If you really want to start splitting hairs then use a vernier to measure the inside and outside diameter of the pin that goes through the pulley to calculate it's cross sectional area. Using some basic forumla you can get a stress value for shear stress. Very simply - force divided by area. That is probably the most likely way it would fail. You could go further into other stuff and then also even strain - which is change of length over original length, a dimensionless value, of course. Or just do the maths on a possible z-drag type system and estimate how much force a group of 4 people could exert on a system and then (ignoring friction, otherwise the calcs become slightly trickier) find out the force on the pulley. Then return to the basic shear stress formula..

The chances of you using a pulley on a river are few and far between. Although I NEVER compromise on safety the kind of ropes we paddle with will DEFINITELY snap before the pulley ever fails, I have no doubt. (I have a degree in engineering in case you didn't know). I'll still stick with my smaller (weaker...? ) pulleys in the safe knowledge that they are fine for the purpose I use them for and are much, much lighter to lug around... Each to their own though. Make your own decisions.

You forgot the airspeed velocity of an unladen swallow--another very important equation!

Ah yes. Thanks!

As an update, I still haven't gotten a response, but the drawstring piece is fixed, and the neck doesn't seem nearly as bad as I thought. Still haven't had a chance to paddle with it, but I will probably test it at the USNWC before I take it to Nantahala. If it doesn't work, I will probably let my dad use it and just use my NRS Mystery S/S instead.

As an update, I went to a local store to check out the IR Session 2.5, but the neck was still loose on me . I may end up getting a full drytop, such as the Level 6 Mack, PeakUK Deluxe HD, or something in that price range (<$200).

Here's another pulley option that I may get: www.rei.com/product/635119 . Any opinions on it?

I ordered the Level Six Knight today. I have also purchased a Petzl Fixe pulley, a few more Rock Locks, and some more webbing. Any recommendations for drypants without latex gaskets? My main choice right now is the Kokatat Tempest, because it has a good waist closure, booties, and isn't too outrageously priced ($159, compared to $230 for the Palm Sidewinders). I also am looking at the IR Splash Pants. Any feedback?

I have the IR splash pants for about 3 years now, still holding up fine. As with tops tho, any pants without latex gaskets are really only semi dry, if it's cold out and I expect to be swimming I'll wear my drysuit. Having said that, I can wade around rescuing people in the splash pants and have my thermal pants inside stay dry, but after a swim through turbulent water you would be a bit soggy all right. Also largely dependent on how tight the waist on your cag and deck are, to seal the top of the pants.
Just saw your post on the Peak semi dry top - a bit late I know since you said you've ordered a new one, but if the neck is too loose most shops can put a latex neck seal on for 35 euroish (dono what that is in US $, but certainly cheaper than a new cag!) I had the IR semi dry top, and it fitted fine when I bought it, but after a year or so the neoprene neck had stretched out from putting it on and off, so I got a latex seal put on, and it kept me dry for another 3 years or so.
Muireann

I did think about that, but the main problem for me is that the waist was adjusted by a drawstring, and the end piece kept snapping off, even when it was just in my closet. On the PeakUKUS site, the description of the waist on the Semi-long says "Neoprene AO2 outer seal with light weight X2.5MR inner." and the waist on the Deluxe Long HD, which has a much better waist closure, says "Neoprene AO2 outer seal with light weight X2.5MR inner.". In other words, PeakUK was lying about the waist closure, and had I known that, I can assure you that I wouldn't have bought it/asked for it as a gift. I have decided to keep it though, since for the price, I can just let my dad use it for rafting trips, and it should be better than the outfitter splash tops.

As for the pants, the 3 things that drew me to the Tempest were 1) Kokatat's name, 2) fabric booties, which are similar to those on their drysuits, and 3) a good waist closure. It seems like the booties should last much longer than latex, require less care (303 Protectant), be more comfortable, and if something does happen, it would just be a patching and re-seam-taping job.

I just got my Knight today, and I have a few initial observations. On the front, the waist adjustments have velcro to keep them in place, but my waist is too small, and the pieces have to overlap across the DCS neoprene area. The front pocket is huge. If you look at a pic of it, the pocket goes pretty much across the whole torso, and is about 4 or 5 inches high. The closures are neoprene with velcro sewn on, as well as some nylon. The nylon isn't as comfortable as neoprene, like on the Extrasports, but is still fine. Overall, it seems like a great jacket, and I can't wait to try it out on the water soon.