View topic - Canoe on roof rack: Need front & rear tiedowns if . . .?

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PostPosted: August 15th, 2017, 9:34 pm 
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I am just getting back into canoeing after literally decades away from it, and have never before needed to carry a canoe on my car's roof rack.

The car is a Mercedes 300 body series and has a really good Thule roof rack made for Mercedes by Thule. The front and rear crossbars are spaced 30 inches apart, and are secured to the roof via 3/8"bolts that threadinto boltholes hiddeen via flip-up doors. I have the set of 4 Thule Portage blocks on the crossbars to prevent any side movement of the canoe. The car is 15 feet long.

The canoe is a 16-1/2 foot Wenonah Solo Plus, and is the "Ultralight Kevlar" version. It weighs 42.6lb despite the Kevlar, because it has 3 adjustable seats and a foot brace. It has "tumblehome sides", with the maximum canoe width being about 32" and the gunwale width being 29". I mention the tumbelhome and the Kevlar because clearly itis important to not crush the canoe sides via too much tension on the roof tiedowns.

It is VERY difficult to find any attachment points on my car for both front and rear tiedowns. Nothing under the bumpers. I tried front and rera tiedowns today from the trunk lid edge and the hood edges, and got spooked because one of the hood tiedowns marked the paint near the edge of the hood when the tiedown "vibrated" on the road.I got the marks out by cleaning them and rewaxing,but I don't want to risk damaging the car paint - the car is pretty costly.

My usage dictates that most canoe hauling trips will be about 6 miles including return, at speeds not exceeding 60 kph.SOME trips may go as far as 30 miles including return, at speeds up to 80 kph.

Iwon't be going out on windy days, as the lakes (which are long and narrow) and coastal areas become too choppy with wind for my skill sets.

With those conditions, do I really need front and rear tiedowns?

Jim G


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PostPosted: August 15th, 2017, 10:28 pm 
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Twist your webbing and it won't vibrate.

I use these under the hood and twist the webbing when I loop through them for the truckers knot:
https://www.mec.ca/en/product/5022-901/Quick-Loop-Tie-Downs

I usually use rope (except for the webbing loops) to avoid the vibration issue. I just picked up a short boat from the US with my wife's Honda Fit (foam blocks, no roof rack) and used a length of webbing through doors. When I got to freeway speeds there was a very loud hum and the entire car was shaking! I popped in to the next rest stop and twisted the webbing which stopped the vibration.

I would trust a name brand roof rack mounted to a bare roof over one mounted to factory rails but still think tying to the car as well is best. Worst case Ontario, the angle of the boat causes it to catch wind and put upward pressure on the roof rack. Probably unlikely though.

Most practical reason to tie to the hood is the car topping a canoe on a windy day at highway speeds you may find the boat rotates (bow moves left or right with respect to the car). Tie two individual ropes from the canoe to the hood tie downs and you will reduce the movement of the boat.


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PostPosted: August 15th, 2017, 10:55 pm 
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Neil Fitzpatrick wrote:


. . .I would trust a name brand roof rack mounted to a bare roof over one mounted to factory rails but still think tying to the car as well is best. Worst case Ontario, the angle of the boat causes it to catch wind and put upward pressure on the roof rack. Probably unlikely though.
. . .

.


I'm not sure you understood the way my roof rack is mounted.

Mercedes provides 4 recessed metal boltholes that are welded into the steel roof framing of the car. Each bolthole is covered by a small 1" x 3" flip-up door when not in use. When in use, the flip-up doors are flipped open, and each of 4 THULE towers is bolted into each such bolt hole via a 3/8" diameter bolt. Two Thule crossbars are used. 4 Thule "Portage" blocks are bolted to the 2 crossbars (2 to each of the front and rear crossbars). There are no roof mounted "factory rails" in this setup. In addition, there is NO contact with the factory paint. The towers sit about 1/16"above the car roof - only the BOLTS in their flip-up-door compartments contact the car! So,no chance of paint damage.

So,the towers and crossbars are solidly bolted via 3/8" bolts to the car's roof frame, and so cannot move or slide. The Thule Portage blocks are bolted to the crossbars either just inside or just outside the canoe's gunwales (just INside on my installation). These blocks make it impossible for the canoe to get "cocked" (i.e. it cannot become misaligned from the centerline of the car). A tiedown on each crossbar secures the canoe to the Portage blocks and crossbars,so the canoe cannot move up, down, or sideways.

