Compass talk with a nuclear physicist.

id. painter · 01-10-2003, 08:17 AM

Last night i called my father (nuclear physicist) and ask about compasses. Whow, he had some very interesting things to offer.
The first thing he mentioned was it was about 100 times better to navigate with a G.P.S.
Then i started asking questions.
He has two boats , a 24 ft.Bay Liner and a 16 ft. Alumaweld Intruderfor fishing.He lives on the water in B. C. Canada. His home is at the mouth of the Nimpkish river on the North East side of Vancouver Is.
He said that he has gone through 2 and maybe three different compasses just trying to adjust them. He is very scientific and exacting, followed the directions exactly, and never could correct for any error in the compass.
He said that he couldnt get them to be absolutly correct. He would adjust the compass going one direction and that it would be off ,more,after a 180 degree turn around. He was not impressed with consistency or accuracy. .
He said that he has had the best luck with a 20$ hand held (with no adjustment screw).
He was pretty sure that after trying to adjust the compass it worked worse than when he
started.
He has spent many many day fishing the ocean with out a G.P.S. he is now 70.
From his perspective you cant even begin to be exact navigating with a compass. BUT,
He did say that he uses his compass to navigate a straight line (driving) from point A. to point B...."Its easyer to maintain course" with a compass.
After this conversation i realized that i do know how to use a compass(generally).
I spent many day hunting Elk and White tail in N. Idaho and used a compass to keep safe and always made it home.
He also mentioned that Your compass dosnt need to be exactly correct to help especially if you mostly use it to keep a heading.
If my electronics fail, ill be able to get back to the contnent and hope its the same state i departed from.. id. painter

black magic · 01-10-2003, 10:07 AM

ID
Compasses are very accurate devices. They always lineup exactly with the line of magnetic force that is influencing them at any given moment. The problem is usually the environment they are in, not the compass. Any deviation that the compass shows from the earths magnetic north is almost always caused by influences aboard the vessel itself. There is a process that must be followed before any adjusting of the compass should be attempted. Even after adjusting the compass to compensate for local influence some error may still exist. It is then possible to construct a deviation table for the particular vessel. After doing all of this it is very likely that you will have a very accurate indicator of any heading. This is all explained in fair detail in a publication called 'Chapman Piloting'. This book is called by many 'The Boaters Bible' as it covers seamanship, piloting and boat handling extensively. It can be found at almost any large book store or marine supply.

Mark Mc · 01-10-2003, 10:14 AM

Well, everyone is entitled to their opinion. Maybe from the perspective of a physicist, you can never get the tolerances "accurate enough." In practice, when you get a very good marine compass (like $400. on up), and a good marine technician who knows how to compensate it, that tech will set it up right without any problem.

My old boss Pete (may he RIP), on one of his boats, would run through pea soup fog out of SF Bay, round point Bonita, and head the 20 miles to C buoy with nothing but a compass and a watch. I can remember how he would say, "we should be coming up on C bouy any time now." Then in 30 seconds we could hear the buoy, then we could see it almost dead ahead.

This is how many guys navigated for years. Yea it's so much easier now, but it sure seems that living in this modern age with all our gadgets has created this myth that the old ways don't work anymore, or they can't be trusted.

