Thursday, 30 July 2009

Half a Chain... of Chain

Ok, so the title is cheesy. A chain in surveying is a measurement 66 feet long. I just bought half of that... in chain. Get it?

Anyway, I've been in the hunt for high quality anchor chain at low budget prices lately. The stuff at Home Depot and Canadian Tire says "Imported by: COMPANY" but doesn't say where from. When I Googled the company names I get websites that say they both manufacture and import chain and cable. Again, no hints of where.

Now I'm fairly patriotic, but that isn't the driving factor in my chain dilemma. The driving factor is that Chain made in ISO countries tends to be more dependable than chain made to ISO standards in non ISO countries. As it was explained to me, some places try to hit the top of the standard, and maintain consistency, while others are just happy to be within the bracket.

When your family is depending on this chain to hold you in place you want to know that it is at the top of the standard. Every link. You want to be sure that the chain was made to spec and accurately tested and reported. Around here that means it should say "Made In Canada" or "Made in USA" on it. In big letters. It should also be graded, and marked with the grade. I think stuff made in Europe would be fine too.

Chain of unknown origin can be had for cheap. Chain that is tested and proven is more pricey. I don't do pricey well.

The car that keeps on breaking was broken down (again) last week, and being that it is completely weird, it needed custom fasteners to hold components in place. I needed to go to an industrial supply to buy screws of strange sizes. 4 of them. While I was there I noticed they had chain and shackles there.

It was labelled "Made in CANADA." Each link was stamped with its grade. the price was reasonable. I had my source. Finding me chain is the first good thing I the piece of crap car has done for me. Oh - and pulling the boat straight on the trailer that one time.

How much chain to carry is an interesting question. According to the bible of small boat handling; "Chapman Piloting: Seamanship & Small Boat Handling", you need 1 foot of chain for every 1/2 foot of boat as a minimum. For Iris that would mean a minimum of 12-1/2 feet of chain. BUT... More chain allows the anchor to dig in better, and 12-1/2 feet is a MINIMUM. Since the chain is heavy, it drags the anchor across the bottom of the lake, forcing the flukes in, so more is better.

To figure out how much chain and rope you need out to anchor overnight, you need to complete the following math:

(Freeboard X 7) + (depth of water at high tide X 7) = 7:1 scope

Aside: In bad weather/strong currents/exposed anchorages, this is usually changed to a 10:1 scope ~ (Freeboard X 10)+(depth of water at high tide X 10) = 10:1 scope

Since I'm too lazy to actually do the math, I got to thinking about cutting the work in half. Our freeboard (height from the top of the water to the bow of the boat) never changes, so I could round it to 4 feet, and be pretty sure I was safe. 4 X 7 = 28 feet. I can mark the anchor rope at 28 feet and automatically add on the (depth of water X 7) part to it. No problem. Now how to mark it?

AHA! I could just be extra safe and get 28 feet of chain (rounded up to 30 feet for an extra degree of safety). Now when I go to anchor I automatically let out all the chain as the freeboard part of the equation, and then let out (depth X 7) of rope (sailors call it rode). Bingo - Half the math, and all the pleasure!

The weight of the chain to buy is a little more specific. Since the chain is there to weigh down the anchor, dampen shock loads to it, and slow the movement of the boat, you want to be sure it is heavy enough to do its job. You also want to be sure it won't be too heavy and hard to handle.

In Chapman's it suggests that 1/4" chain is adequate for a boat like Iris. I wanted to be sure that on Georgian Bay, where things can get bad we would be held well, and the weight of the chain would really dampen our movement, so I went 1 size up to 5/16"

After all this thinking and hunting, I bought 30 feet of 5/16"Canadian made chain, cleverly asking the clerk for half a chain... of chain. She didn't get it.

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