Checking the compass...

[zzyyxx]

Nope, current models have a solid-state magnetic compass in them.

Wouldn't like to comment on its accuracy, but it's nothing to do with GPS.

In which case it's likely to suffer from the same deviation effects as the boat compass it's
next to. Which in turn will likely be affected by any magnets in the phone or it's signal if it's
turned on.

I've never been able to measure anything accurately enough to have to worry about deviation
in a plastic boat, but then I'm pretty poor at measuring things.

 

[prv]

In which case it's likely to suffer from the same deviation effects as the boat compass it's
next to. Which in turn will likely be affected by any magnets in the phone or it's signal if it's
turned on.

Oh, indeed. I'm certainly not suggesting checking the steering compass against a phone app.

Then again, I'm also dubious about checking it against a hand compass, for much the same reasons.

Far better to check against the surrounding world, using a transit.

Pete

 

[zzyyxx]

Oh, indeed. I'm certainly not suggesting checking the steering compass against a phone app.

Then again, I'm also dubious about checking it against a hand compass, for much the same reasons.

Far better to check against the surrounding world, using a transit.

Pete

Indeed, just pointing out that gadgetry can give an illusion of precision, and people forget that mobile
phones (and other electronics) are deviants themselves.

 

[awol]

who anyway would own a SeaWych whose main feature is vertical keels for easy moulding ? Not a sailor that's for sure...

Slagging off a man's boat (unless it's a generic AWB) is beyond the pale and in your case smacks of pots and kettles. An apology is in order.

 

[VicS]

VicS,

you are beginning to bore me with half-arsed comments;

who anyway would own a SeaWych whose main feature is vertical keels for easy moulding ? Not a sailor that's for sure...

I happen to know the difference between variation and deviation, am a YM offshore and have sailed cross- Channel as skipper since I was 16 - how about you ?

What on earth is the matter with you that cant take a little joke.

Youve been bickering and arguaing unnecessarily with people on here for weeks

And now you stoop to vulgarities and personal insults


What the boat i own has to do with it i fail to see. Seem to see amny more Sea wychs than A22s anyway Three SWs in the yard at opresent. used to be one A22 but that went a ggod few years ago.

Couln't afford anything grander when i built it. History did not pan out right so never bought anything grander later.... no need went sailing with someone with much better boat..... at leat the childern have benefitted cos the money has gone on helping them buy their first homes

Sorry if you are geuinely ill. Take break go somewhre nice comeback when you are feeling better.

Dont bother to reply... not interested in reading anymore or the rubbish youve been posting recently.


Sorry about the typing cant be bothered to correct it.

 

[johnalison]

Far better to check against the surrounding world, using a transit.

Pete

We are somewhat short of transits around here since mud is rather unreliable and buoys tend to move.

A hand-bearing compass from the stern, foredeck, shore or even a dinghy is quicker and more flexible (you can check on any heading). You can do a complete swing but basically need the main cardinals to judge errors.

 

[prv]

We are somewhat short of transits around here since mud is rather unreliable and buoys tend to move.

No piles, jetties, church steeples, headlands, hilltops? (Actually maybe not the last two on the East Coast I guess )

If you're willing to trust your GPS position (and it doesn't have to be that accurate if the object is far away) then you don't even need a transit, just one object to take a bearing on and compare compass against portland plotter (or video plotter )

Pete

 

[phanakapan]

Well we have a steel boat, a rubbish old compass, some random magnets screwed onto the compass support table to supposedly correct it- but they're going rusty... and we are in a part of the world where the variation is 10-11 degrees East; plus a lot of the time the aries is steering (so to the wind, not a bearing). No surprise, we don't fret too much about a degree or two of deviation!! We do have a hand bearing compass, an electronic hand bearing compass, 2 plotters , 1 fixed and two handheld GPS, (which go in the oven when lightnings about) and I am pretty good at pilotage using known positions on the land. So all in all, half a circumnavigation later, I am in no hurry to draw up a deviation card.

We fancy doing a circumnavigation of Great Britain when (if!!) we get back; sorting the compass out will become a priority then.

