Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 28-10-2005, 04:40   #16
Registered User

Join Date: Nov 2004
Location: Currently based near Jacksonville FL; WHOOSH's homeport is St. Pete, FL USA
Boat: WHOOSH, Pearson 424 Ketch
Posts: 591
Going back to my question for a moment, I'm surprised no one mentioned that splicing 8-strand to anchor chain is one of its advantages; that's the only factual advantage I can come up with based on our discussion so far (re: replacing my 3-strand in order to generate more room for chain in the anchor locker).

I am not convinced that splicing nylon to anchor chain presents a problem because I don't find that to be true in fact, nor do I hear from others that they have discovered their nylon to be damaged. We all cut apart these splices, well served when first made up, and inspect them periodically without discovering any problems and so I suspect this is more a theoretical worry than one proven in the field. On a test bed, sure. But an anchor will yield before the rode I use reaches any large portion of the line's breaking strength, and in fact I almost never have to veer so much rode as to ride to the splice. I think this is true for many others out cruising, simply because cruising boats don't typically rely on short lengths of chain for their primary rode.

I also don't think generalizations are, all by themselves, helpful here. E.g. Rick was pointing out that double-braid is significantly less stretchy than 3-strand...but that's not necessarily true. To use Samson's cordage as an example, for same line dimension double-braid has 2/3 the elongation of 3-strand. That in itself isn't 'significant', it's just 1/3 less. But more to the point, if choosing double-braid with its much higher strength rating (over 8-strand), I can move down in line dimension and obtain the additional stretch for the same strength at less cost and, especially important given my goal, less volume (due to smaller line dimension). To Rick's point about avoiding double-braid mooring lines, this is one reason folks choose double-braid rather than avoid it: smaller line dimension, easier storage and less cost, sufficient strength for the fittings employed.

It seems to me the ease of splicing 8-strand is the argument in favor of 8-strand; the question in my mind is whether that alone justifies the choice.

Jack
__________________

__________________
WHOOSH, Pearson 424 Ketch
http://www.svsarah.com/Whoosh/WhooshSection.htm
Euro Cruiser is offline   Reply With Quote
Old 28-10-2005, 05:22   #17
Senior Cruiser
 
Talbot's Avatar

Cruisers Forum Supporter

Join Date: Jun 2004
Location: Brighton, UK
Boat: Privilege 37
Posts: 3,579
Images: 32
Quote:
splicing 8-strand to anchor chain is one of its advantages; that's the only factual advantage I can come up with based on our discussion so far
Surprised you think that that was the only advantage posted, because my earliest post clearly says that other advantages are:
It is a delight to handle by comparison to 3 strand.
It stows in a much smaller space.
It doesnt kink.
The one that is most relevant to your original post is that it will stow in a much smaller space due to the nature of the cordage, thus you have more space for extra chain or extra rope in the same locker space. Why is this - because the octo can be stowed exactly as you place it, whereas 3 strand frequently has a mind of its own and needs to be carefully stowed in a coil to prevent tangles when next needed.
__________________

__________________
"Be wary of strong drink. It can make you shoot at tax collectors - and miss."
Robert A Heinlein
Talbot is offline   Reply With Quote
Old 28-10-2005, 05:43   #18
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,585
Images: 240
Although I’ve never used (myself) nor spliced 8-strand “plaits”, I have handled them, and can verify Talbot’s assertions that:
- It is a delight to handle by comparison to 3 strand.
- It stows in a much smaller space.
- It doesnt kink.


Splicing (Eye) Instructions for 8-Strand Nylon Ropes:
http://www.samsonrope.com/home/pdf/C..._EyeSplice.pdf

and:
http://www.yalecordage.com/html/pdf/...eye_splice.pdf

Brait to Chain Splice:
http://www.yalecordage.com/html/pdf/...ain_splice.pdf
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is online now   Reply With Quote
Old 28-10-2005, 07:59   #19
Registered User
 
CaptainK's Avatar

Join Date: Sep 2005
Location: Phoenix, Arizona... USA
Posts: 2,386
Images: 7
Yeah.

To answer BC Mike's question, about the NAVY switching types of ropes.

That kind of problem existed for quite a long time, with the NAVY. They call it synthetic line snap back. And yes, it can be extremely deadly to any salior. Taking off limbs and cutting a person in two!!

