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-   -   Sizing of Dock Lines... (http://www.sailnet.com/forums/gear-maintenance/56110-sizing-dock-lines.html)

MedSailor 07-11-2009 05:57 PM

Sizing of Dock Lines...
 
So the dock lines that came with my boat are so old, large, stiff, and crustified that I could probably use them to fend OFF if necessary. They're a bear to use and barely fit through our fairleads. I think I'm going to break with my tradition of line use which is: Halyard becomes, sheet becomes, dockline, becomes, fender line.

I think it's time to treat ourselves to new lines for our docklines. The question though is, what size? We're quite a bit larger than my last boat and weigh in at about 30K pounds. Some of our lines creak and squeak when it's windy, which is something I'd like to avoid.

If they're oversized do they still creak or is it just the small ones? How about 3 strand vs 8plat? Suggestions?

MedSailor

scottyt 07-11-2009 06:07 PM

3 strand seems to hold up better esp when dealing with rough surfaces.

i have a 8 k 27 foot boat and use 3/8 but i keep 1/2 on board too for storm stuff. you might want the same thing but up a step, use 1/2 for normal stuff and 5/8 or 3/4 for heavy weather.

you also need to realize that even you boat wont easily be able to break 3/8 but its chaff that gets you in the end. you might better off with 1/2 and spending the extra on chaff gear

3/8 breaking is around 4400
1/2 is 7500
new england ropes

nereussailor 07-11-2009 07:22 PM

I've got 1/2" and 5/8" on my boat. I use the 1/2" for everyday docking, and the 5/8" for storms. for a boat of that displacement, I wouldn't go any smaller than 5/8".

Dave

ploughboy 07-11-2009 07:42 PM

Let me suggest we think about this a bit differently. Look at the configuration of the boat in the dock and imagine the tension on the docking lines as the wind comes from all quarters. What do you want the lines to do? My stern lines on my 40 footer are 3/4 inch because of the chafe on the dock cleats and because if the stern moves it could impact my neighbor. My bow lines are 1/2 inch 3 strand ( so what if the bow moves laterally in the dock) and the spring lines holding me off the dock are 5/8 double braid. More than a couple of feet and I'm on the dock. Hope this helps.

pdqaltair 07-11-2009 08:08 PM

Good points. I always found that the best thing to do was to spend a few days...
 
Quote:

Originally Posted by ploughboy (Post 504558)
Let me suggest we think about this a bit differently. Look at the configuration of the boat in the dock and imagine the tension on the docking lines as the wind comes from all quarters. What do you want the lines to do? My stern lines on my 40 footer are 3/4 inch because of the chafe on the dock cleats and because if the stern moves it could impact my neighbor. My bow lines are 1/2 inch 3 strand ( so what if the bow moves laterally in the dock) and the spring lines holding me off the dock are 5/8 double braid. More than a couple of feet and I'm on the dock. Hope this helps.

on the boat, through all of the tides and wind directions helps. You get a feel for how it moves, both at home, and at other docks. When I got my new cat, which JUST fits the slip, I had to learn new tricks.

Regarding squeaking, using hollow nylon webbing (rock climbing stuff, BlueWater 2" Climb-Spec Tubular Webbing at REI.com) over the line cuts the squeaking best. My stern line passes right over my berth, making me an expert on silencing line squeak, at least on my boat!

Cal28 07-11-2009 09:40 PM

thanks to all for the information here ... reading with interest as I need to replace them as well ...

MedSailor 07-12-2009 01:00 PM

Quote:

Originally Posted by pdqaltair (Post 504561)
on the boat, through all of the tides and wind directions helps. You get a feel for how it moves, both at home, and at other docks. When I got my new cat, which JUST fits the slip, I had to learn new tricks.

Regarding squeaking, using hollow nylon webbing (rock climbing stuff, BlueWater 2" Climb-Spec Tubular Webbing at REI.com) over the line cuts the squeaking best. My stern line passes right over my berth, making me an expert on silencing line squeak, at least on my boat!

My last boat came with dynamic climbing rope as docklines. They didn't squeak if I recall (though none of the lines did) but they were stiff as boards. How long have you had your climbing rope on the boat and are they still supple?

MedSailor

pdqaltair 07-12-2009 01:25 PM

I use the webbing over conventional double braid dock lines....
 
So I do not know the answer.

I believe the answer lies in the fact that climbing ropes are not designed to be very UV resistant, and the the cover gets very stiff when exposed to sun. The ropes are for a different purpose. They are designed to endure horrendous shock loads, knot and release easily, slide smoothly over rough surfaces, and then be retired young.

However, I have used dynamic line for anchoring (17 years for the oldest one) and have not found it to stiffen at all. It still has a very easy hand and good stretch. Only the very end - kept in the sun - got stiff, so I cut it back a few times. It is the sun.

So, the outside of the webbing will get faded, but the inside will stay nice and slippery.

Also, climbing ropes and ropes for use in a windlass are opposites: a climbing rope is designed NOT to grab on roughness, a good anchor rode (for windlass use) MUST grab in the gypsy. I've got to believe that octaplait would be a nightmare on the local crag.

paulk 07-13-2009 06:33 AM

Nylon is the material of choice for docklines, because the stretchiness it has cushions the shock(s) of waves against the boat and dock. That's why your anchor line is probably nylon as well. (Though in the Med, people tend to like chain better.) Braid was developed partly in order to reduce stretch, so...3-strand or other twisted line would seem to be indicated. For a boat as big (and HEAVY) as yours, 1" nylon docklines (25mm) might be a bit light. 30mm or more might be better. Even if the bigger stuff is overkill on the strength end of the equation, it gives you a safety margin in the inevitable event of chafe, so you won't have to replace it for a longer time.

AWEllis3 07-13-2009 08:18 AM

"If you don't know your fish, know your fishman."

The West Marine catalog has a chart showing line types, brands and recommended applications. A well qualified opinion in a quick and easy format.


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