LadyInBed
Well-known member
[No message]
Logged miles
- Thread starter LadyInBed
- Start date
Sgeir
Well-known member
Interesting question, though the alternatives in the question are not really mutually exclusive. Hope nobody decides to survey peeps on their passage plans, or lack thereof.
heerenleed
New member
Only use my GPS. Reaseon is simple: the log is underreadung by some 40%. Have no idea what may cause this, have vckecked everything, even found a new 'grey box' and installed it, new impeller... Still no sensible reading. It is an older B&G system: Hornet MK4. Anyone any ideas?
cheers
cheers
john_morris_uk
Well-known member
If everything else fails/US switch off GPS or whatever, and you are going to have to resort to navigating by log and compass, surely the only meaningful reading is 'distance through the water'?
Or do you mean log for the purpose of personal record of miles sailed? I guess a lot of Channel racers would be very upset if they could only log 60/70 miles for a race from Portsmouth to Cherbourg that had gone via various channel bouys and the Casquets!
If you mean 'what do you note in the log book?' then if you habitually note what the speed/distance log reads when you write your logbook/mark the chart or whatever you do, its a good habit and it makes life a lot simpler if the worst happens.)
Or do you mean log for the purpose of personal record of miles sailed? I guess a lot of Channel racers would be very upset if they could only log 60/70 miles for a race from Portsmouth to Cherbourg that had gone via various channel bouys and the Casquets!
If you mean 'what do you note in the log book?' then if you habitually note what the speed/distance log reads when you write your logbook/mark the chart or whatever you do, its a good habit and it makes life a lot simpler if the worst happens.)
Evadne
Active member
Being something of a Luddite I only use the gps when all else fails. Which is surprisingly often, considering how many years I sailed without one...
Robin
Well-known member
I'm sure you are aware that you can adjust the log to correct the speed and distance readings, there is usually quite a range of adjustment possible. However if you have done this and it is still reading slow then probably the cause is the location and/or alignment of the impeller. The impeller should be mounted on or close to the centreline and normally should be well ahead of the keel to avoid errors where the waterflow diverts around it.
heerenleed
New member
Indeed, the adjustment screw is up to the max... As the boat is a Nicholson, and the instruments are the original ones, I cannot believe that Camper & Nicholsons put an impeller in the wrong place. Of course, it had crossed my mind, but then again, underreading by no less than 40% could hardly be caused entirely by a wrong alignment or a wrong pot......
Sea Devil
Well-known member
whilst one should have a 'back up' in the form of a log it seems pointless to use anything but the GPS to record distance and speed etc.
jimi
Well-known member
Why? I like to know both my SOG and speed through the water so
1)I know how efficiently I'm sailing.
2)What the tidal rate is.
however the miles logged by the boat is the distance it has travelled through the water!
1)I know how efficiently I'm sailing.
2)What the tidal rate is.
however the miles logged by the boat is the distance it has travelled through the water!
jamesjermain
Active member
A service will help
My Hornet instruments did exactly the same thing towards the end of their working life. The wind speed also under-read by about 50 per cent. The onset was sudden (fine at the end of one passage, wrong at the start of the next) and was cured by sending all the instruments back to B&G for service. It is an internal electrical problem.
B&G always managed to get the system going again and when it was working it was superb. Unfortunately, in the last couple of years it only worked for a couple of months before failing again so I had to dump them. B&G would only do a full service so it was quite expensive - about £120 a time from memory, 6 years ago.
My Hornet instruments did exactly the same thing towards the end of their working life. The wind speed also under-read by about 50 per cent. The onset was sudden (fine at the end of one passage, wrong at the start of the next) and was cured by sending all the instruments back to B&G for service. It is an internal electrical problem.
B&G always managed to get the system going again and when it was working it was superb. Unfortunately, in the last couple of years it only worked for a couple of months before failing again so I had to dump them. B&G would only do a full service so it was quite expensive - about £120 a time from memory, 6 years ago.
Robin
Well-known member
A 40% error (more in your case if the adjustment is already on MAX) is quite possible. The position of the impeller is often decided by ease of installation and internal access to it. I have previously had to make considerable adjustment to compensate for errors and a 60% compensation is set in in fact on my current boat where the impellor is a bit too close in front of the keel. The fore/aft alignment of the impeller is also very important and often a small change in this will make a big difference. On older B&G logs the impeller alignment was adjustable within it's skin fitting in some cases, we had a retractable one on our last boat that was. Another possibility I am sure you have checked is that the impeller shaft may be damaged/bent. The only strange thing is that this considerable error would have been left unsolved by the previous owner(s).
ShipsWoofy
New member
I had a similar problem with my nasa log.
The thing that worked for me, after advice from the nasa chap was; When underway loosen the top nut and gently twist the log until maximum speed is being read, then use the inbuilt calibration to set up the log as accurately as you can.
