Better gas milage with kayak on J hook

Recently I drove 8.5 hours north toward Traverse City with my new Wilderness Ride 135 tied securely to the bars, I also had a front and back tie down.

My 2012 Jetta had about seven hundred and seventy miles on it when I left; it was not broken in. This is a possible factor but I’m not sure how probable.

I averaged about 23 MPG on the highways going up.

Before coming back down, I put the Thule J bars on, my cousin’s hubby loaded my Ride securely into the J bars so it would not vibrate (a problem I had earlier this summer on top of my prior VW).

The Jetta averaged 31 MPG on the trip back with the kayak on the J bars. This is the same MPG we made without the Kayak on the car when another cousin and I drove that car from below Traverse City to drive across and back the Big Mac. We did some stopping on the way back, exploring the shore of East Bay for secluded beaches and rock hunting.

I will use the J Bars from now on, it is worth the price of sometimes tipping strangers to help me load and unload my kayak if need be.

Lots of variables in your experiment but interesting.

I wonder - what is the elevation difference between your starting point and your destination? That can make a substantial difference in mpg.

same experience.
Ever year I haul a boat up to the traverse city area via I-75. I always get worse mpg going up. I don’t know if it is the elevation or prevailing wind. Once you pass saginaw and head to grayling the elevation seems to climb. Just speculating at this point.

Ryan L.

color me skeptical
Something else is leading to that rather significant MPG loss. Try the trip in reverse or try another trip. Check your tire pressures, air temps, and keep the AC on or off both ways.

It’s obvious
Of COURSE you got better mileage on the return trip from up north. You were going downhill…

Too many variables to decide
1. Wind direction makes a huge difference for our vehicles. Huge.

2. Elevation change also matters.

3. Road surface quality, believe it or not. I get better mpg on smooth, hard, unbroken, fine-grained asphalt than the usual crappy road surfaces we have. There’s an annual report on tire wear that categorizes zones of the U.S. for average tire life. Rocky Mtns. are in the worst category (bad surfaces, lots of curves, lots of climbing and descending, extreme weather conditions).

4. I’ve also noticed that if driving on busy interstate roads, there seems to be a drafting effect from all the vehicles traveling the same direction. This has been observed both with and without kayaks on roof.

5. If you use cockpit covers, that can help, too. I say “can help” because I don’t think there’s much difference if the kayaks sit upright. But if they’re on their sides, a lot of wind hits the cockpit cavern with any side winds.

J Cradles
Now you need Malone J Cradles with their Telos load assist and you won’t even need help.

A tip with the Telos, fold your rear view mirror(s) in before loading or unloading. The mirror will catch the edge of the kayak. You won’t do any damage probably but it will kink up an otherwise easy process.

“downhill” ?!?!
Surely you’re joshing us. There is no “downhill run” of any substance in the “Big Mitten”. The continental glaciers scoured the state nearly flat during the last Ice Ages. Highest point on the whole lower peninsula is only 1700’, near Cadillac. Even the downhill ski areas are under 500 feet in run elevation (heck, I have that much elevation gain in my 3 mile drive to work in Pittsburgh). The elevations of cities along the west coast are around 600 to 700 feet. The surface of the lake itself is 577’ so land relief is minimal. Kalamazoo is 600’ and 200 miles north Charlevoix is only 700’. Winds are mostly hitting you broadside from the west.

I think you can safely exclude geomorphology from the equation.

Tallest feature I recall (other than cell phone towers) from my years in West Michigan was the big stinky landfill at Coopersville along I-96.

I have not yet performed any rigorous mileage comparisions between hauling with the J-racks and without but I do know my vehicles handle better in high wind with the boats on the racks rather than strapped flat on the crossbars. Keeping a well secured hatch cover on makes a noticeable difference too.

I’d interested to see wind tunnel laminar flow studies on various kayak transport mountings.

Everyone knows
that the North Pole is way up on top of the globe, so you have to go uphill to get there. Driving to Australia you’ll get great mileage - it’s downhill all the way. You just have to find the on-ramp to the US-OZ Causeway.

One source of air resistance is when
air gets “stuffed” between the bottom of a kayak and the top of the windshield. I imagine that lifting a kayak somewhat, whether in the old cradles I still use, or in J cradles, could be helpful.

Fairings are known to improve mileage a little with no kayak aboard, but results when the uprushing air from a fairing encounters the underside of the kayak are less consistent.

Another source of mpg error I did not see mentioned is that gas pumps vary a good deal in how completely they refill the tank. I once thought we got ~32 mpg carrying a whitewater tandem canoe from Atlanta to Sylva, NC. But I never have seen such mpg with the same car, racks, and boat, driving all around the country. I really think it must have been pump error.

Good points

– Last Updated: Sep-16-11 2:37 PM EST –

I use that logic when carrying two canoes. It seems that two streamlined shapes would be easier to push through the air when there is plenty of space between them than when the hulls are nearly touching. After all, people who lash two canoes together to act as a catamaran do the same thing, or else the combination turns into a barge that's really hard to paddle.

Regarding gas pump variability, they all shut off when fuel backs up to the nozzle, but some deliver the fuel at higher velocity which can make them shut off sooner and become very "touchy" when trying to add more. With a slow pump I can normally add two more gallons after the pump shuts off the first time, but I run out of patience adding just one gallon with one of those faster, "touchy shut-off" pumps. Coming up one gallon "short" of a fillup on a 15-gallon load if I normally get 23 mpg will artificially boost that particular mpg calculation by 1.6 mpg, which is quite a difference. If all trips were done under the same conditions, this would average out over time, but who does that? We tend to relate miles per gallon to the conditions encountered between the current fillup and the last, so an error like this one can be puzzling if you don't think about how the tank wasn't filled quite as much as it might otherwise have been.

J-Cradle Mileage Better with Deck In
I get better mileage with J-cradles when I carry the kayak(s) deck in.

Too much of a difference
I don’t doubt your data, but I doubt your explanation. There are probably other variables giving you the huge difference in gas mileage. I don’t use J-cradles but the difference between kayak loaded and kayak unloaded is usually less than a few percent. You are seeing almost 50%.

A new car’s computer is still in the learning phase and between that and the actual break-in of mechanical parts, gas mileage can increase quite a bit from brand new to 1000 miles.

Ethanol can reduce gas mileage by 2 percent easy, if used. Differences between summer blends and winter blends of gasoline are also quite striking sometimes.

Many other variables have already been discussed. But hell, maybe you found something good!! See if it holds true…hope it does. I’ve got some pretty wild figures at times and the best estimate can only be achieved over many tanks.

Hills are a factor with new cars
If your return trip was mostly downhill, you would have seen a jump in MPG regardless. New fuel systems shut off fuel to the cylinders when gravity pulls on the car sufficiently to keep it at speed while coasting in gear.

Diesels have done this for many years, and gasoline engines can do it now, too. I take full advantage of the effect with my Jetta TDI, and coast down every hill I can while in gear.

Wouldn’t the MPG
really fall off if you drove the entire distance in reverse? Not to mention the strain on your neck…

Sorry, couldn’t resist…