Empathy List Archives

TJ

Tim Johnson

Mon, Dec 4, 2006 9:16 PM

I am in the process of selecting the electronics to be installed in a
Nordhavn 64 now under construction. My electronics vendor is
recommending that I use a Furuno satellite compass for navigation input
into the autopilot (Simrad AP 25s). These compasses are expensive (over
$6K installed) and I'm not sure they are worth it. Any comments from
members of this list would be appreciated.

I am in the process of selecting the electronics to be installed in a Nordhavn 64 now under construction. My electronics vendor is recommending that I use a Furuno satellite compass for navigation input into the autopilot (Simrad AP 25s). These compasses are expensive (over $6K installed) and I'm not sure they are worth it. Any comments from members of this list would be appreciated.

RR

Ron Rogers

Mon, Dec 4, 2006 11:17 PM

Well, first it would good to know the reasons he offered to support
installing this piece of equipment. The satellite compass is two GPS
antennas - one on each side of the top of your pilothouse. The instruments
computer can calculate the minute difference in the reception of the WAAS
signal and provide a compass heading. Technautics offers a guidance system
that combines a rate gyro device with a single GPS signal to offer course
maintenance/correction - no fluxgate.

I guess the logic is that the Furuno device is cheaper than the cheapest
true gyro compass. You're either looking up the technology/price line or
down it.

Mike Maurice and others could tell us at what point in traveling North to
Alaska for example do you run into compass/fluxgate anomolies?

Lastly, I believe all Simrad autopilots will accept GPS input so you can go
waypoint to waypoint after careful study and while maintaining a watch and
cross-check of radar, etc. Of course you would do this regardless of
guidance source.

Are they suggesting that you have two autopilots? One a backup. A long-range
cruiser should have some redundancy. So the backup for the satellite compass
is a fluxgate?

Ron Rogers
----- Original Message -----
From: "Tim Johnson" tim@timandclair.com

|I am in the process of selecting the electronics to be installed in a
| Nordhavn 64 now under construction. My electronics vendor is
| recommending that I use a Furuno satellite compass for navigation input
| into the autopilot (Simrad AP 25s). These compasses are expensive (over
| $6K installed) and I'm not sure they are worth it. Any comments from
| members of this list would be appreciated.

Well, first it would good to know the reasons he offered to support installing this piece of equipment. The satellite compass is two GPS antennas - one on each side of the top of your pilothouse. The instruments computer can calculate the minute difference in the reception of the WAAS signal and provide a compass heading. Technautics offers a guidance system that combines a rate gyro device with a single GPS signal to offer course maintenance/correction - no fluxgate. I guess the logic is that the Furuno device is cheaper than the cheapest true gyro compass. You're either looking up the technology/price line or down it. Mike Maurice and others could tell us at what point in traveling North to Alaska for example do you run into compass/fluxgate anomolies? Lastly, I believe all Simrad autopilots will accept GPS input so you can go waypoint to waypoint after careful study and while maintaining a watch and cross-check of radar, etc. Of course you would do this regardless of guidance source. Are they suggesting that you have two autopilots? One a backup. A long-range cruiser should have some redundancy. So the backup for the satellite compass is a fluxgate? Ron Rogers ----- Original Message ----- From: "Tim Johnson" <tim@timandclair.com> |I am in the process of selecting the electronics to be installed in a | Nordhavn 64 now under construction. My electronics vendor is | recommending that I use a Furuno satellite compass for navigation input | into the autopilot (Simrad AP 25s). These compasses are expensive (over | $6K installed) and I'm not sure they are worth it. Any comments from | members of this list would be appreciated.

TJ

Tim Johnson

Mon, Dec 4, 2006 11:23 PM

The boat will have two autopilots.

Timothy A. Johnson, Jr.
895 Espinosa Road
Woodside, CA 94062
tim@timandclair.com

-----Original Message-----
From: passagemaking-under-power-bounces@lists.samurai.com
[mailto:passagemaking-under-power-bounces@lists.samurai.com] On Behalf
Of Ron Rogers
Sent: Monday, December 04, 2006 3:17 PM
To: Passagemaking Under Power List
Subject: Re: [PUP] Satellite Compass

Well, first it would good to know the reasons he offered to support
installing this piece of equipment. The satellite compass is two GPS
antennas - one on each side of the top of your pilothouse. The
instruments
computer can calculate the minute difference in the reception of the
WAAS
signal and provide a compass heading. Technautics offers a guidance
system
that combines a rate gyro device with a single GPS signal to offer
course
maintenance/correction - no fluxgate.

