sailboat cabin vent

Best Wind Scoops: How to Use Them Properly

Last Updated by

Daniel Wade

June 15, 2022

Wind scoops are an excellent passive ventilation tool for use at anchor or when moored at the dock.

The best wind scoops are the Plastimo Ventilated Sail, the Dorcap Hatch Vent, the Breeze Booster Hatch Ventilator, the Breeze Booster Port Ventilator, and the Breeze Bandit Hatch Ventilator.

In this article, we'll cover how to use wind scoops effectively for ventilation. We'll also discuss the best situations in which to use wind scoops, and we'll feature five of the best on the market today.

This article is based on information sourced directly from wind scoop manufacturers and sailors who use wind scoops as an alternative to air conditioning.

Table of contents

What is a Wind Scoop?

Wind scoops are a lightweight and stowable alternative to air conditioning. They require no electricity, and they draw large volumes of outside air through the hatch or porthole of a sailboat.

Air scoops aren't as effective as regular air conditioning, but they're more affordable than fans, and (under the right conditions) they can provide significantly more ventilation. They're also highly compact when stowed and made of lightweight sail-like materials such as nylon and polyester.

Wind scoops are sometimes confused with deck cowls. While standard deck cowls can perform the same function, modern wind scoops are much larger and more efficient at ventilating a sailboat cabin.

How do Wind Scoops Work?

Wind scoops work the same way that traditional deck ventilators do, but on a larger scale. These large tent-like ventilators point towards the wind and channel it through the boat. Wind scoops are completely passive, and they take advantage of even the smallest breezes.

And while they're not as effective as air conditioning, they can easily add effective cooling and keep the air in your sailboat from becoming hot, stuffy, and stagnant.

How to Use a Wind Scoop Properly

Wind scoops can be somewhat tricky to use, but most people find the right alignment fast enough. The first step in using a wind scoop is to learn the circumstances in which it is most effective. Most wind scoops aren't designed to be used while underway. This is because of their lightweight construction and position on the boat. The ideal time to use a wind scoop for ventilation is when you're at anchor.

As most sailors know, an anchored sailboat will naturally turn and point into the wind, which is perfect for wind scoops. Wind scoops can also be used when in the marina as long as you orient the induction end towards the wind.

The primary purpose of a wind scoop is to simply redirect an existing breeze into and through a sailboat. The wind scoop is generally mounted over the front (forward) hatch, which must be open completely for it to be effective. This works best as it directs air from the narrowest part of the boat out into the wider spaces.

Remember that wind scoops are most effective when they move air through the boat. Since they don't actually cool the air, the best way to utilize them is to replace the existing air in the boat as often as possible. The best way to ensure that this occurs is to open the rear hatch, as it will allow the most efficient flow of air through the boat.

The same rule applies to other types of wind scoops, such as porthole scoops. In the case of larger wind scoops, you can use the companionway hatch or portholes to finely tune how much air flows through the cabin. Think of the companionway hatch as the thermostat or throttle.

Are Wind Scoops Weatherproof?

So, what should you do with your wind scoop if it rains? Many sailors ask this question, and the answer depends largely on what type of wind scoop you buy.

Standard wind scoops aren't rainproof at all. This is a problem in tropical climates, as it rains frequently, and excess moisture can easily cause mold in your cabin.

If rain is a frequent issue, consider a weatherproof wind scoop. Unlike traditional wind scoops, which are tall and thin, rain-resistant wind scoops are short, bullet-shaped, and elongated lengthwise to reduce the amount of rain that falls or blows into them. These models are also treated and waterproof, similar to a tent rainfly.

Traditional wind scoops move more air than most weatherproof models, which is why many sailors use them in tropical climates regardless. The best way to prevent rain-related problems is to be vigilant and simply close the forward hatch whenever it starts to get stormy outside.

Best Wind Scoops

There are dozens of wind scoops on the market today, including several made by the Windscoop brand. Here are the best sailboat wind scoops available today from several top marine brands.

1. Plastimo Ventilated Sail

Plastimo is a well-known manufacturer of marine ventilation equipment. If you have a newer sailboat, chances are you have a plastic ventilation cowl made by Kastimo. In addition to standard vents. Plastimo also offers a large wind scoop which they call a 'ventilated sail.'

The Plastimo wind scoop  is omnidirectional, which makes it somewhat unique in the industry. That means that this wind scoop will efficiently funnel air down into the forward hatch regardless of what direction the wind is blowing.

