We have a 45 minute drive to our destination and would like, if possible, to load 3 kayaks onto one vehicle (a truck mounted with yakima bars). I’ve heard mixed reports about how doable this is, and about the best configuration for a triple load. We do not have cradles or specialty kayak mounts. Just the bars and good straps.
Are these 22" wide sea kayaks or 30" wide SOTs?
what size bars? can you even get 3 boats wide (90"? yikes!) you will have to stack on sides, in which case a bracket would be nice. else you have to have a few hands to sandwich the boats and strap them together/down, are they all the same size? if not, one will be/might be loose, how long are they, what weights? maybe at the least foam blocks for 2 bottom and make a pyramid? use lots of straps!! take a photo, too!
I have loaded wood on my yak, so I know she will take a load, I’d be more concerned with security…
Depends on how you strap 'em down
The bars are plenty strong enough, if properly mounted. After all, boats don't weigh much. Strap each boat separately. Ideally, you will provide each boat with straps that anchor from side to side in addition to the straps that pull it straight down (that would mean using three straps or ropes for each boat at each cross-bar location). Of course if you just use one strap per boat at each cross-bar location and make it TIGHT enough, the boat's not going anywhere. If you can't fit the boats all side by side, and they are not fragile, you can stack them, with two in the first layer and one in the second layer. Again, all boats must be tied down separately, NOT to each other. I sometimes see whitewater kayakers with boats on their roof stacked three layers high!
Bear in mind that plastic boats cinched tightly down onto cross bars will become dented, and in time those dents usually become permanent. You really don't want to cinch a composite hull to a cross bar without padding of some kind. Hull cradles of some kind are really the way to go. That way, only moderate tightness in the straps is needed, rather than boat-crushing force pulling the boat against tiny bearing surfaces.
By the way, I've carried two canoes and one kayak a few times, and don't even give it a second thought. When I do that, all three boats are well secured. The weight is the last thing I think about.
Consider getting a stacker
As long as you have the cross bars that can handle it… with long enough bars you can get four boats up, two on each side of the stackers. Then just use straps, maybe get some foam to pad between the boats if they aren’t plastic.
I have a set of 20’ straps
that come in real handy for carrying multiple boats. I’d strap each one down on edge individually, and then put the long straps (or rope) over all of them. I’ve had a canoe and 4 whitewater kayaks on my car this way.
The stackers work great as well. Last weekend we had my 13’ WW canoe on edge against a stacker for a 2 hour highway drive to the river. I was a little concerned, but it worked out fine. If you boats are long you might want bow and stern lines.
I do it all the time
One one each side in J cradles, and one in the middle on saddles,
Or with two yaks and a canoe; one yak on each side in J cradles, and the canoe in the middle using gunnel brackets,
Or with three yaks and a canoe:One yak on each side in J cradles, the canoe in the middle using gunnel brackets, and the third yak nested against the canoe and one of the yaks that are on the J cradles.
With a good rack system, and cam-lock buckle type straps,(two per boat) the whole gang of them become part of the truck.
Looks like you said 17-18 foot boats in the other thread, so probably talking sea boats here. So if they’re all 22 inches (+/-), and you don’t have a stacker, then I’d put one boat deck-down in the middle, and strap it down. Then lean a boat on each side of that one, decks facing the center boat, and strap them to the center boat. Add bow and stern lines, and a belly strap over the whole deal. Should be solid.
4 folding j-racks across the top of a truck rack is also a great way to go, but darn expensive!