You are responsible to check the boat before it goes out. If you don't think the boat can handle the conditions, don't rent it. If you are not an experienced catamaran sailor, buy it. Make sure you can right a capsized boat unless you want to be rescued. It takes 265 lbs in the right place, using the right technique to right a 16.
Technique is the key ingredient.
TLYC does not guarantee that a rescue boat will be available. You will only be charged for the rescue if you accept the assistance, so sometimes it takes a while for the boat to go out. You accept responsibility for everything. Being dependent on yourself alone, and making the proper preparations before you go out are an important part of what sailing is all about. Under no circumstance should you go further than the islands.