Lucas is aiming for a place at the Beijing Paralympics
British crews missed out on medals in the Paralympic categories at the Miami Olympic Classes regatta.
In the single-handed 2.4mR class Helena Lucas finished fourth with her main British rival Megan Pascoe in seventh.
Niki Birrell and Alexandra Rickham were the top British finishers in the two-person Skud 18 class in fifth place in their first regatta together.
Athens Paralympian Allan Smith and Jackie Gay were sixth after struggling in the second half of the event.
The Sonar crew of John Robertson, Hannah Stodel and Stephen Thomas were third going into the final day of racing but could only finish sixth in their last race and slipped down to fourth overall in their class.
The races formed part of the British selection trials for the Paralympic Games in Beijing in September.
"It's certainly been a tricky week for the sailors," said the RYA's Olympic manager Stephen Park
"The selectors will now consider the outcomes of this regatta to determine what the next steps will be for all those concerned - whether that be to select, or to continue the trials process at future events."