MicroTransat

admin
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MicroTransat

Postby admin » Fri Jan 20, 2017 8:54 am

AYRS has received the following letter, which I'm posting here and inviting the sender to join the forum. Comments are welcome.
Admin
______________________________________________________________________
Your advice about a crazy idea.

I'm sending this email, as owing to a mistake on my part, I was planning to come to the London Area
meeting on Saturday to seek advice about a project I’d like to investigate. As it’s on Sunday
and I have a prior commitment I won’t be able to come along.

I’m contemplating making an entry in the Microtransat, autonomous division/ sailing vessel class.
http://www.microtransat.org

I first came across your society after being given a set of books by a former member of my Yacht Club.
The subject of the book is self-steering and I couldn’t help but investigate it’s origin as it is a most unusual book.
I particularly like this kind of work as I’m a Yachtmaster and interested in technology.

My purpose in approaching your society is to seek your opinion as to whether you consider the idea
of building a vessel (max length 4m) propelled by wind power only and to send it on a mission to traverse the Atlantic
completely autonomously is feasible.

The response I am hoping to get is along the lines of
a) You’re completely mad
or
b) That’s a most intriguing idea, let’s talk!

I anticipate that it will require the following:
    Custom:
    Hull(s),
    Mast(s),
    Rigging,
    Sail(s),
    Steering and Rig control,
    Power generation and management,
    Navigation, Communications and Collision avoidance systems (my area of interest as I’m an IT consultant)

There isn’t much I can think of that can be obtained off-the-shelf so it calls for some
innovative thinking from people who like a challenge and can come up with novel solutions.

There are a number of reasons why I am contemplating this project.
1) My granny taught me that ‘nothing is impossible if you put your mind to it’
2) No-one has succeeded so far, and quite a few have tried.
3) I want to do this before the French do!
oh yes, and my wife says I should follow my dream!

I hope that you might pass this email onto members of your society who may be interested
or at least willing to offer their feedback on this subject.

kind regards
Richard Walker
PS I work in Southwark but live in Bracknell.

Robert Biegler
Quiet member
Posts: 11
Joined: Sun Jan 08, 2017 7:54 pm

Re: MicroTransat

Postby Robert Biegler » Wed Jan 25, 2017 8:26 pm

My purpose in approaching your society is to seek your opinion as to whether you consider the idea
of building a vessel (max length 4m) propelled by wind power only and to send it on a mission to traverse the Atlantic completely autonomously is feasible.

I know it’s feasible for a moderately-sized team of professionals, because Saildrone (http://www.saildrone.com) went from California to Hawaii, and they report a total of 60000nm sailed so far. I have no idea whether technology has progressed to the point where a smaller team of amateurs, with a presumably far smaller budget, can achieve the same thing.

The response I am hoping to get is along the lines of
a) You’re completely mad
or
b) That’s a most intriguing idea, let’s talk!

How about c) are you mad enough to talk to me?
It occurred to me a while ago that a sailing tethered airship (an aerostat) would make a very nice ROV for offshore research. Stephane Rousson has put this into practice: http://proafile.com/multihull-boats/article/zeppy-3-across-the-med-by-wind-powered-airship. I have two designs for paravanes that I think would be more reliable than the Costes design that Rousseau uses, but I don’t have comparative empirical data. I think Bernard Smith’s variation on the scheme, with a wing stuck on the belly of the aerostat, would be stable in altitude at least when analysing the static case. Even for that, though, I know just enough maths to realise that I can’t work out a closed form equation describing the feedback. I might have to take the brute force and ignorance approach and write a programme to model it, but doing that for a dynamic model is well beyond me. and I have an idea for another design that would need less modification of the aerostat, thus cutting down costs.

I did look into buying a small aerostat, with a payload of about 1kg, to test the platform with plain old radio control, but gave up when I found out how much the helium would cost. And when I searched for hydrogen, I only found stuff on hybrid cars, not on hydrogen suppliers.

If you were interested in that approach, there would be quite a lot of up front development. I doubt it could be done for this year, and I estimate costs in the range from £5000 to £20000. Control systems would come on top of that. My plan was to contact a company that makes aerostats to carry radar systems, mostly for the military, and see whether they are interested in branching out into something rather more civilian.

One advantage of this configuration, which is what makes it so interesting for research, is that you can put your sensor package 50m above the surface. Radar reflectors, AIS receivers and senders, cameras and so on would not be obscured by waves. So that, at least, would help in implementing collision avoidance as you would at least have a clear view.

Also, I have absolutely nothing to offer on the robotics side.

