Rode and Chain

[riptide]

Hi all.I need to get ground tackle for my 34' Irwin.I have a simpson lawarence manual windlass and they specify 1/2" rode with 5/16" chain.Should this be sufficient for my boat? I am thinking 200-250' of rode and 50-100' of BBB chain.I plan on using a cqr type anchor-any thought on what size?I get different answers from diff. suppliers.I plan on cruising Bahamas and east coast of US.Should I also get a claw type anchor and if so what size?I already have a danforth type anchor.The windlass instructions say that I need to get a rode that doesn't have a long lay-does anyone have info on a way to tell the lay of rode from pictures on E-bay ect. thanks Mark

[GordMay]

A 34 Ft sailboat will typically want an anchoring assembly with a working load limit of between 900 (working) to 1800 (storm) pounds.

Accordingly, 5/16" Chain (±1,900# WLL) will be more than adequate.

Unfortunately, ½"∅ Rope is only rated about 700# (3-strand) to about 800# (double-braid); so should be up-sized to 5/8"∅ minimum (working anchor).

“Lang” lay refers to wire (not nylon) rope.

[riptide]

Thanks for the reply.Qouting from the original paperwork with the windlass-the rope should be 12mm.[1/2"]diameter 3 strand nylon.If the lay of the rope is long then it may be necessary to use 14mm. diameter.I don't have conversion table handy -is 14mm. equal to 5/8"?I'm with you ,I would feel much better with 5/8 rode as a minimum.Do you think 5/8 will fit gypsy or will I need to use drum on other side?Also I need a stripper for winch but don't seem to be able to find one.Thanks again Gord, Mark

[svHyLyte]

5/16" Grade 30 BBB (i.e. short link) chain has a working loand limit of 1,900 lbs per Gordo's post. (See BBB* Windlass Anchor Chain )

New England Ropes' 1/2" 3-Strand Nylon Line has a rated tensile strength of 7,500 lbs. Assuming a 300% "safety factor", it's .working load would be, accordingly, 2,500 lbs (see New England Ropes - Product Details )

An alternative to 3-strand that is not subject to hockles; and, stores more easily and compactly in a chain locker, is plaited line which has similar strength to 3-strand and makes for an easier (in my view) rope to chain splice that works well with the SL555 gypsy (see New England Ropes - Product Details )

Note that for the Bahama's, the CQR may not be the most desireable anchor given common bottom conditions. A Fortress type would be one alternative as a secondary.

FWIW...

[Liam Wald]

I have a 33 foot boat with a manual windlass. I have a Rocna 33lb primary anchor on 150' of 5/16ht and 250' of 5/8 3 strand.
With 150' of chain I almost never use any nylon rode as anchoring is mostly in 30' or less and that gives me 5:1 scope. That is why I suggest going with a little more than 100' of chain.
Don't worry about the nylon rode fitting the gypsy. Just pull the nylon in by hand and when you get to the chain drop it on the gypsy.
Also a good idea to have a snubber for the chain so the load is not on the windlass.

[Lost Horizons]

Experts suggest not upgrading rope size, for it will reduce its elasticity; 1/2" is considered adequate for a 34' boat. Personally, I am using 5/8" on mine and would be hesitant to go to 1/2". As for the length of the chain, ideally, it is no longer than what you anticipate will lay on the ocean's bottom (to resist chafe) for your typical anchoring depth. In my view, 60' of chain is adequate for anchoring in Florida and Bahamas waters. I currently have 35' (of 5/16") and sometimes wish I had more. As far as anchors go, I am using 33 lb claw on my boat. I had never experienced a problem with a claw type of anchor, except a couple times in New England trying to set it in a dense vegetation. Maybe it was a lack of experience those days. If I cruised long term, I would probably gotten a 44 lb Rocna or Manson Supreme.

[Hudson Force]

Riptide, 'just a caution for something that you may be aware of already..... all 5/16" chain will not fit on the same windlass gypsy. BBB, High Test & American High Test are all 5/16", but with different links/foot. 'take care and joy, Aythya crew

[GordMay]

Originally Posted by svHyLyte

... New England Ropes' 1/2" 3-Strand Nylon Line has a rated tensile strength of 7,500 lbs. Assuming a 300% "safety factor", it's .working load would be, accordingly, 2,500 lbs (see New England Ropes - Product Details )...

According to your link:

The Cordage Institute specifies that the Safe Working Load (SWL, or Working Load Limit WLL) of a rope shall be determined by dividing the Minimum Tensile Strength (TS) of the rope by a Safety Factor.

The safety factor ranges from 5 to 12 for non-critical uses, and is typically set at 15 for life lines.

I wouldn't endorse your assumption of a safety factor of 3.

ie:
3-strand at 7500# TS ÷ 5 = 1500# SWL
7500# ÷ 10 = 750# SWL
7500 ÷ 12 = 625# SWL

See ABYC’s Working Load Limit chart:
➥ http://www.cruisersforum.com/gallery...&cutoffdate=-1

And their Design Load chart:
➥ http://www.cruisersforum.com/gallery...&cutoffdate=-1

[svHyLyte]

Gordo---

With all due respect, I may only be a retired licensed structural engineer with 25+ years of professional experience but I did sleep at a Holiday Inn last Friday. While I am tempted to do so, I will not comment on the matter of "Specifications", which are arrived at by committees. There is, however, an old proverb worth remembering: "A Camel is a horse designed by a Committee."

