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tomkielyOffline
Post subject: Solved - Major Compass Problem  PostPosted: Nov 03, 2011 - 02:41 PM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
To make a long story short, I bought my CD28 in CT last November and stored it there for the winter. Due to the orientation & location, I did not notice that there was a severe deviation problem with the compass at the lower helm until I headed east on LI Sound bringing back to MA. In a nutshell, the compass was ďlockedĒ on about 240 until I moved it to the Port side of the salon during the trip home. It works fine as long as it is not in the factory default location that most of the CD28ís have. While it was an inconvenience, I left it on the Port side until the end of the season. After removing all equipment that I had installed last spring, the problem remained. I disconnected both batteries & shore power, and using a hand held compass traced the source of magnetic influence to an area in the PVC pipe that leads to the fly bridge located about 1ft. above the dash board. I have pulled out everything from the column except for the Volvo wiring harness, the throttle & shift cables, and the hydraulic lines for the steering. Since these are all original equipment, I canít imagine they have any bearing on this problem. Using light from above and a mirror, I canít see anything extraneous inside the pipe. I have had a couple of other knowledgeable people look at this and there does not seem to be any obvious explanation. The boat is stored in an easterly orientation this year and yet the magnetic influence forces the compass to display 240. Last year the boat was stored heading in a westerly orientation.

I realize this is a stretch, but I am hoping there is something peculiar to this whole set up that might have caused other CD28 owners to experience a compass problem that seemed to originate from the PVC leading to the flybridge or some other area.

Thanks,

Tom Kiely


Last edited by tomkiely on Nov 14, 2011 - 01:58 PM; edited 2 times in total
 
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djmarchandOffline
Post subject:   PostPosted: Nov 05, 2011 - 08:02 PM



Joined: Oct 15, 2010
Posts: 31

Status: Offline
Tom:

Have you tried disconnecting 12V power? Don't rely on the 1,2,all switch- disconnect the battery terminals. If the problem remains, then it is not an electrical issue. Having said that, I don't know what else it could be.

David
 
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tomkielyOffline
Post subject:   PostPosted: Nov 06, 2011 - 11:53 AM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
David - Thanks for the response. I have disconnected both 12 volt batteries and 110 shore power. Problem still exists. I have removed all but the stock items in the tube hoping that I will be able to see some sort of a foreighn object, but no luck to date.

Tom
 
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JoeBoaterOffline
Post subject:   PostPosted: Nov 08, 2011 - 11:02 AM



Joined: Jul 21, 2006
Posts: 134
Boat Summary: "Mariner II", Hull #047. 1986 28 Flybridge. Shipwright Harbor, Deale, MD
Status: Offline
Interesting problem. I have a flybridge model too, and I've actually added a fair amount of wiring to the tube, and I still only have minor deviation with the compass.

Are you sure the source is in the tube, and not inside the helm console?

If you solve it, please post back here and let us know. Very curious.
 
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tomkielyOffline
Post subject:   PostPosted: Nov 09, 2011 - 11:43 AM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
I'm not sure - I'm open to any explanation - but I have looked inside the console and used the handbearing compass to check for any influence. It isn't until I get up near the tube that the handheld starts to show the problem. When & if this get's resolved, I'll be sure to post it.
 
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ekroekerOffline
Post subject:   PostPosted: Nov 09, 2011 - 12:57 PM
Site Admin


Joined: Jul 12, 2006
Posts: 58
Boat Summary: "Sea Queue:, Hull #190. Fall River MA, 1989 CD28 cruiser.
Status: Offline
Exactly how did you decide that the source was near the PVC pipe? (maybe the source is 180 degrees opposite, for example) Remember a compass doesn't "point" of course, just aligns with a field.

I presume all microphones and speakers were removed from the equation? (although the deviation sounds more severe). Just looking for known permanent magnet locations, sorry for another obvious statement on something you've undoubtably handled long ago.

Although my hull isn't a flybridge, it was on the manufacturing floor with yours (mine is #190). I could stop by sometime and see if anything is obviously different on your boat.
 
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tomkielyOffline
Post subject:   PostPosted: Nov 09, 2011 - 01:18 PM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
Ed - Thanks for the feedback. Using a handheld compass and the old needle & thread trick, I moved around the whole area noting where the magnetic influence seemed at it's greatest. It is a very radical influence. The handheld lines up at 240 quite suddenly when within about 12" of the left hand side of the tube. I did remove everything from the immediate area (VHF, Radar, etc.) and pulled everything out of the tube except the stock stuff as noted above. A friend's boat - #185 - is stored a few boats away, and the both of us have looked at both boats together to see if we could detect any differences. I'll keep your comments about 180 dgrees in mind the next time I go to the boat. Thanks for the offer to stop by and look. Perhaps in a while if I haven't made any progress, I'll take you up on the offer.

Tom
 
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ekroekerOffline
Post subject:   PostPosted: Nov 09, 2011 - 02:01 PM
Site Admin


Joined: Jul 12, 2006
Posts: 58
Boat Summary: "Sea Queue:, Hull #190. Fall River MA, 1989 CD28 cruiser.
Status: Offline
Hmmm, do you have an autopilot (like the Raytheon SportPilot or something similar mounted on the steering gear?) Although I do and don't have a compass issue.

