Mike Slinn



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• Long-awaited Raymarine C70 update available
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Practical Sailor

I’ve had problems with timed transmit mode on my Raymarine C70 for years. The v4.29 software update seems to have finally solved the problem. Updated documentation is here.

NOAA has a useful service called Dial A Buoy. Unfortunately, the only phone number listed is 888-701-8992; if anyone knows of a non-800 number, please let me know.

Please, no bad puns about San Francisco and “Dial a Boy”. This is a high class blog.

The Microtransat Challenge will feature seven robotic craft, without crew, competing in a race across the Atlantic Ocean.

This historic transatlantic race will run between September 29 and October 5, 2008 and start at Viana do Castelo, Portugal. The finishing line lies between the Northern tip of St. Lucia and the Southern tip of Martinique in the Caribbean. The USA is fielding up to two teams, and France, Canada and Portugal will each field a team.

The Pinta was designed at Aberystwyth University, Wales, UK. Pinta is expected to sail for three months at a maximum speed of four knots. Its designers hope the Pinta will become the first robot to cross an ocean using only wind power.

According to Pinta designer Mark Neal, “This is the first time anybody has attempted to sail across any ocean with an automated boat. The big issue in robotics at the moment is longevity and flexibility in a complicated environment. Something that can survive for two to three months completely unassisted while doing something interesting is a major challenge. If it does get there I will be seriously cheerful. It will open up all the oceans to environmental monitoring by robots.”

For more information:

• http://blogs.zdnet.com/emergingtech/?p=919
• http://www.aber.ac.uk/compsci/public/research/research-groups/intelligent-robotics.php
• http://www.gamesfather.com/video/Search-Microtransat-updated-1.htm

In a recent blog, I mentioned that I was developing Linux-based open source navigation software for Willow Garage. In the course of doing this, I discovered that CodeWeavers’ CrossOver Linux product allowed Coastal Explorer / Chart Navigator Pro to run in a win2k bottle. That doesn’t mean that NMEA devices work with programs running under Crossover Office - that would require some extra magic. The Willow Garage autonomous vessel project was canceled before I had time to get GPSes working with CE/CNP under Linux. If anyone is interested in adding NMEA 0183 and/or NMEA2000 support to a Windows navigation program running under Linux, contact me to discuss costs.

On another note, I discovered that the OpenEV package that I had been interested in extending into a nautical navigation program was based on older graphics technology, so I started programming a prototype that ran on Linux. Here is a screen shot:

I wrote the software in Python v2.5.2 using PyGTK v2.10, PyCairo v1.4.12 and Glade v3.4.1 for graphics support, running on Ubuntu Linux v7.10. I used GDAL 1.4.2 to read S-57 vector charts, and imported Google Earth KML data and GPX data using LXML. I used an Internet Communication Engine (ICE) bus to access remote instrumentation data.

Having played with the prototype for a while, were I to undertake a similar project in the future, I think I would design a GUI patterned after that of The Gimp (floating toolbox and multiple viewports), and employ a more sophisticated architecture. I’d write code using a mixture of Jython, Java, C and C++ instead of Python. It would be very cool to have a power efficient navigation computer running on Linux … it would be more stable than running on Windows.

I’m working on a NMEA2000 network. Because this system is highly customized, it is set up on a bench for software development and system debugging. In the following picture you can see that an Agilent E3610A DC power supply is providing 11.75 volts DC to the bus, via a yellow cable that ends in a T junction. On one side is a Maretron M000002 NMEA 2000/ USB Gateway, and on the other side is a Maretron WSO1000 weather receiver.

Missing are two terminators and T junctions to hold them. The terminators are on order but haven’t shown up yet. Unfortunately, without the terminators no data will flow

NMEA 2000 networks should be terminated at both ends, as shown here. Terminators are 120 ohms. In order to terminate one can either use an in-line terminator, or a T junction and a separate terminator.

Maretron’s NMEA 2000 connectors are identical with many other manufacturers (but some manufacturers are non-standard.) Compatible manufacturer product lines include Garmin, LowranceNet and Furuno NavNet 3D. Garmin’s product line seems to be the most readily available.

Garmin T junction p/n 010-110780-00 (WM #9505173; Defender #256993)

Garmin male terminator p/n 010-11081-00 (WM #9505199; Defender #256995)

The Maretron NMEA 2000 Gateway is cool. Using Maretron’s free N2K Analyzer software allows you to browse the NMEA 2000 devices on the network, and update their software.

