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Simrad Autopilot won't hold course well

Discussion in 'Electronics' started by CSkipR, Jul 14, 2012.

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  1. CSkipR

    CSkipR Member

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    Recently my autopilot will not hold a course well when put into the "Auto" position or when I use the "Nav" function to head to a specific waypoint. Several times the screen flashes "error you have lost heading" in Nav position.
    Is it possible that the power steering could cause this problem if the pressure was lower than the specs call for. Noticed the gauge was around 5psi and I believe it should be between 10-15 psi. I pumped it up yesterday but won't have an opportunity to run it for a few days.
    If this will not cause the problem what are some other possible issues?
    Thanks
  2. K1W1

    K1W1 Senior Member

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    Hi,

    This type of message would make me look at where the AP gets it's heading information from.

    What compass are you using to drive it?
  3. CSkipR

    CSkipR Member

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    Great question I am not sure which one. I believe it is one of the RM E120 but not sure. A few months ago I wired up a new Standard Horizon 2150 vhf with AIS and GPS. Is it possible that my connections messed up something and has created a weak signal, etc.?
  4. K1W1

    K1W1 Senior Member

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  5. Capt Ralph

    Capt Ralph Senior Member

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    The Simrad pilot in NAV position it requiring nema183 data. In auto mode it reads / follows a compass course. The smaller heading numbers on your display will go blank if you loose the heading sensor/compass data.
    I think you have interfered with the nav data going to your pilot from your gps or other L/L equipment.
    If you installed your new VHF and taped into your gps for L/L data, It may be bringing the quality of the NEMA183 down and your pilot can not get a good data sentence.
    Also, 183 uses a differential transmission protocol. Simply put, one of the leads is near logic low (or ground) potential. If wired incorrectly, it could also inject other strange problems with any equipment connected to it, including heading sensor data.
    Disconnect your data leads to your new vhf, usually an old RCA type jack, and note if your problem goes away.
    You would loose rudder at the wheel also if the reservoir pressure was to low.

    What AP model do you have? Some boxes offer multiple data in/out connects.

    Was just in New Smyrna anchored south of the inlet last week. I like that area.
  6. C4ENG

    C4ENG Senior Member

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    Go simple first I would say. What is your rudder limit set to on your auto pilot?

    To low of a setting like 5 degrees, while in certain seas conditions, can be to much limit for your vessel to stear course and the auto pilot goes to error being to far off course just like it should.
  7. CSkipR

    CSkipR Member

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    The model is an AP26. It has been great for the past 3 years always holding a compass course to the same degree as on my compass or right on using the Nav tracking. I am thinking you are right as I tapped into a terminal bar where there was other nema wires from RM and other equipment. Will put the GPS wire off and see if that corrects the problem. Thanks to all that answered and I will advise in a few days if that corrected the problem. Its not fun returning from the Bahamas and having to manually steer for 8 hrs. We also love New Smyrna. If you get back down here call or email me when your coming and we can get together for a cocktail.
    Thanks Skip
  8. Capt Ralph

    Capt Ralph Senior Member

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    The AP 25/26 use AC-xx control boxes. Depending on the model (check manual) you should find a couple of in & out 183 terminals.

    We run our Bert slow and with the small rudders, it's pretty hard to draw a straight line. Bless our pilot. Last trip we made from Strangers Cay to Ponce inlet nonstop. We got blown out this year with that %^& last TS. Parts of Jax and areas west are still under water.
  9. CSkipR

    CSkipR Member

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    The Cabo holds its position pretty well. Sorry to hear about being blown out. We were at Green Turtle from June 8th until July 12th and had some of that TS in GT for 3 days. Miserable. Thats a pretty good run from Strangers to Ponce. I would like to try a straight return from GT to Ponce but it would really put me uncomfortably close on fuel (240nm) (700gls fuel capacity) and with the wife I'm not going to try. Sometimes after our stay in the Abacos we run to West End and i run directly from there to NSB approx 175nm. Thanks again for the help.
  10. MBevins

    MBevins Senior Member

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    Just a question: What happens when you connect a nema 2000 device up to a nema 0183 device (your AP)?
  11. Capt Ralph

    Capt Ralph Senior Member

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    If it's a Simrad AP, the newer displays have a socket in the back for the Simrad SimNet. It's about 85% nema2000 compatible. Any attempt to connect nema2000 to the AP has to be made here.
    You can not tie the nema2000 to a 183 connect. Entirely different ways to push a signal on a wire.
    183 to/from 2000 converter (black box) adaptors are available.