Fergus
Well-Known Member
Pretty rare I reckon!?
So how many of you carry an up-to-date deviation card for your boat?
- Thread starter Fergus
- Start date
FWB
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Re: So how many of you carry an up-to-date deviation card for your boa
Deviation card, I dont even have a compass! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Deviation card, I dont even have a compass! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Boathook
Well-Known Member
A what ? Compass seems accurate to 5 degrees, helm person steers to 10 degrees and GPS corrects to 1 degree.
France here I come or is the West Country !!
France here I come or is the West Country !!
AIDY
Well-Known Member
is that a bit like sending a postcard, from a destination you may not of intended to arrive in.
graham
Well-Known Member
I heard a story about a yacht bound from Cork to Falmouth ended up in the Bristol channel after the crew stowed a seagull outboard in a different locker to usual. /forums/images/graemlins/smile.gif
All that type of fun is over now with GPS.
All that type of fun is over now with GPS.
jerryat
Well-Known Member
We carry one for our back-up Sestral compass. Yes we have GPS (and three spare GPS handhelds) aboard but still want to ensure that if all fails, we'll still end up in St Lucia ..... or was that Rio ....?
Vagabond
Well-Known Member
Now that is a very good point.
In the 70's we set off for Cherbourg and when we (nearly) got there my dad had to ask a passing yacht which way it was!
We had found land but not the port. We were only a few miles out but had missed the target totally.
In the 70's we set off for Cherbourg and when we (nearly) got there my dad had to ask a passing yacht which way it was!
We had found land but not the port. We were only a few miles out but had missed the target totally.
PeteCooper
Well-Known Member
We have no deviation in my boat, although I sometimes see the lads with a glint in their eye.
FWB
N/A
Re: So how many of you carry an up-to-date deviation card for your boa
I believe Chichester always used to deliberately aim to the left when making a landfall. That way when he reached land he knew to turn right to reach his destination.
It was fun navigating in those pre gps days, Lyme Bay seemed like an ocean. Do you remember the SeaFix RDF set ! ?
I believe Chichester always used to deliberately aim to the left when making a landfall. That way when he reached land he knew to turn right to reach his destination.
It was fun navigating in those pre gps days, Lyme Bay seemed like an ocean. Do you remember the SeaFix RDF set ! ?
Robin
Well-Known Member
We Do!
We had a swing done professionally for our last boat, then had to have it repeated, still didn't trust the results and in the end did it again myself. When we bought our current boat there was no card and the YM Ocean Instructor owner said there was no deviation. I swung it quickly but carefully as an initial check at slack water neaps in Studland Bay using a differential dGPS and taking COG figs at a steady speed after it settled, we had a deviation of up to 9 degrees on easterly headings! I have had it on my joblist ever since to do the job again but the initial card has proven spot on. I swung the last one using a Pelorus (Davies Instruments, about $30 then from West Marine USA) and taking bearings of the sun's shadow compared to known bearings via astro tables (I have an astro program on a casio mini-computer), time was taken from the GPS clock.
We had a swing done professionally for our last boat, then had to have it repeated, still didn't trust the results and in the end did it again myself. When we bought our current boat there was no card and the YM Ocean Instructor owner said there was no deviation. I swung it quickly but carefully as an initial check at slack water neaps in Studland Bay using a differential dGPS and taking COG figs at a steady speed after it settled, we had a deviation of up to 9 degrees on easterly headings! I have had it on my joblist ever since to do the job again but the initial card has proven spot on. I swung the last one using a Pelorus (Davies Instruments, about $30 then from West Marine USA) and taking bearings of the sun's shadow compared to known bearings via astro tables (I have an astro program on a casio mini-computer), time was taken from the GPS clock.
John_Lana
Well-Known Member
Re: We Do!
We do too - although we have a gyro in addition to the magnetic compass....
John
We do too - although we have a gyro in addition to the magnetic compass....
John
Vagabond
Well-Known Member
Re: So how many of you carry an up-to-date deviation card for your boa
SeaFix RDF .... was that the gun type thing with NHS type earphones!
I do remember dad being the first in the marina to get a VHF, a Seavoice that used crystals. I kept pestering him to get a 'M' crystal as I had heard that the powerboat racers used that one.
