Harpoon (2019) on Netflix

Plot summary

Jonah is a down on his luck twenty-something whose best friend is Richard, a wealthy man given to violent outbursts. Richard suspects his girlfriend Sasha and Jonah are involved. One morning he ambushes and beats Jonah. Sasha pulls him away and explains that the messages he found were about a birthday gift: a speargun. Richard feels guilty. To apologize, he takes Jonah and Sasha for a day trip on his yacht. The tension seems to ease as the three relax on the water. Then a confrontation turns physical. The struggle damages the yacht's radio and leaves all three stranded in the middle of the ocean with few supplies.