Empathy List Archives

RT

Ron Trossbach

Tue, Oct 11, 2005 1:04 PM

Dan,

You asked the T&T List last week if anyone has any second thoughts about
Nobeltec.

I purchased and installed Nobeltec IR2 Radar with Admiral in March and have
been very happy with it with a couple of exceptions that we are working on.
At the Annapolis Boat Show their rep told me about version 8 which displays
DSC emergency positions, the free Electronic Navigational Charts (ENC) from
NOAA and AIS info. The Admiral upgrade price was about $500 which seemed a
lot higher than the same upgrade for Visual Navigation Suite (about $150).

One of my problems is with heading sensors.
We have six different opinions on which direction we are going (two different
Nobeltec fluxgate compasses, the Simrad/Roberson autopilot, two magnetic
steering compasses and the GPS COG).
Nobeltec technical support (good people) sent me the second fluxgate when I
told them how much deviation I was experiencing (up to 25 deg).
The new one (in a different location) was no better than the first.
Now they are going to send me a solid state fluxgate by Maretron that Nobeltec
is shifting to.
Hopefully that will solve my problem.
If I can, I'd like to put the autopilot on the same compass and if I can find
a way to display the heading at the two helms, I may try steering with it.
I'm hoping my problems with MARPA jumping around may go away then too.

The only other problem I have is that the system does not calculate the
bearing of CPA. It gives a CPA time and range only and I have to estimate the
bearing from the displayed track on the screen. The answer they gave me is
that the ISO doesn't require a bearing. ISO's are not my thing. Maybe
someone on the list can explain that.

Ron Trossbach
aboard SUNNESHINE, a Sabreline 36

Dan, You asked the T&T List last week if anyone has any second thoughts about Nobeltec. I purchased and installed Nobeltec IR2 Radar with Admiral in March and have been very happy with it with a couple of exceptions that we are working on. At the Annapolis Boat Show their rep told me about version 8 which displays DSC emergency positions, the free Electronic Navigational Charts (ENC) from NOAA and AIS info. The Admiral upgrade price was about $500 which seemed a lot higher than the same upgrade for Visual Navigation Suite (about $150). One of my problems is with heading sensors. We have six different opinions on which direction we are going (two different Nobeltec fluxgate compasses, the Simrad/Roberson autopilot, two magnetic steering compasses and the GPS COG). Nobeltec technical support (good people) sent me the second fluxgate when I told them how much deviation I was experiencing (up to 25 deg). The new one (in a different location) was no better than the first. Now they are going to send me a solid state fluxgate by Maretron that Nobeltec is shifting to. Hopefully that will solve my problem. If I can, I'd like to put the autopilot on the same compass and if I can find a way to display the heading at the two helms, I may try steering with it. I'm hoping my problems with MARPA jumping around may go away then too. The only other problem I have is that the system does not calculate the bearing of CPA. It gives a CPA time and range only and I have to estimate the bearing from the displayed track on the screen. The answer they gave me is that the ISO doesn't require a bearing. ISO's are not my thing. Maybe someone on the list can explain that. Ron Trossbach aboard SUNNESHINE, a Sabreline 36

MM

Mike Maurice

Tue, Oct 11, 2005 3:38 PM

"Ron Trossbach" rontrossbach@msn.com
At 09:04 AM 10/11/2005 -0400, you wrote:

One of my problems is with heading sensors.
We have six different opinions on which direction we are going (two different
Nobeltec fluxgate compasses, the Simrad/Roberson autopilot, two magnetic

There are 2 parts to your problem for which I have some experience.
The first part is the problem, for which I have had a LOT of
experience. This problem with heading sensor jitter or jumping around
is pretty wide spread. Since I see this frequently on various boats,
I have the suspicion that the fix is not necessarily easy. Which
brings us to the second part, the fix, the part for which I have
LITTLE experience.

The smaller the boat the less space you have in which you have to
place the heading sensor and by implication the space to isolate it
from external interference, and place it in the most useful location.
Consider for a moment the heading sensor in an ordinary bowl type
magnetic visual compass. The globe may be 5 inches in diameter, but
the card is often only 1 inch in diameter. Visual magnification of
the card does not make up for the lack of real size. In the "old
days" on real ships the card that was used for steering was often
8-14 inches in diameter and due to this size, it was a lot more
stable than anything we are generally using today, especially on
boats under 20 meters in length.

In some respects a small boat needs a card bigger relatively than a
big ship in order to compensate for it's smallness. So, now comes the
flux gate compass which is really small and you say you want a stable
heading output from this and you are going to put this on a small
boat which is inherently unstable. I read all this and I don't know
whether to sit down and cry or laugh. But, I can imagine pulling your
hair out in frustration, trying to fix this.

To put it bluntly, I have serious doubts that on boats under about
38-40 feet anyone is liable to get rock steady headings without
spending a lot of money. It might be cheaper to buy a bigger boat. In
the meantime, the people who sell these solutions can be counted on
to sell you all the fixes they can think up.

As a side note. I remember a 120' yacht that had a tiny flux gate
compass for it's heading sensor; it ran the autopilot and saying that
it was unstable was an understatement.

I predict it is going to be a long, cold winter.

