What kind of rope for towing?

Wanting to pick up some rope to use to tow my son the lake when he gets tired paddling. Based on some searches, I picked up some 1/4" diamond braided poly from Home Depot, but now am noticing that the listed working load is only around 90 lbs. I’m guessing this cheap HD rope isn’t the right stuff, so can someone point me in the direction of what I should be looking for?



Are you paddling?
If you are paddling, a 90lb working load will be fine. That usually indicates a breaking strength of about 900 lbs, and you aren’t likely to generate the force equivalent of 90lbs by paddling.

If you want the best, get the Northwater Sea-Tow system. It’s really good for that sort of thing, but likely more than you need.

It’s strong enough

– Last Updated: Jun-13-11 9:56 PM EST –

First, the working load limit is a lot lower than the actual strength, but more to the point, you'd have to be Superman to ever put more than ten pounds of tension in the rope while towing, except for very short bursts. How do I know? I have an ancient electric trolling motor that generates 12 pounds of thrust, and it can move a small fishing boat as fast or faster than I can row it, and I can row with more power than I can paddle. Years ago a friend and I used an electric motor that produced 18 pounds of thrust, and it would easily make the boat go faster than a person could row it.

More important than strength is whether or "knot" you can work with it easily. Diamond braid is usually pretty easy to work with.

i use paracord fro everything
not sure if it will work for towing but it is from parachutes so its pretty strong

Same here…Paracord is great stuff, very strong, light, and holds a knot well yet is easy to untie.

Floating dock line from BPS
I picked up a 15’ piece of 1/2" black floating dock line from Bass Pro Shops for puttering around with my daughter on creeks and lakes. It has a pre-tied/fixed built-in handle on one end.

For the right situation, it’s perfectly adequate. 90% of my towing is pulling her empty boat while she swims or sits on my back deck.

When I’m guiding, I use a Kokatat tow belt and wear that.

1/4" diamond braid poly rope …

– Last Updated: Jun-14-11 10:31 AM EST –

....... 1/4" single braid polypropylene rope (and may have a synthetic core) will have an aprox. breaking stress point load of 310 - 387 lbs. at the knot or attach point when new , not abraded , not subjected to UV degradation .

In general the 90 lb. working load can be multiplied by a factor of 5 for safe use breaking load considerations but ...

the more conservitive and specific calculations to determine safe use breaking load may found this way . Rope circumference (1/4" x 3.14) squared = ____ , x 900 = ____ , x (1.4 for polypropylene) = ____ , minus 50-60 % = ___ .

.25 x 3.14 = 0.785 ... 0.785 x 0.785 = 0.616225 ... 0.616225 x 900 = 554 ... 554 x 1.4 = 775 ... 775 minus 50% = 388 ... or , 775 minus 60% = 310

So let's just say that your son and kayak weight about 150 lbs. . It is not difficult to imagine that 150 lbs. becoming 310 lbs. or much greater under a momentary magnification of stress during towing , such as a wave or rock/log , or hard jerk could create .

The rope is stretched tightly during the momentary magnification of stress and if it breaks ... the resulting recoil of the rope (especially thin ropes) could snap back like a rubber band and cause injury .

Further , best practice is to chose a rope that would double the most conservative breaking stress load .

A 90 lb. working load means exaclty what it sounds like ... it should not be used with greater than 90 lbs. of weight attached to it ... it "DOES NOT" mean it's OK to ignore the 90 lb. working load rating and use it with heavier weight loads attached to it .

Floating line
We have bow lines on our kayaks with snap hooks. Just clicking the hook onto a bungee works fine in flatwater.

My sister with her son in tow about 8 years ago.


Peak stress much less than that

– Last Updated: Jun-14-11 9:42 AM EST –

I've towed boats before, sometimes in choppy conditions that few solo canoers or rec kayakers would ever experience, and have never, by my best guess, put more than 15 pounds of tension in the tow line (and those were brief instances, not a steady pull). As a solo paddler (or solo rower) a good good method is to have the rope attached to your body, not your boat, because that way any jerks in the rope pulling from awkward angles don't mess with your boat control. In fact, kayakers do it that way all the time when rescuing a weaker paddler (that's why they use tow belts). If peak stress were as great as you suggest, people would get hurt while doing so, and also would get tipped over or yanked out of their boats. In my experience, the rope barely ever gets tight and the hardest jerks when the waves are big hardly amount to anything at all. I can think of other examples, but my main point is that I don't want the O.P. to be fearful about how dangerous this is going to be.

sounds good enough
Generally, for SK towing you need the following

  • quick release system
  • snag free attachment
  • and line, length determined by conditions. A bit longer is better than shorter, since you can daisy chain the unused part
  • where to store that line

    Sea Kayaker magazine had a writeup by Brian Day how to make your own, not that hard.

