On Thu, 3 Dec 2009 14:58:24 -0800 (PST), max camirand
wrote:

On Dec 3, 4:13*pm, "Steve Lusardi" wrote:
Max,
This compass issue is real and it is expensive. Here are your choices. magnetic and true. Magnetic compasses deliver a magnetic
bearing referenced to magnetic north. They come in 2 flavors normal and flux gate. Both are influenced by external magnetic fields
even undersea cables, which can be really exciting when sailing on auto pilot. Of the two, the flux gate is the most reliable on a
steel boat, as you mount the sender high up on the mast away from local influences and in your case, is the best bang for your
buck. These are NOT primary ship compasses. This technology is yacht or workboat. All magnetic compasses must be swung at
installation and reswung every year. These can be found used, but if you buy used, plan on sending the unit to a compass house for
servicing and certification. They will need it, especially if you buy from an Indian ship breaker's yard. Gimbaled, flat faced
compasses are available used, but are rare and they are expensive $500-1k. Most cannot be used to take visual bearings. Hand helds
are you best bet there.

True bearing compasses come in two flavors gyro and now, satellite. Ships under 500 tons require at least one gyro *and a
satellite compass as secondary under IMO rules. Ships over 500 tons require two gyro compasses. Gyro systems cost $20k new and the
gyrospheres need replacing every 5 or so years at $8-10K each. Satellite compasses operate using phase comparison of the carrier
signal and are very accurate, if installed correctly on the centerline. Both deliver a true bearing. Gyro compasses lose accuracy
above and below the 80th parallel and suffer speed distortion. Satellite compasses cost between $5k and $8k, run on low power,
very reliable, but will lose its bearing under severe storm conditions, however the good commercial ones have internal fluxgates
and inertial sensing chips that perform automatic dead reckoning under signal loss conditions. Used gyros are a bad deal because
most will have duff gyrospheres, use lots of power and are expensive to service. Used sat compasses are non-existent. The cheapest
new is Furuno, but they won't dead reckon. They have two models, one more accurate than the other. Both affordable. All true
compasses also require repeaters, some are stepper driven, some are differential and others are NMEA 0183. Rotating repeaters have
a max ROT rating. If you have a small boat that can turn quickly, their ROT rating can easily be exceeded. Older stepper repeaters
are typically rated around 6 degrees per second and the newer NMEA ones are around 20 degrees per second and electrical resync
buttons The older ones are mechanically reset. The rotary NMEA repeaters are $2500 each new and very very rare used.

I have a CPlath gyro, a Sperry Marine sat compass, a B&G Flux Gate on the mast and a failsafe CPlath magnetic. I have done it all
and own the T shirt. Bought everything second hand and rebuilt them, except for the Sat compass. I bought that new.
Steve

I'm trying to minimize expense and electricity consumption, so I can't
have any sort of compass that puts a constant drain on the batteries,
as superior as a fluxgate compass may be. Swinging a magnetic compass
isn't a problem.

In your experience, have you found handheld compasses to be reliable
for taking bearings from a steel boat? I absolutely need magnetic
bearings for navigation. My first thought was a flat-faced compass
with a direction finder, like the ones we use on ships. The compass
will be mounted on a steering pedestal and therefore is fairly far
away from the nearest part of the steel hull and deck. The other two
options are a handheld bearing compass or a relative bearing direction
finder on a fixed card (add relative bearing to compass heading to get
compass bearing).

I probably should have asked at the same time... I'm also looking for
a rotator log.

-m

One method that used to be used was degree markings scribed on the
compass bezel with "0" degrees aligned with the fore and aft axis of
the vessel. You then sighted across the device and obtained a sight
line that was "X" from your heading. A poleras? Polaris?

If you have a steel hull boat then you will need to compensate a
magnetic compass. It is a well understood problem and not especially
difficult to solve. I suspect that any compass maker can give you
advice.


Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Max,
Those compasses are not compasses. They are compass repeaters. The compass is elsewhere on the ship.Please reread my earlier
answer below. Another solution to the hand held swinging dilemma, might be to swing the compass positions where you would take
your sightings and simply create an offset table for each one. This too is common practice.
Steve

"max camirand" wrote in message ...
On Dec 3, 4:13 pm, "Steve Lusardi" wrote:
Max,
This compass issue is real and it is expensive. Here are your choices. magnetic and true. Magnetic compasses deliver a magnetic
bearing referenced to magnetic north. They come in 2 flavors normal and flux gate. Both are influenced by external magnetic
fields
even undersea cables, which can be really exciting when sailing on auto pilot. Of the two, the flux gate is the most reliable on
a
steel boat, as you mount the sender high up on the mast away from local influences and in your case, is the best bang for your
buck. These are NOT primary ship compasses. This technology is yacht or workboat. All magnetic compasses must be swung at
installation and reswung every year. These can be found used, but if you buy used, plan on sending the unit to a compass house
for
servicing and certification. They will need it, especially if you buy from an Indian ship breaker's yard. Gimbaled, flat faced
compasses are available used, but are rare and they are expensive $500-1k. Most cannot be used to take visual bearings. Hand
helds
are you best bet there.

True bearing compasses come in two flavors gyro and now, satellite. Ships under 500 tons require at least one gyro and a
satellite compass as secondary under IMO rules. Ships over 500 tons require two gyro compasses. Gyro systems cost $20k new and
the
gyrospheres need replacing every 5 or so years at $8-10K each. Satellite compasses operate using phase comparison of the carrier
signal and are very accurate, if installed correctly on the centerline. Both deliver a true bearing. Gyro compasses lose
accuracy
above and below the 80th parallel and suffer speed distortion. Satellite compasses cost between $5k and $8k, run on low power,
very reliable, but will lose its bearing under severe storm conditions, however the good commercial ones have internal fluxgates
and inertial sensing chips that perform automatic dead reckoning under signal loss conditions. Used gyros are a bad deal because
most will have duff gyrospheres, use lots of power and are expensive to service. Used sat compasses are non-existent. The
cheapest
new is Furuno, but they won't dead reckon. They have two models, one more accurate than the other. Both affordable. All true
compasses also require repeaters, some are stepper driven, some are differential and others are NMEA 0183. Rotating repeaters
have
a max ROT rating. If you have a small boat that can turn quickly, their ROT rating can easily be exceeded. Older stepper
repeaters
are typically rated around 6 degrees per second and the newer NMEA ones are around 20 degrees per second and electrical resync
buttons The older ones are mechanically reset. The rotary NMEA repeaters are $2500 each new and very very rare used.

I have a CPlath gyro, a Sperry Marine sat compass, a B&G Flux Gate on the mast and a failsafe CPlath magnetic. I have done it
all
and own the T shirt. Bought everything second hand and rebuilt them, except for the Sat compass. I bought that new.
Steve

I'm trying to minimize expense and electricity consumption, so I can't
have any sort of compass that puts a constant drain on the batteries,
as superior as a fluxgate compass may be. Swinging a magnetic compass
isn't a problem.

In your experience, have you found handheld compasses to be reliable
for taking bearings from a steel boat? I absolutely need magnetic
bearings for navigation. My first thought was a flat-faced compass
with a direction finder, like the ones we use on ships. The compass
will be mounted on a steering pedestal and therefore is fairly far
away from the nearest part of the steel hull and deck. The other two
options are a handheld bearing compass or a relative bearing direction
finder on a fixed card (add relative bearing to compass heading to get
compass bearing).

I probably should have asked at the same time... I'm also looking for
a rotator log.

-m

On Dec 3, 9:12*pm, "Steve Lusardi" wrote:
Max,
Those compasses are not compasses. They are compass repeaters. The compass is elsewhere on the ship.Please reread my earlier
answer below. Another solution to the hand held swinging dilemma, might be to swing the compass positions where you would take
your sightings and simply create an offset table for each one. This too is common practice.
Steve


On a ship, the magnetic compass is usually directly atop monkey's
island. You can put a direction finder on its face and take magnetic
bearings. The only time I've ever needed to do this was when showing
an apprentice how it was done. In the wheelhouse and on the bridge
wings, they're all gimballed gyrocompass repeaters, of the stepping
kind.

