Those Damn Leaks: How to Find and Fix Boat Leaks
The source of a boat leak is not always easy to find (or fix). here’s how i diagnosed and repaired a troublesome boat leak on my sailboat.
Spring (and the preceding winter) is the time to prepare our boats for the upcoming boating season. In this article, I will discuss finding and addressing two significant leaks into the aft cabin of my Hunter 410 sloop, Bay Poet.
But first, a little bit of history on my boat (and the leak).
When one agrees to purchase a boat, a marine survey by a professional surveyor is highly desirable and if the vessel if being purchased with a loan, the lending institution will likely require one. Since my purchase funds were not secured by the boat, I did not necessarily need a survey but I wanted one since I was a first time buyer. However, certain things are not necessarily revealed during a marine survey. A leak on the starboard side of the aft cabin was one of those.
The excitement of the purchase allowed me to overlook the dark, softened wood on top of the locker at the foot of the owner’s berth. However, a heavy rain over that first winter disclosed the existence of an ongoing issue. Some time later, a more serious leak appeared to present itself on the port side of the same cabin. This was becoming serious. Bareboat charterers were beginning to complain and I saw a drop in my charter revenues. I had to do something.
Finding the Source of a Boat Leak
To find my boat leak, I started looking around the boat for likely suspects. I looked at all the obvious and usual suspects: deck cleats, lifeline stanchions, port lights, and the base of the classic Hunter arch. (I have an early model of the Hunter 410 so the arch is fiberglass and not the more common stainless steel roll bar style of arch).
Typically you look for stress cracks, loose mounting hardware, missing bedding compound, or concentrated streaks of dirt or rust. Even to a detailed examination, I found none of those things. However, my Hunter 410 has a heavy rubber rub rail that covers the deck-hull joint. I could not discount that possibility of some flaw being hidden by that structure.
Next came the online research. Almost immediately, I found forum submissions discussing my exact problem . Rub rails such as mine do hide leaks and what’s more, the point of entry may not be in the vicinity of the place where the leak manifests itself inside the cabin. I was going to have to have the rub rail removed so that I could do a more detailed and unrestricted inspection of the deck-hull joint. As Dirty Harry said in Magnum Force (1973), “A man’s got to know his limitations.” I was going to have to have professional help in removing the rub rail.
Enter Haven Harbor Marina and their crew of service professionals. I got an estimate for time and cost. (You always do that too, right?) The Service manager told me that they could not start taking the heavy rubber off until the average daily temperature was about 50° F. It was important to get this done but given that temperature constraint, spring launch and commissioning was going to be quite late this year.
I was quite pleasantly pleased when the Service Manager emailed me in mid-March to say the rub rail was off. This also involved removing the bow stem and forestay. (Yes…can you hear the yard bill racking up?). My helper and I headed to the Bay Poet.
We first looked over the exposed joint…looking for anything blatantly obvious. The most obvious thing was the clumps of gray, hard, gummy remnants of butyl tape that had been squeezed into the space behind the rub rail some time after the boat had been built. This was on the starboard side of the inclined transom and therefore, an area of possible concern.
I also inspected the screws through the joint. Nearly all were shiny and still snug showing no signs of any pernicious leakage. We began washing and scrubbing the small shallow channel between the T-rail and the topside.
My first big ah-ha moment was about to happen. I began scrubbing what I thought was a streak of black dirt and a possible clue to the port side leak. I had no idea how right I was. The “black streak turned out to be an 18 inch crack between the horizontal lip of the deck flange and the vertical coaming around the cockpit.
Worse yet, there was a matching crack under the hull flange. It had the look of damage that might have been caused by a HARD port landing. Whether it was the previous owner or a charterer, we had found the port side leak.
The starboard side was less obvious. There were some anomalies and imperfections in the fiberglass on the deck side flange. There were of the nature of bubbles or clumps of fiberglass and gelcoat. There were also some voids through the gelcoat but none were much bigger than the size of a pencil eraser. Nonetheless, I was going treat this side as well. Admittedly, I was less secure in the starboard side diagnosis.
Repairing the Boat Leak
Even though I had already estimated the cost and schedule, I asked the marina for a quote to repair the cracks. First of all, my estimate was 16% below the $6000 I was quoted. More importantly, given the spring commissioning work going on, they could not possibly schedule the 5 days it would take to do the job. As I anticipated, that exceeded my budget and the time I had to get the boat ready for charter season.
I opted for a more expedient and inexpensive fix. I would use a marine grade sealant to fill the voids and holes and hopefully seal the leaks. There are a number of choices of sealant. All options work well above or below the waterline. The final choice came down to cure time.
While 3M 5200 produces the strongest bond, it takes up to 48 hours for the initial cure and up to 7 days for a full cure…at some nominal temperature. On the other hand, while 3M 4200 has a weaker but quite adequate bond, the initial cure time is hours with final cure time of 24 hours. Both handle similarly in application and clean up.
Life Seal may be another option but the Service Manager recommended the 4200 so that was good enough for me. The cost of all of these sealants is comparable. See the table below for side by side comparison.
Marine Sealant Comparison
My method of application of the sealant was the same on both sides of the boat. I used a caulk gun to squeeze out a bead of compound. Then I used a gloved finger as a trowel to smooth and level the sealant with the T-rail on the joint and onto the hull or coaming accordingly.
In the case of the port side crack, I poked sealant INTO the voids before smoothing over the area. I had also taken the screws out of the T-rail to investigate the condition of the exposed core laminations. All but one screw hole looked fine. I squeezed a little sealant into that hole before I replaced the screw. Sealant squeezed out from both sides when I tightened the screw.
