Boats must be properly lit. This includes launches. The regulation is the Rule 25 of the International Regulations for Preventing Collisions at Sea 1972 (as amended) (882K) ColRegs and is published on this part of the POLA website.
This is interpreted by Steve Kerr on the ARA site (slightly amended by me) as follows
LIGHTS Between sunset and sunrise all rowing boats must carry two white lights, one pointing forwards, one backwards with a minimum angle of 180 degrees spread of beam. Lights should be mounted in front of bow and behind the cox to avoid obstruction from the crew or rigger from any angle in the 180 light beam. Rigger mounting is not acceptable. Red lights must not be used in place of white lights.
White clothing on bow and cox makes a big difference at night. Reflective is even better.
Club Requirements for lights
It has been, since April 2002, club "advice" that in addition to the two lights on the boat that the crew carries a third, spare, white light. This is common sense since, if a battery runs out, you have a spare. Also it has been known for crews to have a collision and the existing light getting knocked off into the water and, under such circumstances, to have a spare is sensible. The Slims crew that did have a collision with another club one night in 2004 and, thus, lost a lamp not only had a spare for the crew but also for the other crew that lost its lamp -THAT is good planning.