Fluxgate Compass Location

bottomscraper · Post by **bottomscraper** » Oct 22nd, '06, 18:48

I am in the process of installing our new Raymarine S2G Autopilot on Mahalo. The previous Autohelm 6000 system had the fluxgate compass mounted under the deck near the base of the mast. The instructions for the new unit indicate that the best location is between 30% and 50% of the water line measured from the aft end. That would make the old location further forward than desired. I am considering mounting it in the locker under the chart table but that would not be on the center line.

Where do other CD36 owners have their fluxgate compass mounted?

Rich

Bill Cochrane · Post by **Bill Cochrane** » Oct 22nd, '06, 19:03

Rich,

I have two (one for the autopilot, one for the chartplotter) in the forward portion of the underseat locker, port settee, just aft of the head bulkhead and against the inboard face of the locker, in front of and below the hatch opening. Seems to work well and there is no ferrous metal or current carrying wiring in that area (so long as we remember what can and cannot go in that locker).

I believe the location is specified to minimize movement; close to the 3-axis center of gravity. Close to the base of the mast should statisfy that, I would think, so your old location should work. FWIW.

Regards, Bill

patturner · Post by **patturner** » Oct 22nd, '06, 19:14

I just installed the same autopilot and put the fluxgate under the galley sink, against the innermost corner of the small cabinet. Do you think the sink would cause any problems. I have nothing else under there (manual galley pump) and no current. It is pretty close to the center line and just about right where they want it fore/aft.

Watta ya think?

Pat
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HERBAL SHOP
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HERBAL STORE

John Nebilak · Post by **John Nebilak** » Oct 22nd, '06, 19:32

I also positioned a fluxgate compass under the chart table in the "wet" locker and it seems to be working fine. Considering the complications with running the cable more foward, I think the wet locker bulkhead works great.

David van den Burgh · Post by **David van den Burgh** » Oct 22nd, '06, 19:47

Our compass is mounted under the galley sink as well - at the bottom of the cabinet. No problems to date.

Bob Luby · Post by **Bob Luby** » Oct 22nd, '06, 20:33

Yankee Dory (CD-36) Has the compass sensor mounted in the bottom of thd gallley sink cabinet - Amidships.
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Mercedes-Benz Type 300
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Vaporizer Store

Troy Scott · Post by **Troy Scott** » Oct 22nd, '06, 20:54

Rich,

The flux gate sensor in my CD36 was installed under the galley sink, on the inboard side of the locker. I suppose it worked OK, but I never used it. I've removed it and will probably install it elsewhere because I plan to make the locker just forward of that space into a battery locker. The house batteries will go under the "L" of the L-shaped settee. However, if I decide to include a new cabin sole in my refit I may put sealed batteries UNDER the sole. Thoughts?

-Troy

Bob L · Post by **Bob L** » Oct 22nd, '06, 21:47

We have our flux gate under the galley sink. Every so often, something ferrous placed indiscriminately close causes problems (fly swatter with steel handle, metal bucket of citronella). We've learned to watch what we stow in that area.

Parfait's Provider · Post by **Parfait's Provider** » Oct 22nd, '06, 21:54

Parfait's is in the space under the port settee just forward of the galley sink. Seems to work just fine.

Mike · Post by **Mike** » Oct 23rd, '06, 07:43

Rich,

When I replaced the AP on Journey's End I put the fluxgate compass right where you had it on Mahalo. I considered both sides of the bulkhead separating the galley and aft port settee but rejected it because the fresh water pump was located on this bulkhead under the galley sink.

I also considered placing it on a stringer under the main cabin sole, I had the sole removed at the time, but decided out of the bilge was safer.

Mike

Cathy Monaghan · Post by **Cathy Monaghan** » Oct 23rd, '06, 11:41

Rich,

You're supposed to install it as close to the center of the boat as possible, and away from any large chunks of magnetic metal (like the engine or your tool bag or canned food), of course the location of bulkheads and cabinetry make this nearly impossible. Anyway, I've installed mine beneath the sink in the galley farthest forward and inboard, and that location has worked out alright for us (CD32) so far.

By the way, we're using the same fluxgate compass for both the autopilot/heading sensor and radar/chartplotter. I've got them networked together via SeaTalk. The heading sensor has its own source of power from the panel so it can be used with or without the radar/chartplotter turned on.

Cathy
CD32 Realization, #3
Rahway, NJ
Raritan Bay

John Danicic · Post by **John Danicic** » Oct 23rd, '06, 13:51

To all:

After temporarily experimenting with various locations around the cabin, I installed my fluxgate high up in the bilge, (just under the floor boards) aft of the aluminum fuel tank. It's right on the center line. There are no other ferrous parts even close to it nor do I store any near it. The compass is almost spot on with all points except Easterly; off about 12 degrees south. My bilge is not overly wet so I am not too concerned about moisture. Other locations I tried: Sink cabinet, forward of the water tank in the quarter berth, high and low in the hanging locker; all had much greater errors around the card. Or in the case of the sink cabinet, I store my tool bag there which tended to create great directional havoc when I wasn't working on a project and the tools were put away.

I would suggest mounting it different places temporarily and go sailing. See what each location works best for you after a bit of trial and error.

Sail on.

John Danicic
CD 36 - Mariah - #124
Lake Superior.

Len · Post by **Len** » Oct 23rd, '06, 15:03

The factory mounted the fluxgate compass, directly on center high in the bilge below main floorboard access cover. This is behind the alum gas tank and within two feet forward of the engine. Easy access but why would you ever need to access it except to remove it.
Personally, I enjoy the game of comparing my compass heading (binnacle mounted floating card type) to the chart plotter heading (GPS) to the autopilot heading (fluxgate).On top of this if you ever noticed there are many areas on the coast of Maine where the charts indicate "magnetic disturbances" area.

bottomscraper · Post by **bottomscraper** » Oct 24th, '06, 19:30

After weighing all the options I decided to put the new fluxgate in the same location as the old one. If it doesn't work I can move it. The sink side doesn't work for us because that is where the water pressure pump and tank are located. The "wet" locker would be ok but that is where we keep our "everyday" tool bag. The locker under the port side "L" also has tools and other magnetic stuff. The main bilge access has a big bilge pump and the valves for the 3 water tanks.

Thanks for all the ideas!

I just got done installing the rudder position sensor. I made a bracket for it out of King Starboard. I must have crawled in and out of the quarter berth access hole about 25 times today. Lucky for me the actual drive unit is the same as our old one so the mounting for that is done. (We will keep the old one for a spare). Mounting that would have been a big job.

The Cape Dory Board

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