en_tn_condensed/mrk/04/37.md

a violent windstorm arose

Here "arose" is an idiom for "began." Alternate translation: "a violent windstorm began" (See: rc://en/ta/man/translate/figs-idiom)

the boat was almost full of water

It may be helpful to state that the boat was filling up with water. Alternate translation: "the boat was in danger of being filled with water" (See: rc://en/ta/man/translate/figs-explicit)