Over the weekend I sent a bitcoin transaction to a relay 12.6km away with no cell network or internet connection. Here's a tweetstorm about how I used @gotenna and @SamouraiWallet to do it
My original objective was to see if I could use the 4 gotennas that I have to send a transaction 19.2km. Gotenna gives the maximum range in open environments as 6.4 km gotenna.com/pages/faqs-got…
I used google maps to find a route in my home town(Auckland, New Zealand) that connected high ground points as close to 6.4 km apart as posssible. The route- One tree hill-Mt Albert-Waikumete Cemetary-Parkinson Lookout- is shown below 
This was the equipment I used- 4x gotenna, $40nzd (26usd) entry level android smartphone with no cellular or wifi connection, and some scrim, clothes pegs and cord to attach and camouflage relay gotennas. Wanted to try @COLDCARDwallet in the mix but ran out of time. Next time!
Next was driving out to the cemetery and Mt Albert locations to setup some concealed relay stations. Gotenna let's you put a device in relay mode where it will passively receieve any messages broadcasted with range and relay them on to other gotennas.
The mechanics of the setup was this.My $40 phone with no connection outside gotenna would broadcast a signed bitcoin transaction generated in samourai wallet as a gotenna message, to my girlfriends phone with a cellular data and gotenna connection.
Her phone would recieve the transaction through gotenna, relay it over the internet and if accepted by the bitcoin network her wallet would be credited the balance. My phone= effectively a radio device with a bitcoin wallet and utxos. Her phone= a relay from radio to the internet
First transaction was One Tree Hill to Mt.Albert. Direct gotenna to gotenna. Transaction sucessful, Total distance 5.61km.
Next I made my way to Waikumete cemetery. This transaction would be relayed from my gotenna, through the one I had stashed on Mt albert, on to my girlfriends phone and gotenna on One Tree Hill. Transaction successful, one hop of 7.06km and another of 5.61km- total 12.67km.
Last hop was planned for Parkinson lookout- 7.15km away. This was pushing the distance but there was great visibility and elevation. Couldn't get this one through. However my girlfriend experienced an app crash and speaking to the samourai guys this may have been why.
I attempted a couple on broadcasts on the way down but no luck again. By this time I was needing to get back so had to wrap up testing there.
A couple of caveats- due to needing to reconsile spent utxos it's only possible to send one tx offline. Then you need to connect said wallet to the internet otherwise it will reference a spent utxo. Coldcard and other solutions re change addresses maybe an easy fix here
Theres no way for the offline broadcaster to know if the transaction has been relayed via the internet or seen by a gotenna device. An acknowledgment message relayed back would be cool.
Lastly I want to thank @gotenna @goTennaSupport and their mesh community for being back within a few hours with techsupport to help fix a pairing problem- great customer service and....
...Also the @SamouraiWallet team for helping with some teething issues getting this working. This was great fun and I hope to be back soon with some more field reports
