estaban encrespando
-they/you were curling
Imperfecto progresivo para el sujeto ellos/ellas/ustedes del verbo encrespar.

encrespar

Eran muy lejos de la costa y, además, el mar y el viento se estaban encrespando por momentos.
They were very far from the coast, and in addition to that, the sea and wind became choppy at times.
Palabra del día
el villancico