Omnidirectional wind scoops are ideal for most situations, and they're particularly useful when you're docked at a stationary marina. The Plastimo wind scoop is shaped like a pyramid and held up by a line that usually runs up the mast. The eyelet at the top of the pyramid is ideal for attaching to a halyard, so this wind scoop is easy to deploy and requires no bulky poles or separate rigging.

The wind scoop itself is made from polyester, which is lightweight and durable. Polyester is also soft and flexible, which prevents annoying whistling and flapping sounds. The primary drawback of this design is that it isn't particularly water-resistant, and it will readily funnel rainwater down into the cabin if the hatch is left open during a rain squall.

In other weather conditions, the Plastimo wind scoop shines. Thanks to its durable stitching and halyard-hung design, it can stand up to strong wind gusts without tearing or coming off. It also fits most standard sailboat hatches.

2. ATN Dorcap Hatch Vent

Here's a unique all-weather wind scoop designed to hold up to rain, wind, and spray. The ATN Dorcap wind scoop  is self-supported and fits most standard boat hatches.

The ATN Dorcap wind scoop is essentially a large stowable sea cowl designed to mount sturdily to the hatch of a sailboat. Unlike most wind scoops, this ATN model is stubby and low-profile. These design features make it resistant to water and wind gusts, as there's less of an opportunity for weather influx.

The scoop itself has rigid supports and doesn't need to be Leathered to a halyard to stay upright. It has adjustable airflow settings for maximum airflow and maximum rain protection. This air scoop features a 'dam' in the base of the inlet, which helps prevent water that runs along the deck from getting into your cabin.

Despite its small size and air dam, the ATN Dorcap wind scoop moves a remarkable amount of air through the cabin. It can be operated from inside the cabin as well, which means you won't have to scramble on deck during a rainstorm to close the hatch or disassemble the air scoop. This is ideal for anchoring in tropical and subtropical climates where heat and rain often accompany each other.

The primary disadvantage of the ATN Dorcap wind scoop is that it is not omnidirectional, and it can be tricky or impossible to reposition-,if the wind direction changes. However, at anchor, this is rarely a problem.

3. Breeze Booster Hatch Ventilator

The Breeze Booster Hatch Ventilator  is the wind scoop equivalent of a supercharger, and it's well known for moving an enormous amount of air through sailboat cabins. This self-supported wind scoop is ideal for medium and large sailboats in areas where the wind is usually insufficient for other smaller wind scoops.

The Breeze Booster is a large cowl-shaped wind scoop. It is self-supported and does not require a halyard. This means that it's taut as useful on powerboats. This wind scoop is about as tall as it is wide, which allows it to efficiently harness slight winds and channel them throughout the cabin. The scoop itself is very easy to set up, and it can be oriented in any direction without much trouble. This makes it ideal for use at anchor or when docked in a marina.

Another advantage of the Breeze Booster wind scoop is that it allows sailors to adjust the hatch independently. This means that you can fine-tune the airflow from inside the boat or close the forward hatch completely in the event of a rainstorm. The scoop itself provides little protection from the elements, though it offers shade and doesn't impede the user from closing the hatch.

As far as its application is concerned, the Breeze Booster ventilated hatch is comparable to the Plastimo Ventilated Sail. It works well at anchor or in the marina, though it doesn't stand up to high winds as well as the Plastimo. That said, it's easier to set up at the expense of size.

It stows larger than the Plastimo, as it's self-supported and requires some rigid parts. The manufacturer states that, when stowed, this wind scoop takes up about the same amount of space as a traditional umbrella.

4. Breeze Booster Port Ventilator

Sometimes, a giant air scoop over the hatch isn't necessary, and an extra ventilation boost over a port will suffice. That's where the Breeze Booster Port Ventilator  comes in. This smaller wind scoop is designed to mount over a traditional sailboat porthole or portlight, and it works well as an additional source of passive ventilation.

The primary advantage of the port ventilator is that it's mostly weather resistant due to its size and location on the side of the cabin. It can keep the air inside flowing even when you're not aboard, which allows you to lock up or button up your hatches. It also works well while you're on board and at anchor, as you can point it forwards towards the wind.

The Breeze Booster Port Ventilator is designed for use with inward-opening ports, which means you can adjust the airflow from the cabin or close it when it rains.

The Breeze Booster port vent air scoop is constructed of flag stock nylon, which is durable and lightweight. It also includes a screen, which is a necessity in areas with mosquitos and other insect pests. And like the standard large Breeze Booster, the port vent wind scoop is also self-supported with PVC framing.

