I had a Regal 2665 that we used to trailer almost every weekend. I highly recommend having a written checklist to follow and a standard flow around the boat at the ramp. I have forgotten to put in the drain plug, undo a transom strap, and other common mistakes at the ramp. Pro tip: don't try to undo a forgotten transom strap while the boat is in the water on the trailer. I did that once and the strap jammed with the boat now floating the trailer but no longer aligned with it. That was a "fun" launch.
Put the truck in 4WD approaching the ramp unless yours can shift on the fly. We had an '03 Avalanche that had to roll a good ways before the 4WD would kick in. I don't think I really needed 4WD most of the time, but I didn't want to find out when it was too late. Ramps can be slippery and every little bit helps. This tip applies more to loading than launching.
I've heard this one doesn't matter for LED lights, but I always unplugged the trailer lights before backing down into the water.
I used long lines to the bed of the truck so I could walk the boat off the trailer, tie up, and go park the rig. I also had a jacobs ladder (
https://www.greatlakesskipper.com/shore ... ylon?gQT=1) off the bow in case I had to get on/off the boat from the trailer while launching.
The easiest was having my brother-in-law along so he could back the rig in the water while I stayed on the boat, but most of the time I had to do it by myself. If at all possible I always tried to start the motor before disconnecting from the trailer. It's one thing to winch an 18 footer back up on the trailer. I would have hated to have to do it with my Regal (can't remember ever having to thankfully).
Always be ready with a plan B to get the boat back on the trailer in case you find you are unable to launch at the chosen ramp. I had two instances where that came in handy. Once was a new ramp we were trying that turned out not to be steep enough, and once was a ramp we used all the time that ended up shoaling off the end. Where we boated we were typically one of the largest boats to use those ramps, so usually the first to find out if there were any problems.
The question was only about launching, but one of the most common issues I see when loading is people backing the trailer in too far. Most of the boats and trailers I've had liked just a little bit of bunk at the water's surface. This helped align the boat as we pulled onto the trailer and was still deep enough that the boat was able to get reasonably close to the winch if not up against the stop.
The whole time we had the Regal I kept saying how nice it would be to have a boat ready to go in the marina. Now I have a boat that is ready to go in the marina and I keep thinking how nice it would be to have a trailer for some variety and maintenance.
