What is maximum safe cross-wind in a Jayco Precept

[tsmatx]

I live in an area where high winds (Santa Annas) become a problem several times a year. Sometime we actually postpone trips because I feel the winds are to high and I'm nervous. Generally I get spooked with cross winds over 20 MPH, especially since there are many canyons where gusts may reach 40 or 50. Does anyone have any information/opinions on what is a "safe" wind to drive it? I'm mostly concerned about getting blows into a different lane and hitting or sideswiping another vehicle.



Is it actually possible for cross winds to blow over a class A like mine? I have seen where semis have been blown on their side not too far from me.


Thanks for thoughts.

[fizikpal]

I don't know the answer to this but it sounds like you exercise common sense when planning a trip. I could not think of a more terrifying experience then getting pushed over by a crosswind (well having a spider on my lap would be pretty close)

[Vicr]

I have first hand knowledge in driving in heavy cross winds. 50 MPH gusts in southern Idaho blew my 35S into the other lane of traffic. Fortunately there were no vehicles in that lane. And yes winds can be strong enough to blow over a moving or stationary motorhome. When the winds pick up or are constant the safest thing to do is stay put if you haven't left or if you are on the road find a place to park until the winds die down.

[hawkster]

Can only relate my experiences from 5 yrs of ownership. 15 mph you can definitely feel but I don't consider that unsafe, 20 mph might be borderline. I would consider 25-30 a no go as I have driven in 30-35 mph side winds. Really you can just slow down to maybe 45 mph but it's really stressful driving.

[Jagiven]

A gust blowing you into another lane and blowing over is two different things. I decided to calculate what it would take for wind to tip your Precept. Per the calculations below it will take a 150+ mph wind gust. I expect you will pull over long before you get tipped over.

Calculations, based on a simplified model;

Your 31UL, out of the factory weights 22000 lbs empty 26000 lbs loaded. It is 33' long, and I assumed it is 11' tall, total cross sectional area 363ft^2

A 53' empty semi trailer weights between 14000 and 16000 lbs, height 13', this can be a challenging number as some unit are skirted and some are not. and wind can flow under a trailer. For simplicity, I assumed skirted, and no tractor. So cross sectional area of 689ft^2. Almost 2x the cross sectional area of your Precept and about half the weight.

Wind Force calculation P=0.00256xV^2

P = Pressure (psf), weight/cross sectional area
V= Wind speed (mph)

Rewritten equation to solve for wind speed
V= (P/0.00256)^.5

31UL Precept

Empty
22000 lbs/363 ft^2=60.6061psf
(60/0.00256)^0.5=153.09311 mph

Loaded
26000 lbs/363 ft^2=71.6253 psf
(71/0.00256)^0.5=166.53641 mph

53' Empty semi trailer

53ft long*13 ft tall=689ft^2
lbs/ft^2
14000/689=20.3193

P= weight/cross sectional area
V= (P/0.00256)^.5
(20.3/0.00256)^0.5=89 mph wind speed

I decided to look at my 23B

23 foot long wall, 10 feet tall = 230 ft^2
weight 5000 lbs
5000/230=21.7 psf
(21.7/0.00256)^0.5= 92 mph

A wind gust of about 92 mph would tip my HTT, about the same as an empty semi trailer.

Side note, about our experience in high wind; We were setup in a CG in Montana with the stabilizers down a couple wind gusts came through out of absolutely no where. One side of our HTT came off the ground. At the time I guessed we experienced wind guests close to 100 mph. I guess I was not to far off.

[EA37TS]

When we had the Thor Challenger, 37 foot class A, on a trip to the outer banks we experienced winds strong enough to blow me into the other lane going across one bridge. Then on NC12 they were doing construction on the Oregon Inlet bridge and we got stopped (one lane traffic) at the top of the bridge. the wind was so bad it was blowing the hard hats off construction workers and we thought we were going to get blown over. The wind blew my side view mirrors into the coach and out of adjustment. The wind gusts that day were right at 40 MPH with sustained winds at 25 MPH. Right after we crossed the bridge the construction workers quit work for the next 2 days because of high winds.

Since then I will not hit the road if winds are over 20 MPH if crossing high bridges or 25 MPH on the flat lands. I am getting ready to retire in a couple of months and there is no longer any reason for me to be in a hurry to get anywhere.

Things to keep in mind when driving in crosswinds are whenever a truck passes or you go under an overpass those crosswinds may go away for a few seconds and the manner in which you are holding the steering wheel (tight) may cause you to move into another lane. If you are towing the crosswinds can also cause the TOAD to sway so you need to keep your eyes on the road and th navigator should keep an eye on the TOAD in the rear view camera.

To me driving in a crosswind is like riding a motorcycle. The minute I say I'm no longer afraid is thee minute something stupid will happen.

Be careful, be safe and enjoy the ride.

