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