Confessional: admit to boat-related things you've never quite understood...

[Uricanejack]

Does this require jeans?

Chapps?

 

[Uricanejack]

My burgee and bits of ribbon on the shrouds, are firmly locked on to apparent wind.

Mine to

 

[Uricanejack]

Astro in a nut-shell!

At any particular moment, any celestial body (Sun, Moon, planet, star) is directly over a specific point (the nadir point) on the Earth's surface. If you know this point (which requires an ephemeris and time), and measure the elevation of the object using a sextant, in principle you know that you're on a circle centred on that point, whose radius is 90 - the measured elevation in degrees. You can use that circle (which because you know roughly where you are from DR, you can regard as a line perpendicular to the direction of the nadir point) as a position line in exactly the same way as any other position line.

Of course, there are a lot of other things to take into account, such as the effects of your height above sea-level, atmospheric refraction and (for the Moon) parallax errors, but in principle it really is as simple as that. Of course, the mathematics of spherical trigonometry is a bit tricky, but people have kindly worked out rule based methods of side-stepping that bit.

One of us is muddled quite possibly me. Muddeling my navigation or reading and comprehension I'm not sure.

Astro or Celestial Navigation as opposed to Terrestial. I suppose NASA must be into Exta Terrestial Navigation to find the Moon, Mars and other planets I believe voyager has now left the Solar System, Wondering what kind of navigation it is.

According to me.
If a "star" is at your zenith exactly 90 alt your position line is a dot. Not a line. you are at the stars terrestial position.
If your star is within about 1 or 2 degrees of your zenith your position line is definitly a circle and can be plotted using a drawing compass. Plot stars position measure the true zenith distance. If 1 deg you are 60 minutes from the stars position which can be drawn or plotted using lat scale and compass.
Theoreticaly you could also calculate time and azimuth and plot bearing and get a "fix" but unless you are at the N Pole the Stars move to fast. 15 deg per hour or 4 minutes per degree or 15 minutes per minute. 4 seconds per minute.

Hopfully I have now muddeled everyone.

 

[colind3782]

Why is there not a decent 12V DC plug and socket? Using a cigar lighter socket is ridiculous.

My elderly, Spanish built, Furia has dedicated (but now redundant!) 12v sockets all over the boat. They are slot shaped, about an inch long with small bits at the ends, like a long narrow C shape. Haven't seen them anywhere else.

 

[john_morris_uk]

The sound signals are actualy based on the international code of signals, single letter signal flag meanings. and morse code.

Signal flag Echo or E single letter meaning, I am aletering course to starboard. Morse . , dot or 1 short blast.
Signal flag India or I single letter meaning, I am altering course to port Morse .. , Dot Dot or 2 short blasts.
Signal flag Sierra or S single letter meaning, I am using astern propulsion, ... , Dot Dot Dot or 3 shorts blasts.
Signal Flag Hotel or H single letter meaning I have a Pilot on Board, .... , Dot Dot Dot Dot or 4 short blasts
Signal Flag Tango or T single letter meaning, underway making way. -, Dash or 1 long blast.
Signal Flag Mike or M single letter meaning, Underway Not making Way, -- , Dash Dash or Two long blasts.
Signal flag Oscar or O single letter meaning, Man over board, --- , Dash Dash Dash. or 3 Long Blasts.
Signal Flag No5 guess the meaning No Its Not actualy get the F!#$ out the way % short Blasts.

Don't worry I'm not so good at sail trim

Actually I am going to be a smartypants and admit I knew that as I also know morse code very well and was therefore aware of the relationships you describe - but that's another story.

You've missed out "D" for "difficult" One long and two short, which also fits the pattern. I sometimes chat to YM candidates about the very logic that we are discussing here and the relationship of the sound signals to morse code.

However I would still argue that there's a bit of chicken and egg about some of the signals and I still think that there's some logic to the shortest code letter "E" being one short (and chosen as commonest letter in normal English), but also the more frequently used of the sound signals indicating which way you are turning.

 

[nigelmercier]

... in principle you know that you're on a circle centred on that point, whose radius is 90 - the measured elevation in degrees...

I started this reply to ask you to explain this, then it suddenly made sense. Thank you.

 

[nigelmercier]

The sound signals are actualy based on the international code of signals, single letter signal flag meanings. and morse code...

You learn something new every day, or two things today. I always assumed that starboard was one blast because it was "senior", and therefore first.

 

[onesea]

Why is there not a decent 12V DC plug and socket? Using a cigar lighter socket is ridiculous.

Caravans have them 2 pronged things, I had to buy a converter as all my gear has Cigar lighter sockets!

 

[reeac]

True wind is what you feel on a boat at sea that is not moving, but is still subject to tides and currents and so is not stationary geographically.

I have no problem with the concepts of true and apparent wind but now you've lost me. The boat isn't moving but is not stationary?

 

[Uricanejack]

Actually I am going to be a smartypants and admit I knew that as I also know morse code very well and was therefore aware of the relationships you describe - but that's another story.

You've missed out "D" for "difficult" One long and two short, which also fits the pattern. I sometimes chat to YM candidates about the very logic that we are discussing here and the relationship of the sound signals to morse code.

However I would still argue that there's a bit of chicken and egg about some of the signals and I still think that there's some logic to the shortest code letter "E" being one short (and chosen as commonest letter in normal English), but also the more frequently used of the sound signals indicating which way you are turning.

