solar boat headed to Hawaii

[Damon McMillan]

Hi all,

In case you're interested, I launched a solar-powered boat from Avila Beach, California this past Saturday.  It is heading to Hawaii.  You can check out the tracking page here:

https://www.google.com/maps/d/u/2/edit?mid=1gESD9GA-zAgTrYO6eEalvvFi0OdkYvM&usp=sharing

The boat is currently reporting telemetry once every four hours via satellite modem (Rockblock).  However, I have to manually update the tracking map with new telemetry, which I will try to do once per day.

This boat was going to be a prototype for a product that I wanted to launch, but there are several things about the design that I don't like (mainly relating to how difficult it is to build and transport).  So I'm probably going to start over with a blank slate.  But I at least wanted to see how it performed in the ocean.

This boat is similar in size to my SeaCharger from back in 2016.  One significant difference is that it only has one 100-watt solar panel instead of two.  So far it seems to be going faster than SeaCharger in spite of having half the solar power, which is probably a result of the more efficient propeller (8-inch diameter instead of 4.5-inch diameter) and smaller keel.

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

[Robin Lovelock on robin@gpss.co.uk]

Brilliant Damon. That tracking link works puuurfect :-)

https://www.google.com/maps/d/u/2/edit?mid=1gESD9GA-zAgTrYO6eEalvvFi0OdkYvM&usp=sharing

Robin & Snoopy http://www.gpss.co.uk

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[Ivan Krasin]

Hi Damon,

very nice boat! Good luck in this adventure.

By the way, what is the way of steering? Somehow, I don't see a rudder on the photo (or maybe I am glitching?).

krasin

[Alastair Lidstone]

Good luck Damon! I loved your SeaCharger and its great to see a new boat!

How do you plan your recover the boat when it arrives? 

Alastair

On 12 Feb 2025, at 04:39, Ivan Krasin <imkr...@gmail.com> wrote:



Hi Damon,

very nice boat! Good luck in this adventure.

By the way, what is the way of steering? Somehow, I don't see a rudder on the photo (or maybe I am glitching?).

krasin

On Tue, Feb 11, 2025 at 10:30 AM Damon McMillan <da...@bluetrailengineering.com> wrote:

Hi all,

In case you're interested, I launched a solar-powered boat from Avila Beach, California this past Saturday.  It is heading to Hawaii.  You can check out the tracking page here:

https://www.google.com/maps/d/u/2/edit?mid=1gESD9GA-zAgTrYO6eEalvvFi0OdkYvM&usp=sharing

The boat is currently reporting telemetry once every four hours via satellite modem (Rockblock).  However, I have to manually update the tracking map with new telemetry, which I will try to do once per day.

This boat was going to be a prototype for a product that I wanted to launch, but there are several things about the design that I don't like (mainly relating to how difficult it is to build and transport).  So I'm probably going to start over with a blank slate.  But I at least wanted to see how it performed in the ocean.

This boat is similar in size to my SeaCharger from back in 2016.  One significant difference is that it only has one 100-watt solar panel instead of two.  So far it seems to be going faster than SeaCharger in spite of having half the solar power, which is probably a result of the more efficient propeller (8-inch diameter instead of 4.5-inch diameter) and smaller keel.

<IMG_9539.jpg>

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

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[Oliver epsom]

Hi Damon,

Excellent work, this looks like a brilliant boat.  I will track it with interest.

Olly

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/CH3PR84MB36812A2EA312A45AFB7F891DF3FC2%40CH3PR84MB3681.NAMPRD84.PROD.OUTLOOK.COM.

[Damon McMillan]

Thank you Ivan, Alastair, and Oliver!

I don't think I'll recover the boat in Hawaii.  I have a friend there who will go out and take some pictures if the boat actually makes it there.  It will be useful to see if it has barnacles on it, what kind of shape the propeller is in, etc.  Then I would send it somewhere else and see how far it can go. 

Right now the boat is not headed straight at Hawaii, but more towards the south to hopefully get a little more sun.  Once it reaches the latitude of Hawaii, it'll go straight west.

There is a rudder on the boat, but it was obscured by my friend's legs in the picture.  I probably should have taken a few more pictures!  But here are some images of the CAD model:

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

[Jorge Cabrera Gámez]

Hi Damon,

The boat seems to be performing very well. Great work!

