I’ve got some bolt-on hood loops that I plan on attaching to my vehicle to serve as bow tie-down anchors. The question I have is this:
Does the angle of the tie down ropes matter? I could mount the hood loops up near the headlights so that they are ahead/in front of the bow of the boat. But it might be easier to attach the hood loops in a position closer to the windshield that would have them behind the bow of the boat. In either case, the bow tie-down ropes would be pulling down and to the side, but is it important that they also be exerting forward force, or, alternatively, rearward force?
In case such info is useful, the rear tie-down ropes will necessarily be exerting forward force (as well as downward and sideward forces, of course). Another way to put this, perhaps: When viewed from the side, should bow tie-down ropes be closer to parallel with stern tie-down ropes (forward mounted) or closer to perpendicular with stern tie-down ropes (rearward mounted)? Or does it even matter?
I apologize for the clumsiness of this post. If I could have thought of even more convoluted wording, I surely would have included it…
just make sure…
that when viewed from the side (also known as an elevation view) the bowlines and sternlines are not parallel. I prefer them to be at opposing angles. In other words, the bowline comes back down toward the stern and the sternline down toward the bow. In order to do this with the bowlines, I have secured loops around the steel struts that are part of the hinge at the back of the hood near the windshield. They tuck away nicely under the hood when not in use. Fortunately my SUV has 2 steel eyelets for towing purposes on each side, below the rear bumper that serve nicely for the sternline.
What problem do you want to handle?
If you want to avoid the boat being able to slide backwards to the rear of the rack should there me a failure of the front strap or ropes, the bow line needs to angle forward. If you just want some tension to be able to see if things are moving, you can go further back.
One other option is to run a strap or loop of rope around the front hood bumpers and use that to tie the bow line to. That’a what we do, though it causes some interesting questions when the cars go in for an oil change and the loop is sticking out.
My experience is
that there is a tendency for the boats to slide forward with hard breaking for instance and so if possible I try to have a line set up to resist forward movement. It could be a line from the bow to a loop mounted up more toward the windshield.
Had good results
…placing the loops even with where the tie point on the boat is. With the boat well balanced on the racks, if you were to drop a plumb bob from the boat attach point where would it fall on the hood? The fender bolts even with that are about where the loops should go. No sense getting real finicky about it, measuring to the 1/16th inch and such, but right about there. (When you place your boat to do this, it might be worth your while to note whether it sticks out more than 4 ft. past the rear bumper. At least some states require flags and/or lights if it does.)
Set up like this the tie down ropes will be drawn tighter if the boat slips - no matter whether it slips forward or back. I like to put an extra wrap of rope around the boat attach point to add further resistance to keep the bow from slipping to either side in case a front strap breaks, loosens, or hasn’t been tightened properly. Usually that’s the main function, in my view, of the front tie down - to prevent the boat’s going caddywompus if puffed by a passing truck or side wind. I’ve found it’ll also help keep wet wooden gunnels from getting warped while drying on a long drive home, if that’s a concern of yours.
BTW, ALWAYS rock your car by pushing/pulling on your boat before you drive and whenever you stop for gas, food, or whatever. That’ll let you see if anything is working loose while on the road before it gets critical. Most folks do that anyhow, but if you’re new to all this, it’s worth mentioning. I doubt there’s a person here who hasn’t needed to snug up a rope or strap on a long drive.
Can alter attachment to boat too
As has been pointed out, it's best if the bow and stern lines oppose each other. That is, if the boat moves in a direction that causes one set of lines to loosen, it won't actually move much at all because it's causing the other set to tighten. If you attain an angle in your bow lines that goes upward and toward the rear from near the headlights to the bow of your boat, see if you can make your rear tie downs go upward and toward the front. There's no law that says the tie-downs at either end must attach to the ends of the boat. They can attach anywhere you please. When I carry a Jon boat on my roof, I have at least one line from hooks built into my bumper going forward up over the roof to a seat in the middle of the boat. With a canoe I angle a pair of lines forward from the rear bumper to a middle thwart. Doing this with a kayak takes a bit more ingenuity, but I've done it a few times and it's actually quite easy - you just need to rig a harness.
If your bow tie-downs go nearly straight up to the bow, as it seems they are likely to if going from the rear of the hood to the front of the boat, there's not much you can do to make the rear tie-downs oppose them because there's no angle to oppose. If both sets go straight up, they WILL get tighter if the boat shifts position, but the boat will have to move much farther before the motion is snubbed to a stop than if the lines were steeply angled and in opposition (if the reason for this isn't clear, just disconnect your main tie-downs and leave the vertical ones in place, and push the boat around. You'll see how much farther it can move than with angled, opposing lines. Still an okay system though, because the boat still won't come off the roof if all else fails).
As a final idea, you can have your front tie-downs angle up and to the rear, and you can make your rear tie-downs go up and to the rear as well, just because it's easiest, but then run another line from your rear bumper, forward up over the roof toward the front, even all the way to the bow if that's the only convenient connection point. That line will keep the boat from moving forward while the bow lines will keep it from moving backward. The rear pair will function only to keep the rear of the boat centered while the other three keep forward-backward motion under control. The front two will help keep the boat centered also. All this is mainly insurance in case the main tie-downs or the rack fail, but depending on your type of rack and type of boat, the front and rear pairs may provide extra stability against sideways shifting of the boat in cross winds too.