This model is highly affordable and compact, making it a great option to start with if you're new to wind scoops.

5. Breeze Bandit Hatch Ventilator

Here's another durable wind scoop designed to stand up to gusts and windy weather. Like the Plastimo ventilated sail, the Breeze Bandit wind scoop  is omnidirectional and capable of harnessing wind from all directions without adjustment.

The Breeze Bandit wind scoop is essentially four wind scoops sewn together back to back. It has four panels that harness wind from all directions simultaneously, and it channels the wind downard and into the hatch. It's tall, thin, and lightweight, making it ideal for use on sailboats.

Interestingly, the design of this four-paneled wind scoop is not new. It was rediscovered in a centuries-old British Navy manual, as similar canvas designs were once used to cool and ventilate tall ships. In other words, it's a proven and highly-effective design.

Unlike the originals, the Breeze Bandit is manufactured from durable and lightweight polyester. Like the Plastimo Ventilated Sail, polyester was chosen to provide longevity, tear-resistance, stretch-resistance, and to eliminate flapping and wind noise.

The sides of the Breeze Bandit are reinforced with 1" webbing, providing rigidity when deployed but allowing it to collapse and stow in a compact package. The webbing is also double-stitched, which provides much more durability than some competitors. The Breeze Bandit fits hatches up to 21 inches square.

It mounts at the base with stainless steel snaps, which are durable, unobtrusive, and easy to install. The Breeze Bandit rigs up with a halyard connected to an eyelet at the top, and it stands 6 feet tall when deployed.

The primary disadvantage of this design is that it's not rainproof, and you can't close the hatch while it's deployed. That said, it's easy to simply unbutton the base and close MOB the hatch in the event of foul weather.

6. Davis Instruments Windscoop

We can't forget to include name-brand wind scoops on our list. The Davis Instruments Windscoop  is one of the most popular passive hatch ventilators on the market today, and it's the namesake of products in this category.

The original Windscoop rigs up like the Breeze Bandit and moves a large volume of air into the cabin. It must be pointed into the wind to work, but its tall and wide design makes it the most effective wind scoop on our list. It's also almost universally compatible with sailboat hatches and companionways. It fits any opening up to 4 feet wide, which makes it an option for sailboats such as the Catalina 30 that have unusually large and non-square forward hatches.

The original Windscoop is compatible with screens and mosquito nets, making it ideal for bug-filled areas. Installation is easy, as it doesn't require tie-downs. Simply feed it through the hatch and rig it up to a halyard.

The original Windscoop is affordable, and it makes a great addition to your standard cruising gear lineup for warm weather. Due to its quick and easy install, it's also great for clearing the cabin after cooking or working with fume-producing chemicals such as paint, varnish, stain, or epoxy.

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I've personally had thousands of questions about sailing and sailboats over the years. As I learn and experience sailing, and the community, I share the answers that work and make sense to me, here on Life of Sailing.

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Cover your boat cabin's vents and duct openings with quality discount marine vent parts from Great Lakes Skipper's vast inventory. We carry boat locker ventilators, boat blower vent covers, hose vent covers, round vents, square vents, and 12v boat ventilator fans from makers like Perko, Tracker Marine, Dometic, Norcold, ITC, Oceanair, and Baja. With marine boat air vent covers, vent grills, and ventilation parts at great discount prices, Great Lakes Skipper has what you need to keep your cabin looking great.

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Simple Tips to Improve Boat Ventilation

As ventilation experts explored ways to make indoor spaces safer during the COVID-19 pandemic, we became curious about ventilation in our boats. What products and practices ensure that we maximize the volume of air exchange belowdecks, as measured in cubic feet per hour (CFH)?

While this exchange of fresh air provides direct benefit to our health, it also provides an indirect benefit by preventing the growth of mold and mildew. Generally, to successfully combat mold in any given space you need at least one air change per hour, and for boats from 25-40 feet that is about 700-1800 CFH. Good ventilation also helps remove warm moist air created during cooking that can condense on the inside of the cabin—creating the moist environment that mold loves.

We’ve looked at ventilation dozens of time over the past 10 years, but most of those previous studies focused on a particular product group—fans, hatches, vents, opening portlights, or air-conditioning systems. In the September 2020 issue we narrow the focus to passive ventilation—cowl vents, dorades, hatches, “wind scoops,” and other ways to boost the exchange of air on board without any mechanical assistance.

