Your Thule stays intact, you are correct. The Thule stays on the car, the boat/ boats will stay on the car, the way you describe the tie down, no doubt. But if a rack fails and both towers are ripped off the car of the front bar, the boat/ boats are still securely tied to the rack, but the rack is no longer secured to the car. Bow and Stern lines by design are not taut and with the front bar not attached to the car anymore there is slack, at 75 mph and possible cross winds those forces are going to make that boat/boats move and when they move just a little bit to catch side wind it is over. That could happen with a Baseline System. I would not go 75 mph with kayaks on the roof.
Bow and Stern line description, depends on the length of the kayak and length of the roof area. Bow and Stern lines can be at quite an angle and the nose of the kayak would not be taking the brunt of the load, the strap would. Canāt quite envision what you mean by a āPoly Strap around the Bow and Stenā unless Bow and Stern lines are near vertical, if they are at a bad angle, force would pull the Poly Strap right off of the Bow and Stern.
I had a small little ford focus and bought a rack from a local outfitter. He actually installed mine to the car where he drilled holes into the ??door frame? I think this is where it was. So it was basically permanently attached to the car in several locations on all 4 doors That thing was not moving and it was such a snug fit. As long as my straps were good and tight and not showing any wear and tear where they would snap it really was snug.
With those Baseline type racks for bare roof cars where the end clips wrap around the top of the door frame, it would seem you could drill the bottom side of the clip and bottom side of the door frame and put a sheetmetal screw there, not for uplift, the hook takes care of that, but to keep the clip from moving out and disengaging the door frame. If the hook (clip) stays in place, it is not coming off.
If you only use a bow tie down, the front bar becomes a fulcrum. Downward pressure on the bow creates downward pressure on the front bar, but upward pressure on the back bar. Snugging a bow line without a stern line in place can be the primary cause of failure. Itās quite a long lever. Itās an easy way to compromise your roof rack.
If you use bow and stern tie downs, and pay attention as youāre snugging them up, the rack will be held to your roof by those lines. Always watch the bar and towers on the opposite side of the fulcrum as youāre snugging one end down. Get them both snug before giving the final snug down. I think this is probably a good example of why this is important.
You feel that having a Bow Line but not a Stern Line caused the right front tower to pop off and if there was a Stern Line it might not have? What do you think of going to the underside of the hook on the tower that slides onto the door jamb and drilling it and the door jamb and putting a Sheetmetal Set Screw into it?
I wish i had a picture of how mine was done but i donāt have it or car. But it took him a few minute to do it and that thing wasnāt going anywhere.
I think it increases the potential of a failed rain seal around the door, so Iād be careful about it. But yes, if any of your 4 points are compromised, it can increase the chance of failure of any of the 4 points. Iām not looking at the rack, and can only guess. The Yakima special screwdriver that I have can slip/click before things are snugged because the tower screws arenāt turning freely.
A properly tied bow keeps the bow from moving left to right. If the other end of the lever can still move, this still creates a twisting force. If your back towers are being pulled up instead of held down, that might provide for even a bit more give from the back. The front right was the one that popped off. Thereās a reason, even if it isnāt particularly obvious.
If nothing is compromised and nothing can twist, does a tower pop out?
I donāt know for sure how these towers are attached. I do know the whole thing can be much more soundly secured with both bow and stern meaningful and secure tie downs.
You can countersink the screw, so it creates no more potential for a failed rain seal than the bracket itself. I do not think I could trust the Yakima Baseline tower anchors without a set screw. You scare me about the Yakima Torque wrench giving false torque values, that can be very dangerous with someone who is not familiar with it. But it is true, if the bore and the bolt threads are not clean AND properly lubricated you can get false torque readings even with a good torque wrench let alone a give a long screwdriver that came with the kit. ARp goes to great lengths about this and developed their own special lubricant to help provide true torque values.
Correctly installed bow and stern lines and moderate speed.
In over 25 years of kayaking Iāve seen and heard of my share of boats coming off of cars and rack failures. However, Iāve never seen or heard of a properly secured kayak coming completely off of a vehicle due to the action of wind alone. Pretty much every case where a kayak and/or rack completely separated from a vehicle was due to the lack of properly used bow and stern tiedowns or a serious vehicle accident.
Thatās not to say that a serious rack failure might not tear up your vehicle somewhat, but the rack and kayak should stay with the vehicle and not endanger others.
