Knots? Part 1

Recently on The Rocketry Forum MarkG asked how to attach a Kevlar line to a nose cone screw eye.
His original question was about a LPR rocket with (probably) 135 lb. Kevlar.
Some of the responses sounded like they were directed towards MPR knots using stronger Kevlar.

Here's the knot preferences from those who responded:
(These numbers are from this recent post from MarcG and an a similar posted question from May 2012)

Bowline = 10 votes
Figure 8 = 7 votes
Polamar  = 6 votes
Two Half Hitches = 6 votes
Improved Clinch Knot = 2 votes
Square Knot = 2 votes
Duncan Loop = 2 votes
Uni Knot = 1 vote
Rapala = 1 vote
Lark's Head = 1 vote

Pat B said it best:
Many of the knots that were designed for fishing were obviously designed with small diameter fishing line and tend to have an excessive number of overlaps. Those knots tend to get a little large when used with larger rope.

Stealth6 adds good advice:
One thing to keep in mind, that lots of folks don't realize, when choosing a knot - ANY knot will actually weaken your rope/line; some more than others. So, remember that your 750lb. cord will NOT hold 750 lbs. of force once you tie a knot it it. This is just one of the reasons you need much more strength in your line than simply the heaviest weight you need to hold.

SQUARE KNOT
Click on the words "Square Knot" above to go to the Animated Knots website.

I tend to use a Square Knot for most attachments and have rarely had a separation of a nose cone.
Notice both ends of the red and blue lines exit out the same sides. Tied properly, this line won't slip.

Many tie this and could lose a nose cone or have a Kevlar /Elastic shock cord line come loose:
GRANNY KNOT

The "Granny" Knot is a common mistake – the second half knot has been tied with the red rope crossing "under" the blue This knot tends to slip and its use should be avoided.


More of the mentioned knots will be covered in an upcoming blog posts.