Miss B Haven · 01-10-2003, 10:38 AM

id - Not sure exactly where in BC that is, but I can tell you there are a LOT of local magnetic disturbances in the Islands up north. Even if he had corrected his compass perfect in a particular spot, a few miles away would be? Gotta watch those charts up North. There are also professional services to swing your compass for you.
As far as steering a straight line, yep - great for that. Also- your GPS will give you a heading that your currently on. You can check your compass against that in any given spot or heading. GPS is NOT subject to local disturbances or any deviation caused by objects in the boat.
The problem with compass nav is when you get in close. Your compass won't tell you if you're inside or outside the Jetties in the fog. And of course if you don't know where you started at, a straight line will get you to the beach, but you may not know which one. It won't tell you where that red bouy that marks the entrance or the spit is. It won't tell you that there's ship traffic headed your way. It also won't tell you if you are cross tracking (crabbing) in the wind or current.
If my GPS goes down, yes I'll be steering by compass but my other eye will be on the radar (it actually is even when the gps is up). Just like you should follow your gps waypoints on a nice clear day (to make sure they are correct and you know how), you should run your radar on nice days to get a feel for the radar picture of your route (before you need it). You can follow the bouys on radar all the way from the CR ( locally known as the spark plug -it's a radar transmitter bouy) to the marina if you had to. Of course you need a good chart or have them memorized too. Even with the GPS working, radar is the only thing that will let you know of ship traffic. It is also very comforting to have a bouy on the chart plotter and also see the return on radar.
Your depth finder is also an invaluable tool for navigation. Knowing the depth profile offshore will tell you how close to the beach you're getting and when to "turn away" and start looking for those bouys/jetties. And, like the bouys you can actually navigate the mouth/river and follow the channel if you know ahead of time what depth contour you are looking for (and what to watch out for).
I'm sure there are folks out there that are perfectly comfortable running blind in fog. I'm not one of them. Give me a pitch black night and I'm ok, fog makes me very nervous even with all the "stuff" working. I don't know if you have run in fog, but I would recommend you do that before heading offshore by yourself. I have been "caught" in fog on the way back in a number of times. The ocean out of the CR can be nice and clear, but the river and mouth can be near zero (I have heard the coast guard report "zero vis" many times). The first time this happened I was freaked to say the least. I am now moderatley comfortable with running in it. It's a matter of practice (knowing what to do) and confidence in myself and my electronics/compass. Just a matter of doing it enough to get a routine down and having a mental "chart" of the route in my head.
Unlike trailering a boat down the freeway to go fishing, taking a boat offshore is an experiance where getting there (and back) really is half the fun.
As the fellow who sold me Miss B Haven said when we finalized the deal:
"Good luck and enjoy the adventure" :smile:

PeterMac · 01-10-2003, 12:06 PM

Nimpkish valley/river. What a place that must be to live.

PeterMac

bait boy · 01-10-2003, 12:06 PM

For those that don't know already there is a 10-15 degree variance in the Newport area. I found this out last year trying to steer a course for the jaws. Comparing the compass heading to the GPS is a very good idea. The GPS does not give rats behind what the local variance is because of the way it determines its course.

id. painter · 01-10-2003, 12:11 PM

My father is an old timer, he has always been a do it your self kind of guy. He made a 4.0 G.PA. in Neuclear Physics, before the calculator (slide rule) . Everyone who directly works for him has a P.H.D.. Super bright guy. I would be willing to bet that he understands a compass better than any boat tec. It is his life, his boat and he would never trust a boat tec. with that responsibility. His 2 cents worth.
If you havent noticed, i have ask no questions about anything except safety equipt. Nothing about jigs, limits,cleaning tuna, rods, reels ect.ect.... I must have a little of the old man in me . A little overly cautious. I need to feel confortable before i can have a good time.
FIRST THINGS FIRST. id. painter

rojo · 01-10-2003, 12:26 PM

black magic. thats the first time I've heard Chapmans mentioned here..It is the bible of boating everyone should read it, I keep a copy on the boat at all times....Roger

id. painter · 01-10-2003, 12:27 PM

PeterMac. It is really fantastic up there. My father goes up around the first of April, and stays till the end of Sept. He spends all summer munching sea food, and relaxing. He earned it. id. painter

Miss B Haven · 01-10-2003, 04:17 PM

Good point Rojo. I 've got it on board at all times along with my Bowditch. Man do I need to study that Bowditch though. If you really want to learn to Navigate- thats the book. Added those to my list on "whats on your boat".

PS - Anything going on down at Warrenton? Last time I was there a piling had broke off on Paula Jean's finger. Any new damage or stories?

