OK, lets try to get that photo to show

If I understand you correctly, the new platform would be attached to the existing bars. In that case, the support base doesn't get any longer. You'd have to move the bars forward and back to do that, or rest the new platform directly on the car roof.

Or did I misunderstand you?

Nice boat, BTW.

Laszlo

Tight lines from stem and stern to the car frame should stabilize it enough.

Hooper Williams - Brevard, NC 

   Laszlo,

You are right that the best thing would be mounts on the roof farther apart, but the rails and bars themselves are quite stiff and have plenty of capacity.  The problem is there is a limit to how tightly one can tie the skerry to the bars, so if the supports on which it bears were farther apart, it would give better leverage to control motion of the skerry.  As Hooper says, bow and stern lines help, but modern small utes don't have the easy, stout front and rear tie points like my old Jeep Cherokee had.  I've learned the trick from someone else of making web loops to fasten under existing fender or other screws under the hood and I figure I can do the same under the rear, but it ain't like the old days with the family's IH Travelall.  Now that was a hauler  :-)

The one shortish trip I've taken it, in the bare epoxy form you see, had me worrying as I watched it waggle in the interstate wind, so I'll have to do better .  If I have to pull the trigger on a trailer, I will, but it'll make storage more awkward and will require adding the hitch, etc.

I would try the Thule gunwale brackets to eliminate the wiggle. Two ratchet straps over the center section at the crossbars, and front & rear tie downs would give me plenty of confidence at highway speeds.

I use loops made from nylon webbing for my anchor points. A long loop in the front goes through a hole in the skidplate under the motor and wraps up over the front bumper without scratching the painted plastic. A smaller loop in the rear gets closed into the hatchback and i make sure the loop encircles the latch before shutting the hatch. 

Best of luck.

Dave

   Well, I'm about done with painting the interior, so once the rails are varnished, it's going on a short trip down to the Bay for christening, so I'll probably go Dave's route for now, and save a custom rack build for later if that doesn't work.

On this topic, different car...

Just about done with my Skerry build (painting and varnishing now) and plan to cartop it on our Honda Odyssey for a long road trip in July. The standard roof rack and cross bars we have on it are about 50 or 51 inches wide. Beam on the skerry is 54". The cross bars are farily close together, so boat will probably be resting on the rails. Is that overhang a serious issue when securing with straps?

I haven't thrown it up there yet to try it out but thought I would tap the wisdom here while working on the finish. 

This is me leaving Boat School a couple of years ago.  There's not a lot of distance between the bars on the Saab, plus the bars on the Saab roof rack are quite short, so before I left home I made up a couple of longer bars out of 2 x 3's and some scrap carpet.  I secured these to the Saab bars with some large SS hose clamps, four places on each bar.  I also came prepared with a couple of lengths of 1/2" line.  While I was building the boat, I bored a 5/8" hole through each breasthook so I could put a stopper knot on the line and secure the boat fore and aft to the tow eyes that Saab had been kind enough to provide.  (The front eye is removable and is ostensibly provided for hauling the car up onto a flatbed in the event of a breakdown.)  This arrangement worked like a charm.  The boat was completely stable and I was easily able to maintain highway speeds all the way home.  I now use the hole in the bow breasthook to tie off the anchor on a belaying pin.

hokker

Thanks Hokker, that ought to work well for our car, I'll give it a shot. Although I'm not sure I can bring myself to bore holes through the breasthooks at this stage! I am going to attach pad-eyes to both breasthooks, which are secured with four screws each, and then tie down from those. I presume that'll be strong enogh to hold.  

David

   I took a hint from a sailor and builder of other small boats, Garry, who designed and nicely documented his idea at:

http://www.pbase.com/onceagain/cartopper

I have done a quicky adaptation with scrap that works pretty well.  I'll refine it a bit then make a better executed one with better lumber.  I also whacked together a trial version of the CLC kayak dolly design on this site, made a bit more robustly for the skerry, with bigger wheels.

CLC's page:  http://www.clcboats.com/shoptips/fitting_out/kayak_cart.html

My version, with no annotations yet, is here:

https://goo.gl/photos/r9R25d748qjZqsa38

It works, even if it is ugly right now.  I have some rub points which I've padded, but it's easy to lift up and ease down. BTW, even as a crude 1 hour hack, the dolly works a treat, and all it cost me was the lawn mower wheels and axle bolts from a Home Depot with leftover 2x4s, scrap angle and assorted screws.  It doesn't fold down like one of the nice commercial ones, but I'm ok w/ that.

   As far as boring holes in the breasthooks, I had a couple of stainless cleats I found in a surplus bin at West Marine so I snagged them and they're just the right size for a bow cleat.  I have it through bolted so it serves as a bow tiedown (I don't use a stern one right now) and will be the hardpoint for towing or anchoring. Adds a little bling too. :-)

Thanks sawdust, very cool! And that solves the going boating by myself issue I'd been wondering about how to manage. 

BTW, I learned how to drive on an IH Scout, looked just like that Travelall, minus the wood and a bit shorter. Loved that beast of a vehicle.

David 

The 2x4s strapped to crossbars worked like a charm. After a comedy of errors on the hose clamps, I ended up using a dozen heavy guage zipties to secure the 2x4s which held well. Added pipe insulator and duct tape to cushion the rails. The boat and lumber didn't budge an inch over an 800+ mile trip.

I've promised not to leave the wood permanently attached to the car, so the zipties are good for a temporary solution. For the return trip, I'll put some tape over the zipties, they scraped the finish a bit when we dragged the boat on and off. 

A few pics below, with it cartopped, my first row (dog in hot pursuit), and sitting in the rain.

David