Nortek Doppler Velocity Log, measuring Puma’s leeway across the pond

Ben Ellison

Ben Ellison

Panbo editor, publisher & chief bottlewasher from 4/2005 until 8/2018, and now excited to have Ben Stein as very able publisher, webmaster, and editing colleague. Panbo is going to the next level in 2019 and beyond.

3 Responses

  1. Ben Ellison Ben Ellison says:

    PS If you look very closely at the top photo you’ll see that some wag painted “wash when dirty” under Puma’s bow. Go Puma!

  2. Erik says:

    Here is someone building his own dopler device:
    http://sailboatinstruments.blogspot.com/
    He has 4 posts about this topic, so scroll down for more info

  3. Ben Ellison Ben Ellison says:

    A very interesting comment from “hangglider007” showed up on the Yachtingmagazine.com version of this entry ( http://goo.gl/sSzUU )
    There is a clarification that should be made – the Volvo Nortek device is actually an ADCP . Both an ADCP adn a DVL are the same sonar device, in essence. The difference is that an ADCP (Acousic Doppler Current Profiler) focuses on measuring water current speed relative to a platform or fixed point (e.g. “water in motion”), whereas a DVL (Doppler Velocity Log) focuses primarily on measurig velocity of a platform (in three axes also) vs. the sea floor or a water layer (i.e. “Motion in Water”) The Nortek device being used is a small high freqeuncy sensor, with very limited range, focusing primarily at currents near the boat, and integrated with other sensors to derive leeway and other vector velocities. The problem with the small head ADCP/DVL that Volvo is using is that the sensor size results in high standard deviation, meaning that its precision is limited. This is a function of sensor size, frequency, and what I wall call “mode”. As best I am aware, that model is using a narrowband detection mode. Broadband (to which Teledyne held the patents) is 50x more accurate. While I am not allowed to give any details, there are several other teams in both Ocean and Short distance racing who are in process of installing a much better sensor from Teledyne RDI. While the sensor is a bit larger in form factor, it is a broadband phased array which yields better measurement precision because of sensor size and operating mode. (I’m sure you will ultiamtely be hearing more about this from the winners of upcoming races!) A great advantage of the Phased Array is that it is a flat sensor surface to which a conformal “window” can be added, resulting in virtually no flow noise. If you’re interested in more details take a look at the “Explorer” DVL from Teledyne RDI.
    http://www.rdinstruments.com/explorer.aspx
    And speaking of wild modern sensor technology — that might be useful navigating — check out the Leap (thanks, Nat!):
    http://www.leapmotion.com/

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