For your back stay, its not either blocks or rings. In my experience, a combination of the two is the best compromise when converting to dyneema backstay. As it happens, I made a conversion for a neighbor in my marina earlier this week. He is racing
cruiser on a regular basis, and he wanted the ability to trim his backstay as much as possible, without starving the wife and kids
. So instead of using fancy roller- and ball bearing blocks, we ended up making three bridles using three low friction rings (8:1) and then adding a pair of inexpensive fiddle blocks for additional 4:1 purchase
in the bottom, which resulted in a total of 32:1 purchase. A very light weight, low maintenance
, low friction and affordable solution. Use slippery quality single
braid dyneema through the rings and double braid polyester through the fiddle blocks. 16:1 should be plenty for a regular cruiser, but make sure to put the rings quite high up in the backstay. Otherwise you risk not getting enough play for the 4:1 in the bottom if you later on want to add another purchase...
For runners and check stays, I recommend as little purchase s possible down to deck
if you have dedicated winches for the task. The primary goal of this approach is to have as little rope
as possible to handle. Releasing leeward runner all the way down to deck (safely away from your teeth) and tightening it back again when you´re on the other tack, is way faster with a 2:1 purchase, and you don’t end up with too much line cluttering your cockpit
when the runner is tightened. If you don´t have dedicated winches, you obviously need way more purchase.
A common solution for the check stay, is a 4:1 purchase (becket fiddle cleat in the bottom, and fiddle on top) on the bottom of the stay, where it is connected to the runner. On my boat
I duplicated this original solution when switching to dyneema, but the cleat on the becket fiddle block wasn’t able to securely hold the new and thinner line, so I simply added a piece of dyneema and a low friction ring to double the purchase (now 8:1), hence cutting the force required to hold the bitter end in half. It also made adjustment so much easier. In this application you don’t need more than a couple of inches of play anyway, so even though you have to pull twice as much line to adjust if accommodating this 8:1 solution, the difference it barely noticeable. After four seasons, I´m happy to say it turned out great, and I´ll strongly recommend this approach. As I have dedicated winches for my runners, I only have 2:1 down to deck. Less rope
to trip on, and faster adjustment.
I might be able to make an illustration or add a photo
or two if needed.
Good luck to you. The Brummel splice is easy, and as we all know, it´s great fun pimping your boat, when it can be done without ruining the budget