Mark Mc · 01-10-2003, 05:00 PM

Monsieur Bait-a-boy-ya,

Good reminder; actually it's a 19 degree variance (right on that chart everybody has now). But what's a few degrees between friends! Or between the chicken ranch & Newport?

Seriously though, folks should be aware of the difference between true north and magnetic, both for their GPS setup, and also when communicating with each other (ya I ran 240 from the bouy, and I'm dead in the water"). "Is that 240 magnetic (compass) or true?" 19 degrees is a whopping difference.

Uglygreen · 01-10-2003, 06:26 PM

Well, in contrast, my grandfather (of the same generation) was a Wyoming wheat farmer, born in the same house he died in. Here was one of his favorite sayings:

"Good Enough is ALWAYS good enough, Perfect is ALWAYS a pain in the ass..."

He had lots of other Wyoming whear farmer sayings, not many of which are repeatable here.

UG

[ 01-10-2003, 07:27 PM: Message edited by: Uglygreen ]

id. painter · 01-10-2003, 11:39 PM

All good input. My father is very exacting and will tolerate no deviation. He did say that he thought that the boat environment was the trouble.
My father spent years , going to sea with only a compass. Always came home.
One thing he did mention was that he will never go without a compass.
I have driven a boat in the fog, trying to stay on the same track as the day before. I was poor at it, to say the least. My track was a zig-zag, it was a good lesson though. I realized that even with a G.P.S. you could get really confused.
It has become obvious that you trust your compass , and that it can be a great tool if used correctly. My father is probably too critical, much more than any boat tec.
Magnetic interference around the islands??? Ill look into that idea more.. THANKS. id.painter

Miss B Haven · 01-10-2003, 11:59 PM

Id - The charts will say "local magnetic disturbance reported" (assuming I remember correctly). They don't tell you which way or how much! :depressed: :shocked: :whazzup: I think it's probably where the aliens have landed in the past. Dang space dust!

I found out years ago, first time in the fog that I do left turns if I don't watch the heading on the compass (or use the autopilot). I swear the boat is going to the right if I'm holding a steady course on the compass. If I don't watch the compass and "feel" like I'm going straight I am going around in counterclockwise circles. I've talked to other people who do the same thing. Maybe it's a Righthander versus Southpaw thing- who knows. All I know is I quickly learned to trust the compass and electronics

more than I trust myself. [img]graemlins/stupid.gif[/img]

Redbull · 01-11-2003, 05:37 AM

So it's a little off topic, but it's kind of a funny compass story.

I have done a lot of offshore sailboat racing. In 1988 a buddy and I competed in the Double-handed Division of the Pacific Cup which is San Fran to Hawaii. (just 2 people) After we had done the delivery from Astoria to SF, we felt compelled to go over our list again in the final days of prep. prior to the race we felt we needed to have the compass swung (adjusted) before departing. Keep in my, this is ever reliable Loran and Sat Nav days - not the $100 gps days.

After finding our little compass guru in the phone book, he showed up to the boat and saw 'Portland, OR' on the transom. He introduced himself and proceeded to ask if we shipped or sailed the boat to SF? "We sailed of course." To which he promptly responded, "Astoria to SF without a problem a now you want me to screw with your compass. I'll pass."

Smart man!

Pilar · 01-11-2003, 05:39 AM

Time to go to Powells ... and maybe Captains nautical supply, my charts are aged beyond usefulness.

Edit ....

A few thoughts about compass and accuracy.

I was very surprised when after using my compass for a few weeks I turned on the dash backlight and the dial turned about 30 degrees and stayed there.

Then I remembered what I knew about magnetic fields and degaussing. Any magnetic field will interfere with the operation of your compass. Much of what happens with electrical equipment is based on magnetism and it's relationship to electric current flow.

The compass works by aligning itself with the earths magnetic field or any magnetic field it is exposed to. It does this by the old opposites attract, likes repel rule for magnets. So the south end of the needle or compass ball is attracted to the north magnetic pole of the earth and you see the opposite side of the ball when you are looking north, you see north.

