I was eyeing our anchor a few days ago, trying to ignore how rusty the end of the chain was beginning to look. It wasn't working. The last time we used it was five months ago, and sitting unused , exposed to the elements all that time had taken its toll. As much as I would like to put off spending money on something as unexciting and mundane as anchor chain, doing something about those rusty links couldn't be postponed much longer.
Perhaps we could just swap the ends of the chain? The anchor end of the chain gets dunked routinely in salt water, while the bitter end spends less time in the water, staying dry and rust free. Checking back through our maintenance logs, however, I discovered that we already did that a few years ago in Africa, so no, we shouldn't swap the ends again. Maybe we could get it re-galvanized? Hmmm – those same maintenance logs showed we had had it re-galvanized twice before. Even someone as frugal I am might have to admit he'd gotten his money's worth out of the old chain and it was time to think about replacing it.
Determining the type and size of chain for a boat gets confusing. Should we get G3, G4, G43, BBB, HT, 316 stainless, proof, G7 or G8 chain? First, we can eliminate everything but anchor windlass chain – mooring or industrial chain which have different link sizes or may not be suitable for the marine environment.
For our use, we can eliminate stainless chain. Stainless chain looks beautiful and stacks nicely in the chain locker without piling up, but there is disagreement as to its reliability. That aside, it costs about 5x as much as galvanized chain, and isn't in the running for us.
We can further reduce our candidates. It turns out that G3 and G30 are different names for the same chain, as are G4, G43 and G40, and G7 and G70. The number following the 'G' denotes the relative strength of the wire or rod from which the chain is made. For our three remaining candidates then, the relative strengths would be 3:4:7. For example, if a particular size of G30 chain had a Minimum Breaking Stress (MBS) (aka Minimum Breaking Load) of 3000 lbs, the same size G40 would have an approximate MBS of 4000 lbs, and the equivalent G70 chain would have an MBS of 7000 lbs.
The tables below provide the minimum recommended size chain for various boat sizes, based on the MBS of the chain. Unfortunately, most chain suppliers only provide the Safe Working Load (SWL) (aka Working Load Limit and Normal Working Load ) in their chain specifications. For reasons that aren't clear to me, the formulae used to calculate SWL vary depending on the type of chain – sometimes it is 25% of the MBS, sometimes it is 33%. It is safer and more consistent to use the Minimum Breaking Strength when comparing chain strength.
As the tables show, we could use a smaller size chain if it was G40 or G70, while maintaining the same strength. For 200-300 feet of chain, the reduction in weight would be considerable. In addition, it may actually be less expensive to buy a smaller size, higher grade chain.
The final part of the decision process depends, of course, on the size of the chain gypsy. Unless we are planning to buy a new gypsy or are replacing the windlass, which we aren't, our options are narrowed even further. The windlass on Nine of Cups has a gypsy designed for 3/8” G40 HT chain, making the decision quite simple. The only thing left to do now is to shop around for a good deal.
I am leery of buying the cheapest chain I can find for something as important as the anchor chain that will be holding us off the rocks some stormy night somewhere. West Marine lists their G43 HT chain for $6.99 a foot. Ouch! Amazon has a good price on Titan brand chain, a Chinese made chain that has good reviews. Their price for 200 feet, including delivery is $859, or about $4.30/ft. That's better, but when I went to their website to check the specifications, I got a 404 error – URL not found. That was worrisome.
The chandlery here at Atlantic Yacht Basin in Chesapeake, however, can get Acco chain delivered right to Cups for $4.12 a foot. After sales tax, the price ends up being about 3 pennies more per foot than Amazon. It was painful, but I managed to overcome my frugal propensities and actually sprung for the extra $6.00. It's now on order and should be in soon.
As soon as it arrives, we'll paint the depth marks on the new chain, then splice the rope rode to the end of it.