22 miles-ish from the start (I’d first been thinking the race was leaving from Point Defiance, so I’d been going off of the 15 miles-ish from there.
It becomes a bit less attractive at 22 miles.).
My speed (in an 18′ canoe rigged for sliding-seat rowing) ranges from 3mph in crap conditions, to 5mph in pretty good conditions. Assuming 4mph, that’d be an 11pm-ish arrival.
Your mileage may vary… 10 hours would imply you’re averaging 2.25 mph, so you’ll want to compare that with actuals of some of your training outings.