Boats are relatively small spaces, and you’d think that it would be easy to keep interior air fresh with a few ports and hatches. As it turns out, where you install your inlet and exhaust vents is as important as the kind of vent (hatch, port, or vent) you use.

Most sailors know that wind blowing across a uniformly smooth surface such as the leeward side of a well-trimmed sail creates a region of reduced pressure. Just as we can use the resulting suction on the leeward side of a sail to pull the boat forward, we can use pressure differentials in the air surrounding the cabin to maximize the ventilation belowdeck.

Understanding the pressure differentials created by the flow of wind over our boat’s deck is vital to the success of any passive ventilation scheme. Mapping this flow (see the below image), helps explain why some areas of the boat seem stuffier than others. It also explains why passive ventilation methods did so poorly in our testing.

Your boat’s cabin trunk has a number of pressure zones, and these zones change depending on the wind direction. At anchor, the front of the cabin trunk is an area of high pressure, and this pressure reduces slightly as you move aft. The pressure differential between locations along the cabin top on depends many factors, including the shape of the cabin and any items on deck that might interfere with flow. In general, the pressure is lowest just behind the front edge of the cabin trunk, slowly rising to neutral pressure as you move aft—depending on the extent of turbulence caused at the front of the cabin trunk or by other interruptions in the smooth surface that would disrupt the flow of wind.

The companionway area has the lowest pressure. Open a hole anywhere forward and air will be sucked out the companionway. In a breeze, the pressure differential is usually so great that air will push out through gaps in the weatherstripping, escaping even if the companionway hatch closed.

Maximizing air-flow through cowl vents is trickier than it might seem. Air-flow can be interrupted not only by insufficient pressure differential, but also by turbulence. The vertical cabin-sides, dinghies stored on deck, masts, changes in wind direction, and even other cowls can dramatically reduce the amount of wind that reaches the cowl.

The most complicated case is when you keep the boat at a dock with everything buttoned up. The wind can blow from any direction, and depending on the amount of protection afforded by the harbor and neighboring boats, the wind will be light most of the time.

Bottom line: Although many passive vents are rated by CFH, these ratings don’t tell the whole story. Flow will vary greatly depending on the location of the vent, and since the rated CFH is typically based on a 10 knot breeze, the rating won’t give a clear picture of air flow when your boat is at the dock. At many marinas around the U.S., the true wind at deck level is less than 5 knots most of the time.

For more on ventilation, see the September 2020 issue of Practical Sailor. If defeating mildew is your main objective, our eBook The Mildew-free Boat will cover everything you need. If boosting breeze belowdecks is your primary aim, the following related Practical Sailor tests will help you improve the flow of air down below.

Ventilation Can be Improved on Any Boat

Deck Vents: Nicros Water Trap and Plastimos Cool n Dry are Clever and Effective

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Because my last boat (a J/24) stunk of mold, I came up with a solution for my current 38’ sloop that I can recommend without hesitation. I’ve installed an inexpensive modular ‘daisy chain’ of DC USB ‘computer’ fans underneath and behind the boat’s beds, cabinets, and seating areas. The hidden & silent fans are UL Listed and connected to each other via USB-to-USB extension cables (with inline fuse). The fans are each rated to run for 10 years and I’ve run them continuously for the past 5 years with no problems. The fans are all oriented in harmony to increase airflow circulation belowdecks…in and around all of the many spaces where humid air tends to stagnate, and (combined with the Practical Sailor recommended Eva-Dry 2200 dehumidifier) have completely eliminated ‘that boat smell’ caused by mold, etc.. The fans are each rated to run for 10 years and move 64 cubic feet per minute of air, and entire system cost me less than $100 on Amazon. I can recommend it without hesitation.

In light air, no fetch, anchor off the stern. Leave the dodger and Bimini up. Open all hatches, put up the mosquito netting, and the dodger / Bimini act like a BIG wind scoop. The breeze is great and is especially welcome below when the bugs on deck are wrecking your romantic dinner.

We’ve been very pleased with the performance of Karecel fans, which are small and recharge with a USB plug. They have 3 speeds and are nearly silent. We got them from Amazon and the come in black or white. For the price ($18), you can’t beat them.

Your comment above: “The companionway area has the lowest pressure”, conflicts with your diagram showing average pressure at the companionway. Where’s the truth?

