Jibsail & Boom
Home Up Rigging Tips Goldspar Mast Jibsail & Boom Main Boom Assembly Rig Assembly Controls


Last update, December 27, 2009


Supplier Internet Information



Round boom set, Mike Zellanack or sleeved arrowshafts from a archery store.

Extra plastic boom inserts, archery store.

Spectra braided line 80#, Goodwind Kites

#2 sheet metal screw, 1/4" pan head, Stock Item

#2 SS washers,  Stock Item

#140 eye bolt, MMY

#144 eye bolt, MMY

#199 bowsies, MMY

#201 SS bowsies, MMY

#180 hook, MMY

Boom counter balance weight, Mike Zellanack



Drill and bits

Razor knife

Mini hacksaw

Small hammer


Needle files

Tap holder

#236, 3.5mm tap, tool for the #140 eye bolts, Great Basin

#235, 3mm tap, tool for the #144 eye bolts, Great Basin

Blue tape

30-minute Epoxy

Note: The photos are of the previous method of threading boom travel lines. These photos will be replaced at the first refit or building session. Only the threading method has changed. The diagrams on the Main Boom Assembly page are current and presently the suggested convention. This method will prevent previous slipping of the bowsies in higher winds, wild gybes or gusts.


The Jib

This is a very busy part of the rig. There is the standoff to place the jib out over the jumpers, a topping lift and bungee to provide twist to the sail, an uphaul of the luff for draft, a clew adjustment for camber, a sheetline adjuster and adjustment to the length of the jib swivel, which controls rake of the mast. The jib provides an environment for the mainsail and when the two are working in harmony you will be in overdrive. Because of the relationship, the jib, in part is operated independent of the main through the jib trim servo.


Preparing the Boom

Read the instructions that came with the Mike Zellanack booms. Prepare four eye bolts and install them with Epoxy. Use the #140 (20-1/4") for the sheetline and the rest will be the #144. The two on the boom are positioned at 6-1/4" and 20-1/4' from the bow of the boom. Allow these to cure and then install the top two at 2-3/4" and at the very aft end and cure them. All are to be aligned adjacent to the boom except the 2-3/4" eye should be parallel to the boom. If you are installing a twitcher flange, you can thread the eye bolt through the forward flange screw hole rather than do extra drilling on the boom. Otherwise, mount the flange immediately aft of the 2-3/4" eye position.


Measure along the side of the boom and mark at 11" and 21" from the bow of the boom. Drill with a #50 bit and insert #2 screws and washers. This is the same procedure as used on the main boom. You might like to review the procedure except that you will install three (3) bowsies this time. Remember, the line needs to be tight and don't forget the loops. Before you tighten down the forward screw, install a piece of 80# Spectra line with a loop over the travel line that will reach well beyond the bow of the boom. Place a medium CL connector on the center and forward bowsie loops. This will be for the sheetline and topping lift, respectively.


One builder has suggested that the travel line be underneath the boom to prevent snagging on the other boat you said you would never hit. This suggestion has some merit, you be the judge. If you do this, reset the screw placement more forward to avoid the sheetline eye bolt.

Jib Swivel

Thread a SS bowsie on the line off the forward travel line screw. Take this line and put it through the jib swivel eye bolt, through a hook and back through the eye bolt to the bowsie and tie it with three half hitches. Adjust the line so that the bight of the hook is 2" from the center of the eye bolt to the hole in the jib rack. This will be the mean operating length of the jib swivel with a straight mast.



The photos here are from an old process using worm sinkers from a fishing supply. Mike Zellanack has made it easy with his correctly weighted casting that slips into the bow of the boom. This is the way to go.

We use the counterweight and the twitcher here. Some use one or the other.


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