I just replied to the duplicate message you posted in
rec.photo.digital.  It contained:

 I believe that you're understanding of the S5100 is a little off.
It does not allow the lens to be changed.  It does come with an
adapter ring, but that is to allow the attachment of an adapter lens
in front of the Fuji's fixed zoom lens.  This is already a 10x zoom,
giving the equivalent of a 37mm to 370mm zoom on a 35mm camera.
Fuji's TL-FX9 adapter lens extends the telephoto end of the zoom by
a factor of 1.5x, to an equivalent of a 555mm lens.

 Take the pictures in bright sunlight.  The brighter the better, as
it will allow you to use a faster shutter speed.  So will using a
higher ISO setting.  Just as with a pendulum, when motion reverses
direction speed is at a minimum.  You might want to prefocus (to
minimize shutter delay) and take the picture close to the instant
that the boat's motion is at it's ebb.  The motion is fairly complex
so it's unlikely you'll ever be able to capture the boat when
there's no movement at all, but you can probably eliminate much of
it with proper timing, and if your camera is quick enough.