Iāve got a set of Yakima towers on my Yakima rack and found them to be disappointing. They donāt stay in place on those round bars all that well. Every trip or two Iām always tugging on the rack itself checking the integrity . For peace of mind on your okie trip open the car doors and run a strap through the car and around the boats and rack as an insurance policy. You will probably have to put two straps together to do this.
I understand what you are trying to say here, and the idea you are trying to convey is correct but the terminology is not. Your chosen terminology equates applied torque with fastener tension, but these two things are not the same (I think you already know this but are just misusing the terms out of habit, as many people do). Extra rotational friction caused by dirty or ill-fitting threads doesnāt cause a torque wrench to give a false indication of torque. It causes the user of the torque wrench to have a false idea of how tight the fasteners are. A torque-measuring device (assuming it is properly calibrated and is of good enough quality to work consistently) will always indicate the actual amount of torque that it applies, but what it wonāt do is ādo the thinking for youā in cases where rotational resistance is higher than expected. In the end, the only value that matters is tension within the fastener (clamping force). How much torque is required to achieve that tension will vary on account of many different factors, some of which are predicable (these are the factors used to determine proper torque values) and some which are not.
To summarize what I think you were intending to say here, if the tower screws do not turn freely, itās the tension in those screws that ends up being too low when the āproperā amount of torque is applied, but the amount of torque will still be whatever the torque wrench indicates that it is. In such a case, the applied value of torque must be greater than the specified value to make up for frictional resistance to rotation of the fastener so that the fastener ends up being sufficiently tight.
This variation in rotational resistance can work in the opposite direction too. When specified values of torque are applicable for āclean and dry threadsā, an experienced mechanic will apply less than the specified torque if the threads are clean and lubricated, since in many applications the reduction in friction provided by lubrication will result in over-tightening if the specified torque value is applied.
You, of course, are correct on every point and ARP (Not AARP) again goes to great lengths on clamping force and it goes into the design of its bolts to achieve the correct clamping force per torque value along with highly recommending running a chaser tap, cleaning the bolt bore, cleaning the bolt threads and using the correct lubricant to the point of developing their own proprietary bolt lubricant to achieve the correct clamping force per torque. But this was a casual, unedited, off the cuff, type and post comment where the phrase ā Torque Readingā was used instead of āTorque Valueā.But you are correct and there is no need to spread misunderstanding or perpetuate misconceptions.
Iām the original poster, and I want to thank you all a whole lot for these comments and suggestions. I will send a picture but yet, the Yakima towers are the Baseline model. After reading all these, I think I will use my sonās Subaru which has ābuilt-onā towers and cross bars for long trips. For shorter ones Iāll use the Prius, but go slower. And I like the idea of tying an extra strap in the car and across the boat(s). One adjustment Iāve now learned and is not mentioned in this thread: I initially thought there was only one thing to tighten - the main screw that that is tilted down and regulates the tension on the clip overall. But thereās a second screw, tightened by the same wrench, that regulates the angle of the clip against the roof. I donāt think that screw was sufficiently tightened. Thoughts? And again, many thanks.
The Baseline is still ā Clippedā to the door jamb. It is well design, engineered and has good aesthetics, but it is still a clip. Talk to your installer about putting a set screw on the underside of the Clip into the door jamb. The Towers holding on to the round bars is a separate issue. Perhaps that has improved on the Baseline since @tdaniel ās rack.
Edit: The Yakima official instruction video mentioned above, shows all of the adjustments and there are many.
I have a differing opinion of the integrity of the baseline-type racks that clip onto the doorframe of a car. Iām not familiar with Yakimaās system, but on my Thule towers, the clips pull upward and swing inward (toward the center of the car) as the adjusting screw is tightened. Kind of like the clamping motion of one of those claws on an arcade claw game. It makes for quite a secure clamping action, and nothing like a clip simply attached to a strap as on some cheap, universal cross bars.
You could argue that cross bars attached to OEM roof rails on a car have more points of possible failure, as the rail could detach from the carās roof (some are held on with just two bolts per side), and the cross bar could also detach from the rail. In any event, thereās nothing like good bow and stern tie downs to minimize the impact of any possible rack failure.
Bottom line is right here on this one little thread @rickd ās right front tower totally detatched from the car and would not stay on and had to be tied down with a strap, avoiding a major disaster and @chicago_paddler had a tower clip rip off of his car, both Baseline Systems. Thules perform better?