Monday, August 11, 2008

Care and Feeding of Instruments

On TIME MACHINE the quality and precision of the crew-work has reached the point where instruments are the best way to tell if we are sailing at our full potential. Of course a 2 or 3 boat development program with evenly matched boats and crews would be best, but it's just not realistic or practical. So we have invested in technology to measure and report on our progress around the course. In order to benefit from the feedback provided by wind-sensor, the boat-speed sensor, flux-gate compass and the GPS, the crew needs to trust and have faith in the correctness of the numbers. This trust is hard to earn and easy to squander....

Some thoughts on ways to build confidence in your instruments
  1. Feed your sailing program with instruments that can be adjusted and calibrated with many factors. Do you have a heel sensor? Can your boatspeed be adjusted to account for an off center sensor? Can your boatspeed use different calibration factors based on the tack your on? Is your wind sensor up out of as much of the turbulence from the sails as possible?
  2. Care for your instruments by installing them in dry areas and running wiring properly. If you are not extremely confident, get some professional help. Avoiding ground loops, radiated noise from radio transmitters, alternator noise and interference with other electronics is key. The physical routing of cables, the length of service loops, leaving drip-loops and keeping cables out of the bilge are just as important. Don't forget to apply liberal amounts of 'connector grease' to seal moisture out of the connector pins.
  3. Feed your instruments all the latest versions of software supplied by your vendor. Controlling your instruments and getting the best possible feedback relys on software. If you don't keep a PC connected, make sure that the 'brain box' is totally up to date. If you are running a connection to a PC, the latest versions of software will allow you to work with all the features possible. Make sure to run your system with the PC on occasion to assure that calibration factors are defaulting the right numbers. The PC is probably less reliable than the instruments.
  4. Write down the calibrations and settings that seem to be working. Keep a log of your changes. Write it down, even if it does not make sense. Keep copies of log files and any eMails that fly back and forth to your technical support team. Write down all the switch settings and adjustments that you make. This can help to explain weird numbers when they come up.
  5. Get to know the technical staff who support your instruments. Listen with great care and ask lots of questions. They have probably heard it before, but if you are not clear on something.... ask! A good tech support person knows that there is no such thing as a dumb question.... just a dumb answer! Check on their website for new information.
  6. Clean your sensors often. Spider webs in the anemometer or wind vane can appear in just one evening. Bottom scum will grow on sensors fast, since they are not painted with anti-fouling finishes. Mounting brackets at the top of the mast take a huge beating and must be secured with loctite on the screws. When you are up there cleaning the spider webs, give the wand a wiggle to check that's it's still just as tight as last time. Check your cabling and wiring connections at the first sign of intermittent operation.
  7. Learn about wind shear and how it affects the readings you see out on the water. Wind shear is present more often than you might think. Wind shear WILL make your wind instruments tell you numbers that seem just plain wrong. Understanding its effects on your numbers will keep you sailing in the right direction. Taking advantage of shear in your sailtrim can make for huge gains on boats who don't recognize it.
  8. Get confident in your numbers. Work on sailing to target numbers. Sail for 10 minutes at the same true wind angle while the trimmers experiment with the sail settings. Sail for 10 minutes at the same boatspeed and watch what angles you read as the breeze builds and lulls. Put the VPP (polar targets) up on a display and challenge the whole boat to hit the number.
TIME MACHINE sails and races with some of the best of the J/35 class. FALCON is the 2 time National Champion and Mr. BILL'S WILD RIDE is the current national champion. When we are on the course with them, it's easy to measure our performance..... are we doing better or worse than they are. Don't need any fancy instruments, just a hand bearing compass and a good set of eye-balls. But when we get away from the fleet on distance races or when we are sailing PHRF, it's a whole different story. Now we need some trusted feedback to stay on top of our game.... Instruments that we can trust are part of the answer.

TIME MACHINE has the following instrument setup:
  • OCKAM
    • Processor - 001
    • Mast Displays - 005 (4x)
    • Cockpit Display - Matryx (1)
    • PC Interface - 050
    • GPS Interface - 041
    • Masthead/Speed/Compass Interface - T2
    • Depth/Seatemp Interface - 028
    • NEMA tap - 042

  • Software
    • OCKAM OS 4 (Version 4.07)
    • RaceCourse
    • Vport
    • Stripchart
    • EYE
    • DeWiggler
    • XM Weather
  • Sensors
    • Airys 42" Aluminum Masthead Wand
    • Airmar CS4599 Sonic boatspeed sensor
    • KVH AC103 fluxgate compass
    • Garmin GPS
  • PC
    • IBM thinkpad X40, 1G RAM (requires 1.2A @12V)
    • Passive 3 port USB expander
    • Linksys WiFi access point (active only when using EYE)
    • DC-DC converter to power the PC from 12V source

3 Comments:

Blogger mic said...

Nice post! Great information!

1:26 PM  
Anonymous mikel said...

Interesting post, Robert.
We also run Ockam, and have been looking for feedback related to the Airmar CS4599 Sonic boatspeed sensor, since I am quite bored with the paddlewheel. Would you recommend it ?
Regards,

Mikel

2:32 AM  
Blogger J35Skipper said...

Mikel,
The Airmar Sonic has been very solid. As long as the boat is moving, it's quite accurate. When not moving it gets confused and reads between 0.3 and 0.5 knots. I especially like not having to worry about hoist straps and pulling the paddle-wheel, nor do I think about weeds fouling the paddle.

Don't paint it with anti-fouling paint, do remove it from the throughhull in the winter and keep the cables up out of the bilge water.

12:57 PM  

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