Rotating J-Cradles on roof bar

Places, technique, kayaks, safety, the sea...
Post Reply
jb2_86_uk
Posts: 8
Joined: Fri Jul 14, 2017 3:45 pm

Rotating J-Cradles on roof bar

Post by jb2_86_uk » Fri Jul 14, 2017 4:18 pm

Hi all,

My wife and I recently decided to take the plunge and buy our own kayaks instead of renting sit-on-top barges when we're on holiday or otherwise just fancied a paddle. I was in charge of acquiring the roof rack, since it will always be my car and me driving when they are transported. I bought a Thule system with the square bar, the idea was to upgrade to a fancier bar in the future when the savings account has recovered, although I must admit I have been pleasantly surprised with the lack of noise @70-75mph and surprisingly good MPG even with two kayaks on top! Anyway, I digress...

The reason for my post is I am using J-style cradles from Riber, by default, they sit level on the bar and so, the lower, flat part of the cradle is horizontal. Great, except for the fact that this means when the kayaks (12 & 13ft plastic sit-in tourers) are in the cradles, rather than spreading the load across this 5-6" base, it's only resting on one edge, and in my mind this is more likely to deform the sides of the boat where they touch. Does that make sense?

The J-cradles are attached to the bar via a back-plate and two thumb screws, my question is: Has anyone tried using these J-cradles or similar by rotating them slightly on the bar so that the edge of the kayak sits flush against the bottom surface?

I'm loading up again tomorrow so will take a photo or two to show what I mean

Cheers
JB

pathbrae
Posts: 277
Joined: Thu Jun 09, 2011 5:42 pm

Re: Rotating J-Cradles on roof bar

Post by pathbrae » Fri Jul 14, 2017 10:25 pm

I'd not be too quick to modify the mounting of a J-Bar. If you do, and it fails, the manufacturer will use your modification to escape any liability.
For plastic boats, I'd not worry about deforming them if they sit on edge in the cradle - you'd be much more likely to "oil-can" the hull if it was flat on the bars. You could use a bit of foam pipe insulation as padding if there's nothing on the bar already.
Assuming you have reasonably good square section bars, you won't gain anything significant by switching to aero section bars and you might find the J-bars don't fit as well to the rounded profile.
I don't know why manufacturers don't bring out a bar with a flat top and aero section underneath as a compromise......
So much sea - so little time to see it.

User avatar
Douglas Wilcox
Posts: 3519
Joined: Sun May 11, 2003 1:31 pm
Location: Glasgow
Contact:

Re: Rotating J-Cradles on roof bar

Post by Douglas Wilcox » Sat Jul 15, 2017 8:29 am

I agree with pathbrae, get some black closed cell foam and cut some fillets with a bread knife so that the base of the j bar fits the contour of the hull. When we are running shuttles and putting our boats into other peoples' j bars we take some of the little square folding foam sit mats. These are ideal for temporarily padding out a j bar. My car has a curving roof but the more expensive Thule feet/fitting kits take account of the curve and the top of my bars are horizontal.

Douglas

Daker
Posts: 432
Joined: Thu May 11, 2006 5:01 pm
Location: Scotland

Re: Rotating J-Cradles on roof bar

Post by Daker » Sat Jul 15, 2017 1:19 pm

If you want to put the boats on the roof hull-down, there are dedicated V bars available.
However, the general consensus is that boats are stronger and less likely to deform on their edge where there is less surface area and where the seam is.

As above, if they are not sitting square in the J bar, making up fillets / wedges of foam, or just using small bits of pipe insulation to fill the gaps, can make a huge difference.

jb2_86_uk
Posts: 8
Joined: Fri Jul 14, 2017 3:45 pm

Re: Rotating J-Cradles on roof bar

Post by jb2_86_uk » Tue Jul 18, 2017 1:48 pm

Hey folks! Thanks for the tips, sorry I am new to UKRGB and was expecting an e-mail notification from replies!

I loaded up again as planned the following day and had a good look at how it all fitted together, and I came to the same conclusion about the ability to rotate the J-Cradle - regardless of how it interacts with the boat, I don't think there'd be enough clamping force between the cradle & bar - and absolutely agree about if anything did fail, I wouldn't have a leg to stand on.

As per the suggestion by Douglas, I'm going to fashion some foam shim/wedges to make a more suited profile to the base of the J-bar before we go down to Cornwall from Sheffield in a few weeks

Cheers
John

Post Reply