Moisture Rejection Closure by Zazz

moisture rejection closure productCourtesy Zazz Engineering

Zazz’s MRC (Moisture Rejection Closure) product line employs airfoils that pivot open and closed to satisfy ABS regulations.

Internal-combustion engines require air (oxygen) to operate (breathe), and at sea, wherever air goes, so goes water, or at the least, moisture. And for engines, that’s not good. The challenge is to design an engineroom ventilation system that allows in air but not water. And for the engine to run efficiently, there should be a sufficient amount of air at the necessary temperature. This temperature, called the delta t, is the difference between ambient air temperature and engineroom temperature. Generally, it should not exceed 30°F (16°C). (You can learn more about measuring the delta t in PBB technical editor Steve D’Antonio’s article “Venting the Engineroom,” at To maintain the ideal temperature, it may be necessary to install blowers to draw air into the engineroom, and duct fans for exhaust.

Rough weather may also necessitate closure devices that still allow air to flow. Among the companies making weather closures is Zazz Engineering, founded in 2008 by two former employees of Delta “T” Systems, another manufacturer of marine ventilation systems. Greg Newton and George MacDonald are boating industry veterans, the latter with several patents for dripless shaft seals. Zazz’s line of MRC (Moisture Rejection Closure) equipment is made of aluminum and stainless steel. According to the company, its airfoil design “reduces pressure drop and maximizes moisture removal,” of up to “99.3% of moisture at 15 microns or larger, with under 0.9 inches of pressure drop.” Mounted in the intake and exhaust openings of the engineroom, they are 6(152mm) deep, and comply with U.S. Coast Guard 46 CFR 116.610 (b) requirements. The closures may be opened and closed electronically and manually with 5 lbs–8 lbs of force (2.3 kg–3.6 kg-force) applied. McDonald told us his closure “doesn’t take a man and a small boy to muscle into place. Heavy metal plate weather closures are difficult if not impossible to put into place when needed.”

Zazz Engineering, 78333 S.W. Ellipse Way, Stuart, FL 34997 USA, tel. 561–594–0123, fax 561–828–3140, website