Regards,
Mike

Capt. Mike Maurice
Tualatin(Portland), Oregon

"Ron Trossbach" <rontrossbach@msn.com> At 09:04 AM 10/11/2005 -0400, you wrote: >One of my problems is with heading sensors. >We have six different opinions on which direction we are going (two different >Nobeltec fluxgate compasses, the Simrad/Roberson autopilot, two magnetic There are 2 parts to your problem for which I have some experience. The first part is the problem, for which I have had a LOT of experience. This problem with heading sensor jitter or jumping around is pretty wide spread. Since I see this frequently on various boats, I have the suspicion that the fix is not necessarily easy. Which brings us to the second part, the fix, the part for which I have LITTLE experience. The smaller the boat the less space you have in which you have to place the heading sensor and by implication the space to isolate it from external interference, and place it in the most useful location. Consider for a moment the heading sensor in an ordinary bowl type magnetic visual compass. The globe may be 5 inches in diameter, but the card is often only 1 inch in diameter. Visual magnification of the card does not make up for the lack of real size. In the "old days" on real ships the card that was used for steering was often 8-14 inches in diameter and due to this size, it was a lot more stable than anything we are generally using today, especially on boats under 20 meters in length. In some respects a small boat needs a card bigger relatively than a big ship in order to compensate for it's smallness. So, now comes the flux gate compass which is really small and you say you want a stable heading output from this and you are going to put this on a small boat which is inherently unstable. I read all this and I don't know whether to sit down and cry or laugh. But, I can imagine pulling your hair out in frustration, trying to fix this. To put it bluntly, I have serious doubts that on boats under about 38-40 feet anyone is liable to get rock steady headings without spending a lot of money. It might be cheaper to buy a bigger boat. In the meantime, the people who sell these solutions can be counted on to sell you all the fixes they can think up. As a side note. I remember a 120' yacht that had a tiny flux gate compass for it's heading sensor; it ran the autopilot and saying that it was unstable was an understatement. I predict it is going to be a long, cold winter. Regards, Mike Capt. Mike Maurice Tualatin(Portland), Oregon

KB

Kim Boyce and Eric Thoman

Tue, Oct 11, 2005 5:02 PM

Ron wrote:

We have six different opinions on which direction we are going (two
different Nobeltec fluxgate compasses, the Simrad/Roberson autopilot,
two magnetic

Mike wrote:

This problem with heading sensor jitter or jumping around
is pretty wide spread. Since I see this frequently on various boats,
I have the suspicion that the fix is not necessarily easy.

Reply:

Ron, I am not sure that your sensors will ever precisely agree. One reason
may be timing. There is a time lag for GPS to establish a heading and even
more so for it to tell your autopilot. A Simrad rate heading sensor helped
us get our autopilot going in the right direction.

Mike, we have the same problem with Nobeltec jumping around. On a smooth
inside passage it does very well. Once we get into bigger seas the "little
boat" wags all over the Nobeltec chart. It makes it impossible to use a
heading up setting because the chart never stays put. Is there a simple
dampening setting for the NMEA info from the GPS? In other words can you
tell Nobeltec to tell me where my boat is every 30 seconds instead of every
5 seconds? Maybe that would slow down the jumping around.

Eric Thoman
Abyssinia

Ron wrote: >We have six different opinions on which direction we are going (two >different Nobeltec fluxgate compasses, the Simrad/Roberson autopilot, >two magnetic Mike wrote: This problem with heading sensor jitter or jumping around is pretty wide spread. Since I see this frequently on various boats, I have the suspicion that the fix is not necessarily easy. Reply: Ron, I am not sure that your sensors will ever precisely agree. One reason may be timing. There is a time lag for GPS to establish a heading and even more so for it to tell your autopilot. A Simrad rate heading sensor helped us get our autopilot going in the right direction. Mike, we have the same problem with Nobeltec jumping around. On a smooth inside passage it does very well. Once we get into bigger seas the "little boat" wags all over the Nobeltec chart. It makes it impossible to use a heading up setting because the chart never stays put. Is there a simple dampening setting for the NMEA info from the GPS? In other words can you tell Nobeltec to tell me where my boat is every 30 seconds instead of every 5 seconds? Maybe that would slow down the jumping around. Eric Thoman Abyssinia

RR

Ron Rogers

Tue, Oct 11, 2005 6:23 PM

PLEASE tell us of your experience with the Maretron device after you've had
a chance to try it. If it works well, then the question would be, can it
provide data to your Simrad autopilot?

Thank you,
Ron Rogers

----- Original Message -----
From: "Ron Trossbach" rontrossbach@msn.com

| Nobeltec technical support (good people) sent me the second fluxgate when
I
| told them how much deviation I was experiencing (up to 25 deg).
| The new one (in a different location) was no better than the first.
| Now they are going to send me a solid state fluxgate by Maretron that
Nobeltec
| is shifting to.

PLEASE tell us of your experience with the Maretron device after you've had a chance to try it. If it works well, then the question would be, can it provide data to your Simrad autopilot? Thank you, Ron Rogers ----- Original Message ----- From: "Ron Trossbach" <rontrossbach@msn.com> | Nobeltec technical support (good people) sent me the second fluxgate when I | told them how much deviation I was experiencing (up to 25 deg). | The new one (in a different location) was no better than the first. | Now they are going to send me a solid state fluxgate by Maretron that Nobeltec | is shifting to.

trawlers@lists.trawlering.com

T&T : Nobeltec