Dock Line Size ...

[Carl C]

I got my new dock lines today and they look as good as any I've seen. Two year old thread on OSO and not one complaint about them. They are about half the price most charge.

[Hilltopper]

Sorry to be late in this thread, but line size for me is about non-cutting in the hand diameter and not about load capacity. I have always used 1/2 minimum including my 37' sail footers. Too small diameter is hurtful in a blow or a tow!

[Carl C]

Sorry to be late in this thread, but line size for me is about non-cutting in the hand diameter and not about load capacity. I have always used 1/2 minimum including my 37' sail footers. Too small diameter is hurtful in a blow or a tow!

The 1/2" seems perfect for me. It fits my cleats nicely. It's also what Donzi sent me originally for the boat.

[Ghost]

A few thoughts:

• First, I only wrote all this because there's some potentially painful bad information floating around in this thread. Trying to keep people from making bad choices.
• Second, Hilltopper, you're right. 1/2" is nice on one's hand. I'm 100% with you there. I'd even take 5/8" over that if it was the only factor. That's the principal disadvantage of the smaller line I recommend. (For feel I'll also take double-braid over 3-strand also.) My thoughts are that the other factors outweigh those, but I'm on the same page about the preference for larger.
• For the most part, since the days of Manilla rope passed, there is one and only one material for dock lines. Nylon. One needn't look far to find consensus among the experts on this. Try Chapman's I'm sure. Try the West Advisor. Try Boat US.​
  
  • ​http://www.westmarine.com/WestAdvisor/Dock-Lines
  • http://www.boatus.com/boattech/casey...ines-casey.asp
  
  
• And the resources above will be very clear that you don't need (nor want) anything larger than 3/8" for a boat up to 27 feet or so. Of course, when they say that, it's based on the fact that they're assuming you'll have followed bullet 1, and that you'll use nylon like they told you to.
• Despite the claims to the contrary, there actually are a few complaints in the 2-year OSO thread about these very inexpensive polypropylene dock lines from Mad Dog. Not many, but a few. Two or three are about the color running when the lines got wet the first time. One is about the color fading. Only one comment in the whole thread has anything to do with performance under stress. "[the Mad Dog lines] stretched and frayed on pilings in KW and stretched under stress from wave action at LOTO. I had to readjust them numerous times due to stretching." It is also, I believe, the ONLY comment in the entire thread noting the actual PERFORMANCE of the lines under any adverse conditions. FWIW, it is a negative comment. Note that it refers to the lines stretching and NOT rebounding back. It means the lines got permanently longer. So, they became too long, and thus loose when the boat was tied up. My preference for "stretch" is about lines that stretch and then bounce back to their original length right away.
• Not that I am concerned much with the comments in the OSO thread anyway, as I'm not claiming they are worth much. Why not?
  
  • First, the VAST majority of the comments are from guys who just opened a cardboard box full of shiny new pretty-colored lines. They haven't even tried them. They know nothing of how they perform at all.
  • Second, what would we expect to hear from the sample of people in the thread? Especially from folks who clearly don't know that they should be buying nylon, much less why. If one of those polypropylene lines (with the sewn (not spliced) "splices") actually is strong enough not to fail under load, it may well rip out a cleat or break up the glass at the cleat mount, because it doesn't give enough under shock loading. If something ever fails, the guys who didn't understand that stretch reduces load are unlikely to realize the problem wasn't with the cleat or the glass. They are unlikely to realize the problem was with the punishment they gave the cleat and the glass because they chose the wrong dock lines. Put simply, if there is a problem, we are unlikely to hear about it from the OSO thread.
  • Third, most people won't have a problem anyway, as they don't test their dock lines with rough conditions often, if ever. Imagine a thread of people driving cheap, pretty new cars with 1-star crash-test ratings. But nobody's ever been in a wreck. Not likely to find out whether the crash-protection of their cars is sufficient. As before, if there is a problem, we are unlikely to hear about it from the OSO thread.
  
  
• The guy running the business selling ultra-inexpensive polypropylene dock lines sounds like a very good, honest, stand-up guy who delivers excellent customer service. Kudos to him for that. But if that's the case, he also has limited experience. For any who doubt this, note that along with his polypropylene dock lines, he is selling anchor "lines" of the same material. They are advertised, among other things, touting that they FLOAT. "Repels water and float" [sic] as quoted right off his web site (http://www.maddogproducts.com/anchor_lines.html). This is a clear sign of inexperience. No anchor rode should float. It is not just inadvisable, it is a TERRIBLE, TERRIBLE idea. It might sound good to someone who doesn't know any better, but it is TERRIBLE. No one who knows the pointy end from the stern wants a floating anchor rode, much less sells same to others. Again, does not mean he's a bad guy with bad intentions, just means his experience/knowledge is limited.
• Those Mad Dog lines are not spliced. The free end is sewn back onto the line to form a loop. Done with great knowledge and expertise and the right materials, this can perhaps be done well. Per the above bullet, we know this company lacks some very fundamental nautical experience and expertise. Thus, I doubt they are sewing their so-called "splices" with great knowledge and expertise and proper materials. (They aren't even using the right material for the dock line itself after all.) So, good reason not to trust the "splices", EVEN IF one is happy with the dock line material. Which, for all the reasons above, one should not be.
• Ironically, the only example we have of anyone actually challenging a dock line's bona fides under adverse conditions is Carl's. He snapped a 1/2" dock line. And insists a 3/8" 3-strand nylon dock line can't be "sufficient for Lake Erie" simply because it is 3/8". Because he snapped a 1/2" line. Yet:
  
