BBB vs High-Test Chain

[wind rose ll]

l currently have approx 130 ft of 5/16 BBB chain and comparing it to 1/4" Hi-Test chain find the 1/4" to be stronger...l would like to increase my chain length and want to "sound the board" for opinions before l purchase the 1/4", l have capstains for both and my boat weighs 23000lbs loaded.
Dave

[camaraderie]

That's a good reason to switch to a lighter weight chain and it should be fine for you.

[btrayfors]

Cam's probably right, but with a 23,000 lb displacement boat I'd feel a lot more comfortable with the 5/16" G40 HT chain. It weighs about .35lbs more per foot than the 1/4" (so, an extra 70lbs for 200 feet), but gives you much higher working load (3,900lbs vs 2,600lbs).

I've got 3/8" G40 on my 27,500lbs displacement boat, and don't feel that it's any too big.

JMO,

Bill

[little boat]

i just went down from 5/16 to 1/4 on my primary, but my boat weighs less than 3 tons. 1/4 sounds very light to me for your weight.

[GordMay]

Wind Rose is certainly right, in that 1/4" G40 High Test has about the same WLL as 3/8" BBB, and over a third higher-rated than his present 5/16" BBB.
The 26oo# rating for 1/4" H.T. (& 2650# for 3/8" BBB) is appropriate for a typical 40-something sailboat.

[btrayfors]

Gord,

Seems to me the question is not whether 1/4" G40 is stronger than the existing 5/16" BBB; rather, it is what is the correct size chain for his boat?

One doesn't/shouldn't assume that the chain size in present use is the correct one.

And, you can't go just by boat length. A 23,000lb displacement boat could well be in the 40-50' LOA category, depending on construction, and you'd find lots of recommendations for 3/8" chain in that size range. It would be nice to know what boat we're talking about here, but the main factor, IMO, is displacement.

For a 23,000lb displacement boat, I'm gonna stick with 5/16" G40 recommendation. IMO, 1/4" G40 is too light for this boat.

Bill

[GordMay]

I’ve always believed that size (effective projected area) is a more important criteria for determining ground tackle size (loadings), than is weight. After all, we’re not proposing to hoist the boat by this chain.
Notwithstanding, under certain circumstances, displacement may have some additional affect on the dynamic load (under surging & similar conditions).

I could be wrong, and would welcome an education.

[S/V Elusive]

Another point to consider - weight of the chain to help keep an anchor set. Too light of a chain, and (depending on the weight of the boat) with a swell or surge, could cause the chain come up off the bottom. I think??!!??

[delmarrey]

A couple articals worth reading........................_/)

http://www.dulhunty.com/dmp3.htm

http://www.johnsboatstuff.com/Articles/anchor.htm

[btrayfors]

Gord,

Far be it from me to "educate" you; you're a pretty savvy guy from what I can tell :-)

In the real world, both size and type (profile) AND displacement are important factors to consider when setting up your anchoring strategy.

Boat size and type is important because of wind loading and current effects, i.e., how much pull on the anchor rode is caused by wind loading and current effects alone. The greater your over- and underwater profile, the greater will be the effect of wind and current.

However, in gusty weather and situations with considerable wave action, the anchor rode may well be near the limits of its catenary and...when the boat is tossed about by the wave action or gusty winds, the weight of the boat comes into play. Obviously, a heavy displacement boat will put a greater shock load on the anchor and rode than will a light displacement boat.

IMO, one should plan to have a working anchor and rode setup which can easily handle both wind and surge conditions short of true storm and hurricane conditions. I can't count the number of times I've been anchored with other boats in a quiet place only to be hit by nasty thunderstorms with winds over 50 knots, hail, rain, lightening, etc.....only to watch some of the other boats start dragging, sometimes down on one another. Even though they were just out for a nice weekend sail, they should have been prepared for high wind situations, however temporary.

My preference is for all-chain rodes, for their strength, ease of deployment, effect on helping anchors to set properly, and peace of mind. I use 30' 1/2" nylon bridles to help cushion any shock loads on the chain, anchor, and on my deck cleats, as well as to keep the chain from jumping on the roller and disturbing my sleep :-)

Bill

[GordMay]

Originally Posted by btrayfors

... In the real world, both size and type (profile) AND displacement are important factors to consider when setting up your anchoring strategy.
... in gusty weather and situations with considerable wave action, the anchor rode may well be near the limits of its catenary and...when the boat is tossed about by the wave action or gusty winds, the weight of the boat comes into play. Obviously, a heavy displacement boat will put a greater shock load on the anchor and rode than will a light displacement boat. Bill

I understand that a heavier boat will carry more dynamic momentum, when in motion.
But, I wonder how much momentum, that heavier boat, can generate AFTER the catenary has been (mostly) straightened. Not much, I would think.

ABYS & others recommend loading factors depending upon average boat length.
Where might one find equivalent loading factor recommendations, based up[on displacement?

I remain open to education.

[btrayfors]

From Anchor Marine (Australia): "The following table is our recommended table for anchor tackle. Care should be taken when using this table as boats with more windage or displacement may require heavier tackle in rough conditions."

See also:

Sea Anchor: Your First Line Of Defense When Facing Heavy Weather

http://www.spade-anchor.co.uk/dimensions.htm

and just Google "anchor recommendations boat displacement" for dozens of other references.

And, while you're at it, just THINK about it a little.....what is going to put a heavier load on the rode and anchor: a 2 ton vessel or a 20 ton vessel?

[Alain d'HYLAS]

Originally Posted by GordMay

I could be wrong, and would welcome an education.

see on rode body

[GordMay]

Bill’s (2) PARA-TECH links do recommend Sea Anchor Sizes (analogous to anchor loading) based upon both Length & Displacement, but also suggests that: Sizing is first based on length overall with weight, keel configuration and windage taken into account next.

I have thought about just a little, and suspect I’d see a heavier anchor load from a 20 pound, 400 square foot sail, than I would from a 4,000 pound keel.

I have read Alain’s excellent & exhaustive tutorial on “Tuning an Anchor Rode”. I’ve even understood much of it. I don’t see where it addresses boat displacement as a loading factor.
Help.

[camaraderie]

Interesting discussion... but my take would be that 1/4" HT would be as suitable as his present rode since it is stronger... and WindRose's question was would it be OK to replace his present rode with it...not whether we thought his present rode was adequate. I would further assume that his boat is the low windage "Bayfield" type in his Avatar and not some condo boat. All in all...I think 1/4 HT is plenty safe but I don't think I'd pay that much extra to save 100 lbs of weight.