It's hard to imagine how the canoe could move, slide, or fall off unless I go out in a real windstorm. But, I never go out in a windstorm, as wind strong enough to be a threat to the canoe on the rack would certainly be an unmanageable threat on the lake or coastal sea! And,asI said above,my maximumspeed is usually 65 kph, and only occasionally on the trips to locations further away gets up to no more than 80 kph. So,not much wind force. There are never going to be real "highway" trips - only local,lower speed trips.

If I do need to use front or rear tiedowns, I will try your "twisted" configuration, but I really wonder if I need the front or rear tiedowns with the solid way the canoe is connected to the car's roof structure. And of course loading and unloading both become MUCH faster if only the rack tiedowns are needed.

Jim G


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PostPosted: August 16th, 2017, 1:06 am 
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When a tower breaks the canoe can slide loose
If you have the funds to insure that the person who is hit by a loose canoe is compensated: sure don't do the extra minute each for bow and stern lines.
Most of us don't have that million dollars .

You've already made up your mind
Stay off the Great Plains. No windstorms and it can still have 80 kph hour winds
I don't agree with your logic It is not much harder to add tie down loops and use them.


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PostPosted: August 16th, 2017, 1:08 am 
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I know how your bolts work. They will hold the canoe, yes, if that was all you had to contend with.

IMH(but vociferous)O you need the front ties to the sides if you go over about 60kph or so. The reason is to protect the canoe from twisting. One source is the force of the wall of wind from a passing truck. It is a light hull and you probably don't want to subject it to the kind of twisting that can happen with only being tied down to the rack. Clearly you understand this in your mention of the risks of tumblehome and being tightly secured. Other winds or forces could also twist or stress it - so secure it. Use those hood-edge things and make sure the lines are taut - that should be enough - and pulling to the side against the lateral forces of the wind (you don't need them to give you vertical holding power). If necessary find or make a higher point (i.e. lower on the hull) to secure the ropes so they have a steeper angle. A yoke or bridle made of strapping would do that but I have never seen one. (BTW I keep mine taut and they are off the paint, if they droop it means time to snug them again.) Tiedowns at the rear are a bit less critical, but they too help prevent that lateral twisting.

BTW: You cannot guarantee that you will not be out with the boat on the car in a windstorm. As one example only, with the canoe on the roof driving home in a in a short summer thunderstorm you can have "devil winds" that swirl and gust to 75+kph. So, you might as well be prepared for it.

And while we are at it, in my conversations with paddlers I have come to believe that the two most common (unintended) ways canoes come off racks are:
1. Not actually tied on. Seems to be more likely to happen when two are being carried, or someone is "helping." Make sure the driver always makes final checks. Enough said....
2. Hard braking and the canoe slides forward. Can be tricky. If you only have top straps then the front strap need stretch only a teeny tiny amount to allow the canoe to shoot forward - depends on how much the canoe bellies out in the 12-20 inches from that strap to the widest part of the canoe. Front and back tiedowns can help - but will still allow some, or much, movement. I recommend a rope, strap, or belt from a solid crossbar running forward to the next thwart or seat of the canoe. Then it can't shoot forward, at least not very much at all.

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PostPosted: August 16th, 2017, 6:10 am 
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I think your rack will do just fine, so long as your remember to tie the canoe so it cannot move forward or backwards as well. It's just my opinion, based on Chevy Caprice Wagon factory rack and Mazda 3 (Thule) rack experience.

Two alternatives come to mind. Webbing attached to a fender bolt under the hood and talking to your Mercedes dealer.

I can't speak to the structural integrity of your canoe in a wind storm though; it might get twisted up.


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PostPosted: August 16th, 2017, 7:28 am 
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The problem of no bow/stern tie downs is not so much the boat leaving the car as it being cranked sideways when a large truck passes the car. Enough pressure can be generated to crack the gell coat against the overhead straps.

After damaging a boat many years ago, I always use bow an stern tie downs on tandem boats. Solo boats are too short to suffer the same problem.


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PostPosted: August 16th, 2017, 7:49 am 
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You don't say what year your Mercedes is, but it has been required for some time now that European cars have front and rear tow hook mounting points in the bumpers. On both my BMW and my Audi, these have been on the passenger side of the car, but that may just be coincidence. There is one tow hook in the compartment where the optional spare tire and jack are located. I purchased a second tow hook from the dealer's parts department.

These tow hooks screw into a port behind a pop-off panel at the front and rear of the car. A strong fingernail or a flat screwdriver blade carefully inserted will get the panel off, although there is usually a retaining leash that needs to be unhooked so you can safely store the panel in the car rather than leaving it dangling.

The tow hooks will (usually) hold the straps or ropes clear of the body panels so there is no worry about abrading the paint.