Regards,

CaptainK
__________________
CaptainK is offline   Reply With Quote
Old 28-10-2005, 23:34   #20
Marine Service Provider
 
GMac's Avatar

Join Date: Oct 2005
Location: North of the Bridge, thankfully
Boat: R930
Posts: 1,659
I am not convinced that splicing nylon to anchor chain presents a problem because I don't find that to be true in fact, nor do I hear from others that they have discovered their nylon to be damaged. We all cut apart these splices, well served when first made up, and inspect them periodically without discovering any problems and so I suspect this is more a theoretical worry than one proven in the field. On a test bed, sure. But an anchor will yield before the rode I use reaches any large portion of the line's breaking strength, and in fact I almost never have to veer so much rode as to ride to the splice. I think this is true for many others out cruising, simply because cruising boats don't typically rely on short lengths of chain for their primary rode.

100% absolutly true and one of the most sensible comments seen for a long time.

Having done well over 1000 rope to chain splices in both 3 strand and 8 braid (using this for over 6 years now, catch up with the rest of the world NE Ropes) I can say with extreme confidence "If the splice is done right chafe is 100% absolutly NOT an issue"

Not sure I'd be very happy with a double braid on a anchor rode though. One nick in the cover and you get a big instant strength loss.

Does anyone have any significant experience using , or know of any tests or reports, about the “Plaited” Rope-Chain Splice ?

Perfectly fine if done correctly and quite strong enough. I would not use it on a Auto Rope to Chain winch though. After a while when the nylon hardens, as it does, you end up with a very stiff steel reinforced bit of rope that just won't bend around the gypsy. Also after a while the odd link 'may' turn itself sideways and when that one hits your gypsy it can go very bad to the point of "Please Mr Winchmaker, Can I have a new gypsy and seal kit please. Here is the pile of money you want. I just hope you don't want more in case I've bent my shaft". This has and is happening.

But either one I like better then three strand. The three strand twists while hauling anchor. By the time I get the chain to the windless the chain has a twist in it too. Then I'm fighting the chain onto the gypsy.

This sounds like it could be a spinning anchor or fairlead roller problem. Watch closely next time and see if your metal ground grabber is spinning when you winch it up. If it is a spinner put on a good swivel and you'll find the problem will probably go away. Also watch your rode coming over the roller. Is it continually rolling the rode the same way? If so get a new roller or re-shape it even again.

Safe sailing
__________________
GMac is offline   Reply With Quote
Old 29-10-2005, 01:10   #21
Senior Cruiser
 
delmarrey's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Now in Blaine, WA
Boat: Modified Choate 40
Posts: 10,702
Images: 122
Quote:
GMac once whispered in the wind:
This sounds like it could be a spinning anchor or fairlead roller problem. Watch closely next time and see if your metal ground grabber is spinning when you winch it up. If it is a spinner put on a good swivel and you'll find the problem will probably go away. Also watch your rode coming over the roller. Is it continually rolling the rode the same way? If so get a new roller or re-shape it even again.

I have looked for all these questionable problems. The anchor is not spinning,
I have one of thoses fan$y swivels that doesn't work when the anchor hangs from it, and the first 30 foot of chain goes over the roller just fine until the twist over-comes the the rollers ability to keep it staraight anymore. And the "new" roller is the proper size for chain. Basiclly, I need a gyspy for a roller.

Most of my anchorages are over 30 feet due to my draft and tide changes, so with 60' of chain and and 100' + of the WM premium nylon rode the darn thing has a routine of twisting as the rode tightens up.

Maybe I just have much more chain then the rode can handle. All the more reason for switching to the Yale.

And No I will not take off some of the chain. We have a lot of sea grass and clay bottoms in this area and it's hard to sink an anchor at times. I refuse to even use a Danforth. Too many close encounters.

If I could find a swivel that would swivel, when under load, that would solve the problem........................_/)
__________________
delmarrey is offline   Reply With Quote
Old 29-10-2005, 03:19   #22
Registered User

Join Date: Nov 2004
Location: Currently based near Jacksonville FL; WHOOSH's homeport is St. Pete, FL USA
Boat: WHOOSH, Pearson 424 Ketch
Posts: 591
Talbot, sorry I wasn't more clear. What I was attempting to ask is what other advantages 8-strand has over double-braid, not over 3-strand...which afterall is the line I'm thinking of ditching, so it isn't my reference point. Your listed advantages apply to double-braid, as well.

GMac's point about a nicked cover in double-braid is a good example of what I was looking for; he's right, it can be a problem and can even be caused by a rough galvanizing surface on the chain.

