15 February 2010

Cartopping sea kayaks

In my previous post I mentioned tie downs anchor points for sea kayaks when car top transporting them.
Here I would like to talk about my experience with cradles for kayaks.
I soon learned that kayaks can not be transported by just "chucking" them on top of a car and tie them down.
I was wise enough to never do the mistake of just using bungee/ocky straps for securing them (don't laugh, people really use that) and, in the rear vision mirror, see my prized possession tumble down the freeway .
I used proper straps to secure the boat onto the crossbars.
The previous owner of my first kayak told me that she never bothered with those "fancy" cradles that some people use, "the kayak will be fine".
And it was, for about a month.
Then one day I noticed a nice crack just where the kayak met the roof rack.
I must have been a bit heavy handed when securing it, worried it might fall off the roof.
That incident prompted me to learn how to repair glass boats and that after all they have to be handled with care.
While a decent sea kayak can take the force of the surf, a concentrated load in one spot (like a steel bar of a roof rack) can crack the hull.
Plastic kayaks suffer a different type of damage: deformation and oil canning.
I have now tried 3 types of cradles for my kayaks and not all have been successful.
There are several manufacturers of cradles but not all are equal.

Thule Hullavator: a little bit bulky for my style
My preferred one is where the cradle swivels and contours to the shape of the kayak. Some cradles are contoured but rigidly shaped; they might fit just one hull shape but not all. Stress raiser might appear on hulls that are transported on cradles that don't "hug" the kayak evenly.

high-tech layup deforming in tropical heat
Living in a subtropical place my summers get pretty hot.
High tech composite boats often have layups of Kevlar where epoxy is used as laminating resin.
Epoxy's melting point is lower than polyester and in full sun it can become a bit soft.
In one instance I had one very high tech kayak dimple and show stress marks despite transporting it on recommended "J" cradles.

Thule "J" cradles
My best solution for that kayak was to transport it belly up on custom made closed cell foam cradles cut to the exact shape of the deck.
DIY closed cell foam cradles
Since the deck was made of vinylester resin it was more heat resistant.
If your vehicle does not allow for conventional roof racks a foam block can be your only solution, in some cases.
used with permission from British V8 (link here)
My current kayaks don't suffer from heat distortion and I can use standard cradles with hull side down.

Mockpool (SeaBird Designs Northsea) and Sialuk (VCP Nodkapp LV)
A while ago I came across the cradles below.
I am unsure if they would be suitable for kayaks that have light hulls or a plastic one.These pads seems a bit on the small side however they do swivel.
The owner used them to transport a hard chined kayak where the ridge would be strong enough to support his kayak.
Transporting kayaks in the summer heat poses problems.
Before you permanently damage your prized possession on a long hot drive test the hull of your kayak and make sure your cradles offer enough support.


  1. Gnarlydog,

    I just discovered that I seem to have developed the same kind of hull deformation/depression on my new Valley Aquanaut carbon/kevlar. I had my boat up on my J-racks for about a week, lashed down very tightly. The deformity is just forward of the seat and across the keel. Should I be concerned about the structural integrity of the hull? Is there any way to reverse the "process". I was thinking that jamming some closed cell foam inside between the deck and the hull, and storing the kayak belly-up in the summer sun might reverse this issue.

    p.s. btw, your site is an incredible resource!

    1. Kevin, I believe you must got alarmed when you saw that happen. Top of the line kayak that should be strong and all and then dimpled like that.
      I am not a fan of J cradles (read: hate them) but lashing tight sometimes is a necessity since the cradles don’t “cradle” the kayak that well.
      Leaving the kayak leashed down tight for a week maybe was not the best thing to do ( I usually relax my straps after the drive) but from my experience the kayak should be recoverable to its former glory.
      Leaving the boat in the sun (not sure what temps you have where you are) could be sufficient to bring the dimples out; that’s all I had to do with my kayaks.
      If the sun does not do it maybe some boiling water (where epoxy does become soft) inside the hull and possibly a bit of gentle pushing with a large tool (piece of wood).
      You could also give Valley a call and ask directly; just to make sure your method is kosher.

    2. Gnarlydog, thank you much for the prompt reply! I'm live in Gloucester Massachusetts, USA and though its not Arizona (lived and kayaked there for a few years), the sun "does" get rather warm here. So hopefully, its radiant heat will be enough!
      When I purchased this kayak, I had no idea of the structural down-sides of carbon-Kevlar construction, otherwise, I would have gone with the normal glass construction. In regards to the week of rack-time, I had a week shutdown from work and was trying to maximize my on-water time.
      Though I've been kayaking on and off for about 23 years, due to a divorce, I had to turn my back on my most loved sport. Now after 3 years, I am returning to something I never thought I'd be able to do again!
      You "do" inspire me Gnarly, thank you!

    3. Thank you for your comment.
      Kevin, there are few other sports that are as rewarding (at so many different levels) as sea kayaking. I am glad that you are back on the water.
      RE carbon/Kevlar. All my current kayaks are carbon/Kevlar with different degree of stiffness. Only one kayak (that I no longer have) caused problems. The manufacturer did replace it with one that has had no problems since. I still think that you should talk to Valley and see what the deal is with your kayak.

    4. ...back again, Valley (UK office) expressed their regret and suggested storing the boat hull-up with a backing foam block in the summer sun to try to alleviate the deformation. It was their opinion that the deformation should resolve itself over time.
      As to my thoughts about keeping my boat up on the racks for that week.....at the time, I felt that having it up on the racks, for an extended period, would be no different than if I were making an extended tour to someplace remote or being on an actual vacation.
      My experience with car topping glass and plastic boats over the years gave me confidence that it wouldn't be an issue.
      Unfortunately, my Valley dealer is about a 2.5 hour drive away. Otherwise, I'd just pop over to them and get "their" opinion.
      Also the boat was sold as a "slightly used demo" for a nice cost savings, so I don't want to get into a fight over legalities and responsibility. Demo = never-again!

  2. Gnarly

    Recently purchased a 3 layer plastic boat. My vehicle is not suited to racks and I would like to try the closed cell foam blocks sitting directly on the roof. What do you think? Do you know were I can get the foam in Brisbane? Also do you think the boat should be carried belly down or up?

    Camira 4300

  3. Colin, I use packaging material for appliances/electronics as material to shape my foam cradles but Clark Rubber probably has something there (expensive).
    Often a soft kayak is best carried hull up and resting the deck grabbing it by the edges might prevent deformation (avoiding pressure in the centre of the deck).
    Properly shaped (contoured) cradles should be OK for a 3-layer PE hull. Keep those straps gently tight (no ratchet straps!)


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