ya, 2nd test, despite loads of glue had same result so have ordered some 'flex' clear potting epoxy. Means can print or machine a nice box and not have to worry about waterproofing. Just get it working then fill it up with this goo. Will also help protect the reed switch and electronics. Tested Jan's software successfully in AP (Access Point) mode which means can change the config file/download data without access to the wifi you setup on the SD card. This means can be sealed forever....at least until battery fails.
I had some problems with the postal service, regarding the box I ordered. A combination of me being away and the post office being closed a couple of days resulted in my package being returned. Annoying situations.
The box I ordered was the same as Jan. Since I had to place a new order I decided to look around for other solutions. I found a box that has a better IP rating (IP68). Unfortunately it is rather expensive for a diy project, but if it solves the leakage problems, I guess I am happy with it.
It is the Bopla Bocube B. I' ll let you know whether it stays dry. And I ll see if I can attach any mounting solution to it.
Venturing down the rabbit hole, just ordered the bits and bobs for 2 units.
Lets see how I can cope with this black arts #@$!!! vodoo electronical stuff
www.parker.com/Literature/O-Ring%20Division%20Literature/ORD%205700.pdf
Handy reference for anyone wanting to design an o-ring seal
The updated manual : docs.google.com/document/d/1j86kj3bNMID3sHCRT7QTYyrL7IHeQnGPec1LajsDfB4/edit?usp=sharing
Translated by Google, but usable I think.
Greetings, Jan.
I wrote another manual for the build of the DIY-logger. This one is specific for the electrical connections and the mechanical assembly. I hope this gives a better idea what is needed for the build !
docs.google.com/document/d/1XJD6BV1Xay4nXo0cDuo_IOtxC_f1LyG7DE7X6KGlAB0/edit?usp=sharing
Got the flex potting epoxy, printed another box, drilled two holes in the side and filled up the box using a syringe. Was a bit tedious waiting the 72hr cure time but the result seems ok. Seems to function ok. Should have drilled the holes on the other side as you can see some air bubbles formed next to the GPS on the board holder step. There is also what appears to be a tiny air bubble on the display (on the 'A') which also would have been avoided if I drilled the holes on the right or top sides. Interestingly, due to the long cure time a little of this epoxy seeped out like water between the polycarbonate face and the box so will need to top up some more epoxy into the filling holes and wait again before taking to the water. It is about 50 grams heavier than the off the shelf box unit without epoxy which is the reason to have a boom shaped fitting to stop it rotating. Held on boom with elastic cord as shown on Jan's video.
Last software version 5.0 ot the diy logger supports now the "oao" log format. This is the binary format that Julien has developed for the motion, and is now widely used as the most compact format for uploading to the gpstc and other sites.
Thanks to Julien for the excellent explanation on his website how to use this "oao" format.
Select to expand quoterp6conrad said..
Last software version 5.0 ot the diy logger supports now the "oao" log format. This is the binary format that Julien has developed for the motion, and is now widely used as the most compact format for uploading to the gpstc and other sites.
Thanks to Julien for the excellent explanation on his website how to use this "oao" format.
Well, that's something I never expected to read for sure. 
There's an undocumented change made recently, accuracy_pDOP is replaced by accuracy_hDOP. So you'll need to pull UBX-NAV-DOP too to fill that field.
Probably worth mentioning that the wireless charging system (Ebay one posted earlier) I've been using is problematic.. Works fine for a few (10+) charge cycles then fails to charge. This includes my epoxy'd one I'd tested a great deal before sealing. Been using these Ebay wireless charges as the cheaper ones Jan has been using still not arrived after 3 months. I'm guessing there is some kind of power surge that cook the protection diodes or something. This is irrespective if plug into the USB or solder directly to the charge chip. Can still charge system via USB after frying but of course this is a bit useless if you filled the system up with epoxy like me. Maybe something else is going on but I've fried 3 systems now with these wireless charges of which one is now destined to the bin. Going to disconnect my remaining working wireless charge unit and wait for the alternative Jan's been using.
I have now 2 different wireless chargers, the first I ordered had a decent ferrite tape (I guess 0.5 mm thick), these works OK. The second one, had a much thinner ferrite tape. The charging efficiency is much worse, after 10 minutes of charging the coils are heating up and the charger will stop charging due to overtemperature. After cooling down, charging starts again. But both systems are still functional. I have now 5 units in operation, 3 with the "thick" tape, and 2 with the "thin" tape. I use different chargers, were some are really sensitive to the temperature, and other not.
