So my buddy broke his center fin on his thruster set up... but were still going to go for a dawn patrol as the forecast is 15 ft at 11 seconds... anyone done this before? how should it affect his performance?

So my buddy broke his center fin on his thruster set up... but were still going to go for a dawn patrol as the forecast is 15 ft at 11 seconds... anyone done this before? how should it affect his performance?