Jack
__________________
WHOOSH, Pearson 424 Ketch
http://www.svsarah.com/Whoosh/WhooshSection.htm
Euro Cruiser is offline   Reply With Quote
Old 29-10-2005, 13:22   #23
Senior Cruiser
 
Talbot's Avatar

Cruisers Forum Supporter

Join Date: Jun 2004
Location: Brighton, UK
Boat: Privilege 37
Posts: 3,579
Images: 32
I believe the first two are still relevant as advantages of octo over double braid, but not quite as significant as over 3 strand.

Octoplait is kinder to hands cause it gives you a much better gripping surface.

It stows in a smaller space cause it is a much more flexible rope.

Nylon (or poyamide) double braid is an unusual rope in UK - the majority are Polyester, and you would have to make a special order to the manufacturer for the nylon ones.
__________________
"Be wary of strong drink. It can make you shoot at tax collectors - and miss."
Robert A Heinlein
Talbot is offline   Reply With Quote
Old 29-10-2005, 15:01   #24
Registered User

Join Date: Jan 2005
Location: Seattle area (Bremerton)
Boat: C&C Landfall 39 center cockpit "Anahita"
Posts: 1,076
Images: 6
Stretch revisited

My advice against using double braid over plait or 3-strand nylon is due to a physics phenomenon not normally taken into consideration, especially in the case of mooring lines. Mooring lines are, in general, severely limited to the dock space available. the less space, the shorter the lines. Even a 30 per-cent increase in stretch under the same linear load produces a 77 percent increase in energy absorption. This increase in engergy absorption occurs over some finite time and is converted into momentum on the boat mass which is dissipated back into the water on subsequent movement against the water inertia. Let's say that you use nylon double braid which, compared with the 3-strand, does not absorb that extra 77 percent amount of energy. That energy is transmitted to the cleat and underlying material of the boat in a time period shorter by the amount that the 3-strand took to make that extra 30% stretch. Comparing the peak load at the cleat between the two cases can reveal a quadruple in tension (or more, depending upon the stretch of the double-braid).

Now I'm visualizing what happens when some jerk passes by boats at dock making a huge unanticipated wake (you are not even there to see it) and the boat, if unmoored, would merely lift up and roll over and back, no problem (except to the nice crystal wine glass that you forget to put away before taking that lovely lady back to her car). When tied down by a double braid nylon dock line now the boat begins to roll and fetches up against that fully stretched line and, if you were there, you would literally hear the pain of the line and deck where the cleat is mounted. Perhaps it pulls out entirely, perhaps the fiberglass (if that's what you have) cracks in a few places that you can't see.

This phenomenon was clearly demonstrated to me once in a lab where there was a huge granite table mounted on leveling airbags. A 200 pound block of steel rode on an air bearing (giving it essentially zero friction over the granite slab). You could push on the block of the steel using only your index finger and a few pounds of force. In only a few seconds of applying a constant pressure the block would easily move and leave your finger at a steady speed. If the block ran into a rail attached with a 1/4" bolt the bolt would shear off. If you let the block run into your index finger, however, and you backed up applying a few pounds again for only a few seconds the block would easily stop with no pain, little strain. This difference is the same as that between a low stretch dock line and a higher stretch one.

Now visualize the boat moored at a place like Monterrey Bay, Calif, where there is ALWAYS some surge. Notice that ALL of the boats at the dock have some means of absorbing the energy of the surge. Those that did not are either damaged or not there anymore. The continuous surge action against the boats quickly reveals what the calm water boaters have ignored with their big double braid short nylon docklines.

Several years ago I was advised by Brion Toss (http://www.briontoss.com/), a noteable rigger, to use a jackline made of polyester to "interface" between chain and nylon and cleats/chocks and nylon in order to use the best advantages of both materials. Where chafe might occur the polyester minimises chafe due to its lack of strecth, where stretch is needed the nylon is used. He pointed out that an MIT study had revealed using two eyes together to join the lines resulted in a strength which would not compromise the strength of either line due to the fact that at each "join" there is a balanced double line.

A previously stated concern about nicking the outer jacket of a double braid is of a concern must be taken into relative consideration: the cause of nicking the outer jacket of the double braid polyester "interface" jackline would result in far less damage or strength degradation than would occur to any nlyon of any type. In addition, the outer jacket of a double braid carries half, not all the strength of the line, compromising only part of that jacket does not compromise the entire jacket.

Talbot's message regarding the use and availability of double-braid nylon in the UK is possibly related to the existence of fewer naive Brits uninformed about the relative merits of nylon and polyester in conjunction with line formation merits.