I will follow it with interest. 

Good luck!

J.

===================================================

Jorge Cabrera Gámez

Departamento de Informática y Sistemas

Instituto Universitario de Sistemas Inteligentes y

Aplicaciones Numéricas en Ingeniería

Universidad de Las Palmas de Gran Canaria

CANARY ISLANDS / SPAIN

Tel.: +34 928 459 644

===================================================

---

De: microt...@googlegroups.com <microt...@googlegroups.com> en nombre de Damon McMillan <da...@bluetrailengineering.com>
Enviado: miércoles, 12 de febrero de 2025 15:49
Para: Oliver epsom <olive...@gmail.com>
Cc: Alastair Lidstone <a_lid...@hotmail.com>; Ivan Krasin <imkr...@gmail.com>; Microtransat <microt...@googlegroups.com>
Asunto: Re: [microtransat] solar boat headed to Hawaii

 

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/CAOZwR408BObunM0e63_4y-eN6p5ErsiNvB9YO3hjtH19eFUs9w%40mail.gmail.com.

[Robin Lovelock on robin@gpss.co.uk]

Hi Daman. Great News, and I see my "Reply All" email earlier did not get through,

but here is a follow up, on the subject of faster boat.

What were the weights of the two boats ? Is the latest one lighter ?

On all Snoopy's boats, the lighter ones are generally faster ;-)

>>

This boat is similar in size to my SeaCharger from back in 2016.  One significant difference is that it only has one 100-watt solar panel instead of two.  So far it seems to be going faster than SeaCharger in spite of having half the solar power, which is probably a result of the more efficient propeller (8-inch diameter instead of 4.5-inch diameter) and smaller keel.

<<

Let me try & find my earlier reply >>>

Brilliant Damon. That tracking link works puuurfect :-)

https://www.google.com/maps/d/u/2/edit?mid=1gESD9GA-zAgTrYO6eEalvvFi0OdkYvM&usp=sharing

Robin & Snoopy http://www.gpss.co.u

<<<

I'm not sure why I did not get the usual copy here.

Did anyone get it ?

It seems my "Reply All" went to Damon & Microtransat.

Robin & Snoopy on http://www.gpss.co.uk

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/AS2PR02MB10275D271C71987FB11A386D5EFFC2%40AS2PR02MB10275.eurprd02.prod.outlook.com.

[Damon McMillan]

Hi Robin,

I didn't weigh it before launch, but it's roughly the same weight as SeaCharger.  Maybe even a bit heavier.  I think the speed is all about lowering the drag of the hull and using as large of a propeller as possible, which necessitates either a low-kV motor or a gearbox.  In this case I use a low-kV motor (50 RPM per volt).

Of course none of these factors will ever produce a drastic change in speed.  Since the power requirement is proportional to speed cubed, factors such as the hull design, propeller design, or size of solar panel will only yield a small difference in speed.  That's good news if you think you're a bad designer and bad news if you think you're a good designer!

Anyway, maybe I've just been getting lucky with currents so far.  The last report an hour ago showed the boat going only 0.9 m/s instead of the 1.5 m/s that it had been reporting several times before.

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

[Robin Lovelock on robin@gpss.co.uk]

Thanks Damon. I've just wasted an hour trying to get my very old but good TotalTide program to show the tidal currents now, and over the coming hours and days, to see if that matches what you see on the tracking. It works in our patch, but not managed to get it to work over wider area. TotalTide was valuable, not only for Snoopy's Robot boat attempts from 2012, but much earlier bottle tracking projects such a http://www.gpss.co.uk/bottle.htm before 2005. You can also allow for effect of wind by surface water moving at 3% of wind velocity ???

The important thing is that a mate gave me an old copy of TotalTide before the UK Admirality re-released it, but with an annual (expensive) rental. Tests showed both versions gave identical results, for year past and present :-)

If you google the subject, I'm sure you will find stuff. There are certainly old links to wind on Snoopy's page http://www.gpss.co.uk/autop.htm - but I don't want to encourage you to waste as much time as me :-)

I'll try and add a few links here, that may help ...

http://www.gpss.co.uk/rbqanda.htm  - see "Do You understand the tide".

