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Discussion Starter #1
In looking at my proposed new anchor setup, the recommended chain is 5/16.

I won't mention the anchor to avoid the usual thread diversion. :D

We will not be utilizing a windlass in the near future (if ever on this boat).

ACCO 5/16 BBB has a SWL of 7600 lb, ACCO 5/16 G40 has 11600 SWL and the ACCO 1/4 G40 has a SWL of 7750.

Cost is a minor issue here but weight savings for the Admiral on the bow might be a larger issue. Acco G40 1/4 is .74 lb/ft, Acco 5/16 BBB is 1.2 lb/ft.

Does 0.5 lb/ft make a difference?
Would there be a problem with utilizing a 1/16 smaller than recommended chain on my new anchor?

Note to Rockter: Notice that I used lb/ft not lbs/ft? :D

Michael
 

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I'd go with the 5/16" G40, rather than the BBB or the 1/4". Going undersized or understrength with ground tackle is just foolish. :)

Get a good chain pawl if you're not getting a windlass to start with. This will make hauling the sucker back on deck a lot simpler. Also, you probably don't need all chain, which would probably hurt your boat's performance. Get about 60' of chain and splice it to 250' of octo-plait nylon. Don't use a thimble between the nylon and the chain, or when you get a windlass, you'll be regretting it.
 

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Michael, this is a chart from New England rope showing the breaking strength of 3 strand nylon line. If you are not going with a all chain rode, check to see the breaking strength of the size of line you are planing to use. I never have seen a good reason to use chain that has a 12,000lbs breaking strength with line that breaks at 7,500.
<TABLE cellSpacing=0 cellPadding=4 border=1><TBODY><TR><TH align=middle rowSpan=2>Size</TH><TH align=middle colSpan=2>Weight</TH><TH align=middle colSpan=2>Tensile</TH></TR><TR><TH align=middle>lbs/100'</TH><TH align=middle>g/m</TH><TH align=middle>lbs</TH><TH align=middle>kg</TH></TR><TR><TD align=right>3/16"</TD><TD align=right>1.0</TD><TD align=right>14.9</TD><TD align=right>1,200</TD><TD align=right>545</TD></TR><TR><TD align=right>1/4"</TD><TD align=right>1.5</TD><TD align=right>22.3</TD><TD align=right>2,000</TD><TD align=right>908</TD></TR><TR><TD align=right>5/16"</TD><TD align=right>2.5</TD><TD align=right>37.2</TD><TD align=right>3,000</TD><TD align=right>1,362</TD></TR><TR><TD align=right>3/8"</TD><TD align=right>3.5</TD><TD align=right>52.1</TD><TD align=right>4,400</TD><TD align=right>1,998</TD></TR><TR><TD align=right>7/16"</TD><TD align=right>5.0</TD><TD align=right>74.4</TD><TD align=right>5,900</TD><TD align=right>2,679</TD></TR><TR><TD align=right>1/2"</TD><TD align=right>6.5</TD><TD align=right>96.7</TD><TD align=right>7,500</TD><TD align=right>3,405</TD></TR><TR><TD align=right>9/16"</TD><TD align=right>8.2</TD><TD align=right>122.0</TD><TD align=right>9,400</TD><TD align=right>4,268</TD></TR><TR><TD align=right>5/8"</TD><TD align=right>10.0</TD><TD align=right>148.8</TD><TD align=right>12,200</TD><TD align=right>5,539</TD></TR><TR><TD align=right>3/4"</TD><TD align=right>13.6</TD><TD align=right>202.4</TD><TD align=right>16,700</TD><TD align=right>7,582</TD></TR><TR><TD align=right>7/8"</TD><TD align=right>18.7</TD><TD align=right>278.3</TD><TD align=right>23,500</TD><TD align=right>10,669</TD></TR><TR><TD align=right>1"</TD><TD align=right>26.4</TD><TD align=right>392.8</TD><TD align=right>29,400</TD><TD align=right>13,348</TD></TR><TR><TD align=right>1-1/8"</TD><TD align=right>30.6</TD><TD align=right>455.3</TD><TD align=right>34,000</TD><TD align=right>15,436</TD></TR></TBODY></TABLE>
 

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Just a reminder that the effectiveness of chain in an anchor system is due to the weight of the chain. My advice if you need higher strength is to go with bigger chain. This is also why the mis-match of rope/chain strength might not be the main consideration.
 

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Generally, most windlasses will require rope twice the diameter of the chain size. If you go with 1/4" chain, you'll be limited to 1/2" rope if you get a windlass, or plan on getting a windlass later on.

5/8" rope has about the same SWL as 5/16 G40 chain. :)
 

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Michael:

Those SWL (safe working load) figures you cite are WAY TOO HIGH! No way a 5/16" HT chain has a SWL in excess of 11,000 lbs. It should be more like 3,900 lbs.

I think you may have read the specs wrong...perhaps in the West Marine catalog listing where they don't know how to place commas correctly :)

Bill
 

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Bill—

I believe he's accidentally written the breaking loads not the SWLs... :)
Michael:

Those SWL (safe working load) figures you cite are WAY TOO HIGH! No way a 5/16" HT chain has a SWL in excess of 11,000 lbs. It should be more like 3,900 lbs.

I think you may have read the specs wrong...perhaps in the West Marine catalog listing where they don't know how to place commas correctly :)

Bill
 

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Ignoring Trolls in 2009
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Discussion Starter #9
Thanks all for the replies.

Bubb,
Haven't got her to the bow on anchor duty yet, but I can always hope. After all I'm a modern guy who believes in equal rights. :D

Dawg,
Your input as always is both helpful and appreciated.

Bill,
You are right, I misread on the WM website secondary to poor comma useage. We will have to send them to the grammer thread.

So the end result of all this. I would probably be safe with 1/4 inch G40 and 1/2 inch line, but will most likely go with 5/16 G40 and 5/8 line.

Merry Christmas to all.

Michael
 

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Merry Christmas Mike... good luck convincing the Admiral to man the anchor line... :)
 
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