Hwy speed with roof top

I will be carrying an Ocean Prowler 15 Angler plus a similar kayak on top of my Chevy Tahoe 4-door. I just bought a Thule rack.

My question is, what would be a safe speed on the freeway carrying the two kayaks? Anyone doing something similar? At what speed do you travel?

Thanks

When I used my rooftop Thule rack, I drove the speed limit, more or less (mostly more). I often carried both an SOT and an 18.8-foot closed deck. Be sure to use bow and stern lines, though! I drove more carefully when the winds picked up because the tracker feet/saddles on my SUV cradled the cockpits but the bow and stern of the long boat took a pummeling.

Janice aka "Big J"

It depends on whether you are using (a) mounts to tour factory crossbars (b) raingutter/pad mounted cross bars or (c)  towers bolted into factory rails (like Yakima landing pads and control towers)

I have always followed the following principles:
(a) drive 55 with bow/stern lines.  factory rails are 99.9% for show.  as soon as possible, use something different!
(b) 75 is pushing it,  these systems put allot of stress on the door frame and are held on mainly by horizontal compression across the roof.  these systems work great for infrequent use (less than once a month) but more use will start to damage the vehicle after a few years
(c) whether its after market or factory rails, check the number of bolts.  if more than 5, go as fast as you feel comfortable.  if less than 5 per rail, see rules for (b)
   I put rails on my cars and top 90 from time to time...

for safety's sake, always use a bow line, and a stern line is strongly recommended.

2c from a nut thats been hauling canoes and yaks for 15+ years

I have no rails on my van and just throw the kayaks on top - bugger the paint job.  I use lines from the bow and stearn to the front and back frame of my van, and one around the middle through the doors that isn't very tight, really just to hold things together if one of the bow lines comes undone.  I've driven 80+ in that configuration.  You're pretty much foolproof if you've got lines from both ends of the yaks.

I'm using Thule crossbars on factory rails. Will use bow and stern lines. I have 6 bolts per rail.

Based on this discussion, looks like I should be able to do 65. I can live with that.

Thanks