That'll have to do - I was about to walk down into our village and spend a few hours chatting in our "Sunninghill Comrades Club" - about all sorts of things :-)

Track me if you wish - that "black SOS" tracker on http://www.gpss.co.uk/contact.htm 

takes you to https://110track.com/mod/share/index.php?su=19C8DFC326C0B3CD9CFE594E5308CCAA

About 6 minutes walk and you can zoom in on google hybrid maps.

BUT it's not Satcomms like SPOT - more like we put in those GPS bottles :-)

BTW the Damon that I know is a young son of Raj, our local Bansal family from Punjab, India.

I'm trying to get him into robot boats, but after radio control boats, instead of cars ;-)

Take Care

Robin & Snoopy

http://www.gpss.co.uk

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/CAOZwR40g39Ecghrz59c_o%3DCts8tGea39Rg0cMmZX046brRGCiw%40mail.gmail.com.

[Robin Lovelock on robin@gpss.co.uk]

Hi Damon. Some of this MAY be of some use.

I'll attach 4 pictures*, from your boats track, Total Tide, but - perhaps most usefull wind speeds.  * sorry if mistakes - damn AOL mail ;-)

You will see something similar if you scroll down the Snoopy page http://www.gpss.co.uk/autop.htm

It seems, looking at the winds now, your boat has been heading directly into the wind,

blowing in the ballpark of 30 knots / 30 mph, so the surface water, moving at 3% of wind speed

would be in the ballpark of 30 x 3 / 100 = 0.9 or about 1 knot or mph.

Probably significant. Did you say what speed the boat should do in flat water ? Sorry if said already ;-)

I also came close to seeing tidal speeds on Total Tide, but it was a bit questionable.

I ran TotalTide here which defaults (though cookies?) to English South Coast Southampton area.

If I zoom in so I see the tidal vectors, then use scroll bars, to move westward, I get to the USA west coast area,

then can just about get a crude coastline map. See example.

If someone got is working well, it could be very useful, since tidal current speeds

can peak in some areas to several knots, and your boat may be steering into the tidal current,

to compensate, and provide a straight line track.

 Take Care

Robin

http://www.gpss.co.uk with Snoopy on http://www.gpss.co.uk/autop.htm

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/1964593760.6469893.1739392262468%40mail.yahoo.com.

[Robin Lovelock on robin@gpss.co.uk]

Good News Damon. If you visit https://www.passageweather.com/ choose the north Pacific map and tap on Animate you will see that in the course of tomorrow Friday and the weekend, that wind will change into a fllowing wind, increasing the boats speed, due to surface water going at 3%. I see you DID mention the boats speed and

it is in the same ballpark. e.g. convert 1 metre/sec to mph. Amazingly good so far - INTO that head wind :-)

I'll add a piccy TT5,GIF showing it - next Sunday 16th Feb 2025 :-)

Take Care

Robin

http://www.gpss.co.uk

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/1712204368.6700489.1739472728906%40mail.yahoo.com.

[Damon McMillan]

Hi Robin,

Thanks for the link to Passage Weather.  That's very useful!  I'm glad to see the winds will be a little more favorable.

The bigger issue is cloud cover.  I hadn't been paying close attention to my battery during the first few days of the voyage, so the battery gradually got lower and lower.  Then there was a lot of cloud cover over the past two days which left the boat mostly dead in the water.  Today it should get a lot more sun, and I've adjusted parameters so that it will spend more time at partial throttle (which will slow it down a little, but not drastically) and only go to full throttle if the battery is topped off.  On the whole, it seems like there are a lot more clouds than when SeaCharger was going to Hawaii.  I guess that's the difference between winter and summer.  And of course fewer hours of daylight.  I tend to focus so much on the boat itself that the route planning is just an afterthought.  That's okay, though, it's good to learn the limits unique to a solar-powered boat.

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

[Robin Lovelock on robin@gpss.co.uk]

Thanks Damon. I just visited your tracking link 

https://www.google.com/maps/d/u/2/edit?mid=1gESD9GA-zAgTrYO6eEalvvFi0OdkYvM&usp=sharing

 then clicked on the last position at south-west end of track, to display details on left,

and - if I read it correct - the last position in Univeral Time ( UT = GMT = local UK time now )

was roughly 12 hours ago ( I'm writing this at about 1745z UT/GMT.