  • he is replacing the clearly insufficient 1/2" line that broke with...wait for it... another 1/2" line, based on diameter alone. Ohhh-kay....that logic fails me...AND
  • his thinking ignores that the stretch of nylon means that a 3/8" nylon dock line can live where a 1/2" polypropylene line with little stretch would fail (or cause a cleat or the mounting fiberglass to fail). The force on a line (and a cleat, and the glass) is equal to the RATE OF CHANGE OF MOMENTUM of the boat that wants to move away, which the dock line has to stop.
    
    • IF the line has little stretch (say, 2-4%) with polypropylene, the boat's movement is stopped with a sharp jolt, where the change in momentum happens in a VERY brief time. So, the force = change of momentum/a very short time
    • IF the line stretches a lot (say, 15%) as with nylon, the change in the boat's momentum is spread over much more time, cushioning the blow like a stretchy rubber band would. Perhaps 5 or 10 times as much time to stop the same momentum. So, the force = the same change of momentum/a much larger time.
    • Making the denominator much bigger makes the force much less. This is how a stretchy 3/8" nylon line can be effectively stronger than a 1/2" polypropylene line with a higher breaking strength but very little stretch. The line isn't necessarily stronger, but the line's stretch causes the force on the line (and the cleats, and the glass) to be much smaller.
  
  
• ​All that said, for most folks in our world, the Mad Dog dock lines will be fine. Most people in this community (and on the OSO thread no doubt) keep their boats on trailers or lifts, use their dock lines simply to launch and retrieve at the ramp, and to tie up at lunch in perfectly calm water. Please don't get me wrong. If that's the extent of what your dock lines will encounter, I expect you will be fine with ultra-cheap, sewn-"splice" polypropylene. You'd be even better off with nylon, but it is unlikely ever to matter. It's only going to matter if it matters. When the weather surprises you. When a jerk hits you with a big wake in a no-wake zone, whatever. If you ever do find out 1/2" polypropylene was a bad idea, it'll be something like that. Like what happened to Carl. Which is why, ironically, he of all people, should consider using the right material this time around.
• 3/8" nylon with a proper splice is by FAR the better choice. Stretching will lessen the load on the line itself on the cleats, on the glass holding the cleats, everything. The fact that the line it ISN'T oversized like 1/2" polypropylene helps it stretch. The fact that it is nylon instead of polypropylene helps it stretch. The fact that it's nylon means it won't degrade from sunlight like polypropylene. (If it's 3 strand, it'll stretch even better. If you are using permanent dock lines instead of transient, double-braid will help with chafe, even if it stretches less than 3-strand. It's a trade-off.) Having a proper splice is likely to help, rather than having a sewn "splice" like Mad Dog offers.
• Some years back, in the interest of safety, Stan (Inferno on the board, a professional offshore racer for many years and a Lifeline dealer) offered us all Lifeline jackets at cost. He didn't need to, but he did it to increase safety in our community. Folks were adding more and more performance to their boats and it was a very generous way to encourage safety. I don't have near Stan's expertise nor experience, but I firmly believe my info on dock lines is largely on the mark. I'll gladly share whatever I know with anyone if anyone has questions or doubts. It's not much to give back, but this is something I know a little about. 1/2" sewn "splice" polypropylene dock lines are, quite simply, a bad idea. A bad idea that most people will get away with because they're never challenged. Parachute cord would be strong enough for most people. But if I can help anyone with dock line or tow-line info, please PM me. I'll share the best info I have. It's not much to give back, but I've looked at this pretty closely over the years.

Carl, at least grab some snubbers for your next trip to Lake Erie. http://www.gandermountain.com/modper...ls.cgi?i=78500 If 3/8" isn't strong enough somehow, bump up to a larger size of 3-strand nylon.

BTW, it's a LOT cheaper to buy nylon than it is to buy snubbers. And, it's a lot cheaper to buy nylon than it is to replace polypropylene every couple years due to UV deterioration. Ironically, the linked sources above mention this also. Polypropylene looks cheap, but it's a sucker bet most of the time. For comparison BTW, the SeaFit 3/8" 3-strand nylon professionally-spliced 20-foot dock lines I mentioned are $15. The 1/2" polypropylene sewn-"splice" 20-foot dock lines at Mad Dog are $13.50. That's $1.50 savings. The UV deterioration of polypropylene is enough to make that a sucker bet compared to the nylon.

