Reeving 6:1 purchase mainsheet systems.
A lot of boats in the 30 - 40' range have a 6:1 mainsheet system which has often been upgraded from a 4:1. Sadly, even though system power has been increased, some of this gain is frequently lost because the system is incorrectly reeved. This means that the falls of rope in the system will rub against each other when the rope is pulled, markedly increasing friction.
This handy guide published by Harken will help you set up your mainsheet in the most efficient way possible.
So, how should a 6:1 be reeved? You will be delighted to hear that there is a trick! Start with the blocks positioned at 90 degrees to each other:
Once you have positioned the blocks correctly, it is actually quite hard to get it wrong. First, we'll attach the sheet to the becket on the lower block and pass it through the correct sheave on the top block.
The rope then leads down to the bottom block and passes through the second sheave (again, the correct sheave is important).
Keep following the pictures, noting that both the sheave and reeving direction is important.
When you thread the fifth sheave, it is vital that the rope go down to the last sheave (the middle one on the bottom block) without rubbing against any of the other falls of the tackle.
Once the system is threaded correctly, you can cleat the rope and put some tension in the system. This causes the two blocks to sit at approximately 45 degrees to each other, but the ropes will sit squarely in the sheaves and the falls will not touch - just what you are looking for!
And while we're on the subject of 6:1 systems, consider using the back of the cleat as a becket.
This has the advantage of ensuring the bottom block sits up with the cleat nicely presented. If you decide to fit a fine-tune system, the second purchase will sit outside the main system, making it much easier to use.
Credit: Harken Tech Team