Vetus Exhaust Systems

Vetus Exhaust Systems: Waterlocks, Mufflers, Goosenecks, Separators and Transom Connections

On a water-injected sailboat diesel, the exhaust line does three jobs: it keeps sea water from running back into the engine, it quietens the exhaust, and it carries the hot gas and cooling water out through the transom. This collection holds the Vetus parts that do those jobs, from waterlocks and mufflers to goosenecks, exhaust gas separators, water swirlers, anti-siphon devices and transom connections. The way to choose is to start with the inside diameter of your exhaust hose, then pick the component for the layout of your engine room.

Vetus Exhaust Families in This Collection

• Waterlocks (LP and NLP): plastic units that stop water flowing back into the engine after you shut it down. The LP75 has a drain plug for winter storage, and the LP range runs from 1 3/16 in (30 mm) to 3 1/2 in (90 mm). The NLP75 is a two-stage unit with a 360 degree rotating top chamber and connectors, floor and bulkhead brackets, about 10 L capacity and minimal back pressure. NLP sizes run from 1 9/16 in (40 mm) to 3 1/2 in (90 mm), with Super versions of the 2 in unit.
• Heavy-duty waterlocks (NLPHD): made from a composite Vetus calls NAVIDURIN, rated up to 260 °C (500 °F), in 40, 45, 50, 60, 75 and 90 mm. Capacity is 4.5 L on the smaller sizes and up to 10 L. Compare the 50 mm NLPHD with the standard NLP50.
• Waterlock/mufflers (NLP3 and NLPH): three-chamber units for extra silencing in 40 to 90 mm (for example the 75 mm 3-chamber), and horizontal two-stage versions (for example the 50 mm NLPH horizontal).
• High-performance waterlocks (MGP, MGS and MGL): for boats with one or two large engines and little room. The outlet rotates 360 degrees, the inlet sits at 45 degrees upward, and they only fit water-injected exhaust systems. Inlets run from 3 1/2 in (90 mm) on the MGP to 8 in (203 mm) on the MGL, with capacities from 23 L to 130 L, a drain valve for winter storage and stainless clamp bands.
• Large-capacity waterlocks (LL, LS, LSS and LG): for long exhaust runs, with a built-in check valve and two securing straps. The LL has non-rotating connections; the LS, LSS and LG have rotating inlet and outlet stubs. The LL75 and the LG90 (about 17 L) are examples.
• Mufflers (DEMPMP, MP and MV): the DEMPMP (40 to 100 mm) cuts noise by mixing water inside the exhaust line with little resistance to gas flow. The MP (3 1/2 to 6 in) was developed for fast craft with powerful engines, about 13 L on the 90 and 100 mm sizes and about 43.5 L on the 125 and 150 mm. The MV (3 1/2 to 6 in) adds a check valve and a connection for a temperature sensor with an audible overheating alarm.
• Goosenecks: plastic goosenecks that raise the exhaust hose above the waterline so water cannot backfill the system, from 1 9/16 in (40 mm) to 6 in (152 mm). The LT range comes with stainless steel (AISI 316) mounting brackets; see the 3 in LT gooseneck.
• Exhaust gas separators (LGS): separate the exhaust gas from the cooling water, reduce noise and include a gooseneck function, for marine engines and generator sets. Five sizes from 1 9/16 in to 3 in rotating connections, with a 1 1/2 in or 2 in drain; start with the LGS5038.
• Water swirlers: in 3 1/2, 4, 5 and 6 in. Fitted directly behind the exhaust manifold, they make sure the injected cooling water mixes with the hot gas. See the 4 in swirler.
• Anti-siphon devices and air vents: valves for 1/2 in to 1 1/4 in hose, or 1 1/2 in (38 mm), supplied with or without hose and skin fitting. The anti-siphon device with valve shares fixing hole centres with the Airvent and can be serviced without tools.
• Transom connections: EPDM rubber with a polished stainless ring (40 to 90 mm, for example the 60 mm rubber), plastic with a check valve (40 to 150 mm, for example the 150 mm TC150) and AISI 316 stainless steel (40 to 150 mm, for example the 90 mm stainless).

How to Choose Your Vetus Exhaust Parts

• Match the hose: most parts here are sized by exhaust hose inside diameter, from 1 9/16 in (40 mm) to 6 in (150 mm). Measure your hose before you pick anything. Rubber exhaust hose is in the Vetus engine hoses collection.
• Waterlock position: when the waterlock has to sit very close behind the manifold, the injected cooling water may not mix with the hot gas and the hose or waterlock can overheat. The Vetus swirler listing says a water mixer directly behind the exhaust manifold prevents this.
• Long exhaust runs: choose a large-capacity LL, LS, LSS or LG waterlock, or one of the larger MG types, to keep the water from running back.
• Tight engine rooms: the NLP, NLP3 and NLPH units have rotating top chambers and connectors to ease installation in tight engine spaces, and the MG types are made for engine rooms with little space to spare.
• Hard service: pick the NLPHD where the exhaust system is worked hard; the listing mentions commercial and coastguard vessels.
• Alarm sensor: the MV muffler has a connection for a temperature sensor, and the Vetus exhaust temperature alarm sensor is a separate item that is not in this collection.

Who It's For

Owners replacing a worn waterlock or transom connection, refits that need to match an existing hose diameter, and installers building a new water-injected exhaust line for a sailboat diesel or a generator set. For a narrower page, go straight to waterlocks, mufflers, goosenecks, exhaust gas separators, anti-siphon devices or transom connections.

Frequently Asked Questions

What does a waterlock do?
It stops water running back into the engine through the exhaust after you shut down, and many designs also help silence the exhaust. Vetus waterlocks such as the LP carry a drain plug and the MG types a drain valve, so you can empty them for winter storage.

What is the difference between a waterlock, a muffler and a gooseneck?
A waterlock holds back the water, a muffler reduces noise, and a gooseneck lifts the hose above the waterline so water cannot backfill. Several Vetus parts combine functions, such as the NLP waterlock/mufflers and the LGS exhaust gas separators with their gooseneck function.

How do I choose the right size?
Match the exhaust hose inside diameter. The sizes 40, 45, 50, 60, 75 and 90 mm cover the LP, NLP and NLPHD waterlocks and the transom connections, while mufflers, goosenecks, swirlers and transom connections go up to 100, 125 and 150 mm. The MG waterlocks go further, with inlets up to 8 in (203 mm).

Do I need a water swirler?
The listing says to consider one when the waterlock must sit so close behind the exhaust manifold that the injected cooling water does not always mix with the hot gas, which can overheat the hose or the waterlock. It is fitted directly behind the manifold.

Which transom connection should I pick: rubber, plastic or stainless steel?
The rubber one is EPDM with a polished stainless mounting ring and mounts flexibly. The plastic version is reinforced synthetic with a check valve. The stainless version is AISI 316 with a high-gloss finish and takes the hose directly. All three are sized by hose diameter.