I guess the logic is that the Furuno device is cheaper than the cheapest

true gyro compass. You're either looking up the technology/price line or

down it.

Mike Maurice and others could tell us at what point in traveling North
to
Alaska for example do you run into compass/fluxgate anomolies?

Lastly, I believe all Simrad autopilots will accept GPS input so you can
go
waypoint to waypoint after careful study and while maintaining a watch
and
cross-check of radar, etc. Of course you would do this regardless of
guidance source.

Are they suggesting that you have two autopilots? One a backup. A
long-range
cruiser should have some redundancy. So the backup for the satellite
compass
is a fluxgate?

Ron Rogers
----- Original Message -----
From: "Tim Johnson" tim@timandclair.com

|I am in the process of selecting the electronics to be installed in a
| Nordhavn 64 now under construction. My electronics vendor is
| recommending that I use a Furuno satellite compass for navigation
input
| into the autopilot (Simrad AP 25s). These compasses are expensive
(over
| $6K installed) and I'm not sure they are worth it. Any comments from
| members of this list would be appreciated.

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The boat will have two autopilots. Timothy A. Johnson, Jr. 895 Espinosa Road Woodside, CA 94062 tim@timandclair.com -----Original Message----- From: passagemaking-under-power-bounces@lists.samurai.com [mailto:passagemaking-under-power-bounces@lists.samurai.com] On Behalf Of Ron Rogers Sent: Monday, December 04, 2006 3:17 PM To: Passagemaking Under Power List Subject: Re: [PUP] Satellite Compass Well, first it would good to know the reasons he offered to support installing this piece of equipment. The satellite compass is two GPS antennas - one on each side of the top of your pilothouse. The instruments computer can calculate the minute difference in the reception of the WAAS signal and provide a compass heading. Technautics offers a guidance system that combines a rate gyro device with a single GPS signal to offer course maintenance/correction - no fluxgate. I guess the logic is that the Furuno device is cheaper than the cheapest true gyro compass. You're either looking up the technology/price line or down it. Mike Maurice and others could tell us at what point in traveling North to Alaska for example do you run into compass/fluxgate anomolies? Lastly, I believe all Simrad autopilots will accept GPS input so you can go waypoint to waypoint after careful study and while maintaining a watch and cross-check of radar, etc. Of course you would do this regardless of guidance source. Are they suggesting that you have two autopilots? One a backup. A long-range cruiser should have some redundancy. So the backup for the satellite compass is a fluxgate? Ron Rogers ----- Original Message ----- From: "Tim Johnson" <tim@timandclair.com> |I am in the process of selecting the electronics to be installed in a | Nordhavn 64 now under construction. My electronics vendor is | recommending that I use a Furuno satellite compass for navigation input | into the autopilot (Simrad AP 25s). These compasses are expensive (over | $6K installed) and I'm not sure they are worth it. Any comments from | members of this list would be appreciated. _______________________________________________ Passagemaking Under Power and PUP are trademarks of Water World Productions, formerly known as Trawler World Productions. To be removed from the PUP list send an email with the subject "unsubscribe" (no quotes) to the link below: mailto:passagemaking-under-power@lists.samurai.com Passagemaking-Under-Power Mailing List

MM

Mike Maurice

Tue, Dec 5, 2006 12:44 AM

Mike Maurice and others could tell us at what point in traveling North to
Alaska for example do you run into compass/fluxgate anomolies?

Just did that.

Lots of wandering on northerly headings in the San Juan Islands(48
north). Tested by changing over to 90 east, the wandering stopped. I
have noticed this before, never tested it so convincingly. An Ap45 with
the standard fluxgate.

Mike

Capt. Mike Maurice
Beaverton Oregon(Near Portland)

> Mike Maurice and others could tell us at what point in traveling North to > Alaska for example do you run into compass/fluxgate anomolies? > Just did that. Lots of wandering on northerly headings in the San Juan Islands(48 north). Tested by changing over to 90 east, the wandering stopped. I have noticed this before, never tested it so convincingly. An Ap45 with the standard fluxgate. Mike _____________________________________ Capt. Mike Maurice Beaverton Oregon(Near Portland)

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Satellite Compass