Mondays 11/23/2009 Question and boating safety Tip ANSWERED.

CaptainScott · Post by **CaptainScott** » Mon Nov 23, 2009 8:09 am

I'm thinking compass.

Saftey Tip:
How many of you have a compass aboard your wonderful boat? Better yet, How many of you have ever USED your compass for real?? I mean other than just to play with? I bet not many! I hope I'm wrong! Why know your compass? Heck, I sail the same waters almost every time I sail! A couple of reasons. The first most notible is FOG! Have you ever sailed in fog? It is next to impossible to know which way to go in the fog without a compass or other assistance! On morning my bride and I were snuggly tucked into a quiet slip in Langly Wa. We woke early so we could get back early only to be socked in heavy fog. The fog literaly blurred the fordeck from the stern. It was THAT thick! Well, grabbing my handy dandy chart of the local area I was very quickly able to calculate a compass heading that would not only get me headed home but kept our keel compleatly clear of Sandy Point! Practicing with my compass during clear calm days when there was no wind gave me the confidence to successfully use my compass when I really needed it.

Learn your compass NOW! Play with it when you don't need it! It us much less stressful!! LOL! Trust me!!

Question for today All our nautical charts have a compass rose on it! Have you ever looked at it and wonder what the heck?

Which of the following are shown on the compass rose on your chart?
1) True North
2) Compass North
3) Compass Deviation
4) Magnetic Variation

Capt. Bondo · Post by **Capt. Bondo** » Mon Nov 23, 2009 9:58 am

I'm going to go with, 1) True North 2) Compass North are shown on the compass rose on your chart?

I believe

Compass Deviation, are caused by magnetic influences aboard the boat and Magnetic Variation, take place over very large area.

FranS · Post by **FranS** » Mon Nov 23, 2009 10:10 am

Im going out on a limb and say "all of the above," but mind you I dropped out of the navigation class... no one told me there would be Math involved

.

Alanhod · Post by **Alanhod** » Mon Nov 23, 2009 2:42 pm

EmergencyExit · Post by **EmergencyExit** » Mon Nov 23, 2009 3:15 pm

Got to practice my compass skillset in minor fashion on that night cruise.

To get to the restaurant we followed the curving west bank north to town, but on the way back I wanted to steer directly to the club docks. Didn't have a course to set, but knew from the reverse C shape of the lake I'd leave town going southwest, clip the east bank no wake zone, then continue to the club.

So I aimed to the starboard of some house nights on the point, noted the heading, and stuck to it. 45 minutes later we got to the west side no wake zone we were only a couple buoys from our dock.

Was a neat feeling !

Bhacurly · Post by **Bhacurly** » Mon Nov 23, 2009 10:36 pm

I'm thinking all the above also...

But I gotta admit I use my GPS and have way points set with approaches when I'm IFR and don't have a regular magnetic needle compass. If I ever lost power and my GPS,,, guess I'd have Pam on the bow pulpit hollering at me, so maybe a compass back up should be on my wish list

CaptainScott · Post by **CaptainScott** » Wed Nov 25, 2009 6:50 am

ANSWER:

1 & 4

The Compass Rose on a nautical chart shows true North and Magnetic variation. Since the Magnetic variation changes from year to year, the compass rose also shows a specific year and an annual change. If you have an older chart you must consider the annual change for any calculations you make! Take a look at your chart today! it is good to be familiar with it!

FYI: to get from compass north to True North you must caculate any compass error, compass deviation, and magnetic variation.

Bhacurly · Post by **Bhacurly** » Wed Nov 25, 2009 11:00 am

DOH!

I shoulda known by my excellant multiple choice test taking skills... How would the map know what any "compass" could be showing...

Alanhod · Post by **Alanhod** » Wed Nov 25, 2009 12:53 pm

Arg,

More proof I should stay on show due to fog.

Thanks
Alan

Windward · Post by **Windward** » Wed Nov 25, 2009 3:48 pm

Greetings from Casablanca! You need to leave those things open until Thursday, mate, although you might have had plans for this particular thursday, I suppose.

When she goes to the coast, three compasses on board Windward (one's a hand bearing compass), plus paper charts, plus laptop with e-charts, plus Garmin 492 chartplotter, plus Garmin eTrex Legend and/or Garmin Colorado 400c. Belt, suspenders, drawstring and elastic waistband, eh?

To remember the sequence, I always use
Can => Compass
Dead => Deviation
Men => Magnetic
Vote => Variation
Twice => True

and DAW --> Down Add West.

So, if mag variation is 6 deg w, I add 6 deg to my compass heading to get true. I've only informally calibrated my compasses, and thus have not prepared a deviation table. On NS and WE deviation is less than a couple of degrees, and I cannot steer that precisely for long.

I also ensure that my GPS is set to mag north. That way, my nav's consistent between GPS and compass.

Sailfrog · Post by **Sailfrog** » Fri Nov 27, 2009 2:34 pm

Jeff,

Thanks for providing that mnemonic the help folks remember. To get to the compass heading from true, I use the mnemonic:

True = True
Virgins = Variation
Make = Magnetic
Dull = Deviation
Companions = Compass

That gives me the course to steer, fog or not.

Dan

CaptainScott · Post by **CaptainScott** » Fri Nov 27, 2009 5:18 pm

That is the one I learned by! Thanks for posting it such that I did not have to!!!

Scott