CrewNerd and XGPS160 – Initial impressions

When I row, I generally have both my iphone running CrewNerd and a Speedcoach XL2 in the boat.  I bring the phone because it is a reasonably lonely stretch of river and it is a recommended safety accessory.  Since I need to have it in the boat, I might as well have it do something useful.

I have used both CrewNerd and Rowing In Motion and there are pros and cons of both.  RIM is a great tool for real time feedback in the boat.  CrewNerd has better data export features and good tools to review a workout on the phone including a map view and nifty graphs of pace, rate, HR and stuff.

The major disadvantage of using CrewNerd versus the Speedcoach XL2 is the accuracy, stability and responsiveness of the pace readings.  CrewNerd works off of the GPS in the iphone.  This provides position data on a 1Hz basis, and the application uses this position data to deduce the velocity.  By comparison, the Speedcoach GPS2 has a GPS capability that provides 5 updates per second.  The impact of this is that Crewnerd needs to use significant smoothing to stabilize the coarse position data.  This causes a significant lag, up to 10 seconds between a velocity change in the boat and the pace display on CrewNerd showing a stable, accurate pace.  You can crank the smoothing dow, but then you end up with pace readings that essentially oscillate around the actual pace.

The good folks who developed CrewNerd recommend that the best way to get more accurate and responsive pace display is to pair the iphone with an external GPS receiver.  They recommend the Dual XGS160.  This provides 10Hz position data.  When paired with this receiver, the pace display responds quickly and settles well.

However, CrewNerd seems to be unreliable with the XGPS160 receiver.  Sander (of “Rows-And-All” fame) has previously described having hangups and the freezing of the CrewNerd navigation display when using the receiver.  This morning the same thing happened to me.  I was 11K into a 14K row, and then the pace and distance displays stopped updating.  The HR display was alive and displayed an accurate number.  I’m not sure what’s going on, but I am not sure whether it is better to have a laggy pace display or have the app stop functioning in the middle of a practice or race.

6 thoughts on “CrewNerd and XGPS160 – Initial impressions

  1. Tony Andrews says:

    I posted this on Sander’s blog as well, but I’ll repost here as well for anyone who missed that…

    Hello folks – for those who don’t know me, I’m the developer of the CrewNerd app. I’ve been hard at work recently trying to sort out the XGPS problems. Some fell squarely on me. I released one round of fixes and I have an update pending now that will resolve a few more minor issues. But I know that several people are continuing to see cases where the readings just appear to freeze, and I’ve seen that myself as well.

    I recently learned of a problem in iOS 8.3 that affects external GPS receivers (see but it isn’t entirely clear if that’s the problem that we’re seeing in CrewNerd.

    The next CrewNerd update includes a new feature that allows you to send me the application log, which will be very helpful in tracking problems like this down. To send the log, go to the settings screen and select “CrewNerd Information”. At the bottom of the screen, press “Send application log” and then send the email that’s displayed, along with any comments you want to add. Be sure to do this *before* you terminate CrewNerd so I can see what was happening leading up to the problem you want to report.

    Lastly, please don’t be shy about reporting problems directly to me, through our customer support site or email. The more reports I get, the easier it is to narrow down the possible causes and arrive at a solution. I try to be very responsive to all feedback.

    Thank you for your patience and support!

    Liked by 1 person

    • gregsmith01748 says:

      Tony, thanks for the reply and the hard work trying to sort out the issues. I think the new feature to allow logs to be sent to you is a great idea.

      I have used CrewNerd for four years and I’ve found it very helpful. You’ve done a great job improving the app over time. The idea of using the Dual xgps receiver to solve the iPhone gps update rate issue is a good one and I’m sure that you’ll get any issues solved that are under your control. I know that things can get complicated when 3 different pieces of software, running on two pieces of hardware all have to work perfectly 10 times a second for two hours.

      Right now, I am using the speedcoach XL2 as my main indicator, and so I can keep running with the xgps160, and give you feedback on any problems that come up. When I use a club boat, and I’m relying on the CrewNerd app only, I think I’ll stick with the internal gps support on the iPhone for now.

      Thanks for continually working to make make a great app better.


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