BTW 1745z = Seventeen forty five zulu has been standard NATO military parlance for years,

then (allegedly) standard Russian military doctrine after collaboration talks when the cold war thawed, a few years ago. Great if it thaws again - enough of that on my "Grumpy" page http://www.gpss.co.uk/grumpy.htm ;-)

Back to the main topic: I see that winds are now shifting in your boats favour:  https://www.passageweather.com/

so we should see, after your next update, even faster progress :-)

Yes, your words about the time of year, and solar power, are close to my heart, even though solar power on Snoopy's boats only have to keep the SPOT Satcoms tracker, computer, and rudder servo working

- sails do the more electrically demanding bit. After this reply, I'll update Snoopy's blog, then do a seperate post, with latest (poor) performance in our garden, on "static test": only comes on when sun "brings it alive".

NOW THE IMPORTANT BIT FOR YOUR THOUGHT: Looking at your boat, it seems to me that you have cracked all the problems of a robot sailing boat. But let me double check: will it sail automatically through defined waypoints,

WITHOUT any intervention, just by moving the rudder ? i.e, if it is sailing in the wrong direction, it will automatically turn the rudder, to correct the error ? When it gets to that waypoint where it should sail due westward, will it do that automatically ? Great if the answer is "Yes". It's obviously useful to have the option to take control, when things go wrong, and the main "Mission" is aborted. We did that on Bray Lake with seperate radio control in early days.

NOW IF THE ABOVE IS CORRECT: I suggest that you could easily add sails, such as on Snoopy's Robot Boats, and - IF DONE CORRECTLY - it should work well without any motor power.

I suggest you could start tests with exactly the same design of boat, but doing some "flat water tests" on a suitable lake, to get the "sailing balance" correct. This did not take long after we came down to adopting the "Marblehead" hull, with suitable deep keel. If there is any significant change to the boat, you obviously repeat the tests,

to "tweak" where the mast goes, forward or aft of centre, and things like the mainsail and job angles.

Note, to keep things simple, I don't attempt to let out the sail when sailing downwind. i.e. allowed to swing 30 degrees either way. Tends to "naturally tack" upwind, and goes fast enough downwind - helped by that 3% surface water drift - we should soon see on your boat ;-)

PERHAPS MOST IMPORTANT OF ALL: there is very little work in "building the hull".

Just a matter of getting a suitable standard  fibreglass marblehead hull, and deep keel,

then filling it full of foam, to cover water leaking in, after simple wood or metalwork

for things like where the mast plugs in, places to tie the stays/strings to, rudder shaft,etc.

Old details are on "Design" page http://www.gpss.co.uk/rbdesign.htm 

Perhaps the most important bit is at the top: "KISS = Keep It Simple Stupid".

Damn American engineer ;-)

Keep up the great work Damon - sounds like Irish blood to me ;-)

Robin

http://www.gpss.co.uk

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/CAOZwR41J_ub3pPY1zrvSLgPeihMvYHi0RDOa7JRr0WyX1bs8eA%40mail.gmail.com.

[Alastair Lidstone]

It’s incredible how it’s travelling in such a perfectly straight line. I can’t believe it’s not affected more by currents and wind. 

Great job Damon! 

On 14 Feb 2025, at 19:08, Robin Lovelock on ro...@gpss.co.uk <gp...@compuserve.com> wrote:



<image.png>

<image.png>

<image.png>

[Robin Lovelock on robin@gpss.co.uk]

Yes Well Done Damon. I reckon this is similar autopilot principles as Snoopy's robot boats,

where they don't use a compass, but rely only on the GPS-based velocity. i.e, direction of movement.

The rudder is then moved accordingly, to steer the boat onto the correct heading.

For a sailing boat, this works great, when the sailing speed is faster than the tidal current.

This can be seen on many of Snoopy's trans-Atlantic attempt tracks.

You will see a nice straight line towards the next waypoint, until the tidal current is faster

- then the boat will drift with the tide, until later in the tidal current cycle.

The sailing speed obviously depends on the strength & DIRECTION of wind.

