Deck (Watchkeepers) Log

[ZenithOcean]

Clarifying

Courseline
This is your intended route, from A to B

COG - Course Over Ground
Your actual course over the ground affective at that moment in time (or at least based on a calcuation by the GPS over seconds/milliseconds)

CMG - Course Made Good
This is your actual course between A and B, of if you didn't do accurately counter the set and drift, A to C...


So for instance, if you travelled along a courseline of 090 out of a bay and were steering of a heading of say 090 Compass, with your GPS showing COG 092. This 2 degrees is probably due to you not applying the Variation and Deviation to your compass heading, and also could be due to the enivronmental conditions (Wind, Set, Drift).
So you then exit the bay into the open ocean, still steering 090, but your COG now shows 099. Your now exposed to more environmental conditions since you have left the lee of the land.

Eventually because you haven't applied any corrections to your heading, you have a CMG of lets say 95 degrees, which is a combination of the COG from before you left the lee of the land, and then after you left the lee of the land.

HDG 090
COG 1 092
COG 2 099
CMG 095

In general, when you are in the deep blue, you'll find that your CMG and COG over the period of an hour will be fairly similar. As you pass over large waves or swell, your COG and SOG may rapidly change for a moment, but then it will stabilise again afterwards.

[goboatingnow]

I have always used CMG in the past tense

CMG in my view clearly is the start point to the boat "made good" is always past tense, its a fairly useless thing in a log, since its an academic calculation, a log should only report what the boat did , not what it theoretically should do in the past.

I can't see the point of off all this is in a log

Mine has lat lon, log and course, and sometime heading( again not that useful). plus simple stuff on the weather etc. Otherwise Ive seen more confusion in logs. In essence all I want if my GPS fails is enough to DR from the last fix.

see this snipet, It confirms my view http://books.google.ie/books?id=duzi...20good&f=false

DAve

[David_Old_Jersey]

Originally Posted by barnakiel

We do not have one.

I take down position / course / speed during my tricks, but I let the first mate sail as she pleases. Being only two onboard we always meet face to face every 6 to 8 hours or so ;-) then we swap our stories and that's about it.

b.

For a non-commercial vessel I actually think that is a far better approach than a deck log / checklist - when you have crew who you can rely on totally (and they are as good as you, if not better!, and the good is good).

Originally Posted by terminalcitygrl

I can't speak to the sailing directly (yet) but my experience in the real world is checklists work! In priority and with fill in the blanks with specific data points (like speed, heading, etc...)

One page that incorporates directions and feedback as a watch unfolds could be very helpful, especially to folks with little experience.

I must confess I was thinking that the deck log approach would be more suited when crew onboard are unfamiliar to the Skipper, or are known to have limitations (nothing wrong with that - Skipper just has to work around the skills they do have, or simply make sure they don't touch anything - important!)

But certainly I can see it having merit as a "hands on" training tool (not on it's own of course) - one thing I have noticed (whether onshore or afloat) is that folks who do genuinely know what they are doing can easily over assume the "obvious" and that things they do as second nature are understood to the same degree by others. and that applies even to those who are good at training others - always something .

Anyway, at some point I will put pen to paper (or fingers to keyboard!). At some point .

[goboatingnow]

David I would suggest that a deck log is too complicated and anyway if they just put junk in that you'll be forced to "make up" the main log anyway,

Suggest you have a simple main log , lat/lon log course and point out to crew what you expect. I mean if they can't do that , are you letting them sail the boat.....while.. you sleep!!

dave

[Ex-Calif]

Originally Posted by goboatingnow

In essence all I want if my GPS fails is enough to DR from the last fix.


DAve

I agree with this.

Lat/Lon, time and heading steered since last fix is pretty much all I need.

I can plot a course to the destination, figure out how fast the boat has been going and calculate set. This will allow me to calculate a mag heading to steer.

The far side of complexitynis simplicity...

[David_Old_Jersey]

Originally Posted by goboatingnow

David I would suggest that a deck log is too complicated and anyway if they just put junk in that you'll be forced to "make up" the main log anyway,

Suggest you have a simple main log , lat/lon log course and point out to crew what you expect. I mean if they can't do that , are you letting them sail the boat.....while.. you sleep!!

dave

Fair point, and something I am pondering over - at the moment I am heading towards simpler (as more likely to be accurate) rather than everything that would be nice to have "just in case". (as less likely to be honest).

In any event, I figure that, depending on what is in there I do have a good chance of spotting when folks have just made stuff up (and folks doing that is also useful to know!) - but I have had lots of practice at spotting stuff like that onshore, although I appreciate not everyone has the nose for that (you should see some of the stuff that folks think they can get away with - even when there is the (theoretical?) risk of going to jail ).

But of fundamental importance is that I want the crew kept away from the main log!

The pondering continues......