How to size rope - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 12-06-2006
ModMMax's Avatar
Member
 
Join Date: Sep 2006
Posts: 36
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
ModMMax is on a distinguished road
How to size rope

The broker who sold us our boat suggested that we buy a spool of 3/4" rope and cut it into the variety of lenghts needed for different docking/rafting/slip situations. We went to a marine store and looked at a spool of 3/4" rope that was sitting beside a spool of 5/8" rope. The 3/4" looked huge. I'm sure the 3/4measurement is when the rope is stretched with rated load, but man, it looked like it would be impossible to knot and/or attach to cleats. The 5/8" looked like it would be difficult to work with but not as bad as the larger size. I could use some advice about purchasing the 5/8" rope as opposed to the 3/4". My boat is a 30,000#, 47' cruiser and yes it is high and will catch a lot of wind. I know there is no definitive answer to this since conditions exist that will cause even the 3/4" to fail, but generally, will the 5/8" rope be adequate? Thanks in advance for your thoughts.
Alvin
Reply With Quote Share with Facebook
  #2  
Old 12-06-2006
Senior Member
 
Join Date: Aug 2006
Location: Arlington, VA
Posts: 1,807
Thanks: 0
Thanked 4 Times in 4 Posts
Rep Power: 9
btrayfors will become famous soon enough btrayfors will become famous soon enough
Alvin,

Buy the 3/4" rope. Your boat size, weight, and high freeboard can put a huge strain on docking and anchor lines.

The 3/4" rope should work very well on the cleats on your boat, and on dockside cleats.

Bill
Reply With Quote Share with Facebook
  #3  
Old 12-06-2006
pigslo's Avatar
Senior Member
 
Join Date: Nov 2004
Posts: 804
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
pigslo is on a distinguished road
All of your rope manufacturers have info online as well as a chart at the West Marine store. As I recall 3/4 is perhaps the minimum your craft needs but you can look it up. I think you can be too small, but not too big. One of the considerations on docklines is that they be made of nylon for stretch.
Pigslo
Reply With Quote Share with Facebook
  #4  
Old 12-06-2006
Senior Member
 
Join Date: May 2002
Posts: 2,517
Thanks: 2
Thanked 16 Times in 14 Posts
Rep Power: 13
Sailormon6 will become famous soon enough
There are numerous charts that recommend the correct size of lines for various sizes of boats. Consult those charts and follow their recommendations. Size does matter. Docklines should stretch, so that they absorb some of the shock when the boat rolls and draws up short on the docklines. That isn't terribly important normally, but when that 30,000# boat is bucking and rolling in it's slip during a hurricane or other severe storm, docklines that don't stretch enough can rip the cleats out of the deck. Oversized lines don't stretch as much as lines of correct size.
Reply With Quote Share with Facebook
  #5  
Old 12-06-2006
camaraderie's Avatar
moderate?
 
Join Date: May 2002
Location: East Coast
Posts: 13,878
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 15
camaraderie is a jewel in the rough camaraderie is a jewel in the rough camaraderie is a jewel in the rough
Mod...3/4 inch has 4500 lbs. higher breaking strength than 5/8 in 3 strand nylon. If you have trouble dealing with 3/4 inch 3 strand then I would suggest spending a bit more and getting 3/4 inch double-braid nylon which is MUCH softer and more supple and easier to tie AND even provides more breaking strength. 5/8" is just not enough for your boat.
http://shop.sailnet.com/product_info...ducts_id/33579 ... I know you can do about .30 cents a foot bettr on the price but I think sailnet will match prices.
Reply With Quote Share with Facebook
  #6  
Old 12-06-2006
Thanks Courtney.
 
Join Date: Sep 2006
Location: IL
Posts: 3,951
Thanks: 1
Thanked 1 Time in 1 Post
Rep Power: 10
T34C has a spectacular aura about T34C has a spectacular aura about T34C has a spectacular aura about
I tried the West Marine on-line product advisor for dock lines. It came back with 3/4", for both 3-strand and braided line, for a boat your size. To me that means that is the min. line size I would recommend. While it may be larger than you are used to, go with the 3/4.
Reply With Quote Share with Facebook
  #7  
Old 12-06-2006
SVDistantStar's Avatar
'72 Pearson 36
 
Join Date: Aug 2006
Location: Charleston SC
Posts: 497
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 8
SVDistantStar is on a distinguished road
Send a message via AIM to SVDistantStar
What about a 1972 Pearson 36 sailboat. It displaces 13,500lbs. My current lines range from 1/2'' to 3/4''. The last owers cut up most of the long dock lines so my longest line is about 25'. Ive been thinking of getting a spool of rope and cutting some nicer docklines(esp now since ive got whipping down).
Reply With Quote Share with Facebook
  #8  
Old 12-06-2006
Thanks Courtney.
 
Join Date: Sep 2006
Location: IL
Posts: 3,951
Thanks: 1
Thanked 1 Time in 1 Post
Rep Power: 10
T34C has a spectacular aura about T34C has a spectacular aura about T34C has a spectacular aura about
I use 3/4" 3 strand dock lines on my Tartan 34 that displaces 11,500. Slightly over sized, but haven't had one break yet.
Reply With Quote Share with Facebook
  #9  
Old 12-06-2006
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,380
Thanks: 1
Thanked 72 Times in 70 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Max, as pigslo mentions all the rope makers have sizing charts. They'll also gladly work with you on the phone or by email.

The size of a rope isn't everything, a better quality fiber or different manufacture can make a thin rope stronger than a thick one. You need to figure out the loads you expect on your lines, and then pick lines that can safely carry that load. "Working" load and breaking load being two very different things, also.

Dock lines should have some stretch in them, so they can absorb the snaps and jerks of bouncing around at the dock. And in time, they will wear and need replacing, so buying a larger spool and putting half away may actually be cheaper in the long run.

Don't be surprised if the lines you select dont' fit properly under some cleats and hardware--it is not uncommon for hardware to be sized smaller and cheaper than it should be. If you can't fit the proper lines under the hardware--replace the flimsy hardware, too.

Some folks secure a boat, really secure a boat, every time they dock, figuring you never an be sure what weather will come through before you get back to the boat. Others are more casual about everyday versus storm prep. That's a choice you can make too, there's no need to use docklines that will hold you in a major hurricane all the time. (You just need to be sure you can and will get back to the boat as needed.)

And of course, if you're out cruising and tying up in other places, it never hurts to have some extra lines stowed. Some old ones that you don't mind using on tarred pilings, some longer ones if you need to float in tidal ranges, etc.
Reply With Quote Share with Facebook
  #10  
Old 12-06-2006
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 9 Times in 9 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Generally, cleats should be 16x the diameter of the rope you're putting on them. So, 8" cleats are generally good for 1/2" line, and 12" cleats for 3/4" line. While this may sound excessive, this guideline generally leaves the cleats large enough to put two lines of that diameter on them without trouble... and the cleats can generally handle the load from the lines without breaking, provided they're mounted and backed properly.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
propeller size dick/happyours Gear & Maintenance 4 03-11-2005 08:41 AM
Hold That Line Tom Wood Gear and Maintenance Articles 0 10-03-2002 08:00 PM
Choosing and Installing an Electric Windlass Sue & Larry Gear and Maintenance Articles 0 09-06-2002 08:00 PM
Size Matters Don Casey Buying a Boat Articles 0 04-05-2002 07:00 PM


All times are GMT -4. The time now is 10:28 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012