Late final yr, 59º North had our first annual “employees coaching” weekend aboard our Farr 65 Falken and an fascinating debate emerged…tips on how to calibrate the depth sounder?
Since I used to be a child and for my complete skilled crusing profession, I took with no consideration that depth sounders learn the water depth. Like, the precise water depth, as measured from the waterline. Clearly this requires a little bit of adjustment for the reason that sensor isn’t on the precise waterline, however usually a couple of toes beneath it, often amidships simply ahead of the keel.
The way in which to do that calibration, by the way, is dockside or at anchor with a lead line. Set the depth calibration to +/-0, then measure the precise waterline depth with the lead line in the identical basic place fore-aft as your depth sensor. The distinction in readings is your calibration adjustment. For instance, in case your uncalibrated depth reads 10 toes, however the precise water depth as measured by lead line is 13 toes, there’s your +3-foot calibration.
However get this—not everybody does it this manner! I used to be frankly shocked when greater than half of the 11 skilled sailors on Falken that day stated they calibrate their transducers from below the keel! WTF? They argued that from their perspective as freelance professionals, they sail on a number of totally different boats, and the depth-below-keel calibration ensures they all the time know precisely how a lot margin they’ve earlier than touching backside.
Being the empathetic chief that I attempt to be, I saved an open thoughts and determined that nicely, if I’m outvoted right here, and since there’s a cheap justification for it, perhaps I can change my methods and we are able to undertake the depth-below-keel normal for the 59º North boats. I spent the remainder of the night time altering the instrument settings and updating the ship’s guide to this new mind-set. Then I went to mattress.
I wakened uneasy. This simply didn’t appear proper! However why did I’ve such a powerful response to it? And is a technique truly proper with a capital R or not? It felt like individuals who use the “heading up” setting on chartplotters as an alternative of “north up”—perhaps not technically improper, but it surely’s simply oh so improper!
So, I reached out to fellow SAIL contributor and seam’nship guru Tom Cunliffe.
“The perennial query of echo sounder depth!” Tom replied, clearly having had this debate many instances earlier than. “An echo sounder is a navigational instrument, not a ‘get-out-of-jail-free card,’ ” Tom defined in an electronic mail. “If it reveals the water depth as 1.8m, and your boat attracts 1.8m, then you might be aground. Whenever you require a depth enter to substantiate a place, that you must know the depth of water, not the depth below your keel. It’s so simple as that.”
Tom ranted on, hypothesizing that many constitution corporations and crusing colleges calibrate to the keel as a result of “they think about their prospects are so silly that they’ll’t bear in mind the draught of their yacht. To infantilize them like that is outrageous.”
I like that Tom signed the e-mail “Maintain the Religion!” So far as I used to be involved, the talk was over. My instincts indicated that depth from waterline was Proper, and Tom clearly and aggressively agreed. However that’s not the top of the story…
Emily Caruso, certainly one of our most skilled skippers and the de facto chief of the depth-below-keel camp amongst our employees, had her personal seam’nship guru in her DMs and despatched the identical query to the one and solely Sir Robin Knox-Johnston, with whom she had labored on the Clipper Race.
“I set mine from the underside of the keel on each boats,” Sir Robin succinctly replied (referring to the legendary Suhaili and his newer Farr 50 Saniula).
Nicely, now what? Everybody agreed that we wanted a 59º North normal that will be constant throughout our boats and packages and be taught the identical technique to all of the crews who sail with us, no matter who the skipper is.
If Tom Cunliffe and Sir Robin himself are at odds over this, absolutely there can’t be a right-with-a-capital-R technique to do it. I made a decision that each are justified, as long as everybody is aware of the settings.
In the long run, I reverted to the best way I used to be most snug with, depth-below-waterline, aka precise depth, reset all of the devices on Falken, and up to date the guide as soon as and for all, although we formally acknow-ledge that there’s a couple of technique to pores and skin that cat (and this makes for an important dialog starter at sea).
As for chartplotters, it’s north up, individuals.
March 2025
Trending Merchandise