Fastest when wind behind, or across the track - difficult to tack up wind.

Bray Lake tests show typical sailing speeds, for direction & strength of wind.

THE IMPORTANT THING is that an electrically powered boat

only needs to have a speed above the highest tidal current experienced

and it will go in a nice straight line. The rate of progress will obviously depend on the numbers.

That's it folks :-)

If I can find relevant images, like tracks, I'll add them,

starting with my looking at the "Snoopy" page http://www.gpss.co.uk/autop.htm

e.g. that old Bray Lake Test shows speed only about 1.5 knots with following wind ...

The 2015 Attempt was VERY interesting, thanks to our Royal Marine Chums - allegedly :-)

BUT this image aa15map3.gif shows the actual track - heading for that "Channel" waypoint,

with superimposed information cleverly added by Peter of Team-Joker.

As always on Snoopy Attempts, something breaks - but we learn from it ;-)

Take Care

Robin

http://www.gpss.co.uk

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/CH3PR84MB36811BB426701F07FA75D6BCF3FA2%40CH3PR84MB3681.NAMPRD84.PROD.OUTLOOK.COM.

[Robin Lovelock on robin@gpss.co.uk]

Should have included Snoopy's 2015 Attempt link: http://www.gpss.co.uk/rbaa15a.htm Enjoy ;-)

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/551398259.931640.1739914194519%40mail.yahoo.com.

[Robin Lovelock on robin@gpss.co.uk]

Sorry Guys but play https://www.youtube.com/watch?v=dk5ZGcxB9Nk&t=319s the 2015 Attempt video.

I only just found it, tucked away on my Youtube Channel, and it should have been on that HUGE LONG BORING

2015 Attempt page. AND ALSO prominent on the 2015 Attempt summary on "Snoopy" page http://www.gpss.co.uk/autop.htm - I shall do these long overdue updates in next few days.

Sorry again :-)

Robin & Snoopy

http://www.gpss.co.uk

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/949527457.932293.1739914624601%40mail.yahoo.com.

[Damon McMillan]

Hi Alastair,

Yes, it is a very straight line.  Kind of makes one think that I might be faking it!  But no, it's just because it's a lot easier to keep an electric boat in a straight line than a sailboat.  As Robin pointed out, as long as it's going faster than whatever current is in the area, it'll stay on the intended path.

This boat has two possible modes of navigation:

1.  Follow a commanded path between waypoints.  If wind or current try to push it off the path, it will steer to get back on the path.  This is the mode it's currently in, and this is why you see the straight line on the map (although if you zoom in, you'll see some spots where the motor wasn't running and it did get pushed off the path).  Typically it's no more than 20 meters the the left or right of the intended path.

2.  Follow a heading.  So it just keeps the nose pointed at the commanded heading and allows wind or waves to push it left or right.

The interesting thing would be to see which is faster over a long-distance voyage.  I like how the straight line looks on the map, so I keep it in the first mode.  But do any of you have a convincing argument for one being faster than the other?

To answer your question, Robin, yes, it automatically moves the rudder about once per second to stay on the intended course/heading (using a compass to measure heading, not GPS-based velocity).  In theory it could be completely autonomous, but I do send it commands from time to time to adjust the power management parameters.  So I'm not following microtransat rules.  I'm more of a hardware guy than a software guy, so I don't think I could make a boat that could cross an ocean fully autonomously without any intervention.

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

[Robin Lovelock on robin@gpss.co.uk]

Thanks Damon. About to play that 2015 attempt video, before shutting down here.

BUT saw your email below - reckon you've already done the difficult stuff, including software ;-)

Night Night :-)

Robin

http://www.gpss.co.uk

[Tony Robinson]

Damon, I'm loving it.

I have a PhD from an Engineering Department, but I'm more of a mathematician/modeller, no longer very practical, so I find the simplicity of your design very inspiring (I've even had a cheap 'Underwater Thruster' in my eBay basket for months, maybe one day I'll surprise the tourists on the local river)

You ask 'do any of you have a convincing argument for one being faster than the other?' and I think I can add something here.   Consider an A to B route where the currents act perpendicular to the route and on average cancel out, that is you'll be taken off course as much one way as another.   A constant heading will weave around on a GPS plot, but would be straight line with respect to the body of water it passes through and so achieve maximum speed relative to the water.   A straight line GPS will weave around in the water, that is it will be longer with respect to the water it passes through.  Now consider head/tail currents, these just decrease/increase your speed, not a lot you can do about them.   So my answer is that constant heading is closest to optimal, but you need to set that heading such that the currents cancel and you are not fighting them.   My guess is that you can estimate currents from water you've already passed through (say as deviations from straight line when on constant heading), others say that future water currents are mapped for you but I have no idea about this.