Don't take my word for anything. Follow the links. Read what the experts say. And read the thread on OSO. http://www.offshoreonly.com/forums/g...ock-lines.html

It'll be painfully obvious that what the folks in the OSO thread care about is:

• appearance
• price
• customer servce

All of which they are getting, in spades. What they aren't talking about is how the lines perform under load when the chips are down and you're not just tying up for lunch in glassy water. And what those adverse conditions do to to their cleats and their glass, when the lines don't have enough give. One or two good folks in the OSO thread tried to point this out, citing expert links, but to no avail. I'm trying to give folks the explanation instead of just citing the experts.

Buying the cheap 1/2" polypropylene lines is a bit like buying a good-looking nerf fire extinguisher for $5. Lots cheaper than a real one. Comes in more pretty colors than a real one. Lightweight. Floats. Fools the Coast Guard on a safety inspection. Does just fine, as long as it doesn't need to deal with a real emergency. And very few fire extinguishers ever do, so...odds are the nerf will do all you need.

Judge for yourselves.

[Ghost]

The 1/2" seems perfect for me. It fits my cleats nicely. It's also what Donzi sent me originally for the boat.

It's also what broke. Can't be perfect, no?

[Just Say N20]

Who knew there was so much to consider regarding dock lines?

I feel so much smarter now!

[Ghost]

Who knew there was so much to consider regarding dock lines?

I feel so much smarter now!

LOL Bill, it's a bit like explaining in detail why round wheels are better than square. Most people never need to hear it. But the guy with the square wheels does. And so do any people whom he is encouraging to buy square wheels, if they are tempted.

[Ed Donnelly]

If you get a gift of lines, how do you tell the difference between nylon and
polypropylene? Ed

[Ghost]

Nylon will sink where polypropylene will float. That's one difference for sure. Most of the nylon varieties (3-strand and double-braid) are well-known, so they're probably recognizable, if you have a close-up pic. Also, I'd expect we can look at the lines and see whether they are properly spliced, or whether they have a sewn "splice" covered up with fabric. While I have read about some sewing methods that are strong, I'm a fan a proper splice.

[Ghost]

I like all the information on this thread. I use 3/8" lines on my 22 Classic and feel they are sufficient. They work well with the size of the cleats and I boat in mostly secluded areas.

My question: What length lines work best for everyone? Normally I only use two lines on my boat. One is 15' long and the other is 20' long. The longer of the two stays attached to my bow eye. The other is used at the stern for tying up at the dock/ramp. Depending on the tide, I feel my bow line could be a little longer for ease of getting back onto the trailer.

I have a red/white Classic and black dock lines.

I'm a fan of having at least 4 dock lines, in case you end up in a slip where you need to have a line out on each corner. 15s are probably enough for half those setups, but I'm a fan of slightly longer, like 20s, based on experience. I have a lot of lines available, up to 35 as needed for docking. But going minimal as you do, I'd have 4 lines at least, doubling up what you have. Perhaps adding 2 more springs as well, totaling 6. I have some pretty small diameter springs aboard. Doesn't take much space, but a good option.

I also built a towing bridle a couple seasons back, which has already come in handy. It's a much more complex rig than anything with dock lines alone, but I think it'd allow me to tow most anything within reason, safely, at about the best speed I could muster. (Say, 9 mph maybe.) But that's extra credit.

[tmdog]

Thanks Ghost, good post.

[Carl C]

You're over analyzing things again. I'm just posting where to get a good deal on dock lines. If you don't trust me then read here: http://www.offshoreonly.com/forums/g...ock-lines.html and save some money on your next dock lines like the rest of us are. Probably good for this too:

[gcarter]

Mike's essay on "momentum" reminded me of the scene in "American Graffiti" where the local punks chain the police car's rear axle to something substantial........just replace "rear axle" with "cleat" or "bow eye"....
Come on, every one remembers that scene, don't they?

[Greg Guimond]

This is what the site has come to ..........

I don't give a rats ass what kind of lines I use. Normally I just pick up whatever is floating in the water and use those for a while. Or I dig out some old decrepit stuff that I forgot I had and use those. Black, white, color, poly, plastic, jute, don't matter. The clothes lines I find floating in the Harlem River are the best but sometimes I have to cut the body part loose which is annoying.

[duckhunter]

Ghost, great tutorial on dock lines. The comparison between lines and other safety gear is apt - 99% of the time it doesn't matter, whether you're talking lines or life vests or fire extinguishers. The 1% of the time when it REALLY matters is worth a small premium for peace-of-mind IMO. Pretty simple risk or cost/benefit analysis.

Anyway, thanks for posting that. I learned some stuff.

If you get a gift of lines, how do you tell the difference between nylon and
polypropylene? Ed

Ed, they're nylon. If they float, send 'em south and I'll choke the vendor with them!