 

[grumpy_o_g]

No piles, jetties, church steeples, headlands, hilltops? (Actually maybe not the last two on the East Coast I guess )

If you're willing to trust your GPS position (and it doesn't have to be that accurate if the object is far away) then you don't even need a transit, just one object to take a bearing on and compare compass against portland plotter (or video plotter )

Pete

Southampton has a lot of transits...

 

[johnalison]

No piles, jetties, church steeples, headlands, hilltops? (Actually maybe not the last two on the East Coast I guess )

If you're willing to trust your GPS position (and it doesn't have to be that accurate if the object is far away) then you don't even need a transit, just one object to take a bearing on and compare compass against portland plotter (or video plotter )

Pete

That's fine as far as it goes but you are only getting one or two readings, which might coincide with the minima of your deviation. You need to have readings at due north & east (or s&w) to more or less eliminate this possibility.

 

[Seajet]

What on earth is the matter with you that cant take a little joke.

Youve been bickering and arguaing unnecessarily with people on here for weeks

And now you stoop to vulgarities and personal insults


What the boat i own has to do with it i fail to see. Seem to see amny more Sea wychs than A22s anyway Three SWs in the yard at opresent. used to be one A22 but that went a ggod few years ago.

Couln't afford anything grander when i built it. History did not pan out right so never bought anything grander later.... no need went sailing with someone with much better boat..... at leat the childern have benefitted cos the money has gone on helping them buy their first homes

Sorry if you are geuinely ill. Take break go somewhre nice comeback when you are feeling better.

Dont bother to reply... not interested in reading anymore or the rubbish youve been posting recently.


Sorry about the typing cant be bothered to correct it.

As if you haven't...

I'm fed up with you playing the chemist ( non engineer ) card with everything mentioned, and as for pots and kettles, one of us has a sailors' boat and it sure ain't a SeaWych.

 

[onesea]

That's fine as far as it goes but you are only getting one or two readings, which might coincide with the minima of your deviation. You need to have readings at due north & east (or s&w) to more or less eliminate this possibility.

Use stantions shrouds dead abeam as long as you know what angle to the boat the object is bearing... Make a pelourus? can never remember there name. so you be more accurate. As long as you know what the bearing is and angle the boat is to that bearing.. Afew meters here and there over afew miles will not matter...

Use the distant object and your hand-bearing compass to check boats heading and bearing is as measured on GPS? (Bonus double check?)..

 

[oldbilbo]

There's an awful lot of flannel being flapped on this subject....

The proper purpose of taking a handheld-compass reading of the 'ship's head' is to compare it with that indicated by the main steering compass - and identify if there is a gross difference which warrants more detailed investigation. On an aircraft in flight, such 'compass comparisons' were/are routine safety procedures, carried out after every significant change of heading, every 15 minutes en route, and after any change of setting to any main compass controls.

Gross compass errors have resulted in enough gross navigational errors to compromise quite enough illustrious careers - and often enough permanently.

Where a gross error is indicated or suspected in the main steering compass, then a more detailed 'check swing' should be carried out, followed by remedial work, then a 'calibration swing' from which a residual deviation card or table is normally produced. This is not really work for misinformed amateurs - it is still a profession - although there is no reason why interested and meticulous yotties could not do a good job.

'Coded Boats' are required to have an in-date compass calibration certificate. Next time you're on such a boat, have a hunt for the Residual Deviation Card and note whether it is still in date - or months/years out. If so, that should be a cue to go look at the Service Dates on the lifejackets and the liferaft, and the fire extinguisher bottles, too. Nit-picking? Or penny-pinching corner-cutting with others' safety...?

 

[johnalison]

I agree that a hand-bearing compass can only give a rough check. Proper care of the compass and log used to be an essential part of a sailor's routine but we have become too blase about this in recent years.

 

[Deleted member 36384]

.... 'Coded Boats' are required to have an in-date compass calibration certificate. ...?

I worked for a charter company and the owner had this carried out every year on his boats. He was tight fisted, as they say, but not on this, ex army thingy Royal Engineers, REME, whatever its called, was he.