If there is one area that needs intensive product improvement it’s marine ventilation! solar vent fans havent been properly updated since the 80’s (and the prices are utterly unjustifiable). There are of course beautiful and justifiably pricey scoops etc in Bronze etc but most of the plastic and resin originated items just don’t address the need for forced air and energy sources most available to small to medium size yachts….Solar solar solar! modular design! micro connectors to discreetly run solar power to various fittings….scoops that really seal, fans that blow and are efficient actually last 5 years! no lousy rusting parts! The biggest culprits are the companies managing the few solar fan products out there….Someone needs to take the challenge and design a growing array of good (affordable) devices to render the interior of yachts habitable! W ith plastic casting and current solar technology there is no excuse for the scarcity of effective devices!

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Get Air Down There: How To Improve Ventilation On Any Boat

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Good ventilation inside your boat is a must for comfort and safety. Here's how to get the cooling breeze flowing.

A wind chute installed over a hatch can help channel airflow below and can even keep light rain out if positioned correctly. (Photos: Fank Lanier)

Nothing enhances the quality of life belowdecks during the heat of summer, or when cruising hotter latitudes, like plenty of cool, fresh air. Good ventilation provides a multitude of benefits including preventing odors, condensation, and mold growth as well as eliminating minor carbon monoxide buildup and its negative effects on crew health (such as headaches and seasickness). Here's a look at ventilation basics and how to make them work for you.

Passive Or Active

There are two types of ventilation systems : passive and active. Passive systems rely on the wind blowing over them to move air belowdecks. They either direct air inside or exhaust it (depending on their type and orientation to the wind). Examples of passive vents include traditional cowl vents, clamshell or scoop vents, louvered hatch boards, and low-profile discs (aka mushroom vents).

Passive vents work best when installed in opposing pairs. While they can move a surprising amount of air on a breezy day, they don't perform well on days with little or no wind.

A solar-powered mushroom vent is ­convenient and easy to install.

Active systems are typically mushroom vents outfitted with a small electric fan installed in the vent body. Some are powered by your boat's 12V DC system; however, most are solar-powered. Many of the solar-powered units contain a rechargeable battery (to facilitate nighttime operation) as well as interchangeable fan blades, which allows them to be used as either an intake or an exhaust.

Ventilation Basics

Efficient airflow requires not only an intake, but also an exhaust. A single intake can't force air into a boat against pressure any better than a single exhaust can remove it against a vacuum.

Assuming a boat is oriented head-into-the-wind (as is typical while at anchor or on a mooring), it's pretty intuitive that opening a forward-facing hatch channels air belowdecks, much like an air ram. Conversely, an open companionway door or aft-facing hatch acts as an extractor, pulling air from belowdecks as the wind passes over it.

Adding a wind chute to your hatch provides even greater funneling ability. The same goes for portlight scoops, which help deflect those cooling breezes down below through vertical portlights.

If your boat has limited or no portlights, consider swapping out some of the “deadlights” (non-opening portlights). Portlights (which open to allow airflow) come in a wide variety of shapes, sizes, and frame materials (e.g., plastic, bronze, aluminum, stainless steel). As such, it is typically easy to find units to replace existing deadlights. When buying portlights, be sure to match the material of the new units to the remaining deadlights or existing boat hardware to prevent the nautical equivalent of an eyesore. Installing portlights , exhaust vents, or even additional hatches over cooking areas can also make a big difference in air quality belowdecks.

Boats at the dock face additional ventilation challenges as they can't orient themselves to the wind. Wind chutes can be repositioned to the sides or rear of a hatch to help funnel air belowdecks, while some traditional hatches are hinged or pinned so that they can be opened to face any of their four sides (a boon in this situation).

Other airflow challenges occur during rainy or stormy weather, which can prevent boats from leaving hatches and portlights open while in port or underway. A tarp or canvas cover rigged over a partially opened hatch keeps rain out and provides ventilation, although the airflow will be less than that of a fully opened hatch or one using a wind chute (which typically can't be used in conjunction with a tarp). The best solution here is a unit that combines the protection of a hatch awning and the functionality of a low-profile wind scoop.

How Much Is Enough?

A well-designed ventilation system should exchange the air belowdecks roughly once every hour. Let's say you have a mid-sized boat with an interior volume of around 1,400 cubic feet. Airflow ratings for passive vents range from 350 to 600 cubic feet per minute (cfm). Intake volume should equal output, so based on the above we would need a minimum of four similar sized vents (two intake, two exhaust) to provide adequate ventilation.