After all, here in the USA between the east and west coasts I've noticed that perhaps one in twenty boats are moored with a proper cleat hitch. Most boats have mooring lines without proper means of absorbing shock loads. Most boats have undersized fenders and most of them are moored in areas thought to be calm. Other than commercial docks, few of the boats are steel capable of tolerating shock overloading without damage.
__________________
Rick is offline   Reply With Quote
Old 29-10-2005, 15:56   #25
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,585
Images: 240
Rick:
Thanks for the explanation. I was misunderstanding your use of dacron/poly’.

Just got around to viewing your photos. http://cruisersforum.com/photopost//...humb=1&si=Rick

I really like your bow eye snubber attachment - particularly the two “extra” strap washers. I like the “Quick Link” attachment at lot less (they only have about 40% the strength of equivalent chain (less if using H.T. or better chain). Standard Bow Shackles are rated about 80% of equiv. chain, and Titanium shackles about equal to H.T. chain (stronger than ‘Proof”). H.T. - http://titan-marine-hardware.com/

I know, it's not your ultimate attachment, just a "snubber", the quick-easy attachment is more than mere "convenience" - it's an important function of the setup.

A also like your durable polyester “Interface” rode connector. I agree with the durability issue you explained on the forum.
FWIW: Although the snug eye-splice at the chain looks neat, and rolls easily over a bow roller or winch capstan, an eye shouldn’t be placed over a fitting with a diameter greater than ½ that of the eye - or the eye should have twice the diameter of the chain link diameter.

How do you like the anchor “Swivel”? I purchased a couple, for myself, when outfitting a customer. Only used them a few times, so the value’s only “theoretical” to me; so I’d be interested in your 'experienced' evaluation.

Gord
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is online now   Reply With Quote
Old 29-10-2005, 16:22   #26
Registered User

Join Date: Jan 2005
Location: Seattle area (Bremerton)
Boat: C&C Landfall 39 center cockpit "Anahita"
Posts: 1,076
Images: 6
Hi Gord

Yes, it would be "nice" to not have to sacrifice any strength due to eye stress loading to a small diameter on a chain. My thinking is that the 5/8 inch diameter polyester double-braid will STILL have more strength than any nylon to chain splice possible that the chain size can accept. In addition, the resistance to fiber crushing when passing over a bow roler is still greater. Replacement of that "interface" polyester piece is relatively easy and inexpensive.

I've done two things to those Kong swivels not visible; Carefull smoothing of the innards which move against each other results in better swivel action under load; bronze washers and bushings fit over the pieces to separate the zinc plating of the chain from the 304 stainless steel resulting in a longer time period before the zinc disappears from the chain and anchor where contact is made. The bronze pieces were measured against the stainless in salt water for galvanic compatibility. There is a wide variation in bronzes in this regard. I also use Locktite green on the swivel fastener.
__________________
Rick is offline   Reply With Quote
Old 29-10-2005, 16:36   #27
Registered User

Join Date: Jan 2005
Location: Seattle area (Bremerton)
Boat: C&C Landfall 39 center cockpit "Anahita"
Posts: 1,076
Images: 6
BTW Gord;

The stainless Quicklink on my bow snubber is WAY stronger than any subber line which might be used and all of the metal is compatible stainless. The Quicklink makes a better installation as compared to a stainless anchor shackle, especially the mating surfaces between the shackle and both the thimble and the U-bolt.

The problem in the use of ordinary anchor shackle designs is that they are rarely installed so that the chain end link or rode thimble is spaced evenly on the shackle pin using proper spacers....have you EVER seen anyone do this properly outside of professional riggers? I have seen pin failure due to this fault caused when a heavy pull and jerk causes the chain link to move to the thread end of the shackle pin thereby applying an inordinate amount of tension on the threads (which are sooo crude on zinc plated shackles) which pull apart.
__________________
Rick is offline   Reply With Quote
Old 29-10-2005, 17:00   #28
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,585
Images: 240
Rick makes a good point about pin spacers to keep the rode centred on shackle pins. All of these components are designed to absorb consistently increasing loads, applied in a straight line (180 degree), at a uniform rate of speed.
Any side loading (off 180 deg) requires a reduction in the WLL rating:
- To 30% at 45 degrees off-line
- To 25% at 90 degrees off-line
ie: a Fittment that has a rating of 1,500#, is derated to 450# at 45 deg load, and to 375# at 90 deg pull.

Likewise load "snatching" (shock) dramatically decreases the ability of the entire rode assembly to perform to design specification. It's nearly impossible to calculate simple derating factors for Shock loading, being a dynamic (pun intended) condition.
__________________

__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is online now   Reply With Quote
Reply

Tags
anchor, anchoring

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 04:47.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.