"Larry" wrote

Nice boat! It looks like there are "fins" pointing down near the stern.
What do they do for her? Do they interfere with underway steering trying
to hold her in line?


She's a water jet boat so she doesn't have the usual rudders, props, struts,
and shafts to serve as the feathers on the back of the arrow. They will
also trap water under the stern when moving slowly on scientific station and
damp rolling. Many jet boats have them but they are usually smaller. We
made them as large as we thought we could get away with to maximize roll
damping. If they are too large, cutting them down won't be a huge job.

--
Roger Long