Internal outhaul in boom


Anyone have any advice on rigging a 6:1 internal outhaul in the boom to prevent twisting.  This boom is 13' long and has an eye strap on the bottom of the boom inside to secure the double block with a becket on the forward end of the boom.  (Double block with a triple constitute the 6:1 purchase)  

Sorry about that, forgot I had these converted for another interested party.

Business end at the far upper right corner gets a straight pigtail; 3mm HSR or something bigger if your exit can handle it, because the pigtail will get more sun exposure, handling and chafe.


Gooseneck end has a bit of red 3mm Amsteel 75 brummeled on a stainless thimble to avoid chafe on the inboard fixing pin.  The short end holds the single block for the 4mm 3:1, and the long end is the working part of the 2:1 through the high load.


This on a J24 reduces working friction by an order of 50% (or greater), and with the working end led to a hanging block at the gooseneck, allows a single crew to lean in and make adjustments to the outhaul while sailing upwind without changes to the mainsheet or vang load.

Last edited by a moderator:

Alex W

Super Anarchist
Seattle, WA
That’s similar to how I did it as well. Also test it externally (as shown in those photos) to verify that your lengths are all correct. 

it’s been a few years without any twisting.  The purple line is our control line, the blue is the cascade, and the far orange line goes to the outhaul car.


The way it shows (blocks oriented to each other at 0degrees and straight reeved) will result in the catastrophic twist that I see every time one of these things is pulled out of a boom.

You want this,, offset at 45-90 degrees on the blocks, and even then your mileage may vary.

Count the number of 180 degree turns that the line makes, it's not good, especially with (F) added in.



Yes their diagram doesn't match their instructions.  Instructions say to lay the blocks at 90 degrees and when done they will rotate 45 degrees to each other.  Problem is I have all the materials blocks and lines so I'll try it externally and see how it goes, if it twists on to plan B!!!