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Old 02-10-2008
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Valiente Valiente is offline
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Quote:
Originally Posted by vega1860 View Post
Valiente, there are a couple of seeming contradictions in your post.

Yes, I see that. Looks like I want it both ways. I suppose it's because it is hard to obtain a taff rail/Walker log these days, and what I've read of them seems to involve losing them to hungry, large fish. I suppose I could use the very traditional method of chucking a board on a bridle off the bow, and counting the seconds until it passes the stern! Fun for the kid, maybe.


Concerning my comment about needing a mechanical log or other manual means of determining boat speed for maintaining a DR position you said:

The GPSes do this quite well, and we keep hourly logs from which we derive set and drift, etc. DR positions are customarily kept and then compared with bearings taken from the shore (when it's visible) or against GPS reports. I plan to add celestial-derived positioning into the mix in order to add another element this summer.

Further down the page you say:

GPS is a great way to *confirm* a position...but it too, can be off: I've seen with my own eyes a significant correction to a GPS display even while it was reporting a good contact with four satellites. Briefly, my boat was doing 130 knots SOG, until I learned I was four miles SSW of where I'd been seconds before! Thanks to pilotage, I knew that the GPS system itself was "having a moment", (I had two GPSes on, and they both went briefly mental) which is why I like to have as many sources of information as possible, like following a 10 fathom contour line, for instance.

OK. You like using a sextant but, remember, we didnít get a good enough look at the sun to get a sight for over a month on our crossing.

No moon or stars at night, either? If I have confirmation of my time, I don't necessarily need a noon sight.


You said:
I differentiate between the deck log and the maintenance log, butwhat I'm talking about here is a record of your position plots, be they by DR, Observation or GPS. My point was the need for position determined by two or more separate means, belt and suspenders, and comparing the relative accuracy of the positions determined by various methods so you are aware of the accuracy you are achieving.

Sometimes the problem is terminology. What I usually do on the lake is to study the lake chart to get a general bearing that combines shortest distance with a safe margin off any known nav hazards (there are few on Lake Ontario excepting a couple of reefs, rocks and headlands). Then I do my plots on a chartbook, a "not for navigation" wire binder collection of older, out of copyright charts that nonetheless suffice for plotting courses. Due to the "bent carrot" shape of Lake Ontario, the logical course will frequently be several miles offshore, so what you want is bearings to whatever landmarks you can see at that distance, of which there are several (CN Tower, Crysler Point power station chimney, etc.) So I will take visual bearings on deck, plus a simultaneous GPS position, and only if they fail to match will I trot out the "official" paper chart. In heavy weather or fog, I will keep a DR in terms of noting how long and at what logged speed (either from the sounder, which has a SOG function, or the helm GPS)and course we've been travelling. I don't mind sailing in fog in terms of navigation, but I do worry about other vessels, which is why I'm looking forward to getting radar. Radar is not necessary for yachts on the Great Lakes in most situations, but I believe it's pretty critical on an ocean-going boat, if you can justify the power draw issues and can interpret the display. I've had a bit of practice at this, and I am fascinated by looking at distant weather via radar, as well as discerning seawall gaps at night and other hard to locate features.



(I might add that I agree with your observations on celestial. Itís just that on a boat the size of a Vega in all but a flat calm sea it is nearly impossible to get a decent sight.)

I would imagine. Our boat is a more stable platform naturally, and having the ability to brace against the pilothouse (handy for binoculars as well) means you can do the bob and weave thing smoothly in order to bring down the sun or planet.

On the subject of logbooks: we use a day planner zipper binder with tabs dividing the engine log, provisioning lists, stowage plan, expense record, position log and daily journal. It has pockets and inserts to hold our passports, vessel documentation, Veterinarians health certificate for the cat, Yacht Club membership cards, Coast Guard inspection certificate etc. You will really impress the Coasties if you whip out the book that has everything organized at your fingertips. The inspection, if they bother to inspect at all after seeing that you have your act together, will go a lot more smoothly. When they ask if you have flares, for example, just flip to the page where you have recorded the purchase and expiration dates and tell them. What could have been an ugly experience ended up nothing more that them standing on the dock filling out the form and me sitting on the boat with my logbook.

That's a good idea. I use a binder with three-hole paper currently, but the "ship's papers" are by the companionway in a plastic slipcover. The zipper binder might be a better idea because it should be at least splash-proof.

Frankly, a lot of my decisions come from having the pilothouse, which I treat as an office...a dry office. I only bring on deck what I need to, which is usually just a handheld VHF and maybe a handheld GPS. If it's raining, I'll move inside unless I need to be actively sailing with a lot of sail trimming.


Good point about the barometer BTW. Essential equipment for offshore, in my opinion, but, like everything else, only if you know how to use it. Laura got quite good at forecasting the weather using the barometer, thermometer and watching the clouds. Then again, you may have a weather fax or satellite internet connection but whatís the fun in that eh?

In addition to the wristwatch (which shows me just now that the pressure drop of the last six hours has levelled off), we have a traditional aneroid barometer, plus a Speedtech recording barometer with humidity and temp readings. Once calibrated, it has proven to be exceptionally accurate (there's a major weather station 200 metres from my dock). I treat the Internet connection (wireless at dock) when I have a laptop aboard like the GPS: it provides some of the data to determine how I plan my day. For instance, if it's stinking hot with a SSW breeze in late July at 9 A.M., and I see on a North American weather map storms in Indiana or Illinois or Michigan, odds are excellent that squalls will form by late afternoon and will march right up the lake. I have also used live weather radar in race situations, not only to determine whether it's safe to race at all, but to gauge where disturbed air is likely to be, and at what point the onshore and offshore winds of evening will trade places. All good fun, if you don't put too much faith in it.

We enjoy being self reliant. We enjoy learning how sailors crossed the oceans in the 18th 19th and early 20th centuries and trying out their methods in our own voyaging. The old ways still work, are challenging and, for us, fun. But letís not be foolish about it. We carry a set of signal flags for fun. Not as a substitute for a VHF.

I made a Q flag, but I have to admit, I don't carry signal flags. Maybe after I get a sewing machine!
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