For those still able to cast away their intellectual Zimners, I repeat: Gumstix to you Sir!

My dear sir, I’ll take the bait; whatever can you be talking about?

Apply Google and imagination - in that order


Are you talking about Microcontroller-jiggery-pokery?

OK - I googled and imagined.

A Gumsti(ck/x) is a great step forward in miniature automation. Since it appears to be the first of its kind, it is probably expensive (!) for what it is - or will appear that way in a couple of months/years. So let’s look at what it can do – this is supposed to be an innovative development class.

First – a Gx (let’s call it that) is a small Linux computer about the size and weight of a stick of chewing gum. It costs about $150 in the USA – not all that many trips to the supermarket in the 7-litre SUV.

If we program the computer correctly, we can in principle do many things. First, the number of radio channels becomes irrelevant – we can do everything you ever dreamed of over a single radio channel. How?

Easy. Take the analogy of a squad of soldiers. Using conventional equipment, it is a bit like a squad in basic training. To make them march you give them the command ‘Quick March’ – and follow it up with ‘Left, Right, Left, Right, Left, Right …’ to keep them in step. In other words, we have to issue a continuous control signal to keep them marching. This is equivalent to a radio channel used for steering or sheeting. The platoon sergeant’s voice can be used for no other purpose.

On the other hand, with a trained squad, they can keep in step for themselves. That’s one of the things they learned in basic training. The sergeant simply has to give the COMMAND ‘A Company, Quick march’, and off they will go – straight off the edge of a cliff if nobody stops them, but in perfect time: the responsibility for keeping in time has been shifted from the sergeant to the squad: it’s part of their training. While the squad are getting to its encounter with the cliff edge, the sergeant is free to issue other commands: ‘B Company, Right Dress’, ‘T Company, Brew Up’, ‘Darling, I’ll be home for lunch’ …

So in a Gx system, all or most things that pass between skipper and boat take the form of Commands – ‘Do this’ - rather than as ‘variable states’ –u.e. ‘Follow my finger and keep following it’. We can shout as a many different commands as we like to as many people as we like through the same megaphone (radio channel).

The trick then is to decide what these commands might do. I have two major thoughts, but there is an infinity of possibilities.

Thought 1:
I am pretty sure (although surprisingly nobody has ever seemed to have tried to find out) that in a reasonably steady breeze (shifts not big enough to justify a tack), a reasonable vane-steered boat is much faster than an R/C one. If it is not, the only possible reason is that traditional vane gears suffer from having the vane in the down-wash of the rig and are not detecting the ‘clean’ wind direction. We can overcome this problem easily by replacing the clanking ironmongery of a traditional with a sub-miniature electronic vane at the mast head.

So, given that we can easily get a ‘clean’ apparent wind direction on the boat, an electronic vane gear can act as a perfect helmsman with total concentration, reacting exactly to every tiny shift in the wind. I do not believe that even the very, very best radio helmsmen do this. A vane steered boat will therefore go to windward faster.

So why not go pure vane? Well we do have these things like bigger shifts and triangular (or more-sided) courses. As the squad reaches the top of the cliff, we need to be able to say ‘About Turn’: we have to be able to tack to avoid collision, we have to be able to round marks, we have to react to shifts, and so on. The point is that the on-board system looks after the humdrum business of keeping the boat in the groove while you look after the clever bits.

Development of such a system is not trivial – but neither is it fantastically difficult. Any bright young engineering students in need of a project? Barrett?

Before we finish with Thought 1, may I leave behind three Sub-Thoughts? First, systems like this are on the way in in the real world: it am told that that latest Mercedes-Benz and BMW Wunderwagen will drive themselves down a reasonably straight, reasonably crowded Autobahn pretty much indefinitely with the ‘driver’ asleep. Second. This technology is not the result of some incredibly original thinking on my part: it is the logical next step given that the Gx hardware exists. If I am writing this here, you may be absolutely assured that Watanabe Consumer Electronics Corporation already has a working prototype and that it will appear as a standard part of all middle-market R/C electronics quite soon. Third, if such a system were available, it would be of great use on full-size cruising boats. I remember many years ago when the Richardson family swapped its trusty Holman 31 Rockabill (long keel, heavy displacement) to the Hustler 30 Skulmartin (shortish keel, separate rudder, medium-light displacement), one thing that he could not forgive the new boat – despite her many other virtues – was he fact that he couldn’t light his pipe: he had to steer all the time. A system that allowed the boat to take over and do something intelligent for a minute or so simply because he wasn’t doing anything would have suited him down to the ground.
Thought 2:
We’ve been through this before, but the means now present themselves. A Footy built like a wind-surfer will go like a rocket – almost certainly. The problem is control. It is hard enough for a middle-aged gent like me to stray on a windsurfer if I am actually on it. Trying to do the trick at a range of 100 yards looks like a non-starter. But with onboard autonomic control of the basics …

