Cynthia Hertzer - Maui Channel

Lanai to Maui

15.6 km (9.7 miles)

5 hours, 41 minutes on 4 September 2018

Observed and documented by Joel Wilson


  • Name: Cynthia Hertzer
  • Gender: female
  • Age on swim date: 49
  • Nationality: United States
  • Resides: Santa Cruz, CA

Support Personnel

  • Keith Baxter - pilot
  • Terry Brown - crew chief
  • Mark Agnello - photographer, nurse, lifeguard, extra support
  • Kathy Hertzer - Doctor, extra support
  • Joel Wilson - observer

Escort Vessel: Big Wave (Maui)

Swim Parameters

Category: Solo, nonstop, unassisted.

Rules: MSF Rules of Marathon Swimming, without exception or modification.

Equipment Used: MSF Standard (Arena 1pc suit – open back, not a knee suit – single fluorescent green latex swim cap, TYR Blackhawk polarized goggles, sunscreen, Desitin)
Non-standard: Freedom 7 Model Shark Shield (towed behind boat), SafeSea Jellyfish repellant sunscreen

Route Definition

  • Body of Water: Pacific Ocean, ‘Au’au Channel
  • Route Type: one-way
  • Start Location: Club Lanai (20.828470, -156.809860)

  • Route Distance: 15.6 km (9.7 miles)
  • Minimum Channel Distance: 14 km (8.7 miles)

Swim Data

  • Start: 4 September 2018, 07:25 (Pacific/Honolulu).
  • Finish: 4 September 2018, 13:06
  • Elapsed: 5 hours, 41 minutes, 32 seconds.

Summary of Conditions

Feature Min Max
Water Temp (F) 80 80
Air Temp (F) 77 86
Wind (mph) 3-5 20
  • Skies: Mostly sunny, occasional clouds
  • Tide: low tide 4:13am (0.22ft), high tide 12:49pm (2.01ft), low tide 7:50pm (0.84ft), high tide 11:13pm (1.03ft) (source)
  • Sunrise/Sunset: 6:11am/6:39pm (source)

GPS Track

Trackpoint frequency: 30 minutes. Download raw data (CSV).

Speed Plot

Nutrition: Every 30 minutes from the boat. Alternating Perpetuem, Heed drinks, plus various Gus (with and without caffeine), 1 dose ibuprofen (200mg), mouthwash for comfort.

Observer Log


START:  7:25 A.M. Hawaii Standard Time Wind at 8-10 MPH from NE (for entire swim) and swell at 3-5 feet.
0:20 minutes   66 strokes per minute (SPM)
0:30  Perpetuem, 10 oz, plus caffeine GU; 1:15 feed time; wind 10 mph, swell 3-5’
0:40  64 SPM; wind 6-8 mph, swell 3-5’
0:50  63 SPM; wind 6-8 mph, swell 3-5’
1:00 HEED  8 oz plus GU (no caffeine); small pee; big stretch
1:11 64 SPM; wind 5-7 ; swell growing to 6-8
1:20 62 SPM; wind 10-12 MPH, swell 5-8’
1:30 Perpetuem, 8 oz. + caffeine GU; 2:30 feed time; small pee; wind 10-12 MPH and swell at 5’+
1:45 62 SPM; wind 12-15 MPH; swell at 5’+
1:55 64 SPM; wind 12-15 MPH: swell at 5’+
2:00 HEED:  ~10 oz; no caffeine GU; ibuprofen (200 ml liquid); mouthwash and pee;  wind 12-15 MPH; swell at 5’+
2:30 Perpetuem, 8.20 oz. plus caffeine GU; pee; wind 10-12 MPH, swell 6-8’
2:45  62 SPM
3:00 HEED:  8.20 oz.  no caffeine GU; add desitin on neck; pee; 4 minute feed time
3:30 Perpetuem, 8 oz. Plus caffeine GU; pee;  3.5 minute feed time; wind 15-18and swell 4-6’
4:00 HEED, ~ 8.20 oz, + no caffeine GU; wind 20+ MPH, swell 6’; 4 minute feed time
4:15 62 SPM: wind 20 MPH and 4-6’ swell
4:30 HEED: 14.20 oz; orange GU+caffeine GU; 4 minute feed stop
4:45 62 SPM; wind 15-20 MPH, swell 4-6’
5:00 HEED, 10 oz, caffeine GU, pee; wind 10-12, swell 3-5’; ~ 1+ mile from finish
5:15 64 SPM, wind 5-10 MPH, swell 2-3’; ~800-900 yards from finish;
5:30 final feed: missed as I was changing into swim suit; wind 8-10 MPH and swell 1-2’;  2:45 feed time
5:41:32 FINISH; wind 3-5 MPH, swell 1-2’;  10.42 miles


