Here's a method used in Hawaii for getting bait down quickly without attaching a sinker (commonly used for baiting the buoys for tuna) where the water is commonly 4,000 to 6,000 feet deep; you sometimes need to get bait down 100 fathoms or less. Tunas won't bite too well if they see all kinds of terminal gear, you gotta hide the hook in a chunk of bait.
You rig a long leader with a bait hook on the end. Attach to a swivel to the mainline. Then bait hook (hide hook) and start wrapping around a smooth stone (1-3 lbs). As you wrap, you use the line to also wrap chum/cut bait onto the stone as well. This is kinda hard in a pitching boat as the line wants to slip off the rock. You wrap 7 or eight times, adding bait and cinching it with the wraps around the rock, you gotta reverse direction a couple of times as you go, then loop the last wrap. Kinda hard to picture I know.
Basically you freespool the rig down to the depth you want, grab the line, jerk hard a couple of times, then the rock falls free (cheap sinkers) and you got your bait where you want it, and also have a small chum slick with it, plus you're not encumbered by a weight.
This works very well and can produce yellowfin tunas anywhwere from 10 to 200 lbs.
Not sure how this would work for halibut especially with the tide running as the heavy sinkers keep the rig on the bottom fishing. Maybe use it when the tide slacks?
Just a thought,
I have a couple of pics of this method, if I can figure out how to get them on here, I'll do it. I'm "computer challenged"!