GMT’s largest Pocket Boom for 32 meter (105-foot) cruising sloop

Bristol, RI, USA – The Gilles Vaton designed yacht Zanzibar has just replaced her main boom with a carbon composite Pocket Boom from GMT Composites. This new boom, more than 12.1 meters (39‘8“) in length and the largest yet built by GMT, weighs only 326.6 kg (720 lbs), complete with rigging and wiring, about half the weight of the aluminum furling boom which it replaced.

Besides the remarkable weight-savings in switching from aluminum to this custom foam-cored carbon fiber reinforced fiberglass and epoxy GMT Pocket Boom, Zanzibar also achieved several other important advantages. Most obvious is the convenience of being able to stow the entire mainsail (or the reefed portion if underway in heavy weather) within the Pocket Boom’s top channel, guided there by simple lazyjacks; this avoids the weight and complexity of internal furling mechanisms while presenting the superior aesthetics of a much slimmer and more attractive profile.

The materials’ difference also effects long-term maintenance and upkeep:
this GMT Pocket Boom’s polyurethane paint adheres to the structural materials far better than paint on aluminum. Zanzibar’s boom includes internal wiring for three Cantalupi deck lights, a useful addition for work underway and for entertaining in port, especially as Zanzibar has an active career in the Caribbean charter trade.

GMT’s Pocket Booms, which can be fabricated for even larger sizes as well as for yachts under 40 feet, demonstrate GMT’s ability to produce complex composite components and structures in limited production quantities and as one-offs, fabricated to extremely precise specifications. In additional to yachting masts, booms, rudders, sprits and poles, GMT also creates products for wafer manufacturing, medical imaging, telescopy, oceanography, security and national defense.

For more information on GMT’s Pocket Booms or other GMT carbon composite capabilities, contact GMT Composites, 48 Ballou Blvd., Bristol, RI 02809 USA. Telephone: 401.253.8820, Fax: 401.253.9395, Email:, Website: