Where exactly do you calibrate your echo-sounder to?

I can, sort of, understand why some people set theirs to 'under keel' - they're boat oriented rather than environment oriented
Click to expand...
I can see why you argue that way but I disagree. The main reason to have depth of water showing is that it agrees with your nav calcs without having to add any adjustment in. Well, if you can't add/subtract a meter or so from your depth calc then you have problems.
If you ever have guests on the boat or allow friends to borrow your boat are you going to trust that they'll know the depth offset.
Far easier to leave the depth gauge at depth under keel so you know - with no further calc - when you're about to run aground - after all, I don't care if your depth calc from the chart and tide tables tells me I'm supposed to have 2 meters of water, if my depth gauge says 0 then your 60 cm out - and it is far more time critical than worrying if you've hit the 10m or 5m contour!
 
Another one where it's set to depth under transducer - if we changed it now, we'd just confuse ourselves! At 0.7m we grind to a halt. Add 0.5m to get water depth - and like Morgana, we do tidal height calculations automatically. No alarms, because we are on the East Coast and frequently sail with only a few cm under the keel. I've used a lead line a few times to check which way to go to the deeper water when we've, er, taken the ground.
 
No idea. Bought the boat recently and haven't checked. I've assumed it is set to waterline, as that is the safe assumption.
 
skipper_stu said:
I got a piece of line with a weight on, dropped it in the oggin and let it touch the nice hard bottom, then I measured the depth of water. I then set the B&G at the depth, thats it, so what I see is what the depth is, makes it easier when calculating, when it reads 1.6 Im going to touch!
Stu
Click to expand...

I do it like that - very accurate to calibrate, easy calculations based on depth of water rather than having to add something to every indicated depth.

But I'm not sure I'd use waterline if I was in the habit of letting others sail my boat because they might make a casual guess that it's calibrated in some other way. Calibration-to-waterline is the least 'fail safe' if people don't take care to find out or if it never occurs to them even to think about it.
 
I am frankly amazed .... I now have this vision of all these people doing secondary port calcs to calculate what depth is going to be over the bar ... squinting at their Echo-sounders so they can tell the others - See I told you so ...

Is that real ? Or is my usual observation of people saying - as long as we get there x hrs before HW we'll be ok etc. with no calculation. Squinting at Echo-sounder so they can tell others - See I told you so ...

Second - lets look at depth waterline setting - so you have to remember draft of boat ... no different to remembering number that boat grounds at if not set to waterline depth ... who really adds the difference - cmon really ? Very few all the time ... many occasionally.

Third - lets look at under keel setting - still have to remember draft of boat, maybe not for grounding as zero = that, but for rough overal depth assessment ...

So really there is no mental difference - you still have to remember a number, you still have to be able to do mental arithmetic ......

And I still don't believe that so many actually do secondary port calcs often as people give perception here ... :rolleyes:
 
Morgana said:
Try sailing on the East Coast..... I do 'em pretty much every weekend i'm on the boat...
Click to expand...

Would having been Ch. Mate on coasters in North Sea, UK coast ... Seismic Survey Ship Ch, Officer ..... in North Sea with frequent visits to many ports, havens, harbours on East coast qualify that I may have some knowledge of East Coast ? Drying berths as well as deep. Ipswitch being a good example ... Great Yarmouth ..... dodging banks along east coast ... Gull Channel ...

Need I go on ??
 
Well if you've spent so much time here, then you'll be well aware of the need to have a good idea of the height of tide, and the need to know how much water there is for many many entrances.... the list you give are all secondary ports.... so you'll be agreeing with me then... :)
 
Morgana said:
Well if you've spent so much time here, then you'll be well aware of the need to have a good idea of the height of tide, and the need to know how much water there is for many many entrances.... the list you give are all secondary ports.... so you'll be agreeing with me then... :)
Click to expand...

Actually no ... :eek: The number of times I actually worked out fully Tidal height I could count on fingers of one hand ... we used the "guestimate" based on tide tables .... based on nearest standard port. I cannot remember being wrong with that as well ! :cool:

Some may now scream - but port used for that secondary may be not the nearest standard port. That is only because of shape of tidal curve, not due to time.

It seems that yachties claim to work out more of this stuff than coasters / small ships that quite often dredge their way to berths ! ;);););)

Don't get me wrong - good for anyone who does ... but I've never had the need to be so exact in a matter that is not so exact ... so many environmental issues affect the correctness of the result that you can still run out of water when calc shows you should be well clear.

Not East Coast ... but a very good example. T******m Marina ... on South Coast. I had my Alacrity there when first had her. She had a draft of about 2ft 6 ..... My pontoon was +/- 2 hrs high tide access, drying. If high pressure system was moving through region - I often couldn't leave or get back to my pontoon due to pressure system holding water level down. That is significant difference. What use then is being so accurate ?
 
johnalison said:
I must be the only person in the country who leaves it at depth-under-transducer.
Click to expand...
No you aren't. We do the same. Didn't know you could offset it at first and we're now so used to it I daren't change it.

Anyway, what's this about stopping when the keel touches? Ours draft is 1.5m and the transducer is 1.1m from the keel. We've had it read 0.4m but SWMBO had to take quite a run up to achieve this. Still got off though :)
 
"Depth under the keel, thats what is important."

If you mean 'am I about to run aground?' - then that is surely the 'important' thing. Whether its a result of you drawing 1.8 metres and the echo sounder reading 1.8 metres or you drawing 1.8 metres and the echo sounder reading 0.00 because you have the offset set to -1.8 metres is irrelevant.

I used to get hot under the collar about this depth setting business, but I have now decided I don't give a hoot.

If you want it set to depth under keel, then that's up to you.

Out of interest, ours is set to depth of water - on the grounds that if I can't remember that I need 1.8 metres to float in, I shouldn't be sailing, but if you want to set your a different way then so what...

The only argument I will take issue with is the one about guests on board or lending our boat out. If we have guests on board, what are they doing making important pilotage decisions about the depth of water without some supervision or overview by myself or one of the family? 'In case we have guests' is a lame reason for me - in fact I believe guests find it easier to understand that the echo sounder reads true depth - and we need it to read more than 1.8 metres than under the keel arguments. If I lend the boat to someone, then they get a full briefing on what is what.

I do get fed up with the 'holier than thou' attitudes of some people when they claim that their setting is the best. Who cares so long as you know what you've set it to. Its one of those cases where there is no definitive right and wrong answer - just personal preference.

Anyway - set it to what you want - the most important thing is that you know what depthe of water you are in and you know when you are about to hit the putty.
 
Our boat is available to be chartered, so I thought it safest to have it set to depth under the keel with 0.5 safety margin. This does mean that the alarm sounds when going into some of the shallower marinas, but I would rather charterers would be alarmed than aground. I also try to remember to check the depth is what I expect when I get on board in our home marina in the last guest have had a fiddle with the settings
Tudor Sailor
 
Babylon said:
Following on from a previous thread, I'm interested to know whether the majority of people calibrate their echo-sounder to the waterline or to under the keel? And, if under the keel, do you further complicate matters by adding an extra safety margin of say 0.2m to the calibration.

We're currently calibrated to under the keel plus a small margin, as this is how the thing was set when we bought her, and I've got used to reading how much water there is between seabed and fibreglass. I'd like to recalibrate to the waterline so that I've one less calculation to do when working out tidal heights, but I'm worried I'd forget that we've changed and run the ship aground!

Babs
Click to expand...

I fink u guys is reely fick if u cant sub yer draft frum yer deppf at watline. stil cant al be bransturgons, supos.
 
You must log in or register to reply here.

Share this page

Top