If using two active vents, they should be matched with two passive vents. If four passive vents are installed, they will automatically adapt to intake or exhaust mode as needed (with the exception of improperly aligned cowl vents).

Vents should be arranged to provide as much cross flow inside the cabin as possible. Passive vents should be mounted in pairs at opposite ends of the boat (to the extent possible) with one facing forward and the other facing aft, which provides an intake and exhaust, regardless of wind direction. A combination of passive and active vents provides the same effect with varying wind directions (or in the case of no wind at all).

More 'Cool' Ideas To Beat The Heat

• Use awnings, side curtains, and biminis to provide shade and reduce temperatures belowdecks during the heat of the day.
• Replace heat-producing halogen and incandescent bulbs or fixtures with cool-running LEDs.
• Avoid cooking belowdecks during the heat of the day. Plan around the heat by cooking galley meals in the morning or later in the afternoon while grilling or serving cold meal items for lunch. Barbecuing abovedecks will also keep the cabin cooler at night.
• For boats without an air conditioner, anchor out or take a mooring ball.
• End the day's run early enough so the engine won't be radiating heat well into the night.

Move It Around

While getting fresh air belowdecks is important, it's only half of the ventilation battle. In our example above, four vents may technically provide enough fresh air, however the interior will be broken up into separate cabins or compartments that can restrict airflow throughout the vessel. So simply installing the correct size and number of vents may not be enough to get the ventilation job done. Equally important is moving that fresh air into all the low ventilation spaces.

Drawers, hanging lockers, and other closed storage compartments will benefit from louvered doors or vent grilles. Just remember these spaces require a way for air to both enter and exit in order to provide good cross-ventilation.

Cabins and heads should also have some kind of ventilation installed, particularly if they can be closed off from the rest of the boat. For these and other such living areas, nothing improves ventilation like a few well-placed electric cabin fans . They make a hot bunk bearable, remove heat from the galley, and help reduce odors and keep moisture down in the head/shower area. Unlike the noisy, power-hungry units of yesteryear, today's fans are both quiet and energy-efficient.

My recommendation is that every bunk have a dedicated fan — two if needed due to size. It's almost as if just the soft whirring sound of the fan alone makes the bunk feel cooler. Although many boats suffer from less-than-ideal ventilation, improvements can be made to most any vessel fairly easily and at minimal expense. The effort spent constructing a hatch hood or installing a few fans will pay cool dividends for years to come.

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Frank Lanier

Contributing Editor, BoatUS Magazine

Capt. Frank Lanier is a SAMS-accredited marine surveyor with over 40 years of experience in the marine and diving industries. He’s an author, public speaker, and multiple award-winning journalist whose articles on boat maintenance, repair, and seamanship appear regularly in numerous marine publications worldwide. Contact him via his YouTube channel “Everything Boats with Capt. Frank Lanier” or at captfklanier.com.

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Ventilation

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Marine Ventilation

Proper boat ventilation practices are required for several important reasons. USCG regulations require potentially explosive fuel fumes be removed prior to engine starting. This is especially critical after refueling. These regulations apply to all gasoline engines including outboards.

Suitable ventilation of passenger areas, particularly enclosed areas, is crucial to prevent carbon monoxide poisoning. Boats with the right cabin vents will have cleaner, fresher smelling cabins. The right configuration minimizes the appearance of mildew and mold. Adequate ventilation of the head area will also go a long way towards preventing unpleasant odors.

Boat Ventilation Systems

Gasoline Engine Ventilation: Gasoline fumes are volatile, heavier than air, and potentially explosive. Gasoline vapors naturally settle in bilge areas if not properly ventilated. The operation of a bilge blower is necessary to evacuate any possible gas fumes from this enclosed space. Marine specific fuel fume detectors should be installed in enclosed areas as a safety precaution.

Passive or Natural Ventilation: A natural ventilating system typically consists of a minimum of two ventilator ducts connected to cowl vents or an equivalent device. Air intake ducting runs from the open atmosphere to the bottom of the bilge compartment. In addition, the system will have exhaust ducting leading midway from the bilge or near the carburetor out to the open air. Larger boats may require multiple vents and ducting in order to provide adequate under-deck ventilation. A passive system will only function when the craft is underway, therefore, a powered ventilation system is needed prior to engine start-up. Natural systems are required for enclosed fuel tank compartments.