This so far has been successful, a few mm either way made quite a difference.
It might be worth trying /forums/images/graemlins/confused.gif
The thing that worked for me, after advice from the nasa chap was; When underway loosen the top nut and gently twist the log until maximum speed is being read, then use the inbuilt calibration to set up the log as accurately as you can.
This so far has been successful, a few mm either way made quite a difference.
It might be worth trying /forums/images/graemlins/confused.gif
snowleopard
Active member
to be able to run up a DR when the gps dies, i keep the log reading in the hourly log.
to give me the day's run on passage i use the trip log on the gps and take readings daily at noon. it gets a bit stuffed when crossing time zones as we have 23 or 25 hour days.
to give me the day's run on passage i use the trip log on the gps and take readings daily at noon. it gets a bit stuffed when crossing time zones as we have 23 or 25 hour days.
BlueSkyNick
Active member
I agree.
I record SOG and STW every hour, but only the distance through the water.
Dunno why I don't record distance covered over the ground - but its not a problem because I always record the Lat and Long at the same time, so if I had to work it out, I could do it quite easily.
I record SOG and STW every hour, but only the distance through the water.
Dunno why I don't record distance covered over the ground - but its not a problem because I always record the Lat and Long at the same time, so if I had to work it out, I could do it quite easily.
webcraft
Well-known member
Not sure what you mean by
very upset if they could only log 60/70 miles
The GPS records distance covered over the ground, not the point to point distance over some arbitrarily defined period. So - if we leave our mooring with the GPS trip reset to 0 and return to it later after a round trip of 20 miles it reads 20 miles, not zero.
Miles over the ground are the only miles worth logging for your personal log / qualifications etc IMHO, and this idea that there is something improper about logging miles over the ground is a hangover from the days when GPS was considered new-fangled and probably cheating. (The RYA are now going over to the view that GPS is the principal means of navigation for most of us, and adjusting their training procedures accordingly).
That is not to say however that you shouldn't have a paddle wheel log as well; it is extremely useful for evaluating tidal stream strength and sail trim while on passage. After mooring or anchoring though I would always put the GPS trip value in the log. Of course, if you are moored or anchored in a tideway and leave the instruments switched on you can always log a few miles on the paddlewheel log while sleeping . . .
- Nick
very upset if they could only log 60/70 miles
The GPS records distance covered over the ground, not the point to point distance over some arbitrarily defined period. So - if we leave our mooring with the GPS trip reset to 0 and return to it later after a round trip of 20 miles it reads 20 miles, not zero.
Miles over the ground are the only miles worth logging for your personal log / qualifications etc IMHO, and this idea that there is something improper about logging miles over the ground is a hangover from the days when GPS was considered new-fangled and probably cheating. (The RYA are now going over to the view that GPS is the principal means of navigation for most of us, and adjusting their training procedures accordingly).
That is not to say however that you shouldn't have a paddle wheel log as well; it is extremely useful for evaluating tidal stream strength and sail trim while on passage. After mooring or anchoring though I would always put the GPS trip value in the log. Of course, if you are moored or anchored in a tideway and leave the instruments switched on you can always log a few miles on the paddlewheel log while sleeping . . .
- Nick
masterofnone
Active member
My Nasa log read exactly 50%, impellor lost one of it's little magnets.
LadyInBed
Well-known member
Definitely not mutually exclusive, I think these replies help to show that there isn't a simple and accurate way of recording distance.
I use a compromise.
For my hourly log I use the gps breadcrumb (10 mins) to go back an hour to give me distance and back bearing of course for the hour.
For the passage log I take the passage time and multiply by an assumed average speed, normally 4 or 5 depending on conditions.
I use a compromise.
For my hourly log I use the gps breadcrumb (10 mins) to go back an hour to give me distance and back bearing of course for the hour.
For the passage log I take the passage time and multiply by an assumed average speed, normally 4 or 5 depending on conditions.
heerenleed
New member
[ QUOTE ]
The only strange thing is that this considerable error would have been left unsolved by the previous owner(s).
[/ QUOTE ]
Exactly. We have red in the logs of previous owners that the thing never functioned perfectly, despite the set having been sent back to B&G several times.
We are considering replacing the complete unit alltogether (we are very tempted by the new Tackticks wireless units) but I am concerned that we may have the same problem if it is the position and/or alignment.
The only strange thing is that this considerable error would have been left unsolved by the previous owner(s).
[/ QUOTE ]
Exactly. We have red in the logs of previous owners that the thing never functioned perfectly, despite the set having been sent back to B&G several times.
We are considering replacing the complete unit alltogether (we are very tempted by the new Tackticks wireless units) but I am concerned that we may have the same problem if it is the position and/or alignment.