I'm loving it - thanks again for sharing your inspiring work.


Tony 

[Philip Smith]

Good progress, perhaps an electric boat is the answer after all!

Regarding your heading options, I totally agree with Tony: sticking to a heading and allowing being carried sideways with the water current is the best strategy. Consider a very strong sideways current which is actually faster than the boat can travel, then trying to stay on a position based course will result in no progress, whereas keeping to a heading will result in a weaving course, but will make progress. (This method of considering an extreme case  is called Reductio ad Absurdium, or something similar in latin, and used in mathematical proofs. It often shows up an answer which isn't obvious if you only look at realistic cases.) Even if you are heading in the same direction as a tidal flow, you are still best to follow a heading, even if some of the time you are actually going backwards. Similarly a diagonal tidal flow.

My course strategy is to only do GPS location every now and again (hourly say, or even less) and calculate the heading to the next waypoint, adjusted if you are currently off-course (what I mean here is that if you are to the right of the ideal straight-line course, then aim to the left of the next waypoint, to get back onto course). Then just try and sail in that heading. So the track in a tidal current is a weave. (Most other boats leaving Britain also look like they follow this strategy.) It also reduces the GPS current requirements, which is quite significant if it is on all the time. The one disadvantage of this is if you are near a coast as you don't want to get washed onto it. So I adjust the frequency of GPS locations depending on how close to the next waypoint the boat is, and put close together waypoints near headlands etc, so allowing less off-course deviation. Plus keep well clear of the coast! You won't really have this problem in the Pacific.

Good luck

Phil Smith

[Robin Lovelock on robin@gpss.co.uk]

Hi All. I'll paste in reply from Dick, not CCd to the MTS Group, 'cos it deserves a response :-)

Before any of that, I've now made important updates to "Snoopy" on http://www.gpss.co.uk/autop.htm

and the linked "2015 Attempt" page - the important thing being that video, not published back in 2015.

you can now go to it via a page or direct to it on https://www.youtube.com/embed/0WQlvWm3cS4?si=dbdAamjOkNZVnHen - Great stuff Dick & Roy :-)

First I'll say, that of all the Microtransat entrants, phil's is the one I admire the most.

That last west to east attempt, rescued by Dick, showed clearly minor changes

to "sailing balance" of the boat, like sails, etc would enable it to steer over a wider arc:

not just a few degrees either side of downwind, but also cross-wind and even (natural) tacking.

On the subject of a compass, I did successfully get a compass based solution working, in 2013 & 2014,

and there is a page with the details on http://www.gpss.co.uk/rbcompas.htm 

All these systems need to be tested on flat water, before the complication of tide.

BUT, I decided against a compass, since the benifits seemed to be marginal, compared with RELIABILITY ;-)

My old "Design" page still holds true, including KISS ;-) http://www.gpss.co.uk/rbdesign.htm 

LOTS going on here: just back from a small Police PCSO meeting in our village, then off again to join June

at our Indian friends, after a bit of "work" on our concrete garden pond, then preparing for our trip

to Exeter tomorrow, maybe leaving Sunninghill at 1100 to book into the Du Vin Hotel, for Pam Coughlan's

funeral next Friday Morning: http://www.nhscare.info 

As always, I use trips to test the trackers, including GSM and SPOT on http://www.gpss.co.uk/contact.htm 

Take Care

Robin & Snoopy

http://www.gpss.co.uk 

from Dick >>>

Well done Damon.  

At least you have a compass in addition to GPS.  I never managed to convince Robin of its importance as he feel GPS alone will suffice.

Cheers, Dick Bailey

<<<

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[Damon McMillan]

Thank you Tony and Philip.  I follow your line of reasoning; makes total sense.