I hadn't thought of creating a deviation table for likely positions of
use of the handheld compass. That's a great idea, and pretty much
solves my problem. I could just get a run-of-the-mill compass with a
hemispherical glass, and use a handheld (or compass-binoculars as
suggested elsewhere) for my magnetic bearings.

-m

On Dec 3, 6:15*pm, matt_colie wrote:
max camirand wrote:
On Dec 3, 4:42 pm, I am Tosk wrote:

Not dumb at all. It is a skill, you desire to get better at it. It all
just depends on how far you want to go with your sport

I'll keep a handheld GPS onboard in case I get hopelessly lost in an
emergency situation

Otherwise, I'm limiting myself to:
lead line
rotator log
compass
sextant
timepiece
binoculars

I'm a merchant marine officer, so I studied navigation professionally
(both the "old" and "new" ways), and GPS has made the job a boring
button-pushing nightmare. I'd like to get away from that on my yacht.
I have no illusions about "going back to nature" or any garbage like
that. Slocum didn't have an accurate timepiece, while I will have one,
and the Polynesians only had some cleverly marked sticks. It's just
that I love navigation and I feel GPS takes all of the magic away from
making landfall. Going back to the methods of the 1800s will at least
involve some level of skill.

Too bad it's more expensive to do things the traditional way.

I have nothing against doing "real" navigation. *That and the paper
charts still work after a lighting strike. *(The story is good, plan on
buying at least three rounds of beer if you want to hear it all.)

Prowl the chandlers and set traps on E-bay. *You might get lucky. *We
that are old enough to use that stuff are dying off fast and the kids
don't want it.

Might I suggest that you get a decent box compass. *They are all flat
top, but that doesn't matter. *Also get a pair of binoculars with a
bearing compass in them.

* *A Sextant is neat, mine is Bendix Mark2. *Been in the family since
WWII. *I Dread to think what any decent device would cost if you could
find it. *A friend has a more modern one with a half silvered front
mirror. *I just can't make it pull down right. *Maybe if I was used to it.

If you want a mechanical chronometer, good luck, they are collectors
items. *A good modern wrist watch will work as well if it is kept at a
more or less constant temperature. *You rate it - just like always.

Are going to do any long passages off soundings? *Because, a taffrail
log is a serious PITA and when you see the shark that snatches the
spinner, you can kiss that one good-by.

Lead lines are an another amazing PITA. *Pretty much useless if you are
single handing. *Lots of them around and often for the price of the lead.

I wish you fair wind and smooth sea.

Matt Colie - Lifelong Waterman, Licensed Mariner (also- 40++ years) and
Perpetual Sailor.

Matt,

Thanks for the tips. I've never used a taffrail log before. I've only
seen them in the movies and read about them. If I recall correctly,
Slocum's spinner was eaten by a shark, as you say. As they seem really
expensive anyway, I suppose I could just estimate my run by taking
speed every watch or every change of weather.

We will be doing many off-soundings passages, but I will never be
single-handing them. I'm not comfortable with nobody being on watch. I
don't scoff at those who do single-hand, but I find it hard to feel
sorry for them when they get run down by ships, because they were
knowingly ignoring collision regulations. They're just looking for
trouble. We're a crew of two (my lovely chief mate and myself), and
we'll try to take on an extra hand for any passage longer than a week
or so, when possible.

I'll probably buy one of the better plastic sextants, because I've
heard they're not so bad (certainly better than some of the crappy
ones I encounter on ships), and the difference in price will be better
spent elsewhere. I know, I know, good instruments are a joy to work
with, but if I splurge for the best in every department, I'll never
get to sailing. A 50$ wris****ch set to GMT makes for a fine
chronometer, and large black-and-white photocopies of someone else's
charts are 8$. I'm not retired nor sitting on a pile of money, so I
have to settle for "good enough" rather than "ideal". You mentioned
that the kids don't want anything to do with traditional navigation...
don't believe in stereotypes; I'm not yet thirty.

