Moderate here is an adj to describe the strength of the waves in the sea. It should read 'moderate to rough'. (the rough, is incorrect).

Is there any more to the sentence because as it stands it make no sense to me (native British English speaker). If it said Carina would create moderate to rough seas over... then it could mean the strength of the ocean waves was medium to rough (but that would mean she was making the sea and waves herself. If there is a more complete sentence it may make sense. Unless someone else understands it.

"To moderate," the verb, with "-ate" pronounced like "eight," can mean to make something less intense. "Adding milk moderates the bitter flavor of tea." "You're talking too loud, please moderate your voice." "Moderate," the noun, with "-ate" pronounced like "it," can mean something that is less intense than something else. "I like my food very spicy, put everything on it, even the habanero peppers." "I like my food moderately spicy, I'll take the jalapeño peppers but hold back on the habaneros, please." "A moderate drinker" means someone who drinks alcohol, but restrains himself from drinking too much. "Moderate" can be a point on a scale of words, and that is the case here. There is an official set of words used to describe the sea state; see https://en.wikipedia.org/wiki/Sea_state for the full scale. Three points on this official scale are: "Slight" means a wave height of 0.5 to 1.25 metres "Moderate" means a wave height of 1.25 to 2.5 metres "Rough" means a wave height of 2.5 to 4 metres The sentence means that Carina would create a range of wave heights, from "moderate" to "rough;" that is to say, some waves would be in the "moderate" range and some would be in the "rough" range.

Thank you all of you. You guys are awesome!