We use Riverside 18" universal blocks to carry two Necky Chathams side by side on our Mazda Protege 5 factory bars. The bars are only 32' apart and thus just bracket the cockpits. We haul either a 16' & 17' poly or two 18' composites. With bow and stern tie downs we have had zero problem with the boats moving around.
On one hot day I did get some hull deformation on the 16' poly because I had the bow line cranked down too tightly. I keep the bow and stern lines looser now.
TIP: I put the 16" poly Chatham on saw horses and poured a couple of gallons of hot tap water into the cockpit. After a few minutes I was able to push the deformation out with a block of wood. I then dumped the hot water out and let it cool.These things are poorly shaped and ridiculously overpriced. Paying over $50 for foam blocks is absurd. I bought the universal kayak carrier when I was in a jam, and I equate it to highway robbery. Not only are they overpriced and poorly profiled to fit most hulls, they tore the first time I tried to fit them on my factory rack.
That said, they get the job done. However, not much more than that can be said about them. If you anticipate the need for foam carriers, give yourself a few days to order a superior product for half the price (as can easily be done online) rather than being railroaded into spending waaay too much money for a mediocre product.Those of you who are getting into kayaking know how quickly the money flies away as you begin outfitting. You walk into a store, look at the pretty boats, and say to yourself, "mmm, that's a nice chunk of change, but the budget wouldn't be stretched completely to the breaking point." Then you look at paddles, PFDs, skirts, bilge pumps, & paddle floats, and your budgetary camel is begging to go to the chiropractor before it's too late!
What made my wallet groan was the realization that I'd have to cart this seventeen foot leviathan from place to place on my car. I walked into R.E.I.(Requires Extra Income), and asked the nice kid what it would cost to get a trick Yakima or Thule rack set-up like all the 'cool' Yakkers have. He got out his catalogs & we started looking at this and that, and the upshot was that it would cost three benjamins and a couple of Andies! Yargh- the Pirate Queen must be at the root of this evil! I walked out of Yuppie Sports Ltd a humbler & much less bouncy Tigger, indeed.
However, back at my local 'yak emporium, hanging on the wall, was a mesh bag marked 'Riverside Universal Cartop Carrier', and it listed for only $59 and change. My alternative was to have all this fancy gear & no boat, so out came the wallet, and an impassioned plea to the yak clerk to pretty please, w/sugar & a cherry on top, show me how this contraption works.
Your sixty bucks & sales tax nets you two foam blocks, tie down for fore & aft, and an athwartships (side to side) tie down. Now I have an old clunky LBMM (Hi, Fools!) '92 Ford Explorer, which DID have a pretty useless factory rack; but this product does NOT require a factory rack to be in place. The foam block slid over my side bars ( if you have no fact. rack, you need to buy some extra straps & run 'em over the roof & inside the car,
& slam the doors on 'em. These are secure, easy to use, come off when not in use (no unnecessary drag), & best of all, cost way less than THREE HUNDRED & SOME-ODD BUCKS!
I've used mine for a month or so, now, and while the couples with two brand new Kevlar Ocean Queens perched high & dry on their Ultima Thule mega-rack, bolted on top of their Caddy Escalade may sniff and snicker as I chug by, I get to the put-in just as secure, and without the need for those little individual locks that keep envious people from stealing their racks (and which, by the way, cost $20 or more apiece, and you'll probably need four!).
OK, rant over. Suffice it to say that it's a great product, at an acceptable price, that does what it's billed as doing. SYOR