Degaussing is something used by the USN to reduce the effect on the earths magnetic field by the steel in a ship. Some mines are magnetically fused and detect a change in the field. Many things can alter or create magnetic fields. Ferrous Steel is a conductor of magnetic fields and concentrates the field by this property of permeability. So when a ship travels through the earths magnetic field it changes the strength and direction of the field near the ship because of the steel. The same is true for any steel objects and the effect is proportional to the size of the object. Any steel object can become magnetized. This greatly increases the interference. I wont even go into stereo or radio speakers. That's a huge magnet.

Even a small steel screw can affect your compass.

While things like Stainless steel or aluminum have a minimal effect. They do not affect magnetic fields.

The other common problem is current in your wiring. That was my problem with the dash lights. The current going through the wires created a field and that deflected the compass.

So I rewired the dashboard (moved the wires) and kept at it until the compass stayed steady no matter which thing I turned on. You can do things to any wiring that is a problem like twist the + and - leads together. This will cancel out most of the field produced by the current in the wires. The best thing is to avoid wiring near your compass.

With your boat sitting still and away from any massive steel object, car, pole barn, D9 cat, whatever .... turn on each electrical thing on your boat and watch the dial on the compass.

I bet some of you will see the dial move at least a few degrees.

Just a thought .......

[ 01-11-2003, 09:24 AM: Message edited by: Pilar ]

Pilar · 01-11-2003, 08:00 AM

Bump

Miss B Haven · 01-11-2003, 08:09 AM

Good excercise Pilar. Now if I can just remember to do it when I'm at the boat! [img]graemlins/stupid.gif[/img]

01-11-2003, 08:14 AM

I can take you to a spot SE (Duke Island area) of Ketchikan where you can run a compass heading and go in a circle due to large mineral deposits.

Pilar · 01-11-2003, 08:21 AM

Keta! Good to see you bro. The mineral deposits are Iron? or Cobalt?

01-11-2003, 09:31 AM

Hi John,

There's copper, cobalt, nickel as well as masive iron deposits.

I wish that I'd had more time on this trip to visit.

rojo · 01-11-2003, 01:34 PM

Mel: Not much going on down there, only gusts to 85 so far this year. Iget down and check things about ever 2 wks, heading down about the 15th.. On compass deviation..on chart the deviation is listed in most compass roses along with e increase or decrease degrees...Roger..ps just got back from the clack with James only 1 fish for 3 rods.. :depressed:

corrirod · 01-11-2003, 03:44 PM

Practice, practice, practice....

Like Miss B says, especially on the nice days, practice. It was mentioned in another thread about having your shipmates learn to operate your boat efficiently, well it's the same with the electronics. Make sure they have a general understanding of what is going on and let them practice as well. Many times during salmon season the fog rolls in to near zero vis. These days are actually fun if you're out with another boat and you want to practice your "no vis" navigation. Several times during the day I will call the other boat, ask for his GPS coordinates, then motor to him. As I start to get close I begin to watch the radar to pinpoint his location. In open water I enjoy the fog. When trying to find the entrance to Depoe Bay in the fog when the sun is going down, that's another story! (a-- so tight I could turn coal into diamonds :shocked: )

You really need to use your gadgets to understand them. There are days when the water is so calm that my radar will pick up birds and crab bouys sitting in the water. It's really nice to know the difference between a bird and another boat when you're running at 20 knots in the fog!

I know how to use a compass, and I do use it to hold a heading, but I don't ever want to have to use it as my sole source of navigation, thus the reason why I carry a backup handheld GPS.

[ 01-11-2003, 04:47 PM: Message edited by: corrirod ]

id. painter · 01-13-2003, 06:27 AM

Great conversation all,, Thanks for you knowledge and advice. i.d.p

Popeye · 01-13-2003, 09:23 AM

I don't have my compass boxed for Newport, but I DO watch my compass versus GPS Coordinates constantly. I think that is probably the best safeguard available if and when, as Pilar calls it, the plastic Jesus goes down. Of course I'm like most, in that I carry a backup GPS.