If any LRIs are reading this, would you please add it to the agenda for your next telecon.
The confusion in this thread and the referenced inconsistency between events is precisely why we submitted this.
If the rule is just ‘securely fastened to the davit’ it makes it significantly easier on inspectors, teams, field reset while not actually affecting the intent of the rope rules. I highly doubt FIRST’s aimed to create this much of a legal hoop jumping exercise for everyone.
What were the specifics on why it was deemed non-compliant with I04? This is nearly identical to the situation asked in Q142.
If that doesn’t work, the first alternative would be a smaller bowline (just large enough to pass the running end through easily). Then, loop the rope around the arm of the davit above the fingers, pass the bitter end of the line through the loop, drop between the fingers, and place the pin, as suggested in Q479.
If that doesn’t work, plan C is a monkey’s fist tied at least 1-1/2" diameter made of about 1/2" round line which incorporates a loop or two (or maybe a clove hitch) of the strap.
Actually it is the head Refs that need to know this and the other rope attachment rules. My team got the “its not the rope it is the attachment”. So it is the ref’s call to make.
I forgot to take my Q&A data and didn’t want to discuss it any further since there were other we needed to do before practice.
Specifically I was told the knot could not be beyond the davit fingers. In your diagram, the knot is between and slightly downstream the davit fingers. In Q&A 455, this is stated as “below” the fingers no more than 2". Q148 is more generic about “loops in the rope.” Q455 addresses this exact situation at the davit fingers and seems to state your suggested technique is fine.
I fixed it by putting the loop over one finger and wrapping the rope (and knot) around the outside of the other finger.
Color me confused.
David
This really doesn’t sound right to me, an inspector should have verified it. Yes, the field has to ensure that ropes are properly installed before every match, but it’s right in the rules:
A Team must submit any ROPE they intend to use in a MATCH
for Inspection. A ROPE must meet the following criteria
…]
E. be configured such that it engages securely with the FIELD with a Retaining Feature (RF) that does not extend more than 2 in. (~5 cm) below the DAVIT fingers.
Inspectors have to ensure that it’s properly designed to engage securely with the field, it’s written clear as day in the rules. If they weren’t, maybe that’s why we’ve heard so many comments on CD about robots falling from ropes with top knots that were too small…
And trust me, rope discussion has been a significant part of LRI training and conference calls. It’s expected that the inspectors are taking a large role in ensuring ropes are designed for proper interaction with the field.
Sounds like your inspectors didn’t read Team Update 05. I04 E was updated to read (emphasis is the changed part):
[The rope must]
- E. be configured such that it engages securely with the FIELD with a Retaining Feature (RF) that does not extend more than 2 in. (~5 cm) below the DAVIT fingers.
Prior to TU05, the RF was required to be above the fingers.
I don’t know, the part outside the e.g. parenthesis says “To interface with the field a ROPE must have a retaining feature greater than 1 in. (~25.4 mm) in diameter to interface with the DAVITS (RF).” Seems pretty specific to me.
That is a good point about the diameter, we will probably make up a few ropes with loops and see if it flies with the inspector at our next event. It might be a tough sell because all the pictures in the rules have knots instead of loops.
Blue boxes pretty heavily influence the rules, and in the case of I04E it seems to provide additional details about the intention of the rule and how it will be enforced while not contradicting the text of the rule.
Consider the blue box attached to I04G, which introduces an additional 2" to the diameter and allowance for compression to a rule that in a strict reading has no room for error. Is it possible that blue box might be ignored because it states something different than the rule it is attached to? Does an inspector have discretion to enforce the rule without regard to the blue box?
A pair of loops going around each finger would be, in total, greater than 1" in diameter. Not each loop individually, but the feature as a whole.
I don’t think the rule and the blue box are contradictory, or that the blue box introduces an additional 2 inches. I see that as an example of how the rule will be enforced - we’ll compress the rope by hand to measure the 10" limit for the loop if needed. Otherwise, you run into an interpretation issue with loops - do I have to sit down and painstakingly make it perfectly circular on the table before measuring it? Do I measure it as it would normally be while hanging from the Davit? The blue box clears up that ambiguity.
I can tell you specifically that, at both Kettering 1 and 2 they allowed loops around the davit (in fact, it was recommended over the monkey fist knot method). I do know that our robot fell twice due to monkey fist failures during semi-finals at Kettering 1 (after hanging just fine 9-10 times). If it’s clarified that hanging the rope by looping around the davit fingers is legal, we plan on mounting our rope that way at our next district event.
It is legal. Look through the Q&A. The manual uses a knot as an example to explain rule, but a knot isn’t the only way to design your retaining feature. Just ensure that the loop is secured so it cannot come lose. (Have the top of the loop sit underneath the rest of your rope so it cannot flip up over the fingers and pin. )
Many teams have used loops. If the RIs take issue you can escalate it to the LRI if there is still a problem, they will work with you to find a solution. There goal is to see every team play.
While it doesn’t help in your districts, as far as I’m concerned for the events I’ll be LRI at, it’s already been made perfectly clear and legal in the Q&A, and has been since at least Team Update 5.