Powered or Forced Ventilation: The USCG revised the regulations in 1980 to require powered ventilation systems on gasoline fueled inboard, inboard/outboard boats. This regulation did not apply to boats built prior to that date. However, it's a good idea to ugrade older gas powered craft to modern systems. This regulation also does not apply to diesel installations. Diesel is not a volatile fuel like gasoline. However, leaking diesel fuel can catch fire, so fume detection is a good idea.

Ignition protected bilge blowers should be operated for at least four minutes before starting engines. The bilge area should also be checked for the possibility of liquid gasoline from leaks and any vapors present.

SAFETY NOTE: Only fuel tanks designated 'for below deck use' should be used in enclosed area. Above deck tanks should NEVER be placed or installed in enclosed areas. Above deck tanks are red in color and are not impermeable to gasoline vapors.

Propane gas Ventilation: Propane gas is similar to gasoline fumes in that it is heavier than air and will sink to the lowest available areas. For this reason, propane tanks should be installed in proper lockers that are sealed from boat interior areas and vented outside of the boat's hull. Marine specific propane gas detectors should be installed as a safety precaution.

Engine Air Intake Vents: Many power boats feature a ducted system to moves fresh air from outside the hull through louvered grills, dorade boxes, air duct hoses and then directly to engine air intakes. It is important that these systems are designed and installed to minimize the possibility of water intrusion.

Passenger Area or Cabin Ventilation: Cabin fans, opening portlights. and deck hatches are important elements of a well designed ventilation system. A solar powered deck vent is an excellent way to circulate fresh air into head compartments. Continually flowing fresh air will help prevent mildew and mold. A combination of powered and passive air vents will ensure adequate flow of fresh air is maintained, even when the boat is unattended.

Carbon Monoxide Precautions: Carbon monoxide poisoning is an insidious, odorless, invisible killer. Carbon monoxide gas (CO) is clear and odorless, often present without the appearance of clouds of exhaust smoke. All boats with gasoline engines, gas powered generators, stoves, heaters or even charcoal grills are potentially at risk for CO poisoning. Engine exhaust system leaks, whether gasoline or diesel, are a potential source of carbon monoxide fumes. All exhaust connections should be routinely inspected for cracked manifolds, damaged pipes, deteriorated hoses, loose clamps, etc. These inspection procedures also apply to generators and all propulsion engines. Hoses should be double clamped for safety. Seal all engine bulkhead compartments to prevent CO gas leakage into passenger areas. Consider installing a carbon monoxide detector as a safety precaution.

Common Boat Vent Types

Cowl Vents are available in a variety of styles, sizes, and materials. Vinyl cowl vents are a popular choice due to their classic appearance and reliable performance. Vinyl vents work well on deck due to their soft rubber construction. Stainless steel vents work well in locations not liable to see continuous foot traffic. A Dorade box is often used to permit air flow while shedding water. Mosquito screens are a popular accessory, to keep fresh air flowing and insects out.

Mushroom Vents are more difficult to install but offer a lot of versatility. Mushroom vents often have a low profile design, making them desirable for deck mounted and hatch mounted applications. Available in passive and solar powered versions.

Clamshell Vents are the simplest in construction and to install. They are not designed to be directly connected to hoses. Clamshell vents need to be selected and installed carefully as they do not shed water effectively.

Louvered Vents are designed specifically for engine air intake applications. Most are rectangular shaped, and intended to be installed on flat surfaces. Available in stainless steel or ABS plastic construction.

Portlights are designed to be opened for ventilation and sealed shut for heavy weather conditions. Mosquito screens are available to keep the bugs out. Also known as portholes, they can be found in a variety of shapes; round, lozenge, rectangular and oval. Typical port lens material is acrylic; some ports use polycarbonate (Lexan) lenses.

Deadlights are also known as portholes. Unlike Portlights, Deadlights are fixed, in that they admit light but are not designed to be opened. They have no ventilating properties. No screens are needed.

Boat Hatch Types

Deck Hatches are designed for through deck and cabin top installations. They feature heavy duty aluminum frames and rugged acrylic or polycarbonate lenses. They are all capable of ventilation functions and can be locked securely for offshore use. The larger ones may also serve as emergency escape hatches.

Access or Inspection Hatches are constructed from resin or plastic, making them suitable for mounting on bulkheads, cockpit sides, center consoles or where foot traffic is unlikely. Available in locking and non-locking versions, they provide offer handy access to lockers, storage bins, fishing tackle, etc. Access hatches must be installed on flat surfaces.