-m

On Dec 4, 5:35*am, max camirand wrote:
On Dec 3, 6:15*pm, matt_colie wrote:





max camirand wrote:
On Dec 3, 4:42 pm, I am Tosk wrote:

Not dumb at all. It is a skill, you desire to get better at it. It all
just depends on how far you want to go with your sport

I'll keep a handheld GPS onboard in case I get hopelessly lost in an
emergency situation

Otherwise, I'm limiting myself to:
lead line
rotator log
compass
sextant
timepiece
binoculars

I'm a merchant marine officer, so I studied navigation professionally
(both the "old" and "new" ways), and GPS has made the job a boring
button-pushing nightmare. I'd like to get away from that on my yacht.
I have no illusions about "going back to nature" or any garbage like
that. Slocum didn't have an accurate timepiece, while I will have one,
and the Polynesians only had some cleverly marked sticks. It's just
that I love navigation and I feel GPS takes all of the magic away from
making landfall. Going back to the methods of the 1800s will at least
involve some level of skill.

Too bad it's more expensive to do things the traditional way.

I have nothing against doing "real" navigation. *That and the paper
charts still work after a lighting strike. *(The story is good, plan on
buying at least three rounds of beer if you want to hear it all.)

Prowl the chandlers and set traps on E-bay. *You might get lucky. *We
that are old enough to use that stuff are dying off fast and the kids
don't want it.

Might I suggest that you get a decent box compass. *They are all flat
top, but that doesn't matter. *Also get a pair of binoculars with a
bearing compass in them.

* *A Sextant is neat, mine is Bendix Mark2. *Been in the family since
WWII. *I Dread to think what any decent device would cost if you could
find it. *A friend has a more modern one with a half silvered front
mirror. *I just can't make it pull down right. *Maybe if I was used to it.

If you want a mechanical chronometer, good luck, they are collectors
items. *A good modern wrist watch will work as well if it is kept at a
more or less constant temperature. *You rate it - just like always.

Are going to do any long passages off soundings? *Because, a taffrail
log is a serious PITA and when you see the shark that snatches the
spinner, you can kiss that one good-by.

Lead lines are an another amazing PITA. *Pretty much useless if you are
single handing. *Lots of them around and often for the price of the lead.

I wish you fair wind and smooth sea.

Matt Colie - Lifelong Waterman, Licensed Mariner (also- 40++ years) and
Perpetual Sailor.

Matt,

Thanks for the tips. I've never used a taffrail log before. I've only
seen them in the movies and read about them. If I recall correctly,
Slocum's spinner was eaten by a shark, as you say. As they seem really
expensive anyway, I suppose I could just estimate my run by taking
speed every watch or every change of weather.

We will be doing many off-soundings passages, but I will never be
single-handing them. I'm not comfortable with nobody being on watch. I
don't scoff at those who do single-hand, but I find it hard to feel
sorry for them when they get run down by ships, because they were
knowingly ignoring collision regulations. They're just looking for
trouble. We're a crew of two (my lovely chief mate and myself), and
we'll try to take on an extra hand for any passage longer than a week
or so, when possible.

I'll probably buy one of the better plastic sextants, because I've
heard they're not so bad (certainly better than some of the crappy
ones I encounter on ships), and the difference in price will be better
spent elsewhere. I know, I know, good instruments are a joy to work
with, but if I splurge for the best in every department, I'll never
get to sailing. A 50$ wris****ch set to GMT makes for a fine
chronometer, and large black-and-white photocopies of someone else's
charts are 8$. I'm not retired nor sitting on a pile of money, so I
have to settle for "good enough" rather than "ideal". You mentioned
that the kids don't want anything to do with traditional navigation...
don't believe in stereotypes; I'm not yet thirty.

-m- Hide quoted text -

- Show quoted text -

As someone who had to learn to navigate the hard way, I'm a great fan
of GPS because of its accuracy and because it removes the uncertainty
from making a landfall.
But I still do things the ‘old fashioned’ way just for the pure joy of
it.

There is nothing quite like shooting those morning stars to put you in
touch with your place in the firmament.

And running up a DR on a paper chart is, as far as I'm concerned, just
something that you should do if you put any value on your life.

I'm told that some of the better plastic sextants are quite good and
they are certainly lighter and therefore less tiring to hold up for
any length of time, than the metal variety.
Being plastic, you mustn’t leave them lying about in the sun as they
could warp.

I used a ‘Walker Log’ taffrail log for many years, I never caught a
shark but I did catch plenty of weed.