by Cynthia Hertzer, September 13, 2018

What inspired you to do this swim?

I’ve done a number of successful (SCAR) and unsuccessful (Tahoe) swims over the past few years. Maui Channel had never called to me, but always seemed like one I could do. I am familiar with swimming near Maui beaches from various trips since I was a child. On Monday, September 4, 2017, my coach Joel Wilson wrote to me “Let’s swim Maui Channel next September, right after the Maui Channel Relay”. Ironically, I ended up swimming on 9/4/18.

Please describe how you planned for the swim.

Joel, unfortunately, ended up having shoulder surgery in February and wasn’t ready to swim a channel swim. We decided to proceed with my swim and postpone his. I had healthy shoulders, a several-years deep distance base, and swam OW several times a month in Santa Cruz. I averaged 28K yards/week from January-August 2018 and included strength training, OW and pool racing and one 5.5h swim in Lake Del Valle in my training (crew chief Terry got to practice feeds on Del Valle). We both attended a March 2018 observer training at South End Rowing Club in San Francisco, CA. My feed kit and I got additional practice crewing on a July Tahoe width solo. Joel had worked with pilot Keith Baxter for past MC relays and a solo. I leveraged past work I’d done with Jen Schumacher and notes/experiences from my past swims to prepare a mental plan (counter-measures) and a feed plan.

How did the swim go, generally? Did you face any unanticipated challenges?

My greatest concerns going into the swim were how I would manage in the wind/swells in the channel and stinging or biting wildlife. I also hoped I would not be too warm. The swim was maybe my 8th most difficult (I put it behind Apache Lake (SCAR) and Lake Tahoe swims because of water temp, time in the water, and taking place at sea level – I have struggled with digestion in Tahoe). I never felt seasick (wish I could say the same for the boat crew). The swells were very organized and consistent with the wind direction, and I was able to balance myself on the water by employing a slower-than normal stroke rate. I could mostly time breathing so that there was no water between my mouth and the air, though ~6 wavelets did break on my head. I knew jellies might be a concern in the channel – wish I had known about the Hawaii Box Jellyfish calendar prior to scheduling the swim – they are regularly more numerous at a certain time in the lunar cycle. Fortunately I did not encounter them, though MC relay swimmers and Van Cornwall’s group evidently did. The ~4 little stings I did get, perhaps from blue buttons, faded after a couple minutes and left no lasting impact. I’ve only ever been stung by Agua Malas in Mexico and these stings were less impactful than even those. I had a rashguard, swim tights, and vinegar on the boat but never considered using them during the swim. Looking back, perhaps I wouldn’t have minded even a little more swell/wind challenge, but I’m grateful not to have been challenged by wildlife.

Post-swim I’ve had some forearm tendinitis in my windward arm, so maybe I didn’t need any more rough water after all. The swim made clear the difference between wind swell and wind chop.


  • Turtle at Mala ramp, Frigate bird above Lanai (Swim guardians)
  • Two bait schools ~15-20’ down
  • 2-3 very minor stings from maybe blue buttons (as per pilot)… “Porpita porpita” (as per google)
  • Homo sapiens at Kaanapali Beach


Click to enlarge.


Weather Data

Marine Forecast, Maui Leeward

Lahaina Weather Observations