My boom brake is very simple - a figure 8 "rescue descender" used for rock climbing which i got off EBay for $45 and 20ft of 1/2in polyester braid. The
line is shackled to the starboard toe-rail and runs through the figure 8 to the other toerail, through a block shackled to the toe rail and then back up to the cabin top jammers via a free sheave in the
line organiser. I use a
winch to grind it on. Because of the set-up, it effectively has a 2:1 purchase.
There's a photo of the boom brake on my blog at
S.V. Sunny Spells · Running Rigging.
The boom brake does create a bit of an obstacle on the side decks, but you get used to it pretty quickly. I run my jacklines OVER the boombrake
lines, which also keeps the tether hooks off the deck, at least over that area. However, having an intermediate "catch point" in your jacklines is not such a bad thing - if you get washed along the deck you'll get stopped midway rather than dangling over the transom!