Wireless charging is a terrible field. There's only one really usable family of chipsets and they're all unavailable now. Which is why those modules sold for 5usd earlier are unavailable now too: the chip's price per reel 5xed and it ain't profitable anymore.
Finally the wireless charging widgets Jan uses arrived from AliExpress. They worked fine with the Ebay charging mats when placed directly on but refused to work if the separation was more than about 1mm. I was busy trying to 3d print a box with 1mm wall thickness when it occurred to me the Ebay charge mats could be a bit dodgy. I turned them over and all 4 of the ones I have have serious heat distortion and they run really hot. Since I didn't own another charge mat I lashed out today and bought the cheapest 10W mat I could find from the local consumer electronics store. (one with good ratings, warranty and I could return etc) Now the Aliexpress (jan's) Rx version works fine with up to a 3mm gap but struggles with 4mm with this particular charge mat. The wall thickness of the box I'd epoxy'd up was 4mm plus the 1 or 2mm gap of the wireless charge receiver packaging etc. It had worked ok charging without the epoxy but failed to charge once I'd stuffed the epoxy in. Tried it with the new charge mat, charges fine! No need to put in bin, bonus! End story is the ebay charge mats I purchased and listed earlier are dodgy and dangerous but the receiver part seems to work fine...in fact better than the Ali express version as far as charge range goes. Pretty sure a higher power/better quality charge mat (15W) would give more charge range (meaning thicker wall thickness/stronger box/more tolerance etc).
Good result Flex, got all my main bits, just got to get sd cards and make some cases as mine are somewhere in the world taking the scenic route
Since the epoxy filled unit started charging I've taken it for a few runs. However, due to the extra mass it tends to rotate on the boom so the face points down, even in fairly low chop which becomes annoying after a while. This tends to happen in Jan's basic box design but only in rougher chop. Changed the design to make a much lower profile but also have the CG directly under the boom (battery and charge mat underneath) so regardless of chop the display points towards you. The GPS has its own little pocket to minimise amount of epoxy used. Have sealed two units but not filled with epoxy yet as testing a few cycles. I started sanding the boxes to give a nicer finish but realised this was a mistake as the dust gets in through the epoxy fill holes...need to do this last.
G'day Oh knowledgeable gurus
I've been let's loose with the soldering iron putting 2 units together.
is there a link for software to upload?
type slowly for me please
Jim had a good proposal for "alfa information". How to know after a jibe if you gonna hit the magical "50 m circle" ? With some math, it is possible to show this valuable information on the screen. P1 is the "-250m" point, P2 is the "-150m" point before the jibe. With these points we can identify a straight line. After the jibe, the information of the actual distance to this line (red arrow) is shown on the screen. To know if you pass the point "P1", also a "progress bar" is shown on the screen. 250 m after the jibe, the progress bar is 100%. To have a valuable alfa, the distance should be less then 50m.
"Wind 23" is the "red distance" of 23m, the progress bar shows here ~30m after the jibe, Aa is the alfa after completion. Still have to do some water testing, but the season here is on its end (winter).
Greetings, Jan
My Garmin Datafield shows the live alpha distance both graphically and numerically.
Have a look at this topic:
Garmin GPSTC Datafield - to complement the Motion Simple Logger | Windsurfing Forums, page 6 (seabreeze.com.au)
Some have asked for the 3D print design of the low profile counterbalanced box. I've used mine for a while and pretty happy with it. I've stuck it on Thingiverse for those interested. Note in my rush to fill my first two units with epoxy I forgotten to put a leash mount on the box so my first two units I had to add this after the fact by bolting a fitting using the epoxy fill holes. The attached STL and subsequent units I make have a leash mount. www.thingiverse.com/thing:5138252
First test sessions using Jan's DIY GPs's (made two) set up as Boom mounts as per Jim's fantastic printed deign, these things are F'ken awesome!!!
I'm long sighted and after decades of excessive solo activity my short vission is officially shot to the sh1thouse with my normal GPS's GT31 and GPS Logit on a phone so I have to sail with sunnies which have +2 reading lenses fitted and I still strugle to read the units when stoped on the water, These things with the bully buster font and the white black contrast I can read without any issues or reading lenses.
I thought it would be an issue not having the unit's in line of sight but it's not an issue and easy to glance over, The HUGE font for the main speed stands around 20mm tall and is in Bold as well so theres no missing that.