The primary failure mode of rode is not rupture (due to rode surpassing its ultimate strength), but chafe, which knows no bounds. I have rarely seen rode failure due to rupture--but often due to chafe. If one properly prevents chafe, relatively smaller rode for a given yacht is desireable as its elastic properties gobble up energy.

In my view, 1/2" diameter 3-strand is quite adaquate for an Irwin 34.. Viewpoints are necessarily subjective, however, hence, the old saw" "Different ships, different long splices." The cost difference to the OP is negligible.

FWIW...

[klem]

Unfortunately, forces exerted on your anchor and rode are not an exact science but the numbers given above are reasonable. The chain meets your requirement for strength, just make sure that you get the right type to fit the windlass. The line's breaking strength far exceeds your loads. You can debate safety factors and I wonder why such high safety factors are placed on lines when normal safety factors are on the order of 3-4 rather than 15. However, just because the line is rated for the load, that does not mean that it will hold up to the chafe associated with cycling up to that load. Personally, I use 5/8" line but plenty of people use 1/2" and do fine.

One thing that you haven't answered is whether your windlass is appropriate for the boat. I would guess that it is but you might want to make sure that it is adequate before sizing everything around it.

As far as anchor selection goes, check out some of the anchor threads. CQR anchors work well in some bottoms but will not set in others. Claw type anchors set in most bottoms but their holding power is quite low for their weight. Some of the new anchors like the rocna set in any bottom that a cqr or claw set in and have very good holding power. If you got one of these anchors and kept your danforth as a storm anchor, it might work quite well and you wouldn't have the complication of two anchors and either two rodes or switching it back and forth.

[Orion Jim]

Your 34 has the same displacement as my 31 and this is my setup. My primary is a 33# Bruce with 92' of 5/16 BBB and 175' of 3/4 3-strand. My lunch hook is a 25# CQR with 20' of 5/16 BBB and 225' of 1/2 3-strand. They both lead to my manual windlass from my bowsprit.

[GordMay]

I expect that the “high” safety factors placed on fibre rope, in anchoring applications, may have something to do with the uncertainties of dynamic shock loading and chafe; which our structural engineer rightly claims is the commonest failure mode.

A camel is a remarkably well designed animal, for the conditions it faces; whereas a horse would be remarkably ill-suited to those conditions. Notwithstanding the problems of consensus decision-making, I would choose a committee of experts, over a single incompetent.

[riptide]

Now I stepped in it didn't I?Winch is Simpson-Lawrence Hyspeed model 0051090..Iv'e owned boats in 25'-30' range for many years and Iv'e always used 5/8 rode thats why I'm asking about 1/2 rode .I think if it will fit my gypsy I'm going to use it-I'll jsleep better.If it doesn't fit gypsy I may try it on drum on other side of windlass.Thanks for all the input -Mark

[Bill_E]

OK, I'll add a little.

I've got a Sunbeam 37 (I know no one has heard of these) that is really a 34 ft boat with a 3 ft swim platform. But it displaces about 18500#. Maybe for anchoring purposes the displacement isn't as important as the freeboard (wind forces) or the keel dimensions (currents). Perhaps one of the engineers could comment on this.

When I purchased it, it came with a mondo stainless steel Bruce (I've never weighed it but it is heavy). It has a Lofgrens manual windlass and about 125 ft of 5/16 G4 chain. As a "backup" I purchased a Raya 1000 anchor (ancoralatina.com) that weighs 12.5 kg.

Sailing the Thorny Passage I had no trouble with the Bruce in the Bahamas because we were always in pretty shallow water and sandy bottoms. In the DR we had a couple of issues. First, there were a couple of places where 125 ft of chain wasn't enough so we had to add some rode (we used 1/2 inch line that was aboard) and there was one particular case where the Bruce just wouldn't hold (kind of rocky). So we put the Raya on and it grabbed immediately.

Now I'm going to add to the ground tackle and I've got to figure out a slightly different roller system for the Raya and I'll add about 100 or 150 ft of 5/8 triple strand nylon. And maybe I'll add a smallish Fortress style anchor in the aft lazarette for emergencies and a lunch hook at times.

Bill

[thinwater]

Originally Posted by riptide

Thanks for the reply.Qouting from the original paperwork with the windlass-the rope should be 12mm.[1/2"]diameter 3 strand nylon.If the lay of the rope is long then it may be necessary to use 14mm. diameter.I don't have conversion table handy -is 14mm. equal to 5/8"?I'm with you ,I would feel much better with 5/8 rode as a minimum.Do you think 5/8 will fit gypsy or will I need to use drum on other side?Also I need a stripper for winch but don't seem to be able to find one.Thanks again Gord, Mark

The challenge is the the rope-to-chain splice, which is slightly larger than the rope. Brait is also a possiblitiy, which is a little stronger and can be spliced to chain. The splice needs to be re-made every few years, according to wear. It's simple.

There are 2 places your anchorage is likely to fail: the seafloor (drag or something sharp), or the bow roller. So check your roller very careful for rough spots.

If I am anchoring in a spot with a rough bottom, I use all chain (or enough chain to avoid abrasion) and a very long bridle to absorb waves. ther is no pressure on the bow rollers.