Used my yakima racks for 30+ years and aside from my favoite canoe its the best paddling investment I have made. DO tie down bow and stern. Very important. Probably more important than the rack itself. Prefer not to kill the person following me if something does let go.
bow and stern lines are your best bet for any boat, with the possible exception of very short whitewater boats.
install a nylong webbing loop to a bolt on each side of the engine compartment. make it long enough to reach above the hood when shut.
The bow line will keep your boats from becoming an unguided missle in a crash, and keep them from flipping back, end over end behind you if a rack fails on the highway.
the angle and slackness of the bow line gives you the best way to monitor a boat secured to the roof.
I had J racks on my factory trail blazer racks for quite a while until I caught a strong cross wind while going 55mph. the wind grabbed my boat and swung it way out to the side of my vehicle. Didnt come off or break but the bar bent and my boat was sticking over the dividing line into oncoming traffic. May have not been secured properly, may have not had adequate racks, Either way it was the last time I did that.
i would agree and use the bow/stern lines. front to back stability will help from the boats twisting at all i used these guys and my bow stern lines came with small rubber strips that cover the lines to keep the paint and lines from rubbing. http://www.orsracksdirect.com/yakima-8004021.html
I use one set of Yakima J hooks and one set of West Marine foam blocks on my 2005 Subaru Forester racks to haul a pair of 17 ft sea kayaks. . The 05 Forester racks were such that a relatively long radius (distance between bars) is possible. Because of bar placement I’m able to delete the bow and stern straps. (crowd gasphs in unbelief) Many newer factory racks do not allow this. So the boats need bow and stern straps as well as straps at the bars. I do not strap to the j hooks. I loop the straps around the bars and over the boat then loop under the bar on the other side and connect the strap to itself. Essentially the strap pulls the boat down towards the factory bar. Do not use ratchet straps.
Trailers…You can use a cheap Northern tool trailer. You can use a cheap junk yard home built like mine. But for slickness nothing beats the Yakima folding trailers. They baby the boat down the road smoothly no bounce. They are easy to load. They fold up for storage.