Santa Cruz Island Swim, Part 4: The Data

Santa Cruz Island Swim, Part 4: The Data


In case you missed it:

The shortest-line distance from Santa Cruz Island to the mainland is 16.4 nautical miles (18.9 statute) – starting at San Pedro Point, finishing at the southern end of Hollywood Beach, north of the entrance to Channel Islands Harbor. Capt. Forrest actually plugged in a slightly more distant waypoint – the resort at Mandalay Beach – which made it a 16.6-nautical mile swim. I don’t know why, but that’s what he did.

To break Ned’s record, I had to average 1.59 knots (2:02 per 100m, 2945m per hour) across the channel. To break 10 hours, I had to average 1.66 knots (1:57 per 100m, 3074m per hour). My neutral-condition (i.e., pool) pace for a swim of this distance, at my current fitness level, would be approximately 2.3 knots initially, fading gradually to ~2.05 knots.

My progress for the first five hours (corresponding to the nighttime portion of the swim) was as follows:

  • Hour 1 — 1.4 nautical miles
  • Hour 2 — 1.8 nmi
  • Hour 3 — 2.0 nmi
  • Hour 4 — 1.8 nmi
  • Hour 5 — 1.5 nmi

Given my average progress over hours 1-5 (1.69 knots), the conditions may have been as much as a 20-25% “tax” on my swim speed. These conditions included a consistent Force 4 blow out of the West, only abating near the end. There were some currents, too, especially in the first couple hours. Here’s the SCCOOS model for that morning (click to enlarge):

1:00am (0:20 elapsed)

4:00am (3:20 elapsed)

7:00am (6:20 elapsed)

10:00am (9:20 elapsed)

After a slow “witching hour” (4-5 am, only 1.5 nautical miles), I made better progress after sunrise:

  • Hour 6 — 1.6 nautical miles
  • Hour 7 — 1.7 nmi
  • Hour 8 — 1.7 nmi
  • Hour 9 — 1.7 nmi
  • Hour 10 — 1.8 nmi (pro-rated)

Here’s a chart of my “rolling” speed, averaged over six consecutive 10-minute SPOT tracker intervals:

My stroke rate was my typical 64, with patches of 60. Nothing exciting there.

And here’s the Story of the SPOT:

Not a bad line.

Stay tuned for the series finale!

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