Additional Marine Ventilation Resources

The Chapman Book of Piloting and Seamanship is the essential guide for power and sail boaters. Chapman features an extensive chapter describing the requirements of safe ventilation systems for gasoline powered vessels. In addition, there is a detailed write up of how to safeguard against carbon monoxide poisoning.

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Technical Help & Advice

We supply a wide range of vents and ventilation equipment, designed to extract heat, smells and gases from various different areas of the boat. Whether you want an air suction vent for the engine room or a dorade box to prevent water from entering the ventilator, you'll find it in this section.

Our vents and ventilation equipment come from only the best brands, such as; Jabsco Rule, SHURflo, Perko, Vetus and Maestrini. We also offer high quality equipment from our very own 4Dek range and ducting hoses from our range of Seaflow hoses. Whatever your ventilation requirements, we offer the vent to suit the style and application you want. For any questions you may have, our sales team are available to talk to you.

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Ventilation

Ventilation Proper ventilation is important for the maintenance of your boat, and is a necessity for the comfort of you and your crew.

A good ventilation system will:

• Reduce moisture and humidity belowdecks when the boat is left unattended.
• Reduce the chances of mold, mildew and musty air development caused by trapped moisture and humidity in the boat.
• Help electronics and fabrics last longer by maintaining a drier climate.
• Reduce the likelihood of blisters caused by moist air saturation of the hull.
• Active and Passive Ventilation
• Passive ventilators, such as cowl vents, clamshell vents, louvers, grilles, ventilating sails, ports and hatches simply provide an access path for air to enter or leave the interior of the boat. As long as either the boat or the air itself are moving, they work just fine. Of course on those hot, still days when the only things moving are the mosquitoes, they’re not much help.
• Active ventilators, such as Nicro’s Powervent 3000, Day/Night Plus Solar Vents and Stainless 12 Volt Vents all incorporate a fan to keep air moving even when the boat or breeze is still. Solar energy or ship’s power is used to power the fan depending on the ventilator. These vents come with both intake and exhaust fan blades for flexibility in creating your ventilation system.

Designing a ventilation system that works A properly designed ventilation system provides adequate air circulation throughout the boat without allowing water from waves, spray or rain to come aboard. Experts recommend that your ventilation system should provide at least one air change every hour. This means provisions must be made for both the intake of new air and the exhaust of old air. Set up your system to provide a “crossflow” of intake and exhaust ventilation wherever possible. If you only add one active ventilator, use it for exhaust.

A typical 30-footer has about 800cu.ft. of belowdecks interior volume. Unfortunately, this space is often broken up into distinct cabins or compartments that may restrict the free movement of air throughout the boat. Therefore, simply installing a pair of vents rated for 800cu.ft. per hour of airflow may not be adequate to get the total ventilating job done.

Each cabin and head should have some kind of ventilation, especially if the space can be closed off from the rest of the boat. Louvered doors, or vent grilles in solid doors help air circulate into lockers, forepeaks and other isolated areas of the boat.

During wet or rough weather, you’ll need to be able to shut off or remove vents to prevent water from finding its way below. Racing boats may need to use vents that can be removed while the boat is in use in order to keep the decks free of possible snags.

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• Free Delivery on UK mainland orders over £100 excl. Highlands / rural areas

Showing all 34 results

AAA Ventilator

Ventilator Complete Stainless Steel 200 X 86mm

AAA Solar Powered Vent With Battery

Plastimo Vents

AAA Solar Powered Ventilator

Vetus Athos Mushroom Ventilator

Vetus Cowl Ventilator Libec

Plastimo Cool’N Dry Dorade – 210mm – Blue

Vetus Portos Mushroom Ventilator

AAA Mushroom Vent

Mushroom Ventilator Plastic

Vetus Scirocco Shell Ventilator

Louvrent Vent Stainless Steel

Butterfly Vent Stainless Steel

Roca Louvred Ventilator

Vent Stainless Steel 5 Slot

Ventilator Louvre Round Vent Electro Polished

Clam Shell Ventilation Vent For Boats

Perko Clamshell Vent

Louvred Tube Vent

AAA Butterfly Vent

AAA Shell Vent

Ventilator 200 X 100mm

Plastimo Clam Shell Vent

Midget Ventilator

Plastimo Pvc Vent 80mm

AAA Vent Liner

Vetus Cowl Samoens Ventilator

Vetus Cowl Ventilator Chinook

Ventilator 70mm High Pvc

Plastimo Replacement Cowl For 16922

Ventilator 100mm High Pvc

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