    Some people incorporate bungee into the towing system, that is not necessary for some ropes, since certain weaves and materials have quite a bit of give

    Folks add floats to towing systems, for obvious reasons ( so it does not sink when quick released), those can be incorporated into tow pack itself. Even though it is tempting to put float next to carabiner, it creates more problems than is worth.

    Carabiners should have smooth gates, material is mostly defined by were you paddle and the money available for purchase. Plastic carabiners used for water skiing are OK as well.

    Attachment should be smooth - knots tend to snag on lines too much.

    Read about the ropes here: www.mcmaster.com, search “About fibrous rope”

    Oh, you may purchase pre-packaged tow system :slight_smile:

I gave an estimate of 150 lb. load …

– Last Updated: Jun-14-11 11:48 AM EST –

..... if the attached load being pulled is 150 lb. , all it would take is a momentary light jerk to realize or exceed the full 150 lb. load applied to the rope .

gbg , how is it possible that you believe no more than a 15 lb. load could be applied to the rope at any time ??

All it takes is the tow vessel going one way and the towed vessel being momentarily stopped or going the other way (shock load) for the rope to realize or exceed the actual weight it is pulling .

A 90 lb. working load means just that , you shouldn't attach more than 90 lbs. to it because the chances of exceeding the breaking point load are real , even more so by a factor of 50-60 percent at a knot or attach point . The calcs. I gave prior are the way it is determined .

A brand new 1/4" single braid polypropylene rope will have about a 775 lb. breaking point under controlled continous pull ... this not taking into consideration the weaker breaking load at a knot or attach point , nor any form of shock loading . This is basically just stretching the rope until it breaks .

Can you tow a kakyak with the 1/4" poly rope ... sure you can . Can it break if the breaking point load becomes exceeded ... sure it can . Can you exceed the breaking point load towing a kayak on 1/4" poly rope ... sure you can if a shock load is momentarily applied .

The method or condition that causes the breaking point load to become exceeded is variable , and the rated working load takes into consideration all the variables .

not 150 lbs
i don’t think the load will approach 150lbs on the water.

when I paddle, the water is supporting my combined boat and body weight. During the stroke the forces on my paddle are less than 10lbs of pressure.

when towing you are overcoming the mass of the towed boat not the weight of the boat. And you are moving that mass on a realatively frictionless surface.

Simular to moving a 4 ton sailboat closer to the dock by pulling on the dock line by hand, there is never a 4 ton load on the dock line.

Don’t hang 90 lbs from it
"A 90 lb. working load means just that, you shouldn’t attach more than 90 lbs."

It actually means that you should not apply more than 90 pounds of force to it. You could achieve that by free hanging 91LBS from it or by tying it to a car and a tree, coiling it up, and then driving your car away from the tree. It is fine to attach 10,000 LBS to it as long as you don’t try to accelerate that 10,000 LBS by applying more that 90 LBS of force to it.

Didn’t you ever see that guy pull a train with his teeth?

Worst-case scenario of a sudden yank on the rope happening with enough force to go enough high enough above the OSHA LBS working load limit and then the breaking rope causing any sort of injury seems unlikely. Getting hit by a drunk power boater seems way more likely.


P.S. 90 LBS of force on a 250 LBS loaded kayak should generate 0.36 G’s of acceleration. Anyone ever felt that much acceleration for a moment during a tow when there was slack taken out of the system quickly?

Here’s my reasoning

– Last Updated: Jun-14-11 12:53 PM EST –

First, I have done this many many times, once in waves that were as high as my head. The rope was around my waist, the kayak I was pulling was 13 feet long and weighed 45 pounds, the paddler was 120 or 130 pounds, and there was 30 pound of cargo on the boat too. Still, in spite of the waves, the rope going slack and tightening again, and me pulling the oars as hard as I could because I didn't want the guys in the University of Wisconsin Rescue lookout tower to think we were "stuck" in the wind, at no time did I feel the slightest discomfort from the rope. It NEVER jerked hard, and it never got very tight at all. Period. Remember, it only takes about five pounds of force to move a kayak through the water at a pretty fast speed. Waves will slow the boat being towed, but they will not stop it suddenly or make it pull the other way.

