Trip Report: Bass Lake, CA (2015-Feb-16)


Date: 16 February 2015
ROV: #1689 "Spanky"
Profile: One 37 minutes dive to ~12M
Goal: To get some more hands on time in lake conditions
What went well: The desiccant packet prevented any fogging, ROV able to unstick its tether
What could have gone better: Pre-dive check before leaving home
Location: Bass Lake, CA

Note: Video’s are at the end of the trip report


  • 17:40 minutes: Ambient light vs artificial light comparison
  • 27 minutes: ROV caught on something, went down and found the tree stumps that the tether had wrapped around and used the ROV to lift the tether free.

Bass Lake is located in the foot hills of the Sierra Mountains 18 miles south of the South Gate for Yosemite. Normally a hot spot for boating during the summer, I took the family up in the off season over the long President’s day holiday to hang out and fly the ROV.

Day 1

Upon arriving at the lake, I was struck by the lack of water. No matter what others might report, the California drought is still in full effect. At least that was my first thought… read on…

Showing the low water level from the Northwest approach to the lake:

I went online to double check the water level. This dam does feed an hydroelectric power plant down stream, so apparently this is the normal winter level. But given the red line that shows last years level was so low and the lack of any snow on the visible mountain peaks I’m going to hold on to my earlier assessment that the drought will still be a major problem.


Given the low water level, I took advantage of being able to explore the lake bed on foot :speak_no_evil:. Nothing much to see really, and I figured that was a preview for what the actual ROV flight would probably look like.

We stayed at “The Pines” which has some dog friendly accommodations which was nice. Took them awhile to ready the accommodations so we hung out at the local bar while we waited.

Had a late lunch at Ducey’s on the balcony with a view that screamed water shortage:

This was the first flight of this ROV and so I spent the early evening unwrapping the tether so that I could place it on a spool… that took a good 90 minutes and some patients.

I attempted a night dive that evening but ran in to all sorts of problems. It all traces to the fact that I did not do a pre-test right before leaving. Turns out the SD card I had been using had been removed from the unit. It took me a good 45 minutes at night on the dock before I figured that out. By the time I burned another SD card the laptop was out of juice. Lesson learned: Pre-check the final configuration before leaving.

Day 2 (dive day)

Drove to the Eastern end of the lake near the dam.
Found a nice cropping of rock to setup my mission control. It was nice and sunny, 66 degrees F but felt 10 degrees hotter.

from: Weather Underground


My setup on the rocks

I let out some tether and motored across the surface about 50 Meters to that I could descend down where I knew it would be deep. This worked out okay, as I could have one hand on the gamepad pushing forward and the other holding the tether spool. The ROV provided more than enough pull on the tether that I could unwind with just the one hand.


My goals had been to get some more hand on time with a 2.7 unit in lake conditions. The ROV itself operated just fine. The fact that the motors can generated so much pulling force proved really useful when trying to operate it one handed as it kept the tether pulled tight and kept the ROV headed straight without any direct input from the pilot. The most useful data for me were the artificial vs ambient light operation of the camera in lake conditions. I hope to use that and similar data to optimize the camera response in the future.

Below are the video highlights for the actual dive:
Shot of the obstacles that will eventually entangle my tether
Comparison #1 of ambient vs artificial light performance of the camera. Notice that the camera frame rate slows to capture the ambient light.
Comparison #2 of ambient vs artificial light performance of the camera.
Getting untangled from some stumps underwater


Great report and write up Brian

I like how you have included the weather and water level data. It helps add perspective to your expedition.

~ Charles


Mid year follow up. As you can see in the graph below (bottom line is this year water levels), my prediction was spot on. Looks like the water level was not refilled at all… and it should be at its peak levels right now.