And I lost quite a few spinners, not to sharks but due to my own
stupidity.

You know what its like, you arrive somewhere new, you’re all excited
about having arrived safely, you’re anxiously looking around to see
where to go etc, so forget all about that spinner, you stick the
engine in reverse!!! Clonk, clonk goes the spinner against the hull as
the line wraps itself around the prop, then twang goes the hook that
attaches the line to the back of the log.

But I guess that’s all part of the fun.

Anyway, good luck to you I thing you are doing the right thing, just
put a cheap handheld GPS in a sealed plastic box with some spare
batteries for those anxious landfalls.

Mike.

http://www.diy-wood-boat.com

On Thu, 3 Dec 2009 21:08:57 -0800 (PST), max camirand
wrote:

I could just get a run-of-the-mill compass with a
hemispherical glass, and use a handheld (or compass-binoculars as
suggested elsewhere) for my magnetic bearings.

When I started cruising back in the early 1970s that is how everyone
on small boats was doing navigation. Hi tech was having a radio
direction finder which had to be coordinated with compass headings,
and a rotating arm depth sounder. Really hi tech was having a Loran-A
set with the oscilloscope and manual pulse delay adjustments but
almost no one had one except for high end yachts with plenty of
battery power.

"max camirand" wrote in message
...
Hi group,

I'm looking for a real gimballed marine compass, with a flat face
usable with a direction-finder. All of the compasses I've found online
have a hemispherical glass face, which makes them useless for taking a
bearing. I also strongly suspect that hand-held bearing compasses are
useless on a steel boat such as mine.

The only flat-faced gimballed compasses I've found are desk
decorations.

I'm looking for something similar to a real ship's compass, without
the giant compensating balls & bar (I will compensate it with
magnets). Anyone know where they can be bought?

Regards,
-Maxime Camirand

Seem to be a few on ebay
#200412065291
#270495395158
#220521183176
May need to come up with a gimbal, but it'll be a lot cheaper that the 7500
euro job.

For me nothing beats this for shooting a bearing: #140364873863

mmc wrote:
"max camirand" wrote in message
...
Hi group,

I'm looking for a real gimballed marine compass, with a flat face
usable with a direction-finder. All of the compasses I've found online
have a hemispherical glass face, which makes them useless for taking a
bearing. I also strongly suspect that hand-held bearing compasses are
useless on a steel boat such as mine.

The only flat-faced gimballed compasses I've found are desk
decorations.

I'm looking for something similar to a real ship's compass, without
the giant compensating balls & bar (I will compensate it with
magnets). Anyone know where they can be bought?

Regards,
-Maxime Camirand

Seem to be a few on ebay
#200412065291
#270495395158
#220521183176
May need to come up with a gimbal, but it'll be a lot cheaper that the 7500
euro job.

For me nothing beats this for shooting a bearing: #140364873863


Marching compasses work well for me too. That one is a replica - so the
accuracy is an unknown. Better to search eBay for "marching compass".
There again, you don't want one that's marked in 0-400 graduations. Good
ol' 0-360 is the way to go!

:-)

Brian W

max camirand wrote:
On Dec 3, 6:15 pm, matt_colie wrote:
max camirand wrote:
On Dec 3, 4:42 pm, I am Tosk wrote:
Not dumb at all. It is a skill, you desire to get better at it. It all
just depends on how far you want to go with your sport
I'll keep a handheld GPS onboard in case I get hopelessly lost in an
emergency situation
Otherwise, I'm limiting myself to:
lead line
rotator log
compass
sextant
timepiece
binoculars
I'm a merchant marine officer, so I studied navigation professionally
(both the "old" and "new" ways), and GPS has made the job a boring
button-pushing nightmare. I'd like to get away from that on my yacht.
I have no illusions about "going back to nature" or any garbage like
that. Slocum didn't have an accurate timepiece, while I will have one,
and the Polynesians only had some cleverly marked sticks. It's just
that I love navigation and I feel GPS takes all of the magic away from
making landfall. Going back to the methods of the 1800s will at least
involve some level of skill.
Too bad it's more expensive to do things the traditional way.
I have nothing against doing "real" navigation. That and the paper
charts still work after a lighting strike. (The story is good, plan on
buying at least three rounds of beer if you want to hear it all.)