The WSO100 includes a software emulation of a Maretron DSM250 color display. Unfortunately, the WSO100 is made of thin plastic and is extremely delicate. Below is a picture of another unit that was dropped onto a linoleum floor from three feet (by someone else!) This $600+ unit is now garbage. Maretron told me that the three orange-red rubber inserts that face inwards are very sensitive to pressure, and will fail if squeezed.

After the terminators arrived I discovered that both WSO100s worked, however the broken unit reported that the temperature was 1.5 degrees warmer than the temperature reported by the other unit. Wonder what the tolerance on these units is?

I’m helping out at Willow Garage on their autonomous boat project. The onboard navigation computer actually drives the boat, and is supervised by an onboard mission planner. I’m working on a rudimentary remote navigation program so mission personnel can give high-level directions to the mission planner. Both the onboard computer and the remote computer run Ubuntu Linux. All high level software is written in Python and will be open sourced. The remote computer receives a copy of the instrument data feed via wireless.

The only customizable navigation software I know of (EC2007 from SevenCs) costs 5 figures and although it runs on many platforms, it is not very extensible and is not open source. What’s more, there are no other decent commercial navigation software packages available for Linux. Happily, I found a really nice open source GIS package that runs on Linux and Windows which can read S-57 charts such as those published by NOAA. The package, called OpenEV, is written in Python and even has a python command line interpreter … most cool! If you want to play with it, get the FWTools download since the Vexcel download is old. All software dependencies are included in the download. OpenEV is not a navigation program, but it is a great start for building one.

This project I’m currently working on will not result in a generally useful program, but OpenEV could be a great start to an open-source marine navigation program. If you are a programmer with time on your hands, read on. If not, but you would like someone to create an open source navigation program, contact me and offer me a lifetime supply of donuts

Here is a screen shot of OpenEV running on Ubuntu Linux with a customized toolbar menu:

This section for salty geeks only

You can download S57 vector chart data from here. After you download and unzip the charts you want, start up OpenEV and load the file with the 000 file type.

OpenEV is written in Python and uses PyGTK, which provides Python bindings for the GTK+ libraries. PyGTK takes care of memory management and type casting.

If you want to try customizing OpenEV, here are few hints:

• The toolbar can be modified by editing xmlConfig/DefaultIconFile.xml; menu icons belong in pics/.
• The menu can be modified by editing xmlConfig/DefaultMenuFile.xml
• Plug-ins must be placed in tools/
• An example plug-in is provided in pymod/toolexample.py

I found it helpful to use IDLE (apt-get install idle) to browse the Python classes. If you write a script and place it in the FWTools directory, you can launch IDLE as follows:

cd "$(dirname $0)"
export PYTHONPATH=pymod:lib:$PYTHONPATH
idle&

Once IDLE is launched, use the File/Path Browser menu item to browse the source. Double-clicking on a file, class or method will display the code.

The syntax for the embedded Python interpreter is defined here.

Gotta get back to work… anyone else interested using OpenEV to create a navigation system?

I recently gave a presentation about the potential for a wave-powered autonomous research vessel at Willow Garage. Unlike some other wave-powered vessels, my proposal attempts to generate electricity from waves.

Titanium is a special metal because it is very strong, very light, and is highly resistant to galvanic corrosion in sea water. Titanium has the highest strength-to-weight ratio of any metal. Unalloyed titanium is 45% lighter than steel, but is at least as strong. Titanium is used to make propeller shafts and rigging, fishing line and divers’ knives, and is non-toxic even in large doses.

Titan Marine Products specializes in manufacturing titanium marine hardware, including hose clamps and through-hulls. Hugh Richards, product manager told me that “Titanium is almost totally passive, from a galvanic point of view. It won’t speed up galvanic corrosion of other metals.”

Richards said that Titan Marine intends to provide titanium replacements for all metallic components found in a boat bilge. Titan Marine’s R&D staff are currently working on seacocks and tailpieces, and hope to bring them to market next year. Because titanium degrades at temperatures approaching 1500-1700 degrees, high temperature applications such as exhaust manifolds and exhaust hoses are not planned.

Berkeley Point is a small mail-order firm that resells Titan Marine Products titanium products as part of their product line. Defender carries a limited selection of titanium marine hardware. West Marine does not carry titanium marine hardware at this time.

