Main closing loop material & Type IIA sheathing strength

[pchapman 279]

What material is commonly being used these days for main container closing loops?

1000 lb Spectra seems to be one choice; but I also see loops that are still made of the thin nylon sheathing with the diagonal dotted lines -- Type IIA, which I understand is essentially coreless Type II nylon cord.

I have seen the type IIA listed as 225 lb strength, but I've also heard 100 lb. Why the discrepancy? Or is it a mixup about different kinds of sheathing?

I'm wondering whether the sheathing is considered strong enough these days, given that stronger (although more easily damaged) Spectra is now available. In pre-Cypres days, reserve loops for 1 and 2 pin containers were often made of the sheathing.

[hookitt 1]

You are correct with 225. It's plenty strong for a Main. Perform the obvious Maintainance by replacing it as needed.

I use cypres loops on all reserves.

My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

[Hooknswoop 19]

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I have seen the type IIA listed as 225 lb strength, but I've also heard 100 lb. Why the discrepancy? Or is it a mixup about different kinds of sheathing?

Para-gear doesn't list the tensile strength of Type IIA, but using:

Type II, 4 inner strands (core material), 400 lbs.
Type III, 7 inner strands, 550 lbs.

Then there is an increase of 150 lbs. for 3 strands, so each strtand is 50 lbs.
For type III then, 7 X 50 = 350 for the strands and 200 lbs. for the sheathing (Type IIA)

To double check that with the Type II:
4 strands X 50 lbs, = 200 lbs. for the strands and 200 lbs. for the sheathing(Type IIA).

So, it looks like type IIA has a tensile strength of 200 lbs.

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What material is commonly being used these days for main container closing loops?

Type IIA, Spectra, Dacron (I don't like using Dacron for main closing loops), all sorts of line is used for main closing loops.

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I'm wondering whether the sheathing is considered strong enough these days, given that stronger (although more easily damaged) Spectra is now available.

I use Type IIA and have never had a problem. Replacing the loop when it gets worn is important. The binding tape (Type III) used for pull up cords is very abrasive and can wear through a tight closing loop very quickly. Spectra is fine, just make sure the washer you use is the correct size because the knot can be smaller with a Spectra loop and get pulled through the washer and grommet.

Always keep extra closing loops handy, so that when you notice your loop is worn, it is easy to replace. If it is a hassle, it is too easy to put off replacing it.

Edit to add, Cypres reserve closing loop material is rated to 180 Kp (X 2.205 = 396.9 lbs.) and is made of polyethylene.

Hook