Burnham_Bob
Well-Known Member
my gps instructions say the anchor drag can be set to a 'user defined value'. Does anyone have any suggestions of what would be a useful setting without waking me up when the tide changes?
gps anchor drag setting - recommendations please
- Thread starter Burnham_Bob
- Start date
Slipstream 34
Well-Known Member
We use Rough guide 2-3 x the amount of chain we have out.
craigsmith
Well-Known Member
Unless you're not swinging, you need to set the central position for the GPS when (where) you drop the anchor. You then allow for a swinging circle of your rode length (more or less), plus a few meters for GPS error. If you go outside that radius, you know it's because the anchor has moved.
Of course getting the initial position accurate, and accounting for the position of the GPS on the boat itself, can be easier said than done. But it's possible to get a fairly accurate alarm set-up.
Of course getting the initial position accurate, and accounting for the position of the GPS on the boat itself, can be easier said than done. But it's possible to get a fairly accurate alarm set-up.
jimbaerselman
Well-Known Member
If you're anchoring in a reversing tidal stream you should be mooring, with fore and aft anchors, their rodes lashed together. You'll then be swinging in a very small radius, and highly unlikely to drag on the tide turn.
Without a moor, each time the tide turns, most anchors will trip and reset - offering a nice possiblity of picking up some debris, then dragging.
So prevent, rather than warn?
Without a moor, each time the tide turns, most anchors will trip and reset - offering a nice possiblity of picking up some debris, then dragging.
So prevent, rather than warn?
christo2024
Well-Known Member
I agree totally with CraigSmith
Make sure you set it when the anchor touches the bottom. Not easy of course if the GPS is below but thats the way it should be done
Make sure you set it when the anchor touches the bottom. Not easy of course if the GPS is below but thats the way it should be done
noelex
Well-Known Member
[ QUOTE ]
my gps instructions say the anchor drag can be set to a 'user defined value'. Does anyone have any suggestions of what would be a useful setting without waking me up when the tide changes?
[/ QUOTE ]
The anchor drag settings are normally in nm to roughly convert to m multiply by 2000. So .03nm is about 60m.
If the alarm is set where you drop your anchor .03 should be OK for about 50m chain (remember if the GPS areal is near the back this distance should be allowed for.
If you have a GPS that can set an offset alarm you do not need to dive down below when you drop the anchor as the plotting function usually makes it clear where the anchor was dropped with a straight line from the drop point as you reverse back to lay out the anchor chain.
It is sometimes useful to set the alarm with tight parameters (say .01 or .02) where you are laying with the prevailing wind and current (rather than where the anchor is). If the wind or current change the alarm will awake you. This allows you to check the anchor is still set and no other boats have swung too close with the change of conditions etc.
Finally I have found an EGNOs fix improves accuracy and allows tight parameters to be set without any risk of false alarms
my gps instructions say the anchor drag can be set to a 'user defined value'. Does anyone have any suggestions of what would be a useful setting without waking me up when the tide changes?
[/ QUOTE ]
The anchor drag settings are normally in nm to roughly convert to m multiply by 2000. So .03nm is about 60m.
If the alarm is set where you drop your anchor .03 should be OK for about 50m chain (remember if the GPS areal is near the back this distance should be allowed for.
If you have a GPS that can set an offset alarm you do not need to dive down below when you drop the anchor as the plotting function usually makes it clear where the anchor was dropped with a straight line from the drop point as you reverse back to lay out the anchor chain.
It is sometimes useful to set the alarm with tight parameters (say .01 or .02) where you are laying with the prevailing wind and current (rather than where the anchor is). If the wind or current change the alarm will awake you. This allows you to check the anchor is still set and no other boats have swung too close with the change of conditions etc.
Finally I have found an EGNOs fix improves accuracy and allows tight parameters to be set without any risk of false alarms
Refueler
Well-Known Member
If its' a plotter and tracking your movement ... then don't worry about setting anything till you are 'brought-up' (naval parlance for anchor holding and vessel laying to anchor rode comfortably). Worrying about pressing a button is 'panic' and unnecessary.
Once you are happy with position and craft is sitting nicely to the anchor / rode. Zoom in on plotter till you have clear point of drop ..... mark it as waypoint / POI / whatever system your plotter uses to mark and use the coordinates. Now set a guard ring round it of rode length + small amount to allow for boat length etc.
How you set it depends on GPS model ... most use the XTE function .. Cross Track Error - that is distance of desired track. So even with a plotter that doesn't have Anchor watch - you can still fool one into doing it.
Hint : There's always an easier way to do it !! /forums/images/graemlins/laugh.gif
Once you are happy with position and craft is sitting nicely to the anchor / rode. Zoom in on plotter till you have clear point of drop ..... mark it as waypoint / POI / whatever system your plotter uses to mark and use the coordinates. Now set a guard ring round it of rode length + small amount to allow for boat length etc.
How you set it depends on GPS model ... most use the XTE function .. Cross Track Error - that is distance of desired track. So even with a plotter that doesn't have Anchor watch - you can still fool one into doing it.
Hint : There's always an easier way to do it !! /forums/images/graemlins/laugh.gif
A
Anonymous
Guest
noelex has given you the right answer. However, until you know the holding, and where there is a fair tidal stream, I suggest that you do want to wake up on the change of tide, for the first few tides at least.
starboard
Well-Known Member
I always use 0.03nm.....that way I never have any false alarms when I swing wereas 0.02nm sometimes does alarm..........that said I generally anchor in very shallow water no more than 5m and often a lot less as we only have a max of 3m range here on the Clyde......I always sleep peacefully,never drag and usually spend about 30 nights at anchor per summer.