The Bench

I realize I have been remiss in not discussing our newest software product here: DeWiggler! "What is DeWiggler?", you ask. It’s just about the biggest break-through ever in automated calibration! It removes the tack-to-tack difference, or "wiggle", in calculated wind direction. It does this by providing very accurate calibration values for the parameters upon which wind direction is dependent.

Calibration has traditionally been done manually, with a human noting and calculating the numbers. This takes a bit of artistry to determine what is good data and what is bad data. Sometimes it’s obvious, like when there is too much or too little wind or the waves are too high. Other times, it’s a bit more difficult, like when there is a lot of wind shear throwing off the tack-to-tack wind angles. Most people can do the boatspeed and compass calibration reasonably well, but sometimes the wind calibrations take more than one try to get a good value. This of course can make life difficult, because getting everyone’s schedule together to go out for a calibration run can be pretty impossible. Add the variable weather conditions to this problem, and a racing program might not find the time to do all the calibrations. And it’s nigh impossible to calibrate during races, because everyone is focused on other duties.

Older methods of automated calibration were not much better. They still had the scheduling problems of manual calibration, and they relied on a person to initiate and end the calibration run - this required that the person operating it knew when to begin and end (it’s not always obvious).

DeWiggler solves a lot of these problems. While running, it guides the user through the process rather than relying on the user to guide the program. It tells the helmsman what course to steer, how much distance is left on the leg, and how long to stay on a tack when sailing. Best of all, it can remain running during a race to collect data, so that there are as many data points as possible for the largest sample size!

There are two main parts to DeWiggler: the boatspeed & compass calibration, and the wind calibration. The first part is best accomplished under motor, as it requires that the boat is steered to specific courses over a specific distance. It checks the direct boatspeed and compass readings against GPS data, subtracts the effect of current, and produces a compass offset and boatspeed calibration correction. On the T1 processor, a file can simply be copied to the CF card for the complete compass offset correction.

The second part calculates the wind calibrations. The best part of this is that if the program is left running during a race, it will monitor the wind readings for the entire race, throw out the bad data (like that collected during the pre-start), and produce calibration values from that data. This even allows enough data to be collected to compute a good upwash slope value - something that is typically pretty hard to do manually! It also can analyze tacking performance.

When calibrations were done manually, it was considered a good calibration if the wind direction solution only had a tack-to-tack error of less than 5 degrees, with 3 degrees or less being ideal. For those boats that have completed the DeWiggler calibration, tack-to-tack errors have been consistently less than 1 degree on the first try! This was considered a very difficult proposition when calibrating manually, but it has become the expected norm with DeWiggler.

DeWiggler also can assist with setting the correct calibrations. It can determine the current calibration values set in the system, determine if the screw settings are correct (and if they match the current settings), and then guide the user to set the screw values to the newly calculated values. It really makes the calibration process as painless as possible.

The program is free to download, install, and run. The user is charged only when an analysis of the data is done. The analysis can be purchase through our web store, a servicing dealer, or direct from Ockam. Please see our DeWiggler web page (also linked from the main Ockam page) for more information.

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We have created a knowledge base for our user community. It is a place to ask questions, get answers and simply discuss use of the instrument system. The questions and answers will be kept accessible for future reference, so as we cover topics there, we will be able to build a larger repository of knowledge specific to our instrument system. We hope this will allow people access to answers not just when we are available here on-site, but whenever they need answers and have access to the internet.

Use of the Knowledge Base is simple. You can just browse the topics without creating a user account, but if you have a question, or if you have something to add to the discussion, you must create a user account and log in. The discussion is divided into broad categories which should cover most subjects. Just start your topics in the appropriate category, and continue from there. All we ask is that everyone keeps civil and patient, just as you might in a face-to-face interaction.

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The web store software has been updated to allow use of
shipping by the United States Postal Service. We can now ship by Global Express Guaranteed, Express Mail Services, or Priority Mail Services.

The software is still a little buggy, and may not allow processing of
these methods. If you would like to use one of these shipping methods,
but the web store will not allow you to use them, please select any other shipping method and indicate your preference to use the postal service method in the order remark. We can then provide a cost and time estimate so you can make a decision.

Here is a synopsis of the different shipping methods available through the USPS:

Global Express Guaranteed:

• shipments to addresses outside the US only

• delivery in 1-3 days (excludes weekends)

• final delivery by FedEx

• requires physical delivery address (no PO Boxes)

Express Mail Services:

• domestic: delivery in 1-2 days, can be optionally delivered on Sundays and holidays

• international: delivery in 3-5 days, final delivery by local postal service

• tracking available

Priority Mail Services:

• domestic: delivery in 2-3 days, including Saturdays

• international: delivery in 6-10 days, final delivery by local postal service

• tracking available on all except Flat Rate International envelopes

Please see the USPS web site for complete information on their services.