If anyone is still reading at this stage, there will be typing fingers (damn, gave it away: my lips move as well) itching to tell me that this will destroy the sport, that they want no truck with microcontroller higgledy-piggledy, it’s deskilling things, what about the cub-scout, etc.

I repeat my usual sermon.

The cub scout (or at least the Eagle scout) is not interested in Footys because they are frankly boring. They are not boring because they don’t proceed at super-light speeds (neither do robots) but because they use technologies that the majority of people who use this forum find acceptable. Let’s be charitable and say that they’re the over-40s. So we’re asking a clever guy of, say, 14 to do what someone 3 times his age - essentially his grandfather – thought was a fun way of doing things. Why should he find it remotely interesting? He might just as well be making models of goose-foot harrows. Even (I repeat, EVEN) drugs and sex and rock’n’roll are more interesting.

Cost. Shame on you. Most of the ‘it’s got to be cheap at all costs’ brigade come from the US - although they have some very talented British colleagues.

If you want to make a quasi-religion out of cheapness, fine, but I’m not joining in. If what you mean is affordability, I don’t think there are many people here who can’t raise $150 for a serious hobby if they want to. It will pay back directly because the effort you have to put into making it work will keep you out of the pub, which will in turn reduce your health insurance bills, etc, etc, etc. And if you’re really that poor, what about going to the supermarket on a bicycle with a trailer, like they do in Holland? Transfer the cubic inches from rattling Japanese iron to pumping American thigh muscle?

Is it going to destroy the class? No idea. But let’s develop it first and ban it later if we don’t like it.

End of rant. Light blue touch paper and stand weeeell back!

Wow Angus! Well said. Even more so because in your rant about technology advances you appear to have discovered spell checker! Only one word out of place in the whole manifesto as far as I can tell.

Your cub scouts are probably not going to flock to r/c sailing with “gumstix” in any more numbers than they do now. There are more adrenaline pumping games to capture their attention.

I learned to sail with my father on a Shearwater catamaran in Fire Island’s Great South Bay. That was adrenaline pumping! When we became landlocked my dad discovered vane sailing and a fix for the inland sailing jones was at hand. I got my first boat at ten when I could lift my Dad’s Marblehead out of the pond at Central Park. I wanted to sail to spend time with my busy father. After some success and discovering a support group of lots of dads I was hooked.

What is unfortunate is that a lot of men find r/c sailing as a way to get out of the house and away from familial responsibilities, not as a means of bonding with their sons or daughters. Racing sailboats is one of the hardest intellectual games available. As a teachable sport it provides fathers with a means of imparting spacial and scientific thinking to their child. Unfortunately, to be any good at it requires years of perseverance and problem solving. It is not a quick starter for a generation accustomed to the fast rewards of video games, or endless circular wave jumping on a jet-ski. Adding some wiz-bang technology so the boat will sail itself isn’t going to jazz up a comparatively slow moving sport. It will only cheapen the rewards to be gained by commitment.

Here’s a possible application – duplicate the automatic sheeting system from the first US R/C champion boat.



WOW… We were to visualize all of that from a single word. I failled and designed & progrommed micros starting w/a 4004 if you know what that is.

If it is done by someone, we can always change the rules to two servos only.

Ah, you are talking about microcontrollers.

Robot guys have been using these to control there servos for a long time.

The latest these days is, rather than controlling the actuators (servos), from brain (laptop say) through conected wires to the servo controller, is to have the microcontroller on board (brain), controlled by wireless interface, that then sends commands straight to the servos.

Personally, I’d go with Axon Microcontrollers. Some, like the Paralax type (Basic stamp II, etc.). Some like the Atmel’s.