Happy days! /forums/images/graemlins/smile.gif
SeaFix RDF .... was that the gun type thing with NHS type earphones!
I do remember dad being the first in the marina to get a VHF, a Seavoice that used crystals. I kept pestering him to get a 'M' crystal as I had heard that the powerboat racers used that one.
Happy days! /forums/images/graemlins/smile.gif
MoodySabre
Well-Known Member
One came with the boat I bought last year but I haven't checked it. Looking for someone to swing with (don't tell Mrs Crew /forums/images/graemlins/wink.gif). Two GPS on board seems to overcome the need even though it seems seaman like to know. I tend to point the boat from the GPS and then follow the heading that it gives on the compass. Steering by GPS is a bit tedious - like digital watches - one number out and it matters.
Slow_boat
Well-Known Member
Re: We Do!
Nope, havn't got one but don't really need one for coast hopping. I can only steer to plus or minus 5 degrees at most anyway! I was always tought to aim for landfall up-tide of my destination.
Nope, havn't got one but don't really need one for coast hopping. I can only steer to plus or minus 5 degrees at most anyway! I was always tought to aim for landfall up-tide of my destination.
sheeplove
Active Member
Re: We Do!
Having been "swung" when boat was new, now keep track of changes with known transits & GPS. All seems to agree - so far!
Having been "swung" when boat was new, now keep track of changes with known transits & GPS. All seems to agree - so far!
Roberto
Well-Known Member
I made one last year, I took bearings every 15° so had a nice smooth-ish curve, but most of it was on one side of the zero axis, that is most of the deviations were Easterly (max 5/6°), with just one quadrant with westerly deviations of no more than 2/3°...
I interpreted this as the compass axis being slightly misaligned with the boat axis (indeed, when unbolted the compass body has a small degree of freedom right-left), does this sound a correct assumption or are there any other reasons for such a disparity between the amounts of western and eastern deviations ?
cheers
I interpreted this as the compass axis being slightly misaligned with the boat axis (indeed, when unbolted the compass body has a small degree of freedom right-left), does this sound a correct assumption or are there any other reasons for such a disparity between the amounts of western and eastern deviations ?
cheers
Roach1948
Well-Known Member
Re: We Do!
I'd be interested to know your swinging technique/procedure as I have a new engine and compass and I as they are quite close together I am sure there must be some deviation...
I'd be interested to know your swinging technique/procedure as I have a new engine and compass and I as they are quite close together I am sure there must be some deviation...
Richard10002
Well-Known Member
Re: So how many of you carry an up-to-date deviation card for your boa
[ QUOTE ]
I believe Chichester always used to deliberately aim to the left when making a landfall. That way when he reached land he knew to turn right to reach his destination.
[/ QUOTE ]
Popular scuba diving technique aswell.
On a general cargo vessel in the early '80's we were heading for Khor Fakkan, (just outside the persian Gulf), and sailed up and down the coast until we saw the entrance.
Richard
[ QUOTE ]
I believe Chichester always used to deliberately aim to the left when making a landfall. That way when he reached land he knew to turn right to reach his destination.
[/ QUOTE ]
Popular scuba diving technique aswell.
On a general cargo vessel in the early '80's we were heading for Khor Fakkan, (just outside the persian Gulf), and sailed up and down the coast until we saw the entrance.
Richard
Twister_Ken
Well-Known Member
Re: So how many of you carry an up-to-date deviation card for your boa
>Khor Fakkan<
You 'aving a larf?
>Khor Fakkan<
You 'aving a larf?
copterdoctor
Well-Known Member
Re: So how many of you carry an up-to-date deviation card for your boa
Not just Chichister, that was accepted practice (not so many!) years ago. Yes I remember RDF okay for a single bearing but I never managed a fix.
Compass Correction? Never missed France from a range of 60 miles, or any other country come to that so never felt the need.
Not just Chichister, that was accepted practice (not so many!) years ago. Yes I remember RDF okay for a single bearing but I never managed a fix.
Compass Correction? Never missed France from a range of 60 miles, or any other country come to that so never felt the need.