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Putting the boat away for the winter…It’s a sad time of year in the Northern Hemisphere. Unless you’re one of those die-hard few that keeps sailing your big boat in the winter, it’s time to put away the big toy until next spring.

Most people are very aware of the mechanical preparation given to putting away boats. There’s the adding of antifreeze where needed, the fall service for the engine, the fuel stabilizer added to the fuel tanks, clearing out the fresh and waste water tanks, and the general clean-up before closing everything tight against the weather. But how many people give attention to the electronics? In my experience, not many.

First, be sure to remove any displays that are outside and bring them home with you. It’s likely that you won’t see the boat much over the winter, so you’re not going to catch any small problems that can lead to bigger problems. Freezing water expands, so if there’s a little water left on the displays, it can force open the seals and cause leaks. I’ve gotten more than one display in for repair that has been subjected to a freeze/thaw cycle, and has let in water to damage the electronics. I’ve also had one case where differential cooling caused the glass on a display to crack - the display was mounted in a custom metal pod that twisted the display and broke it! It easiest to just remove the display, cover any holes with tape, and then reinstall the displays in the spring.

Also remove any sensors that are exposed to the elements. These usually include the masthead unit, the speed sensor, and the depth transducer. It’s not usually practical to remove a load pin, but if one is installed, make sure that it is covered - especially the cable. Plastic and rubber tend to get brittle at lower temperatures, so a knock that may not do any harm in the summer may shatter the object in the cold of winter. Just be sure to place the blanking plugs in the through-hull fittings if you take out the speed sensor and depth transducer. It is also a good idea to protect the connector for the masthead unit (a small bag taped over this is usually enough).

The items that are kept below deck - the processor, interfaces, and compass - are fine if left in place. Just be sure that they will stay dry, as freezing water can cause a lot of damage.

These are some general suggestions to decommission your electronics for the winter. Some boats require a little more preparation, but the suggestions given here should help most boats get through storage without too much of a problem.

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There are many sources of noise on board a boat. Once the motor is off and the boat is under sail, things quiet down. Most of us don’t actively think of noises on the boat unless they become worrisome or annoying. The crew can be the most immediately annoying, especially if they don’t like the provender and drink in the galley (or cooler, depending on your boat). However, there is a type of noise that many sailors don’t think about that can adversely affect the operation of the boat: electrical noise.

How do you know that there is electrical noise? It’s usually noticed first on anything to do with audio, so the radios are the first place that electrical noise gets noticed. There might be a hum on the stereo, or whistling on the VHF, or buzzing on the SSB. But there are other places that electrical noise can cause problems. One common place on the Ockam system is the boat speed reading - especially on the 015 "black box" type interface. Electrical noise can cause all sorts of silly values here. Another place is the wind speed; the value for wind speed usually just stays put at or above a particular value if there is a noise problem. I’ve seen a boat with wind speed stuck at 52 knots because of AC induction from an inverter.

Electrical noise is typically only noticed when it starts affecting the normal operation of the boat’s electronics, but it’s almost always present to one degree or another. If you suspect there is a problem, you can try a few things to isolate the source.

First, turn off any generators and inverters. Also turn off any battery chargers. Finally, disconnect any shore power or communication connections (cable TV, telephone, etc.). These are very common sources of electrical noise. If the bad behavior goes away once you have removed these potential sources, then you know that one of them is likely responsible for the noise. Re-attach or turn them on one by one to see when the bad behavior comes back; you should be able to figure out the source.

But what to do about it? In some cases, simply providing a good ground connection can solve your problems. There are also a variety of noise filters available to help remove noise from the voltage supply of a boat. I have found that good battery isolation between banks (again, there are a variety of products that do this) can help immensely, especially on boats that use more than one house bank.

The Ockam system can also be a source of noise, especially the older systems operating with an SSB on the boat. The paper at this link covers several strategies to eliminate this noise. I have found that most boats don’t even get past the first two remedies before the problem is reduced to a level where it is no longer a problem. On the newer systems, the components produce far less electrical noise, so reduction of RFI is rarely an issue.

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It’s been quite a while since anything was written in this blog. It’s not for lack of subject matter - far from it. We’ve been working hard on making some new products, and they are finally coming closer to completion. One product is the new DeWiggler - a semi-automated calibration program. It produces results similar to multiple calibration runs with a top-notch calibrator over many days. Check the web page for a detailed write-up and downloads. We are also working on a few projects aimed at the large yacht market which will likely have applications on smaller boats - keep an eye out for these in the first half of next year!

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