Towing is NOT hard to do because the tension on the rope is great, it's hard to do because you have to double what's already a very weak propulsive force. As paddlers (or roweres) there's really not much extra propulsive thrust in reserve. That's why it's so much work to tow someone.

Kayak tour guides do this very frequently. If there were EVER such an enormous jerk on the line as you describe, kayakers performing tow rescues would be in serious trouble. It just doesn't happen.

Second, as I pointed out in my first post, near the top, you can use the thrust of an electric trolling motor as a guide. I know from personal experience that with a big load in my 12-foot Jon boat, a motor with 18 pounds of thrust will make it plow through the water at a much faster rate than a person could row it.

Finally, I use a long rope (40 feet or so) so that the on any jerk, the sag of the rope takes a bit longer than an instant to tighten. If there are waves, the rope becomes crooked both up and down and right to left when it goes slack, and thee's a bit of friction inthe water as the rope straightens, and that works as well as any bungie cord. I know you've never done this or you wouldn't be arguing with me. DO it. Go rescue a few tired paddlers when the wind is howling and the waves are big. You will change your mind.

Oh, here's one more way of explaining it since you do a lot of fishing. Ever pull your boat over to a snag using your fishing pole? It's not terribly difficult with heavy tackle, right? Tie your fishing line to a ten-pound weight and just TRY to lift it off the ground with your fishing pole. That'll put things in perspective for you.

Escellent point about the G-forces
I’m glad you know how to calculate that. That makes the point perfectly.

So, Force=MassAcceleration

Usually Force is measured in Newtons, Mass in Kilograms, Acceleration in m/s2. Since m/s2 is not oomphy enough, a lot of folks like to divide A by 9.81 and get G values.

US likes their values be traditional, so Force is measured in lbf, and Mass in lbm. Multiplier difference is 9.81

It is rather convenient then to get Acceleration in “Gs” - you take lbf and divide by lbm

90/250=9 10/(2510)= 9

I’m not arguing w/you gbg …

– Last Updated: Jun-14-11 3:18 PM EST –

...... what I said originally referenced the breaking point of 1/4" poly rope , it is what it is and all the towing w/your body or whatever isn't going to change that , it can break at aprox. the load given prior .

The rope would have to reach or exceed that point to break , period . Whether the OP or you or anyone else feels that a such a condition could arise sufficient enough to cause the rope to reach that point is intirely speculative ... if it does , it breaks , period .

My example given was a sufficient shock load .

Maybe we are heading down a river with you in tow ... the 1/4" poly rope tied to my boat and yours ... your boat drifts into a log or hangs on some rocks and stops abruptly ... something has to give ... maybe I get jerked to stop ... maybe the rope snaps ... something has to give . And at 310-350 lbs. of stress the 1/4" poly rope can break at the knot or attach point , period .

suriam seems to know how to calc. the math ... my boat and I weigh 250 lb. , I'm towing gbg , our speed is 3 mph. , gbg and boat weigh 250 lbs. , we are attached by the 1/4" poly rope ... gbg is stopped abruptly ... can this rope experience a shock load that might meet or exceed 310-350 lbs. ??

If it can , it can break ... if not then it won't break . I believe it can but the proper math applied to the scenario will either prove it possible or not .

williams , I think a 4 ton boat …
… in the water , weighs 4 tons .

The question was
about pulling an 8 yr old on a flat lake.

AND even if the towed vessel stopped dead the towing vessel would have to exert over 350 lbs of force to break the line. Between two paddle boats on the water I would not see the rope (even 1/4 inch) as the weak point. If a lost great white shark suddenly swallows the towed kayak whole and takes off the other way it is far more likely that the Dad’s kayak is going to start moving backwards than the line suddenly parting under the stress.

My point is not speculative
I am not speculating about this at all. I have towed other boats in conditions far more extreme than anything except what could happen when attaching a line between a swamped boat in a river and a fixed object, and that’s far outside the scope of this discussion. Kayak belts have a quick release so the rescuer can disconnect in a hurry, but the kind of jerk in the line needed to create the force you are talking about would not allow time to disconnect. Yet when have you heard of someone being flipped, yanked from the cockpit, and getting all bruised up around the waist due a jerk in the line strong enough to break the kind of rope we are talking about? You’ve got boats that take a couple of seconds to change speed by 1 or 2 mph, even at the moment of impact with a big wave (ever have your boat swept out from underneath you when hit by a wave? I didn’t think so), and you are talking as if one boat and its load is getting a high-speed running start or something. I’m just trying to keep this in the real world.