Significant influence just sounds like a good sized permanent magnet somewhere relatively nearby. To have the described influence on your compass, it would have to be BIG or very strong. Some magnetized metal wouldn't have such a large effect unless it was very very close.

Another thought would be to take the ships compass and see if it is reasonably zeroed out in an open field far from influences. There still could just be an adjusting magnet that has fallen off or something (although I'd bet you've already looked at that too).

Might just be the magnetic personality of Cape Dories! [couldn't resist]
 
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tomkielyOffline
Post subject:   PostPosted: Nov 09, 2011 - 02:20 PM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
Ed - No auto pilot. I have taken the ships compass away from any possible source. It is fine. I used it all summer while cruising. I located it on the shelf on port side of the salon with accurate results. All 3 of us who have worked on this assumed that something obvious would be found, because it has to be quite strong. A decent size refrigerator magnet only affects the compass at around 6". This starts around 18".
 
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JoeBoaterOffline
Post subject:   PostPosted: Nov 09, 2011 - 10:35 PM



Joined: Jul 21, 2006
Posts: 134
Boat Summary: "Mariner II", Hull #047. 1986 28 Flybridge. Shipwright Harbor, Deale, MD
Status: Offline
If you move the handheld compass around to the front, rear, or right side of the tube, does it stay locked, or does the interference only occur on the left side? Does it stay locked as you move upward toward the cabin ceiling, or just at the top of the helm?

Any records from the prior owner about modifications made to the boat? New window frames on the starboard side of the boat? Starboard windshield wiper? Shift/throttle controls? Just shooting in the dark here, thinking about what might be nearby.
 
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tomkielyOffline
Post subject:   PostPosted: Nov 10, 2011 - 12:13 PM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
Joe - Have tried to contact previous owner with no luck. Strongest effect is on left hand side about half way up tube. It falls off on the right hand side and as you move up the tube. Windows on port & starboard were pulled out and refinished not replaced. Windshield wipers and control cables all appear to be original. I've got a few more things I'm going to try before I pull everything out of the tube.

Tom.
 
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tomkielyOffline
Post subject:   PostPosted: Nov 14, 2011 - 01:57 PM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
Yesterday I bit the bullet and pulled the only remaining items in the tube - the Volvo wiring harness and the throttle & shift cables. Problem solved. The control cables do not have a stainless core as I assumed but some other ferrous material. Move a magnet anywhere near them and it locks on as if they were a tin can. They look to be original and the previous owner states that he did not replace them while he owned the boat. There are a few hard to read numbers stamped into the outer casing, but I was not able to come with anything after a Google search to try and identify manufacturer or type. While I am relieved to have found the source of the problem, I find it hard to believe that no other owners seem to have had this problem or that Cape Dory would have used this type of cable.

Tom
 
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ekroekerOffline
Post subject:   PostPosted: Nov 15, 2011 - 12:59 PM
Site Admin


Joined: Jul 12, 2006
Posts: 58
Boat Summary: "Sea Queue:, Hull #190. Fall River MA, 1989 CD28 cruiser.
Status: Offline
It may not be the metal type that is the BIG problem by itself, but that the ferrous metal has been magnetized now. Unmagnetized ferrous metal impact will be driven by mass (such as engine blocks) and distance. Magnetized ferrous metal will have a very much larger impact.

In other words, this still COULD be a very unique problem compared to other CD28s.

I wonder if the ground return for power usage in the flybridge inadvertently ran through the control cables, developing a permanent magnetism from the long term current flow? Seems unlikely, as the mechanical connectors at the ends of the cables would make a good/regular electrical connection difficult.

In any case, now you have an measured result and a path to correction. And we have a thread here for other owners. If other owners have information, by all means post (even if very much later in time from these posts).
 
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JoeBoaterOffline
Post subject:   PostPosted: Nov 15, 2011 - 02:06 PM



Joined: Jul 21, 2006
Posts: 134
Boat Summary: "Mariner II", Hull #047. 1986 28 Flybridge. Shipwright Harbor, Deale, MD
Status: Offline
Pretty astonishing. Do you have a plan for fixing the problem? It doesn't sound like compass compensation would be enough.

Maybe you could get some magnetic shielding material and wrap the wiring harness, or maybe just easier (though more costly) to replace the whole harness?
 
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tomkielyOffline
Post subject:   PostPosted: Nov 15, 2011 - 04:02 PM



Joined: Oct 01, 2010
Posts: 88
Boat Summary: Irenicon is a 1989 Flybridge Hull # 192. Her home port is Manchester, MA
Status: Offline
Joe - The wiring harness is fine. It is the control cables that are causing the problem.

Ed - I did wonder about why rhe cables were exibiting such a strong force. At first I thought that something had dropped down the tube and got stuck in the cables, but now that everything is out of the tube, I'll be able to monitor the efect on the compass as I re-install new cables, the wiring harness, etc. If there was some sort of an inadvertand ground, it should be eliminated (I hope) as I go forward with this. When I get a chance over the next few months, I am going to look at the cables on a friend's CD28 that is stored a few boats away at the same yard.
 
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