When a personal watercraft (PWC) passes too closely behind another boat, the primary risk is the potential for collision, which can result in serious injury or damage to both vessels. Additionally, the wake created by the larger boat can destabilize the PWC, leading to loss of control and the possibility of capsizing. This proximity also limits the operator's ability to react to sudden changes, increasing the likelihood of accidents. Lastly, the operator may be at risk of being thrown off the PWC if it hits a wave caused by the larger boat.