Accessories

Thule 830 kayak carrier
This is a good deal for someone wanting to carry a couple of Kayaks, without spending a small fortune.
The only problem was, the instructions were a little vague, and no pictures to guide you. There are drawings, but leave a lot to be desired.
They claim you can carry four kayaks, but until I see a picture of how to do this, I would only carry two.

Still, it is a good deal to take your kayaks to the water.
I'm glad I made the purchase, and the dealer was great, and the price is reasonable

works great!
am carrying two kayaks with this. especially like the front and rear tie-downs that come with it.

Pretty fair carrier
This is my first Thule product after having used Yakima racks for bikes, kayaks, and a canoe for over twenty years. Yakima makes fine stuff, but as you would expect from a system based on round bars there is sometimes a rotational component when various forces act on the load. This can be overcome, but sometimes requires tightening the hardware to a point you worry about stress damage. From a hardware standpoint, the thule square bars make a lot more sense. I purchased the stacker 830 for various reasons, but it supposedly worked well with Yakima bars as well as factory racks. It attached to Yakima without a problem.
In the world of guys trying to tie things onto the car top, I would say I'm about average. I have never (yet) had anything come flying off but its been close. The thule is probably fine for smaller kayaks, but one of mine is an old Torrent(a large, wide boat-- great for kids) and I had trouble keeping it from leaning. I tried several configurations before I found one seemed to work and eventually it leaned also. I finally just accepted it and stopped worrying. Failure to tighten the straps enough was not the problem. I found myself at a gas station standing on the roof on my SUV pulling with both hands. I don't think it could have been tighter.
The front and back tie downs are great and the system works reasonably well, but if I had to do it again I would probably go with two J-Shaped rigs.

Thule 830
Attached easily to a 2003 Honda Odyssey with factory bars. Only bad aspect, the Odyssey doesn't have easily accessible rear tie downs, so the rear tie down melted by being too close to the muffler.

Cheap and it works.
I have two kayaks, and the Stacker works great. Everything you need comes in the kit. The ties are long enough for two boats.. not sure you would be able to get 4 boats in , but it might be possible. I gave it 4 stars... the only down side to the system is trying to slip the tie into the stacker while it is on the roof. I have a SUV and trying to get my arm over the boat to slip the tie in through the hole on the stacker is a bit difficult. Now that I think of it.. you could just put one boat up first, then put the tie in before you put the other boat on.

Anyway, this is the cheapest way to hold two boats on the roof....and it works well.