Best Mainsail Halyard Material

[Brion Toss]

Hi,
He's usually a very, very reliable source, but those figures on Sta-Set vs VPC are wrong. Sta-Set is rated at1.6% stretch at 10% load, and VPC at .7% at 10% load. Yup, less than half the stretch. The 2 ropes are approximately the same strength. The handiest place to check this is on West Marine's site.
Fair leads,
Brion Toss

[allene]

I thought the numbers strange so I checked the data sheets.

http://www.neropes.com/Datasheets/IND_STASET.pdf
http://www.newenglandropes.com/Datasheets/MAR_VPC.pdf

It is easy to correct my table if I could find a source for the numbers for 10%, 20%, and 30% stretch for each line.

I saw the WM numbers but I don't always trust them either which is why I went to the NE Rope data sheets.

[allene]

I have emailed nerope asking them to give me good data. It seems clear that the data below, from their datasheets, is not correct.

It could be a matter of different test methods as I know specifying rope stretch is more complicated than it would appear to be at first.

[GinoDelG]

I just found an article from Practical Sailor (Nov. 2010) rating various lines. In the mid-range category they rate VPC the best and state that it has half the stretch of Sta-Set, although I'm not sure whether they actually tested the numbers or not.

[GinoDelG]

I take that back, reading the sidebar they did test stretch and found it to be half that of Sta-set.

[Brion Toss]

Hi there,
Looks like a typo. Will check with NE Ropes. Note that the pdf shows 1.4% at 10%, while West has the same number at 20%. This, plus the fact that the entire point of VPC is to provide less elasticity, plus a dramatic difference when you actually use the stuff, argues for the lower numbers for VPC.
Fair leads,
Brion

[allene]

You may notice that the graphs from the data sheet show about half the stretch for VPC at 30% compared with the StaSet graph. It is just that the numbers go up much faster with the StaSet. Basically, the numbers look funny in the graph for the VPC as it is showing really very little stretch slope but has this large offset. They might be confusing construction stretch in there somehow. It looks like the VPC has .7% stretch with no load, which just doesn't make sense.

When I put my calculator together, I just put down the numbers from the data sheets. I really have no basis for doing anything else. I will add a note to that effect.