a compass. The mast is on the left side of the photo. The VHF transmission line and the radar cable run across the back of the panel and up the mast. I think experimenting is the only way I'll find out if I can find a spot with minimal magnetic disturbance.

Do what they do on ships. Have a Steering compass and a Standard compass. The Standard compass has been adjusted by a professional and is well clear of all the crap onboard that can swing a compass like magnetic fields generated by DC current. You can put the Standard compass anywhere within shouting distance of the Steering compass. Put the Steering compass wherever you want, within reason. The way it works is you have your mate say "mark" when the Standard compass is on the course you want, you then look up at your Steering compass and steer by that course. You can then make up a deviation table of the difference between what your Standard compass is saying and what your Steering compass is saying. Use the deviation table if your mate is off watch AND you have the same electronics running that you had running when you made the deviation table.

With all the electronics crowded around helm stations that I have seen on many yachts, you can't really put the boats standard compass there and expect it to be accurate.

I agree that those electronic compasses absolutely stink when hand steering. They are too jerky and you don't get much sense of rate of turn. Also, who wants to be reliant on electronics for something as basic as heading? All ships have magnetic compasses to back up their gyro repeaters.

[GordMay]

Preparation of a compass deviation card seems the simplest and most effective solution to compass accuracy, though David M’s suggestion of an extra reference compass also has merit.

The use of lead as an acoustic insulation has been mostly discontinued, in favour of other high density (loaded vinyl) sound attenuation products.
It may now be difficult to obtain lead blankets.

I don’t think you can effectively shield a compass from external electrical interference, and still have it work. Any shielding must be applied to the sources of magnetic disturbance (VHF, Radar etc & associated cables).