Having thought about it some more I’m going to go with the “traditional” triple block system, then if I do get the measurements slightly wrong I just need to use a bit more / less rope rather than find my wire strops need replacing.
Next question is which sized blocks to use? Off the top of my head I’d have said 25mm but when I look around I find that the nearest thing Holt Allen do is either 20mm (which look too small) or 30mm (which look too big and chunky!). Here are links to the relevant bits:
Can anyone help with this dilemma? I’m currently leaning towards using the smaller ones with 4mm line, but will they be strong enough? It’s easy to estimate how much load I can apply to the system, but I am at a loss to estimate how much strain a strong gust might place upon it once it is tensioned and cleated…?