Had to miss a few on purpose. rubbish compleatly forgot that one.

I didn’t know any of this until about 5 minutes ago. “Google”

Samuel Morse didn’t invent the Morse Code.

He invented the first telegraph and a number code based on electrical pulses and the space between them in 1836. First use 1844.
Some other Guy called Alfred Vail who changed the original code and selected most frequent letters used in English by counting the frequency they showed up in the daily newspaper.
He assigned the shortest codes to the most frequently used letters

So he would be the chicken or the egg who came up with E .

The Morse code we use today was developed by some German dude Friedrich Clemens Gerke after he changed about half of it. In 1848 for a telegraph between Hamburg and Cuxhaven

The International Morse Code was adopted at a international telegraph conference in 1865.

Have not yet figured out when it was adopted for use at sea. Or what and when sound signals were introduced

 

[Uricanejack]

I have no problem with the concepts of true and apparent wind but now you've lost me. The boat isn't moving but is not stationary?

Its all about relative motion and true motion.
As I sit here staitionary in my armachair.
My true motion vector =velocity the earth rotates at + velocity the earth goes round the sun+velocity the sun orbiting the gallaxy+the velocity of waht the gallaxy goes around + the vellocity of expasion of the universe. which probabaly has no effect on the true wind.

according Einstien. the greater your velocity the slower time is until you reach the speed of light when time stops.

Mobo's are faster than sail boats
Therefore.
Time is slower on mobos than time is on a sailboat
therefore
Mobos are more boring than sailing

And I can prove it.

 

[JumbleDuck]

Cunningham: a means of flattening the mainsail by pulling down on the luff of the sail. (Instinct says that halyard tension has already sorted out luff tension but cunningham tension works for counter intuitive reasons.

Vang: just another word for the kicking strap. Sometimes ascribed to be an Americanism. A means of controlling the twist in the mainsail.

Danke schön. It would appear that I have a vang, then, but no cunningham to worry about.

 

[VO5]

Actually I am going to be a smartypants and admit I knew that as I also know morse code very well and was therefore aware of the relationships you describe - but that's another story.

You've missed out "D" for "difficult" One long and two short, which also fits the pattern. I sometimes chat to YM candidates about the very logic that we are discussing here and the relationship of the sound signals to morse code.

However I would still argue that there's a bit of chicken and egg about some of the signals and I still think that there's some logic to the shortest code letter "E" being one short (and chosen as commonest letter in normal English), but also the more frequently used of the sound signals indicating which way you are turning.

I was taught D (-..) = Keep Clear. (or danger, keep clear).

 

[JumbleDuck]

I think I saw some about 30 years ago awfull stuff, fairy liquid works.

Fairy Liquid is thickened with salt, which is why it's not a good idea to use it as screenwash. I had a bar of salt water soap on my last boat. It lasted the 22 years I had her, and was probably more useful as a sanding block than as soap.

 

[Uricanejack]

I was taught D (-..) = Keep Clear. (or danger, keep clear).

D -.. I am manouvering with difficulty, keep clear

 

[VO5]

Brilliant! Thank you. Has much unmuddled me on the topic.

Nadir Point = The geographical position of the celestial body in question, expressed as Latitude and Longitude.
This is the location in principle at which an imaginary line punctures the surface of the earth if it were possible to join this imaginary line from the centre of the celestial body to the centre of the earth.

 

[nigelmercier]

True wind is what you feel on a boat at sea that is not moving, but is still subject to tides and currents and so is not stationary geographically...

I have no problem with the concepts of true and apparent wind but now you've lost me. The boat isn't moving but is not stationary?

True Wind is what you would feel if your speed log was reading zero. If you are in a current, you would still be moving.

It's a kludge invented before it was possible to measure Ground Wind, which is the absolute wind passing over the ground. To calculate this, you need a GPS.

 

[Storyline]

You may well skip all the calculations and button pushing, in practice what is most important is to have a rough idea of the magnitude of the difference between the two.
Suppose you are sailing downwind at 7kt, full sails, you feel a nice breeze say 15-20kt (apparent as wikipedia instructs).
Then you want to turn by about 90°-120°-180° around that cape at the end of an island to head for a sheltered anchorage in the lee of the island.
Once you get to the cape (even without local effects) and begin turning to beat towards the anchorage, the apparent transforms into 25/30kt while you are with full sails...

I suppose it's one of the reasons one sees so many engines started at that point

That is why you have to be extra careful when sailing downwind. A few weeks ago whilst at anchor I read an old yachtie mag which had an article written by an accomplished yachtsman (cannot remember name) about three occasions when he was caught out with too much sail up when running downwind. The next morning we set off south down the Sound of Mull on a cracking broad reach. Then the wind came further aft and increased which I did not notice until we had to gybe to avoid the ferry at Loch Aline. A bit hairy and the main came down shortly afterwards and we ended up surfing under genny alone.

 

[nigelmercier]

Here's a sailing question for bargain-end yachtsmen...does any company anywhere still produce and sell salt-water soap?

I'm told this works:
Kirk's Natural Original Castile Soap
http://www.amazon.co.uk/exec/obidos/ASIN/B001D4YDKU/dolcetto-21

 

[chinita]

I aways remember 'No Port Left'.

I can never remember the one for Starboard though.