What is the primary issue when using Kevlar in rescue ropes?

The primary issue when using Kevlar in rescue ropes is that the small bends used in knot tying can weaken the rope. Kevlar is an incredibly strong material, but when it is subjected to tight bends, such as those that occur in knots, it can experience a loss in strength. This is due to the nature of the fiber; while it maintains high tensile strength, it can become compromised under certain conditions, particularly at sharp angles. This reduction in effectiveness can lead to dangerous situations in rescue operations, where the integrity of the rope is critical.

The other options present different aspects but do not highlight the most significant drawback of using Kevlar for this specific application. Kevlar's stiffness may contribute to handling challenges, but it is not the core issue regarding the strength and reliability of knots. Although knot tying is indeed possible with Kevlar, it requires careful consideration due to the potential for decreased strength. Additionally, Kevlar is not overly heavy compared to other materials used in rescue ropes, and weight is not typically a primary concern in this context. The focus remains on ensuring the maximum strength and safety of ropes in critical rescue situations, which is why understanding the limitations of knot tying with Kevlar is essential.