I want a 4:1 or 6:1 outhaul on my boom... so I am wondering how to calculate the loads... I know Harken has mainsheet load calculator... http://www.harken.com/MainsheetLoading/

So what I am wondering is if I use the above calculator... figure the load and then divide by the ratio (4 or 6) then I get an idea of the loading of a proposed outhaul.

Does that seem about right, or am I missing something?

Using the Harken calculator for 12 knots of wind for my mainsheet (I assume the loads are the same for head, tack and clew) I get 219 lbs of force / 6 for 6:1, that means I have about 36.5 lbs of pull to adjust my desired new outhaul under a 12 knot wind load. Seems reasonable if I am correct in the way I am using the calculators.

What I am thinking is a set of fixed blocks near the gooseneck and a set of movable blocks about half way back on the boom with the current outhaul line tied (or with an eye) to the movable blocks. I can run the lead of the fixed blocks to a cam cleat on the cabin top through two turning blocks. Or I could just use a cam cleat on the boom to reduce the clutter.

For reference my E=12.25 and P=31

The illustration is from the Harken page, and pretty much what I had in mind, although I am not sure I could do it internally in the boom.