Think about your location as much as your gear.

Very often there will be 100 boats all anchored around the Mewstone area catching nothing while the boats that sound around and go looking for them clean up.

With that said they do come through that area as well if you are prepared to wait.

You can use pretty much any gear to catch them from 1kg mono to 30lb braid so hard to recommend something without knowing your preferences.

Better off going to your local tackle shop and trying some gear out and matching it to the type of lures you want to use aswell.

For a general outfit I would be looking at a 3-4000 size reel and a 7ft rod with 15-20lb line

 I use a 7 foot rod with a 4000 series Daiwa loaded with 20lb braid and it's perfect. Also doubles to cast lures at queenies and trevally up north (not GT's) and metal for tailor locally.

 I've been having fun catching salmon from a boat, here's one I caught last weekend.

You don't need to spend too much money on a rod/reel.  I used a cheap Jarvis Walker boat rod (2.0m) with a very cheap EFX 4000 reel.  Braid is 20 lb.  The braid probably cost more than the rod/reel combo 

Had no problems muscling it in.  

The important part is finding a lure that casts well.  I use a home made lure that weighs around 50 grams, rear weighted so it casts like a bullet.  There are many lures that work well, the good old halco twisty is as good as any.  It must cast well.  I prefer jigging assist hooks or inline singles compared to trebles, as trebles munch up the mouth of the fish too much causing them problems if you release them.  

 Forgot to mention, I also hooked two salmon right at the bottom in 30 metres, with a very expensive jigging setup and a 100 gram lead slow pitch jig.  Thought they were dhueys.  Should have seen my face when they came up.  When they're around, pretty much anything you've got will hook them.

 You cant beat Smilin Jack lures. Around $15. It is pretty much all you need. Not the longest casting, but from a boat that shouldn't be a problem. Rapala X Rap long cast offer a bit more bling and are great for casting....but they are a a bit more exxy.

People use all sorts of gear..50lb whatever. Don't spend too much. I would go 5000 size reel and 20lb braid and a cheap 6 foot rod suitable for 20lb line. Use 3 feet of 30-50lb  mono as a leader, tie your lure on and you are good to go.

Boat casting rods double up as great soft plastic rods for snapper aswell. Keep that in mind when looking around

I love my Shimano Cranx 9' rod. Paired it with a 2500 Piscifun Spartan and 15lb braid. Makes for a fun fight and also fantastic casting distance when just throwing 40g metal slices. You'll get at least 90m on a cast

 9" rod is pretty hard to handle on a trailer boat. In my opinion, 6'6-7 will be better depends whether your boat has enough room to cast or not.

shimano 4000-5000 size or Diawa LT 4000 size with 20lb braid. 30-40lb leader.

 Yep that's my setup and it's a really versatile outfit. I've caught lots of salmon on it and it's brilliant fun.

Head in to Tackle West and speak with Luke or Honsu. It's my local tackle store aswell, and it has a fantastic range of gear and lures, and the boys there know their stuff and are always willing to help out. Tell them what you're after, your budget, and they will point you in the right direction