Windsurfing Speedo. Doppler GPS - low profile, counter balanced

prusaprinters

With Windsurfing records now exceeding 100Km/hr there is a real need for an accurate feedback for sailors.   All previous systems have relied on a watch screen (impossible too see at high speed) or some sort of audible feedback.    Most are extremely expensive.This is a real time plus data logger ‘speedo’ for Windsurfing with a large screen easily viewable at high speed. The cost is around $60USD at time of post.  It is a Doppler GPS sampled at 10 to 18Hz.  It measures its own accuracy so you can be sure that the speeds/distances you are getting are correct.   This is unlike most watches and phones which have large data spikes leading to erroneous data.  For the die hard speed freaks this is GPSTC approved (currently on a case by case basis)This is a box designed to fit Jan Heynen's DIY GPS as discussed on the Seabreeze thread https://www.seabreeze.com.au/forums/Windsurfing/Gps/Another-DIY-GPS-logger-approach?page=1It is designed to be mounted on the boom, held in place by a loop of elastic cord with an emergency leash.    It is as low profile as possible and the battery and wireless charge mat are mounted at the bottom to act as counterbalance. This stops the unit rotating on the boom in chop so the display always points towards you.You glue a piece of clear polycarbonate to the front (using Dichloromethane) and fill it with clear potting epoxy to make it water proof.  Drill two holes and fill the unit with epoxy using a syringe. For me, the epoxy leaks during the cure process so I use another syringe as a sort of reservoir to keep the epoxy topped up during cure time. DO NOT put masking tape over the screen as shown in the photo as the epoxy seeps along the tape and covers the screen as shown in the photo. You can remove this but it is hard work.I used flexible epoxy which had a 3 day cure time. No doubt you can use other types of potting compound that have faster cure times.I used a router trim bit to cut the polycarbonate face flush with the box and then a rounded bit to take the sharp edge off.Note the pictures don't show the current published design with a leash mount. I only realised I forgot this after I filled my first two units so added a leash mount after the fact bolting them on in the epoxy fill holes. You won't need to do this.The small cavity on left hand side is for the reed switch mounted directly behind the Wifi antenna.I printed this with display side down with supports which seemed to give the best results and use the least filament. Since the epoxy gives it all the strength, I just used draft/fast print settings. These were my first units so haven't bothered to sand them but you can obviously make them much nice appearance if you want to.Edit: I printed these right way up with supports and also got a good result..possibly better. The electronic side can easily be used for any sport needing an cheap, accurate data logger.Print SettingsPrinter Brand:Prusa Printer: I3 MK3SRafts: No Supports: Yes   Category: Sport & Outdoors