Main and Jib Boom Dimensions

[Ted Flack]

I've looked everywhere I know to look and can't find any rule covering the size of the booms. Are there any, other than they have to be straight, and made from glass, wood, or aluminum?

[deafsail]

I've looked everywhere I know to look and can't find any rule covering the size of the booms. Are there any, other than they have to be straight, and made from glass, wood, or aluminum?

http://ec12.org/Admin/EC12_Class_Rules_Oct2014.pdf
9.0 boom

I use 3/8" alum tube boom for main and Jib
from tentpole strong
or
http://www.midwestmodelyachting.com/Mai ... p_155.html
http://www.midwestmodelyachting.com/Jib ... p_158.html


Baron Bremer
EC12-81

[Capt. Flak]

The booms have no length measurement. They are generally long enough to cover the length of the foot of each sail with the extra length for the clue outhaul. The booms start as about 24 inches on average. Most people use an offset with counter weight in front of the tack on the jib. This cannot extend beyond the bow of the boat.

[Ted Flack]

Thanks guys, I should have been clearer in my question.

Are there any dimensions in the rules, or interpretations, for the height and width of the boom section and is there a rule as far as a constant section. For instance if I wanted to have a boom one inch high in the middle section and for conversation let's say 1/4 inch wide and then it got higher at the ends to capture the tack and clew is that OK? I have no idea if I would ever do that (too much work and probably weight) but I am curious about the rule covering such a design.

[Capt. Flak]

A rectangular cross section is perfectly fine, so long as the booms have no permanent bend to them. Not sure what you mean by getting higher at the ends. If you mean they gradually increase in height as you approach the ends, I would think that would be like a bend. However, if you mean there is a short section at the clew that sticks up above the main part of the boom for attaching hardware, I think that would be ok. I would have to see what you mean.

My booms are made from teardrop masts. The groove has been cut off the whole length of the boom except for about a 1/4 inch section at the clew. There I drilled a hole through the tract and inserted a carbon rod. The clew lines on the jib and main as well as the toppinglift on the jib pass around and under this rod and then back along the top of the boom to bowsies. Most all of the rigs that Reichard Kahle has made are done this way.

[Ted Flack]

Thanks Joe, I have now seen Kahle booms so I better understand the rule.

If I get a brain storm I'll make a drawing and send it to you before I proceed.