Everything ages and weakens with time, weather and sun. All you can do is remember what the USAF says (I was trained as a loadcrew for a C-130) “Two is One and One is None” so always use at least three, preferably 4 straps to different anchors.
The advantage to straps is that it distributes the load over a greater area and prevents the rope from becoming a wire-saw on your boat.
That thing about surface area, pressure, and wear and tear on your boat makes perfect sense, but as one who’s been using both straps and rope tie-downs for a long time, I can say that I’ve never seen the slightest bit of damage caused by rope, but my Royalex boats have faint, wear areas which are fine-textured imprints of the weave of my NRS straps. What seems to make sense regarding tie-down damage and what there’s evidence for can be two different things.
Keep what ever you use clean or it will grind your hull.
I have a sequence that I doo before strapping the boat down. I quickly visually inspect the straps, run the straps between my fingers in order to find any blemishes or tears. If the strap doesn’t pass my inspection, it’s not used. I keep my 4 sets of straps in a mesh bag and in a storage area in my Rav4…
I agree that straps have greater surface area that spreads the tension of tying down compared to ropes. For my glass boats, straps: I also tie an overhand knot just past the cam and tighten it against the cam in order to prevent slippage,
I do a few overhand knots
@PaddleDog52 said:
Keep what ever you use clean or it will grind your hull.
They are clean. I’m fussy about that (as anyone who’s familiar with my posts and ways of thinking would likely guess). I think this wear pattern is imprinted right at the location where the pressure of the strap against the hull very light (that pressure becomes less and less, closer to the location where there’s no contact at all), and there’s a tiny bit of vibration there. The strap material is pretty hard, and hammering away on a microscopic scale, and Royalex is very soft. Maybe yanking them super tight would stop that. I only make them tight enough that there’s no chance that the boat might move.
To help prevent any marking, or wear on the boat, I use some very soft and gentle material between the boat and the ropes. Some old synthetic sheepskin seat covers have served that purpose for years.