The only downside is that you do not have tiedowns on both sides of the canoe to hold it steady. You get one connection holding the canoe to one side. I have had two sea kayaks on my roof at highway speeds, both on very windy days and passing transports, with this method and have had no ill effects.


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PostPosted: August 16th, 2017, 8:00 am 
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I use permanently mounted under hood loops like these:
https://www.mec.ca/en/product/5047-417/ ... ops---Pair

The ones suggested earlier that can be closed under the hood work well too.

Then I put a 3" strip of 3M protective film along the edge of the hood where the strap will contact the paint. The film is clear and basically invisible (my car is white). After 2 years I have not worn through it.


I have scratched the paint on my bumper in the past with straps hooked up under the car. Though this was during a long trip on rough gravel roads. Dust gets behind the strap, then slight movement back and forth for a few hours = scratched right though the paint. I don't like straps touching any painted part of my cars. The under hood loops are much easier to reach anyway.


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PostPosted: August 16th, 2017, 9:35 am 
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Exactly what Neil says +++
My wife's small Suzuki has the same kind of locking roof rack described in the OP. It has never let us down. Similarly my minivan factory roof racks work well. In both cases having front and rear tie downs make it all very much safer and secure. I made my own under hood thingys and am really impressed with how well they work at keeping the canoe tight under windy conditions. Weather changes and then there's truck wash too. Might as well be a boy/girl scout and be prepared than not. Tie downs and racks are only as secure as the person doing the tying and securing. I keep a selection of extra lengths of rope and spare straps in a bag stashed in the vehicles.
Rope is cheap and you only really need to learn 1 or 2 knots. Truckers and Bow Line.
BTW I loved using the straps through the car doors approach when we didn't have roof racks and relied on pool noodles wrapping the gunnels. That worked exceedingly well.
Don't be complacent and just let things slide. (Sorry for the pun.) Stop for a moment down the road, especially in wind and rain, and double check everything. Like I say driving conditions can change between home and put-in, take-out and home.


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PostPosted: August 16th, 2017, 11:22 am 
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You guys are convincing me that finding a way to enable front and rear tiedowns is a good idea. That said, the problem I have is how to do it on my specific car.

Here are the challenges:

The 16.5 foot length of the canoe,coupled with the 15 foot length of the car AND the rearward bias of the car's passenger compartment, means that when the canoe is "balanced" on the roof, the stern tiedown point is 1-1/2 feet rearward of the rear bumper. So, the 2 rear tiedowns, secured to 2 web loops trapped by the rear lip of the trunk lid, are "clear" of the car's paint. This is fine.

The bow tiedown though is a different story. The bow tiedown point on the canoe is slightly short of the front license plate, so the front tielines cannot be "in front of" the car's paint. There is also NO solid item on the front of the car to attach the front tiedowns to! The grill, the chassis surfaces under the front lip of the hood, and the "bumper" surfaces, are all plastic! There is even a large plastic panel underneath the chassis forchassis aero purpoases! There is a towhook behind a small body-colored access panel (as mentioned in one of the reply postings above), but only on the passenger side. And, even if there were 2 solid metal points to attach to somewhere, the tiedown lines would contact paint along much of their paths! And asI mentioned above, I have already experienced a paint issue on the very first shorttrip from the canoe dealership.

The only available potential attachment points are the front fender wheel cutout lips,and the hood itself. But both present big problems:

If I attach to the fender lips,the bulged shape of the fenders guarantees lots of paint contact.

I cannot attach to the front lip of the hood, as, almost incredibly, the entire underhood surface,for at least a foot, has NO metal attachment points for underhood loops, on either the hood or the chassis surface under it!

I was able to attach to 2 metal points underneath the passenger and driver SIDES of the hood for the trip from the dealership, BUT with the bulged shape of the hood,avoiding contact with the car's paint is impossible (This model of Mercedes has a large V8 engine and wide tires stuffed into a 300 series body, so Mercedes "bulged the hood and fenders to make everything fit :D ). THAT's where I had the paint issue on the trip home from the dealership. I used webstrap loops to make the connection between the web tiedown straps and the underhood metal points, and one of the 2 webstrap loops, the passenger side, "vibrated" enough at 45 to 50 mph (dealership is 40 miles away) to leave a gritty dirt pattern in the paint. Fortunately, this time, the dirty pattern came off with clean water and application and polishing of wax to the area,but it thoroughly spooked me on using the sides of the bulged hood for tiedowns!

An internet article I read last night seemedto say that you can eliminate or at least diminish this type of vibratory movement of a tiedown via one of two ways:
- Put "twists" into the webstrap, or
- Use rope versus webstrap material (apparently rope does not "vibrate" like webstrapmaterial does?)
Is this true?

