>>1755532>>1755572>>1755588Those are air ducts, that boat is indeed fitted with surface piercing props.
From what I understand, the ducts are there to help get the propellers cavitating during the acceleration phase. They're not mandatory on this kind of steering and pitching surface drives, which are clear enough of the transom to ventilate naturally. On boats (which at this point are usually ships) with fixed, recessed below the hull SPPs, much bigger ducts can be needed in order to maintain the ventilation while cruising.
>>1755535Going fast, making noise, splashing water.
In that order as far as I'm concerned.
https://www.youtube.com/watch?v=Of1RY4M8VqMcavitation starts around the 25s mark, props mostly surfaced by 1min, props properly 'planted' and full power from 2min.