The bit which got me wanting to damage my eyesight a bit more was for the naughtical mile a moving bar goes accross the top of the screen telling you how far you've gone (we've all had those epic runs only to find out when we've gotten home that we've pulled out of the run 150m early)
I like that after each run you get the top results for each catagory scroll through, also in a size I can read easy.
I wish I had of read the post 2 before this with how to identify the proximity as I was trying alpha's yesterday and seeng the wind numbers and not knoing what they refered to (I really need to read the instructions).
You want a good GPS with instant feedback, then these are a very good idea, I am not an electronics person an Jan and Jim can attest but this is actually guite a simple job.
Components are less than $100 per unit
Jims case you will need to know someone with a 3d Printer (or you can use your local libraries one as most have them now).
JIms potting of the units (similar to the motions) makes them fully waterproof.
Have posted anything from these yet that still comes form the motion I've got to send it off to be checked.
Huge thanks to Jan and Jim for all their help, I'm one happy camper.
Select to expand quoterp6conrad said..
Jim had a good proposal for "alfa information". How to know after a jibe if you gonna hit the magical "50 m circle" ? With some math, it is possible to show this valuable information on the screen. P1 is the "-250m" point, P2 is the "-150m" point before the jibe. With these points we can identify a straight line. After the jibe, the information of the actual distance to this line (red arrow) is shown on the screen. To know if you pass the point "P1", also a "progress bar" is shown on the screen. 250 m after the jibe, the progress bar is 100%. To have a valuable alfa, the distance should be less then 50m.
"Wind 23" is the "red distance" of 23m, the progress bar shows here ~30m after the jibe, Aa is the alfa after completion. Still have to do some water testing, but the season here is on its end (winter).
Greetings, Jan
That sounds like a great innovation for feedback Jan. 
But as I understand your diagram, it may not work out the same number as the analysis software programs which use a 50m radius circle. This means you may mot be exactly adjacent to the start point for the best Alpha and in some cases there may not be a straight line to 100m. I'm not sure how that would affect your feedback results?
Some random examples from a session at lake George where I was just gybing to work back upwind after speed runs. None of these are particularly fast Alphas, but they illustrate the possible variations. 
the end point of the Alpha can be anywhere inside the proximity circle which gives the best result:
The entry path can be quite curved:
Here is a classic "Alpha" symbol shaped track, which is certainly not the fastest way to get the best Alpha, but illustrates the wide variation possible for a legitimate Alpha. here I gybe and then star hoping upwind:
Absolutely not criticising. Just trying to show what variations may occur. Hope this helps.
The normal Alfa calculation is not influenced by this extra "Window" information. But you have a point, this "Window" will not always gives you the most optimal advice for course correction after the jibe. Your first example is one that fits rather nice : after the jibe, you are way downwind, and this will be shown as the Window > 50 m (in RED) , I guess more then 65 m. Then, you go more upwind and the Window gets smaller, even less then 50 m !
Due to the cold, I did not test it on the water yet.
Greetings, Jan.
Select to expand quoteelmo said..
>>>>> Have posted anything from these yet that still comes form the motion I've got to send it off to be checked.
Huge thanks to Jan and Jim for all their help, I'm one happy camper.
First sighting looks good Alby, keep them coming.
Just noticed something interesting, the difference in conformity at high and low speed. I guess at low speed you were in the chop climbing up hill to the run start, going fast you're in the smooth.
this is the low speed section, in chop?
This is the high speed run in the smooth
So blue is the motion on Elmo's shoulder, red and green are on either side of the boom. The red and green follow each other very well but the blue sometimes goes in the opposite direction, just shows the difference in movement over chop. I think this strengthens Andrew's argument that most of these micro movements are real
And here's another interesting one, the alpha. A big concern with booms mounts, was what happens in the gybe.
Seems it's not a problem at all, in fact superior to a device worn on the wrist.
Again blue is motion on shoulder, red and green DIYs on booms. You can see at rig flip, the boom mounted sAcc numbers do rise a little, but only to where the Blue has been all along, which has stayed steady, unaffected by the gybe around 0.5.
Looking at the speed graph, I think you could assume, from the speed difference between them, that the green device was on the inside of the gybe, and the red on the outside. But the difference in the actual result is small.
Blue 23.518, red 23.542, green 23.473. So outside of gybe is .024 faster than shoulder and inside of gybe is .069 faster. If you wanted to get pernickety, you could average the two boom units to even this out.
It would be interesting to see what KA72 does with the numbers from the DIY devices.
There shouldn't be a problem, it's the same oao format as the motions. I wouldn't expect it to be any different.