However, to operate these wee brains, you have to know computer programming (Basic, C, C++, java, etc.). Also, some have opensource coding, some do not. Different MCU’s also communicate differently than one another, so pick one based on what laguage you know.

Then there’s the programming and compiling of the chip.

It takes a lot of reading, lots of late, sleepless hours, up programming, debugging, etc.

The future is having markers at the bouy marks, and having the sensors (say infra red, ultra sonic, wifi-camera even) on your Microcontroller, sail round the course autonomously. But for now…ROBO-ONE competitions.

Society of Robots has some good info. about the topic. In England, Robosavy’s forums should provide much info. Get this mag for even more what’s going on with such devices:

As for me, the “Mech Warfare” aspect of robotic programming, has me hooked.
It starts with the Bioloid kit and it’s CM5 controller, then working in “C”, to unlock all sorts of possibilities.


Don’t ignore Pascal as a programming language. It may be a bit ancient, but it is still the prefered language for embedded military systems in the UK. Our Ministry of Deence has (semi?) offcially described C++ as ‘a disaster waiting to happen’. I agree. C was bad enough (‘a write only language’) but it was intended as a thinking man’s assembler - which it was quite good at - not for the mundane applications it has been pushed into since. C++ is a ‘quick fix’ object orientation of C. It overloads all the C naming conventions to maximise unreliability and obscurity. And the suckers fell for it.

That’s 2 rants in one day!:zbeer::graduate:

I don’t know whether I’m totally brain dead as a programer (probably am - hqaven’t written a line of code for about 12 years) but a hardware guy MIGHT persuade me to get involved in this.

Open code.


I hear noises. I think it is a snoring noise. So I won’t bring up assembly language.

I bring assempler up after a very hot curry and too much beer!


Isn’t there something in the UK MYA radio sailing rules which bans electronic devices to automatically steer or trim sails. Indeed couldn’t “Control is restricted to 2 channel radio control gear” be a interpreted as a bar to automation. Anyone an idea what might be legal?

I’ve been thinking about using a PIC microcontroller to allow a genoa, by interpreting a single rc channel to control 3 servos. Centre the control stick for the wind dead astern fully left = close hauled port tack, fully right = close hauled starboard tack. reasonably easy to do, some weight cost, hopefully legal as no sensors are used and sheet positions depend entirely on control stick positions although in a complex manner.

The Gumstix look very cool but post 4AA rule they consume a lot of power.


Verrrry interesting… this could make the transat footy a reality as well… unfortunately, I couldn’t write a line of code if you pointed a gun at my head (well, maybe then, but you get the idea.) That said, I’ll be watching this develop very closely… as for rules, I don’t know if it would be in violation at all… it is less than 2 channels, and there are many ways to interpret that! (As we all well know… cough, cough)

Dunno about MYA, but the Reynolds gadget was fresh in the minds of the writers of some early AMYA classes and sail control by the skipper was mandated. Then it was forgotten …

Probably belongs in RRS Appendix E.



I was hpoing we could leave rules out of this - so let’s just, purely for the purposes of this thread, suspend our disbelief and immagine that rules are the servants of people, not the other way round!


I find all this fascinating, but quite beyond my aged mind to assimilate. I don’t even use a computerised radio transmitter. You clever young guys get on with it, sell it to Mitsubishi Models and when they market it as an idiot proof mass market control system I’ll think about whether it will give me more pleasure than a simple two channel radio gear which works and which I can, up to a point, fix when it goes wrong.

Though Lance Armstrong may be right in claiming that “It’s not about the bike”, in our game, it IS about the boat. The present system may be less efficient than a potential replacement, but it gives the skipper an on going task and minute by minute relationship with the boat. Gumstix, if it worked as envisaged by Angus, would reduce the skipper’s task to vigilance and occasional intervention. The ability to light my pipe while the boat made it’s own way to windward would not, in my view, compensate.

But I stand ready to aplaud the first working Gumstix equipped Footy.


20 GOTO 10


Here you go - a new open source autopilot for US$25! (plus GPS module - $60)

Hey this would be a great add on to a Gumstix ~ cool
The web link below shows some tiny lightweight linear and rotary actuators based on muscle wires.

At 7 quid these are so cheap that I may have a go with them. They do not accept a servo input from a R/C receiver but instead just simple switches.

(Thanks to Lawrence for the link)