Its my first time replacing thru hulls. I took out the old plastic thru hulls for the bilge and macerator pumps. They are just above the waterline. I got all the old silcone off and now ready to install these nice new brass one. Should I use 5200 or 4200? My goal is to set it and forget it and never have to crawl to these hoses again. But in the back of my head is the what if they need to come out down the road. My plan is to acetone the hole, 5200 the brass and hole, hand tighten then 24 hours later button it down. I was planning on 5200 since these are about 3 inches above the waterline and will take a beating. I was doing some research and some say 4200. What silicone should i use? Should I just tighten it up rite from the start or let it set up for 24 hours? any tips?