As you can see, figuring out how to mount front tiedown straps on my car is difficult, particularly with my lack of canoe transporting experience.

What are some good ways to solve this?

Jim G


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PostPosted: August 16th, 2017, 4:03 pm 
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JimGnitecki wrote:
- Use rope versus webstrap material (apparently rope does not "vibrate" like webstrapmaterial does?)
Is this true?
Jim G

Yup. Absolutely. The reason is that the strap, when slicing through the air sideways, works a bit like a reed in a wind instrument, or blowing through a piece of grass between your thumbs when you were a kid. The guy who is sloppy and leaves the straps any old way doesn't get vibration, but the guy who is very careful that they are all flat and oriented the same way might have quite a lot. :-?

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PostPosted: August 16th, 2017, 4:21 pm 
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I have a suburban with a lot of space between front and back racks and I fooled myself a few years ago into thinking I did not need the front and back straps. Highway speeds and strong winds proved otherwise. The one of the canoes twisted pretty far and scared the crap out of me. I immediately pulled over and put the straps on.

Since then I still don't worry too much about front and back straps around town - so I think up to 60km/h you are probably fine. But it is pretty easy to apply them so I almost never go without just the same.


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PostPosted: August 16th, 2017, 4:59 pm 
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vpsoccer wrote:
JimGnitecki wrote:
- Use rope versus webstrap material (apparently rope does not "vibrate" like webstrapmaterial does?)
Is this true?
Jim G

Yup. Absolutely. The reason is that the strap, when slicing through the air sideways, works a bit like a reed in a wind instrument, or blowing through a piece of grass between your thumbs when you were a kid. The guy who is sloppy and leaves the straps any old way doesn't get vibration, but the guy who is very careful that they are all flat and oriented the same way might have quite a lot. :-?


Yeah, I am the type of guy that makes sure every tiedown is precisely flat and oriented the same way,so it sounds like that might have been the cause of the trouble! Thank-you!

Jim G


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PostPosted: August 16th, 2017, 6:09 pm 
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I suspect that a large percentage of the members of this forum have been involved in one or more situations in which a canoe or a kayak came off the top of a vehicle, or almost came off the top of a vehicle. I have been involved in several myself. You don't want this to happen. It is tough on the boat, it is tough on any other vehicles which may encounter the loose boat, and it can screw up your boating trip.

Various posters have pointed out that one reason you need to tie down at least the bow of your canoe when carrying it on the roof of your car is so the bow doesn't get twisted to the right or the left by gusts of wind. Another reason is because the bars of your roof rack are only 30" apart, but your canoe is 16.6' long. Consequently, the rack doesn't do a good job of keeping the bow and stern from bouncing up and down as your car goes over bumps. Ropes which tie the bow to the front of your vehicle and the stern to the back of your vehicle will do a good job of keeping the ends of your canoe from pitching up and down on the roof of your vehicle.

A more important reason to use bow and stern lines when transporting your canoe is that canoes and kayaks are pretty good at slipping out from underneath straps. Canoes and kayaks get narrower towards their bow and stern, straps can loosen when they get wet, canoes or kayaks can slide forward when you hit the brakes hard, and canoes or kayaks can slide backward due to wind pressure. Three points of attachment are better than two points of attachment, and four points of attachment are better than three points of attachment.

Bow and stern ropes can do a pretty good job of keeping the bow of your canoe from twisting to the right or the left, and they can do a pretty good job of keeping the bow and stern of your canoe from pitching up and down. But when your canoe is about the same length as your vehicle, bow and stern ropes don't do a good job of keeping a canoe from sliding forward or backward on the roof rack. There are easy ways to keep a canoe from sliding forward or backward. One way is to attach a boat strap around one roof rack and a thwart or seat which keeps the canoe from sliding forward, and a second boats strap around one roof rack and a different gunwale or seat which keeps the canoe from sliding backwards. These straps will keep the canoe locked in place on your roof rack. If a thwart is positioned right above one of your roof racks, you can wrap a single short boat strap around both the rack and the thwart to hold the canoe in place.

With regard to attachment points: For many years I had vehicles which had tow hooks or other solid attachment points under the front of the vehicle. I recently bought an SUV which had no tow hooks, and which had fiber or rubber sheets bolted under the nose which prevented me from tying ropes to the frame or suspension of the vehicle. But these sheets are attached with bolts. So I replaced one of the bolts with a stainless steel bolt which is about 1 cm longer than the original bolt, and used the new bolt to attach a heavy metal strap wrapped around a heavy D ring. This provides an solid and easy to reach attachment point under the front of my new vehicle.


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