[kblast523]

I owned a Jayflight SLX 185RB and pulled with a Ford Flex. Driving between Dalhart and Texline on one trip I went to Cimarron Canyon NM, I encountered 50-55mph crosswind. The load equalizer worked well to make it stay put, but I could see the ENTIRE left side of the tt in the mirror. Being the Texas Panhandle it was dusty. When I got to the campground that evening the tt was covered with dirt all over, including the interior. Was not real concerned with 'blowover' but might shoulda been.
I pulled a FR Salem 241QBXL with a 2015 F150 and it was a completely different animal. Wasn't so concerned about 'blowover' as I was hitting someone passing me. Air disturbance from the rear in a 35 mph crosswind would cause the tt to try to oscillate across the lane, even at 40-45 mph. 18 wheelers would come up behind me and as they changed lanes, would suck the rear end of the tt over toward them. It was kind of like an early warning I was getting passed, but it even happened with small vehicles. It would skew the trailer toward the passing vehicle, then snap back and try to drag me off the road to the shoulder. Didn't matter which direction the wind was out of, poor dynamics of weight, wheelbase, aero problems and friction anti sway only provided minor damping. Several times while traveling on US2287 between Clarendon and Rhome, I found both the tt and the tv traveling crossways on the highway.
In March 2019 while returning from Phoenix, on I-10 in Western NM, I decided to stop in Ft. Wilcox because of wind. Traveling east with a 50 mph crosswind and gusts to 65, I was getting fatigued chasing the rig all over the road. That's my limit with the JayFeather 23RL. I went back out there this February didn't encounter the wind, but found the new tv (Nissan Titan) to be better planted with the trailer than the F150 was. Maybe those extra 1,000 lbs DO count for something.

[curver900]

Originally Posted by tsmatx

I live in an area where high winds (Santa Annas) become a problem several times a year. Sometime we actually postpone trips because I feel the winds are to high and I'm nervous. Generally I get spooked with cross winds over 20 MPH, especially since there are many canyons where gusts may reach 40 or 50. Does anyone have any information/opinions on what is a "safe" wind to drive it? I'm mostly concerned about getting blows into a different lane and hitting or sideswiping another vehicle.



Is it actually possible for cross winds to blow over a class A like mine? I have seen where semis have been blown on their side not too far from me.


Thanks for thoughts.

I think you are on point... it is really up to your comfort level... We were in AK last year and we had a day where it was windy to the point I just pulled into the next place to camp and waited it out... I don't recall what the wind speed was but it sure tossed us around... and it is just to much work to keep it all together... Never have to be somewhere that would cost you yours or someone else's enjoyment

[tsmatx]

Thanks everyone for the input. It is reassuring that I'm not being overly cautious. And special thanks to Jagiven for the detailed analysis. It makes me feel better about the tip-over issue.

[TaftCoach]

Originally Posted by Jagiven

A gust blowing you into another lane and blowing over is two different things. I decided to calculate what it would take for wind to tip your Precept. Per the calculations below it will take a 150+ mph wind gust. I expect you will pull over long before you get tipped over.

Calculations, based on a simplified model;

Your 31UL, out of the factory weights 22000 lbs empty 26000 lbs loaded. It is 33' long, and I assumed it is 11' tall, total cross sectional area 363ft^2

A 53' empty semi trailer weights between 14000 and 16000 lbs, height 13', this can be a challenging number as some unit are skirted and some are not. and wind can flow under a trailer. For simplicity, I assumed skirted, and no tractor. So cross sectional area of 689ft^2. Almost 2x the cross sectional area of your Precept and about half the weight.

Wind Force calculation P=0.00256xV^2

P = Pressure (psf), weight/cross sectional area
V= Wind speed (mph)

Rewritten equation to solve for wind speed
V= (P/0.00256)^.5

31UL Precept

Empty
22000 lbs/363 ft^2=60.6061psf
(60/0.00256)^0.5=153.09311 mph

Loaded
26000 lbs/363 ft^2=71.6253 psf
(71/0.00256)^0.5=166.53641 mph

53' Empty semi trailer

53ft long*13 ft tall=689ft^2
lbs/ft^2
14000/689=20.3193

P= weight/cross sectional area
V= (P/0.00256)^.5
(20.3/0.00256)^0.5=89 mph wind speed

I decided to look at my 23B

23 foot long wall, 10 feet tall = 230 ft^2
weight 5000 lbs
5000/230=21.7 psf
(21.7/0.00256)^0.5= 92 mph

A wind gust of about 92 mph would tip my HTT, about the same as an empty semi trailer.

Side note, about our experience in high wind; We were setup in a CG in Montana with the stabilizers down a couple wind gusts came through out of absolutely no where. One side of our HTT came off the ground. At the time I guessed we experienced wind guests close to 100 mph. I guess I was not to far off.

There are a couple more factors to consider with a moving RV but I doubt they will impact much. The RV could be in a curve plus the friction between the tires and the road will be less.