A good anchor system is necessary if we find ourselves anchored in the Bahamas during strong winds, usually from the North during the winter.
Seriously, our anchor system should be designed to safely withstand loads of 2400 lbs. (for a 40 foot long boat) according to ABYC standards (intended for the design of the attachment point on the boat for use with a storm anchor).
The "anchor rode" forms the connection between the boat and the actual anchor. The anchor rode may be all chain (most conservative), a combination of rope and chain (most practical), or in some rare cases, all rope (not recommended).
Since I have established the design load based on the ABYC recommendations for the attachment point to the boat for a storm anchor, the chain should be selected on the same load. (The safe working load, SWL, is 1/4 of the ultimate tensile strength of the chain.) My alternatives are as follows:
I've been watching eBay for deals on anchor rope. I found 5/8-inch double braid nylon for $65/100 feet (or $0.65/foot) with a strength of 13,500 lbs. Prices at local marine stores range from $2 to over $3 per foot for similar rope. I have always been cautious about so-called "deals" on eBay but the 5/8-inch nylon rope really seems to be a good deal and it provides a safe working load of 3,375 lbs (incorporating a factor of safety of 4)--40% higher than the ABYC recommended load. The fact that it needs an eye splice may reduce the strength an additional 10 to 15%. (The rope is white with a black tracer and was manufactured last year for purpose as pulling cable rope.) I hit the "buy it now" link.
|Eye Splice in New Anchor Rope|
with Stainless Steel Thimble and Shackle
The new rope arrived about a week later. The same afternoon that it arrived I took it over to the rigging shop at my local West Marine store to have the eye splice made. One of the people in the store took a look at the very solid core of the rope and said they didn't think it could be spliced but they would have Julian (the rigger) take a look at it. As I was about to contact the eBay seller about the problem (I was going to return the rope), Julian called and said he had to "beat it into submission" but it is spliced and I can come pick it up. The eye splice cost only $20.
If the rigger was not able to splice this rope, I would have ended up paying for the rope I have plus another rope at a higher price from a local marine store. A word of caution to anyone else buying rope on eBay--you may have an issue with splicing.
|Four Colored Bands Equals 120 Feet|
With the thimble in place, I was able to mark off intervals of 30 feet, starting the first set of brightly colored bands at 25 feet from the thimble to make 60 total feet (25 + 35 feet of chain = 60 feet) of anchor rode for the first two-band marking. Adding an additional band every additional 30 feet (with the last set of 7 bands at 210 total feet) completes the marking system.
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