If you are new to kayaking or have just recently returned to the sport, you may want to rethink some of that existing gear you kept from your boat and old kayak. As the sport of kayaking has evolved, so have many of the accessories and gear used in the sport. One example is the innovation and changes made to kayak life jackets. About 10-15 years ago you could probably use an old boat vest and be just fine but today that may not be the case. Today's sit-on-top kayaks and even some sit-in kayaks now have premium seats with much more lumbar support. This in-turn has changed the way paddlers are positioned in their seats making standard life jackets much more uncomfortable. Today's kayak life jackets will feature a much thinner or completely absent lower back section. This allows the paddler to sit completely back in the seat making the time on the water much more comfortable. In addition to back design, the sides of most kayak life jackets are much more open than boat vest to allow for the range of movement needed my kayakers during paddling. This can reduce rashes and discomfort after a days paddling.
While additional comfort is nice in itself the larger goal is to have paddlers in their vests at all times. Some states only require a life vest to be on-board but we always recommend wearing a life vest while on the water and a more comfortable vest greatly increases those chances.