A large percentage of the people fishing butts in the straits are going to be anchored up with chum bags in the water, so keep that in mind when drifting. Won't make many friends if you're trying to drift through a cluster of boats, or better yet, drifting down current of them in their chum slick
I advocate for a simple setup. A tuna cord slider with a sliding lead to a two hook leader. I like Big River bait hooks, size 12/0 personally, but big octopus or even big circle hooks work great too. Spreader bars work, but are obnoxious and annoying and honestly pretty lame. A tuna cord slider works just as well, is cheap, and you can make as many as you need super quick. Shoot me a message if you want the run down on making a slider, I haven't been around much the last couple weeks but I'll try to check my messages.
As much lead as you need to stay on bottom. Not sure the typical depth on a lot of those banks on the straights but 1-2 lbs seems likely, depending on how comfortable you are using the kicker/main to control your drift and how deep you'll be fishing. When drifting you'll need to use a motor to insure you stay as vertical with your lines as possible. I like to keep my lines so that the lead maintains constant contact with the bottom as the boat bobs in the swell.
Just about anything works for bait but it's hard to beat large herring. Squid, mackerel, shad, pink belly, tuna belly, it all works, but for my money give me large herring any day. Usually run a large white grub/tail as well mostly just to have something present when you lose your bait. Nothing worse than having your bait robbed at depth and not realize you weren't fishing anything until you do a bait check.
As far as where to find them, I like to focus right on the slope of drop offs. Halibut love to hang out right at the edge of a drop off where current will push food down over the edge to them. Not necessarily super steep edges, but more those gradual sloping edges. I haven't fished the main banks on the straits much but when I've fished the western straits out of NB and Sekiu I've always tried to drift right along those edges and it has paid off often.
I think the guys soaking chum bags and sitting on the hook tend to do the best, but drifting and covering water can definitely produce fish.
I'd spend some time studying the charts and get a sense for the area you're going to fish, and see about drifting those edges. Also pay attention to current charts. Strong tidal currents will make staying on top your lines much more difficult. Also be sure to fish through the whole tide including slack. Halibut are one fish, especially in the straits, that can go on and off the bite based on the tide.
