Jack Knife

Hello.

A free diver from Okinawa.Like thisis.

In a previous post, I mentioned that minimizing unnecessary movement is very important in order to extend your breath-holding time.This applies to both freediving and skindiving.

So this time,JackknifeI would like to talk about💁‍♂️

What is a Jackknife?

It is also called a jackknife or duck dive, but it basically means diving.

You may think that diving into the underwater world is just a simple step, but if you do it right, it's surprisingly easy to dive.👍

In my case, I do a jackknife and sink straight to the bottom, and before I start kicking with my fins, my head is about 3m deep. Since I start kicking with my fins from there, all of the kicking goes into propulsion without any waste, and I can easily dive 5m to 10m.

This jackknife can go underwater if you have it in shape, but if you don't look at how you're doing it, you might end up making a lot of unnecessary movements.🤔

Characteristics of the jackknife that lead to unnecessary movement

・Hold your hands when bending your upper body

・The momentum caused the legs to fall over, resulting in a bent-over posture as the person dived under.

Bend your torso and grab your hands at the same time

This is actually a very common feature.

If you do this, the momentum of the jackknife will be halved, and you will not be able to dive as far as you would like. As a result, you will have to move your legs a lot even though they are not fully submerged in the water, and you will have to kick many times to dive 1m or 2m, which will use up a lot of oxygen. In the worst case scenario, you will just be flapping your legs on the surface of the water and will not be able to dive at all, which could result in failure.🙄

The momentum caused his legs to fall over and he ended up diving in a bent-over position.

This is a common mistake that even people who can do a clean jackknife often make.

You start the jackknife by bending your upper body as if you are bowing, but if you have too much momentum in the bending motion and your upper body dives too far, then when you straighten your body your legs fall behind you and you end up leaning backwards. When this happens, even if you kick your fins you can't go straight to the bottom of the water, but instead go diagonally, and you have to correct your movement to go straight.

When freediving, this can sometimes cause you to lose sight of the rope.

Image of stretching towards the bottom of the water

This is what I often imagine when I do a jackknife.💁‍♂️

Lie face down on the water surface (horizontal) and stretch your armpits out toward the bottom. Imagine you are being pulled by your outstretched arms, and gradually lower your head, shoulders, chest, waist, and legs down toward the bottom.

Once your legs are in the water, you can finally start paddling with your hands. The momentum of your paddling will push your body further underwater.

When the momentum calms down a bit, your fins should already be in the water, and this is when the fin kick begins.

Mastering the Jackknife

I have explained that if you do a clean jackknife, you can start diving without using any extra force. In addition, the quality of your jackknife also affects your mental state when diving.

For example, a diver who needs to reach a depth of 10m to do 15 kicks may end up kicking 18 times before reaching 10m because they were unable to perform the jackknife as they had imagined. This is only 3 more kicks than usual, but if they had done it as they had imagined, they may start to think, "I should have already reached 10m, but still?" or "How much longer until I reach 10m?" This thought causes stress and makes you feel distressed earlier than usual.

Spare timeCalmWhether you're diving, enjoying a good dive, or wanting to go longer, the jackknife is almost always involved.

By consciously observing how you normally dive, or by having someone take a picture of you doing a jackknife, it may be one of the things that makes diving easier than before.😌