Prowl the chandlers and set traps on E-bay. You might get lucky. We
that are old enough to use that stuff are dying off fast and the kids
don't want it.

Might I suggest that you get a decent box compass. They are all flat
top, but that doesn't matter. Also get a pair of binoculars with a
bearing compass in them.

A Sextant is neat, mine is Bendix Mark2. Been in the family since
WWII. I Dread to think what any decent device would cost if you could
find it. A friend has a more modern one with a half silvered front
mirror. I just can't make it pull down right. Maybe if I was used to it.

If you want a mechanical chronometer, good luck, they are collectors
items. A good modern wrist watch will work as well if it is kept at a
more or less constant temperature. You rate it - just like always.

Are going to do any long passages off soundings? Because, a taffrail
log is a serious PITA and when you see the shark that snatches the
spinner, you can kiss that one good-by.

Lead lines are an another amazing PITA. Pretty much useless if you are
single handing. Lots of them around and often for the price of the lead.

I wish you fair wind and smooth sea.

Matt Colie - Lifelong Waterman, Licensed Mariner (also- 40++ years) and
Perpetual Sailor.

Matt,

Thanks for the tips. I've never used a taffrail log before. I've only
seen them in the movies and read about them. If I recall correctly,
Slocum's spinner was eaten by a shark, as you say. As they seem really
expensive anyway, I suppose I could just estimate my run by taking
speed every watch or every change of weather.

We will be doing many off-soundings passages, but I will never be
single-handing them. I'm not comfortable with nobody being on watch. I
don't scoff at those who do single-hand, but I find it hard to feel
sorry for them when they get run down by ships, because they were
knowingly ignoring collision regulations. They're just looking for
trouble. We're a crew of two (my lovely chief mate and myself), and
we'll try to take on an extra hand for any passage longer than a week
or so, when possible.

I'll probably buy one of the better plastic sextants, because I've
heard they're not so bad (certainly better than some of the crappy
ones I encounter on ships), and the difference in price will be better
spent elsewhere. I know, I know, good instruments are a joy to work
with, but if I splurge for the best in every department, I'll never
get to sailing. A 50$ wris****ch set to GMT makes for a fine
chronometer, and large black-and-white photocopies of someone else's
charts are 8$. I'm not retired nor sitting on a pile of money, so I
have to settle for "good enough" rather than "ideal". You mentioned
that the kids don't want anything to do with traditional navigation...
don't believe in stereotypes; I'm not yet thirty.

-m
Max,
As a good friend used to say, "Generalities are typically in error."

You will find that estimating your average speed and there for distance
will not be very reliable (BTDT).

If you are going to run a wrist watch as a time standard, rate it before
for at least a week you start off. And don't wear it as a watch as the
changes in attitude and temperature will throw it off.

"Good enough" will be good enough. If you want to be well ahead, just
keep a log and plot track on real charts. That will put you way ahead
of so many others.

I wish you a boring but successful passage.

Matt

"brian whatcott" wrote in message
...
mmc wrote:
"max camirand" wrote in message
...
Hi group,

I'm looking for a real gimballed marine compass, with a flat face
usable with a direction-finder. All of the compasses I've found online
have a hemispherical glass face, which makes them useless for taking a
bearing. I also strongly suspect that hand-held bearing compasses are
useless on a steel boat such as mine.

The only flat-faced gimballed compasses I've found are desk
decorations.

I'm looking for something similar to a real ship's compass, without
the giant compensating balls & bar (I will compensate it with
magnets). Anyone know where they can be bought?

Regards,
-Maxime Camirand

Seem to be a few on ebay
#200412065291
#270495395158
#220521183176
May need to come up with a gimbal, but it'll be a lot cheaper that the
7500 euro job.

For me nothing beats this for shooting a bearing: #140364873863
Marching compasses work well for me too. That one is a replica - so the
accuracy is an unknown. Better to search eBay for "marching compass".
There again, you don't want one that's marked in 0-400 graduations. Good
ol' 0-360 is the way to go!

:-)

Brian W
Yeah, I have an old one that my "Uncle Sam" gave me. It's never led me
astray!