Sling Design

Sling Design

As I am writing this, we have not tested this design, but it should give you ideas about making your own design


  • 30m of tape with a good breaking strain, please check this measurement using the calculations below
  • UV resistant cotton
  • UV resistant material
  • 3 Rings - Used at the points of the triangle
  • Rope - Used to secure the sling to the boat


The measurements that you will need are

  • Distance between the stanchions - These stanchions need to be close to the mast and are where you will be rolling the casualty aboard
  • Size of the freeboard - With this measurement make sure you are measuring the size of the freeboard, between the stanchions where you will be rolling the casualty aboard
  • Length required at the water

With Salty Lass the distance between the stanchions was 1.8m (A) and the size of the freeboard was 1.2m (B). Now I decided that the length I wanted at the water was 1.2m (C), I chose this figure because I wanted a length that was sufficient to support the casualty and have their head supported to some extent. I then used these distances in the following equation

D = (A * B)/(A - C)

This gave me the length of my design between the base of the triangle and the apex of the triangle (D), the sides (E) can be calculated using

E = √((A/2)2+D2)

Now I had a width of 50cm (F) for my ladder and a step size of 25cm (G) that's the distance between the rungs. For the overlap I had a rather excessive overlap of 12cm (H) but I thought that is would be better to be safe than sorry plus for my own convenience I used 25cm (I) which is 2 x H + 1cm extra in the calculations below.

So the total length of tape required is

  • 1 * (A + I) Base of sling
  • 2 * (E + I) Sides of sling
  • 3 * (D + I) Ladder sides
  • (D/G) * (F + I) Ladder rungs

The fabric section that you require is

  • D * (A - F)

This will give you too much fabric, but that is not a bad thing. I used cargo netting for this section but maybe a different solution would work here just as well.

Hints and tips

These are the hints and tips that I have on making the sling

  • Have somewhere flat that you can lay your sling out, this is so that you can make sure that all the straps are flat
  • I used cargo net for my sides but maybe a different fabric could be used here
  • I used a long zigzag stitch to secure the straps together, this worked really well as all I had to do was stitch forwards and then stitch backwards
  • On the sections that I wanted to intersect I would measure out the space that I wanted and put a pin at the end of the pin. I would then repeat the process on the other strap. These two pins would then form two of the sides of a square for where the straps needed to be joined
  • Only ever use new strapping as it makes it so much easier to sew
  • Use needles that are designed for sewing Jeans together for this project
  • One subscriber suggested having two rings at each point of the triagle, so the load at these points was shared

If I have any complains with my design then maybe another cross piece where the triangle section is would be a good thing

Raising money for the RNLI

The RNLI turned 200 years old on 4th March 2024. So as sailors and people who promote the joy of sailing, we thought that we would like to raise just £200. What we hope is that other people take up the shout and raise their own £200. In the last 200 years the RNLI have saved over 144,000 lives and yet they are funded entirely by people like you. They are not government funded.

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