Nope ... you can leave the 3 bottom strakes off if you aren't going to be beaching the boat. As for bottom paint, the general rule is a) if your boat's a trailer sailer then go with paint or graphite-impregnated epoxy, b) if your boat will just spend up to 6 weeks or so in a slip each year, then use hard anti-fouling paint/coating, and c) if you will keep your boat in a slip all the time, then go the soft ablative anti-fouling instead. The hard anti-fouling can be refreshed as needed, and the same goes for the black graphite bottom. Soft anti-fouling is generally re-applied annually, but that depends on where your boat is kept (how much growth and shellfish attachment occurs each year). Also be aware that anti-fouling is often a regulated product and some bays have rules on what you can and cannot use, usually do the presence of sensitive marine life in the area, ex) commercial oyster beds or designated 'marine aquariums'.
