raymarine e80 - cog problem

[seabright]

Hi,

I have a E80 on board networked with instruments and autopilot.Haven't used it that much since I bought the boat 3 years ago relying instead on a old gps and hydrovane (and pencil...).

We are now in NZ and I have invested in a chip so I am good to go. It does make things very easy and convenient on the w/e jaunts but do have a COG issue. The bearing it gives for COG is consistently out. Everything else is good. The COG it plots on the chart (screen) is right and, if you use the XTE to keep you going on course, then you get to the waypoint. It is just the number it gives for the COG. My second gps gives the right COG.

All are true bearings so not a problem with variation. It is networked with the compass for the autopilot which I can recalibrate (this is a bit out as well) but I assume that this should have no effect on the COG which should be just GPS derived.

Any thoughts would be appreciated.

Thanks

 

[PeterR]

Raymarine COG

I Have a Raymarine C80 at the chart table and ST60 graphics on both sides of the helm. When steering manually to a waypoint I will often set the graphics to show COG and BTW. In open water I prefer this to the rolling road view (the numbers are bigger) but matching the numbers takes a little getting used to because there is a distinct lag between changing course and that change being reflected in the COG. The lag is a damping mechanism to reduce the effect of yawing and allows the plotter to calculate things like CPA under MARPA and AIS. The effect is even greater if you have a gyro stabilised sensor on your autohelm control.

It may be that your problem is simply due to your old GPS reacting quickly to changes of course whereas in your E80 the effect of changes are damped.

However, if as you say they are consistently out there must be another reason. You say all bearings are true but are both instruments applying the same variation? Each instrument will have the option of auto variation selection or manual input. Have a look at what they are using.

 

[seabright]

Thanks

Thanks fro your thoughts. All been checked as these were my initial thoughts. Consistent error even going on a steady course. All very strange.

 

[Bosun Higgs]

I have a C80 but dont use it much ( prefer pencil and paper) so what follows is from an aged and faulty memory!

I believe there is a setting in the menus for deviation as well as variation. Maybe you are using the default variation figure ( again in the menus and a separate setting from the actual number) and the default in my set is a N Hemisphere one

 

[Ian_Edwards]

Upgrading the software?

We have an E80 interfaced via seatalk to depth, speed and wind instruments along with the Raymarine GPS unit. The COG works just fine.
If the unit is quite old and hasn't been used much it may have an out of date version of the software. If you look at the Raymarine website, you find instruction for down loading and updating the software. Our unit is 2years old and I've updated the software twice since the unit was installed.
I found it quite easy to do, if you follow the instructions carefully, but do remember to save any waypoints onto an CF card, because the upgrade may need a master reset, which put the system back into its default condition and erase all the waypoints. The current version of the software is 5.52 and the website is:
http://raymarine.custhelp.com/cgi-bin/raymarine.cfg/php/enduser/std_adp.php?p_faqid=1174
I’ve found this worth doing; it fixes software bugs (and hopefully doesn’t add new ones) and adds capability and it may also solve your COG problem.