I'm going to change the parameter that controls how closely the boat tracks a straight line so that it doesn't try to correct for cross-track error nearly as much.  This should be roughly equivalent to just commanding a heading, but if it sees a persistent cross-current over a long period of time, it still won't stray too far from the intended path.

It won't make a huge difference in speed, though, based on what I've seen so far.  The boat's heading averages 220 degrees (which is the heading/course to its next waypoint), with a deviation of about +/- 10 degrees.  That +/- 10 degrees deviation in the heading is due to the boat's trying to correct for the cross-track error.  So compared to the case where I just command a heading and the boat doesn't attempt to correct the cross-track error, I believe that the boat's speed over ground is slower by a factor of no more than cos(10) degrees, which is 98.5%.  Obviously there are plenty of other factors that have a greater effect on speed.  But if the boat were in an area with much stronger currents, the strategy of just commanding a heading should make a much bigger difference in speed.

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/64335ea6-f4d7-421f-b081-b986d6e57267n%40googlegroups.com.

[Philip Smith]

Congratulations on making it to Hawaii. Your boat makes very direct progress: no wonder sail has given way to power!

Where is it off to now?

Phil

[Robin Lovelock on robin@gpss.co.uk]

Thanks Phil & Well Done Damon !

Made me check tracking link 

https://www.google.com/maps/d/u/2/edit?mid=1gESD9GA-zAgTrYO6eEalvvFi0OdkYvM&usp=sharing

Shows where it landed and off towards South East - but perhaps just to go around island before back home ?

I don't think this good performance is power vs sail - BUT because it is so well engineered !

I've probably said it before, but little needed to add sail powere - IF tested on flat water

to get the sailing balance right. No harm in leaving the power there - for use in emergency,

such as when aborting an "autonomous sailing mission" and getting the boat back.

Or, early testing of sailing missions at sea, to see how well it sails back home from a chosen start point.

Echos of early Snoopy trials 2008 - 2012 before we settled on Snoopy Sloop design.

BUT that was partly driven by "Buy not Build" to save effort & time.

e.g. standard ( second hand ) Marblehead fibre glass hull & deep keel ;-)

No time to work on Snoopy, while higher priority "tasks" exist ;-)

All on "Snoopy" http://www.gpss.co.uk/autop.htm and linked pages.

But let's keep this thread to Damon's good work - in keeping Microtransat alive - just ;-)

Robin

http://www.gpss.co.uk & http://www.nhscare.info & http://www.gpshobby.info 

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[Damon McMillan]

Hi Phil,

Thanks!  The boat is now headed towards Australia to see how far it will go.

It didn't land in Hawaii, but hung around offshore long enough for a friend to go out and take some photographs (attached).  Looks like something was chewing on it.  The spinner (the black cone at the base of the propeller) had a chunk bitten out of it but fortunately the propeller itself is okay.  So I'm a little worried about another visitor, as well as the greater possibility of barnacles attaching themselves now that there are several spots where the antifouling paint has been scraped off.  But we'll see!

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/34a340ca-5207-4774-9878-7e7a6c05265an%40googlegroups.com.

[Patrick Coole]

Where to from here Phil? Incredible how far it has made it! Will you try to return home or keep heading west?

[Damon McMillan]

Hi Patrick,

It's just going to keep going west as far as it can go.  Right now it's heading along the north side of Papua New Guinea and then will go south through the Banda Sea then west into the Indian Ocean.  Of course, it could just die at any time.

It has definitely slowed down a lot lately.  Part of that is definitely due to the clouds, but it might also be picking up some biofouling or I might have some issue with the solar panel.  We'll see...

Damon

Damon McMillan

Blue Trail Engineering LLC

1567 Skyway Dr. Unit B

Longmont, CO 80504

720-526-6388 (business)

801-520-4953 (cell)

www.bluetrailengineering.com

To view this discussion, visit https://groups.google.com/d/msgid/microtransat/63c49f2e-1219-4af7-8140-fb6df55c99d2n%40googlegroups.com.

[Patrick Coole]

Oh great. I am located in Perth Western Australia. If you want to direct it down this way I have a boat and could take a look, possibly clean the bottom. I am not sure how that looks with currents though, may not be ideal coming down the west coast of aus