Dock line size question?

[nathan007]

Well I want to replace one of my docking line and add snubbers. I have a hunter 38, and am trying to figure out if I have 5/8 or 3/4 inch lines..

I used a measuring tape, and on most of my sections where the line is being used and stretched (measured not under load) I measure 5/8, but in areas where the line is "resting" (extra line not used aka after the cleat) it seems to be 3/4...

So, since I'm still a noob when it comes to boats, do I have 3/4 or 5/8 lines?

Thanks a lot

[tarditi]

What type of line is it? Twisted and braided can reduce diameter slightly under tension.

[chris07732]

The longevity and/or failure of dock lines is seldom a function of the diameter and therefore the strength of the line. Most dock line fails are due to being frayed. Next thing is age of line. Exposure to UV seriously degrades line strength over time. I change out my lines (3/4" 20,000 lb boat) every 2/3 yrs. I have 6 lines typically, so I rotate which lines I change out.
A little expensive, but cheap considering the consequences

[John_Trusty]

+1 to Chris' comments ...
Unless you're planning on a hurricane, either line size has much more tensile strength than you will ever experience with a mid-30's boat.

Other than diameter, other considerations that are more important ... Do the lines fit comfortably on your cleats (in extreme examples, larger lines can actually unwind themselves on smaller cleats)? A 3-strand twisted dock line is preferable as they allow more stretch (no need for snubbers), but tend to 'harden' in the sun and salt over years. Periodic inspection for chafe is critical - these are disposable supplies.

[J Clark H356]

I use 1/2 inch braided dock lines on my Hunter 356 and we've had 75 mph winds at out dock on Kentucky lake. Your lines are probably 5/8 and they should be more than adequate.

[danielamartindm]

I use 5/8" double braid on my boat, which weighs ten tons. Chafe, and UV over time will do lines in; slight differences in diameter not so much. 5/8" line fit the factory deck cleats on my boat better than 3/4", which I took as a sign from above :-)

[Drew13440]

5/8s is plenty. You want your dock and anchor lines to stretch a bit and absord shock so your deck fittings don't have to.

[toddster8]

A 22-footer showed up in the marina this summer using 1" dock lines. I can't help wondering exactly what it is they're expecting...?

[David M]

Half inch is fine. Just don't tie it up using only two lines. Four lines minimum. 6 lines would be ideal.

As others have said, chafing will do a line in long before the line parts because it reached its breaking strength.

One of the problems with unnecessarily large diameter lines is that if you want to tie two lines to one cleat, sometimes you will not be able to tie a proper cleat hitch because one line already takes up too much of that cleat.

Think about this. If your dock line has 4 times the strength of your dock cleat, then what is the point of having overkill dock lines when it is going to be that easy for your dock line to pull the cleat out of the dock? Some dock cleats are only held in with lag bolts screwed in an inch or two into the wood and are not through bolted.

[roverhi]

Might want to buy a sample and try it with the cleats on the boat. 3/4" is significantly larger than 5/8' that the 1/8" nominal difference would indicate. If you have to run two lines, like springs, to a cleat, the additional diameter may cause problems especially if your cleats are a little small.

[Mr O]

The previous owner of my 22000lb boat had bought 3/4" three strand which I find difficult to use. It is very stiff when dry and hard to handle, coil, etc. when wet, it stretches a lot and is heavy. I usually have to re-tie the drooping lines. Combing 2 lines on one cleat is barely possible. There are 2 lines that are probably 50' long that act as bow/stern lines as well as spring lines. The next set of dock lines will be 5/8" or maybe 1/2" for ease of handling. Probably braided instead of 3 strand. One on the stern, two on the bow and two spring lines to center cleat.

[Cheechako]

I lean toward 5/8. Easy size for the hands and will fit cleats well. Sometimes 3/4 is a challenge on some dock cleats.... or boat cleats for that matter. If 3/4 fits your boat cleats fine it's good too.

[Bill Creadon]

In sustained wind storms greater than 40 knots double braid lines will fail sooner than 3 strand nylon. The braids work against each other develop heat and break. I have found using double lines with one of each to the same cleat to be most effective.

[savoir]

I don't know what size you actually have but can say that 3/4" is serious overkill. Even 5/8" is bigger than you really need. For a boat with the weight of yours 1/2" would be plenty.

Buy 6 so that you can double up on two of them if necessary. It is unlikely that your deck cleats will hold two 5/8" lines.

[a64pilot]

Last marina I was in required 5/8" for a 38' boat, and required that they be doubled.
I believe that to be a good policy. It's not how strong the line is to begin with, but how strong is it half chafed through and a couple of years old.