Am i too overprotective.....?

my daughter turned 7 in may and my son turned 6 in june.... we go camping with my dad and stepmom at a lake where my uncle has had his lake lot for 18 years and we go there every summer ~ I basically grew up on that lake during the summers... my uncle and cousin are both firemen... and many of their friends are paramedics... police... firemen... heres where i get jumpy... i have no problem with my kids swimming near the dock as long as they have their life jackets on... neither of them really know how to swim... they know the motions but couldnt do it w/o the jacket... my dad has a huge raft thing thats circular with a small hole in the middle..(not a tube a large circle raft) i said i didnt want them jumping down through the hole... and he didnt understand why... i said cause if they angled off then they wouldnt be near the hole and wouldnt be able to lift the raft... (they swim by the dock while were on the deck about 30 ft. away i ALWAYS have my eyes on them and its set how far they