Rough sea, low winds

Started first morning with a swim - rough sea, will be challenging if it's like this on Saturday.
In the warmest part of the day, I rode the last 80km of the bike leg with Per Morten (one of the other Norw participants). High speed, low winds and decent heat, just above 30 - but feels hotter on first day in the heat and high humidity.
I felt Ok at beginning, crucing in the tailwind at 50-65km/h, but after 2 hours I was empty. No power left...
I don't worry, guess it's because of first day after long travel and/or not taking care of my nutrition. Will be better prepared Saturday.