Zoom Jib Boom: How It Works

Zoom Jib Boom

The Zoom Headsail / Furling System info

The unique and Patent Pending headsail is based on a mirror image 110% jib.   There is no luff tape.  Instead, the sail wraps around the furling extrusion.   The sail includes a grippy center section to assist in the furling of the sail.  Typically vertical battens can be added to allow additional roach.  Most of the rotational force is provided by the head and tack connection, which must not swivel.   Many European furlers, such as Profurl and Facnor furling units, do not have tack or head swivels (i.e. the tack and head shackles rotate with the extrusions) and can be used without modifications.   Harken furlers can be modified by installing a locking screw, for which we can provide instructions.

Anchor Rollers

On newer boats, the forward projection by about 12% of the J dimension keeps the furler aft of the front end of your anchor.   Danforth style anchors or anchors with ‘roll bars’, which sit much higher than a Bruce or Delta style anchor in the roller, may not fit.

Although the center of effort will move forward slightly the mast can be raked back to help offset this.  In experimenting on boats with a very neutral helm, the effect from moving the headsail forward has not been noticeable.

Bow Pulpit

If you have a Euro style walk thru split bow pulpit (typically 2 separate pulpits that start aft of the furler as shown in most of these pictures), the Zoom boom can be fitted with no pulpit modifications at all.

Many American style 4 leg bow pulpits in which the forward pulpit legs are 6-8″ aft of the furler will present no obstacles to the installation of the Zoom boom.   In about 50% of existing bow pulpits, no pulpit modification is needed.  The forward end of the Zoom boom will pass under the lower bar of most bow pulpit.   3 leg pulpits will need to be modified, typically by cutting off the center leg and adding 2 legs further aft or by installing a Euro style bow pulpit.  We can offer replacement Euro Style 4 leg bow pulpits.

On some older boats the furler is often about a foot or less than 10% of J aft of the bow pulpit.  The furler will live just forward of the bow pulpit with the Zoom installed.   It is also possible that the furler can be installed between the upper and lower bow pulpit.  Remember that the furler needs to able to swing through at least a 180 degree arc.  Finally, a bow light may also need to be moved.

To simulate your Zoom boom, cut a 2×6 to at least 15% of the J dimension, (the distance from the forward edge of the mast to the stem fitting clevis pin).  The back end should be cut so that when the 2×6 is parallel with the deck, the cut of the aft end is parallel with your forestay/furling system.  Mark where 12% of J would be.  Now support the forward end with a jib, spinnaker or main halyard so the 2×6 is parallel with the deck and the aft end is 3-4″ above the stem fitting (often right at the furler drum).  Swing the 2×6 from centerline to the side.  If the 2×6 can swing through more than 90 degree’s from the centerline on both sides you should be fine.  If you have questions please send pictures of your bow set up from the side and head on.

Baby Stays / Forward Lowers

Baby Stays are not compatible with a Zoom Boom.  In some cases forward lowers can replace the babystay.  Often, forward lowers are not much forward than the arc the end of the Zoom travels through.   Use a tape measure or a rope tied around the furler at lifeline height.   Run back to the mast.

Add a jib or spinnaker halyard and swing the rope from the furler to the lifelines.  Check for clearance.

Is the headsail too flat to be effective downwind?

Spinnakers use a very full shape to provide stability, but when running deep angles, you are looking for projection or area, not shape.  You want the biggest barn door possible, which is why race boats no longer ease the mainsail outhaul when running off the wind.   Your headsail, when projected to windward, makes for an awesome downwind sail.

What are the negatives?

Probably the most noticeable issue is that your headsail will be harder to roll up, due to the twin 2-1 outhaul lines you need to pull through when rolling up the headsail.  The outhaul lines each pass over 3 primary sheaves in the boom, the stanchion fairleads, a line stopper and a stern pulpit fairlead block which creates the friction.  You may want to go up one size for the jib furling line, and you probably will need to use a winch to roll up the headsail.

Isn’t it time you gave your boat a little extra Zoom?!  Fast is fun, especially when you can make it all happen singlehandedly from the cockpit!  Get ready for a revolution in sailing!