Titan Marine uses a more malleable formulation than what is used in aircraft construction. Because airplane orders are soaring at the present time, the supply of titanium is tight and Titan Marine is encountering difficulty obtaining their marine-compatible titanium formulation. Costs have moved from about $7/lb in 2004 to $40/lb for the titanium stock that they purchase from Titanium Metals Corporation. Update May 30/08: Breakthroughs are being reported in lowering titanium costs by up to 50%.

From Wikipedia: “It is paramagnetic (weakly attracted to magnets) and has fairly low electrical and thermal conductivity.” This would affect a compass, but less than an iron hull, I expect. “It is the ninth-most abundant element in the Earth’s crust (0.63% by mass) and the seventh-most abundant metal… The relatively high market value of titanium is mainly due to its processing, which sacrifices another expensive metal, magnesium. The FFC Cambridge Process may render titanium a less rare and expensive material for the aerospace industry and the luxury goods market, and could be seen in many products currently manufactured using aluminium and specialist grades of steel… The metal can be machined using the same equipment and via the same processes as stainless steel… As a powder or in the form of metal shavings, titanium metal poses a significant fire hazard and, when heated in air, an explosion hazard… Even bulk titanium metal is susceptible to fire, when it is heated to its melting point. A number of titanium fires occur during breaking down devices containing titanium parts with cutting torches. When used in the production or handling of chlorine, care must be taken to use titanium only in locations where it will not be exposed to dry chlorine gas which can result in a titanium/chlorine fire. Care must be taken even when titanium is used in wet chlorine due to possible unexpected drying brought about by extreme weather conditions.”

Another interesting metal is tantalum. From Wikipedia: “Los Alamos National Laboratory scientists have developed a tantalum carbide-graphite composite material that is one of the hardest materials ever synthesized. Korean researchers have developed an amorphous tantalum-tungsten-copper alloy which is more flexible and two to three times stronger than traditional steel alloys.” However, “There is some evidence that tantalum compounds can cause tumors, and its metal dust is a fire and explosion hazard.”

Tungsten is another super-metal, but much heavier. From Wikipedia: “Hardness and density properties make this metal ideal for making heavy metal alloys that are used in armament, heat sinks, and high density applications, such as weights, counterweights, ballast keels for yachts and tail ballast for commercial aircraft.”

The review of marine heads I wrote for the January 2008 issue of Practical Sailor has received more comments than any other article I have published in that magazine. Readers were generous in their desire to share experiences and suggestions.

As part of the follow-up that I usually do after an article is published, I contacted Jabsco and asked their advice regarding the fine black powder that is starting to accumulate just below the the pump handle. The support individual was friendly, knowledgeable, and not only had read the review, but was able to quote back much of it to me from memory. He offered to have his contact information be made publicly available so that customers could easily contact him. The technical support person that I spoke to at Jabsco is Michael Irving +1 978-281-0440 michael.irving@itt.com. I have paraphrased what he told me:

“If the shaft is dry or rough use Vaseline or lithium grease directly on the shaft. Also lift up the handle, use a wrench, unscrew the retaining nut and coat the inside of shaft and inside the cylinder. Every 2 weeks squirt mineral oil/baby oil for 3 seconds into the bowl, and slowly pump the water/oil mixture through the head so the O-ring stays lubricated. The top-most seal assembly can be purchased (p/n 29044-2000).” Irving said this is the part most likely to be wearing according to the problem that I reported. He also suggested that 29049-0000 (p/n 35 & 21) are good spare parts to have on hand.

Irving went on to say that “For 2008, the head’s part number has been replaced with 29090-3000, which has a few new features. The 2008 model has a redesigned pump which fits in place of the old pump. The pump’s plunger assembly was modified to reduce the potential of backflow.” (I have not experienced this problem.) “If a customer is experiencing backflow with an older model head, they can order the 29040-3000 pump assembly.”

I received one of the 2008 pumps, and I will replace the head’s pump on board Jedi at the appropriate time and see how it works.

I happened upon the US Army Survival Manual on the Internet. Chapter 18 is devoted to navigation. Here is an excerpt: “If the moon rises before the sun has set, the illuminated side will be the west. If the moon rises after midnight, the illuminated side will be the east.” There are lots more gems like that in the downloadable PDFs. Store them in your laptop next time you go offshore.

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