Regards

Robert Biegler

Fredthecharlie
Committee Member
Posts: 28
Joined: Sun Oct 11, 2015 5:31 pm

Re: MicroTransat

Postby Fredthecharlie » Sun Feb 12, 2017 12:54 pm

Microtransat some thoughts from the Thorpe Meeting
This subject was discussed at the meeting, but better preparation by providing delegates with the rules I think would have produced more ideas.
It was generally considered not to be a one man project because of the wide range of skills needed to complete the design, construction, testing and getting to the start line in a reasonable time, however as an arm chair exercise offering plenty of scope for thought and maybe searching for a like minded team and some sponsorship (maybe a Howard Fund application).
Last years competition seems to have lost competitors due to lack of communication; the rules requiring regular updates of position, at least one competitor was wrecked shortly after being released and another was caught by a fishing boat.
Reasons for communication failure include lack of power, poor aerials and electronic failure which could be due to mechanical or electrolytic damage.
Power needs to be generated and stored for when generation is reduced by prevailing conditions; PV only works during daylight and wind or movement systems when there is wind or waves.
One member of the audience suggested an all metal monohull including the sail, with a deep ballast keel on the grounds that it would withstand the prevailing conditions in the Atlantic and survive. Would it mask radio signals?
Generating electricity was discussed, PV cells, wind generation and using electrolysis (would the anode erode or the cathode foul?) were mentioned and since the meeting some form of pendulum mechanism comes to mind.
Propulsion using the wind was discussed and self tending wingsails mentioned, like most sailing rigs tacking to windward would make the algorithm for navigation more difficult but a rotor (windmill) rig would simplify things . More information on both these subjects can be found on an AYRS members personal web site www.sailwings.net
Keeping the Electronics dry absolutely essential as salt water corrodes and will cause short circuits so sealing of access hatches is essential as is sealing exposed wire where connections are made, some form of flexible diaphragm might protect sealed compartments from pressure fluctuations that might draw water in.
I wondered if a trimaran with a water filled ballast keel to allow recovery from knockdown using several wind mills to generate electricity and others to provide propulsion might be an option; several small ones keeping the centre of effort lower to reduce capsizing forces; or if the rules permit all to generate electricity and surplus electricity to drive propellers.
FCB

Robert Biegler
Quiet member
Posts: 11
Joined: Sun Jan 08, 2017 7:54 pm

Re: MicroTransat

Postby Robert Biegler » Thu Feb 16, 2017 7:47 pm

Fredthecharlie wrote:I wondered if a trimaran with a water filled ballast keel to allow recovery from knockdown

Why water ballast? For a given weight, lead would give you a lower centre of gravity. The advantage of water ballast is the ability to dump it or take in more. That seems an unnecessary complication while underway, and the boats are small enough that it shouldn't be an issue for transport. Even if roof-topping, being able to take the keel off and keep it inside the car would seem an adequate solution.

Fredthecharlie
Committee Member
Posts: 28
Joined: Sun Oct 11, 2015 5:31 pm

Re: MicroTransat

Postby Fredthecharlie » Fri Feb 17, 2017 8:12 am

My thought was that it would not increase the displacement but would provide a righting moment when the ballast bulb came out of the water, ie at about 80 degrees heel, it would increase imersed surface area however.
F

Robert Biegler
Quiet member
Posts: 11
Joined: Sun Jan 08, 2017 7:54 pm

Re: MicroTransat

Postby Robert Biegler » Sat Feb 18, 2017 4:26 pm

It would increase displacement, though. It doesn't matter to displacement whether you carry the weight in the form of water or something else. If you start thinking of a hull, then mentally add a water-filled keel, you don't need to make other alterations to the hull, and that can give the impression that you don't add displacement. But if you imagine adding a keel of the same shape and weight, filled with a small volume of lead and a larger volume of air, the lead feels more like added weight, yet the effect on displacement is the same. Only, you can get the weight lower down, and you have more freedom to distribute that displacement as you like, because you don't need much volume low down.

Fredthecharlie
Committee Member
Posts: 28
Joined: Sun Oct 11, 2015 5:31 pm

Re: MicroTransat

Postby Fredthecharlie » Tue Feb 21, 2017 10:18 am

Thank you for your interpretation, I agree that the boat mass will be increased but hopefully its weight carrying ability shouldn't be affected; I think that having considered your thoughts a high density bulb and an enlarged volume of the immersed hull might be better it should certainly produce a smoother stability curve although my water ballast might produce a hump giving a manned boat a better chance of recovering
FCB


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