When all was said and done, there was a skim coat layer of at least 1/16” to 1/8” inch over the surface of the gelcoat. The caulk has begun to skim over before I left for the day.
Now the marina has to reinstall the rub rail, reinstall the stem fitting, and retune the rig. It was too cold on their first attempt. The rubber had contracted from the cold and was also too stiff to manipulate.
I am hoping this week we’ll see it all done and that I will find Bay Poet back in her slip.
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How To Find And Fix A Boat Leak
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At some stage, most boats will develop a leak. Here we look at leaks below the waterline and how to find and fix them.
Use a paper towel to thoroughly dry the fitting and surroundings.
Although there are rare examples of the coveted dusty bilge, most owners expect to do a little dewatering on their boat occasionally. However, leaks from above and leaks from below are not created equal. Discounting rainwater leaks, some boats are tighter than others and it's important to know what the normal bilge water accumulation is for your boat. Mental calculations may be required to assess the "normal" state.
Here's a good example. The stuffing box drips every 15 seconds, yielding .12 fluid ounces in 15 minutes and translating to about one quart every three days or so. Not a big deal. If you know what's normal for your boat, you should be able to judge when a leak is getting worse. A bilge pump counter (available at West Marine) is an excellent investment that can be wired into the bilge pump circuit to alert you to potential leaks that might otherwise go unnoticed. Just beware of the faulty logic that a leak ignored will eventually stop.
Unexpected water below the floorboards can be a scary surprise and a mystery leak should make you nervous. After all, you don't know if it's a minor issue, such as that pesky tapered plug on a worn seacock, or the harbinger of doom, a critical component somewhere that is hanging by a thread and just waiting for the right Murphy's Law moment to let go. There can be no peace of mind until the leak is identified and fixed.
Finding The Leak To Nowhere
Often, finding the leak is more time consuming and difficult than fixing it. This is why many repair facilities often suggest: "You find it, we'll fix it." That can be money-saving advice.
Easy-to-find leaks occur at hull fittings. Tools required to find these leaks are simple: a roll of paper towels, flashlight, and small mirror. Check the inside skin of the hull by hand for wetness trickling down from any thru-hull, rudder port (often visually inaccessible), the shaft log, stuffing box, and strut fasteners. Other culprits are trim tab and swim-platform mountings. If it feels wet, move in for a closer inspection. Use the paper towel to dry off the hull and the fitting, and inspect closely using the flashlight. Look for the first appearance of a trickle or drip. Dry it again and verify you are seeing the first point of emergence. Use the mirror to check the backside of the fitting. On a thru-hull, for example, it's important to determine if the bedding compound sealing the thru-hull is leaking, or if it's an attached valve or hose.
Tools of the trade: flashlight, paper towel, and fingertips.
Leaks at skin fittings are comparatively easy to find.
Fingertips are a superb wetness sensor, often finding a leak that is impossible to see.
Pay attention to fittings above the waterline. The crack in this plastic fitting means the boat need only sink about an inch or two before it floods.
On a stuffing box or rudder port, you must differentiate between a routine drip at the packing gland, which can be controlled by an adjustment of the stuffing box nuts, and a more sinister leak from a cracked shaft log tube or from under the backing plate of a rudder port assembly.
Finding a leaking keel bolt on sailboats requires that the bilge or keel sump be mopped perfectly dry so that the very first drop of water welling up from under a backing plate or, worse, from a crack can be positively identified. Powerboats with stern drives most commonly suffer from leaks originating at the U-joint or the bellows. These can be hard to see but look for a slight trickle of water on the inside of the transom below the transom assembly. Many of the sources of the leaks described only become apparent when the boat is underway, "working," so to speak. Seeing them when the boat is quietly afloat in its berth may be impossible. What happens if all the below-the-waterline fittings on the hull check out as dry but the bilge keeps filling up with water? At this point, detective work is required, employing a logical methodology to follow the clues.
First Clue: When Does The Leak Occur?
If, for example, water in the bilge stops rising at the same time the water tank is found empty, it's logical to conclude the two are related. That's an easy one. Is the leak constant whether underway or at the dock? If it only occurs underway, does it happen at every outing, only in big sea conditions, or only at certain speeds? Any intermittent leak needs to be caught "in the act," requiring you to carry out testing underway to duplicate the circumstances under which the leak occurs. The waterline of any boat moving at displacement speeds peaks at the bow wave and the stern quarter-wave. This can submerge thru-hulls that are well above the waterline at rest. Other intermittent leaks can originate at the engine cooling system or running gear and will only show up when the engine is running. If a sailboat only leaks when it's heeling over, a keel bolt or keel sump crack leaking under load or a fitting on the leeward hull side siphoning into the bilge might be implicated. In this case, change tacks and observe what happens.
Second Clue: Where Does The Leak Originate?
If the leak is constant, dry the bilge and identify the direction from which the first trickle arrives. This will at least narrow the search for the point of entry to port, starboard, forward, or aft. However, leaks are devious and boats are built with hidden conduits and inaccessible compartments. The location at which the leak exits into the bilge may be a long way from its entry point into the hull.
Inner liner mystery leaks: Water arrives via the limber holes and collects in the bilge sump, but where does it originate?
Adding an inspection port in the liner or double bottom can open inaccessible locations.
Inaccessible spaces below the floor may hold water, requiring you to cut an access hole to get a pump in there.
This embedded prop shaft strut is suspected of causing a hidden leak. Whether the repair was successfully will be known after launch.
If the leak appears to originate from inside a closed compartment or from under the edge of a hull liner, it may be necessary to cut an access hole and install an inspection port to close the hole later.
Leaks on sailboats with full keels and encapsulated internal ballast can be tricky to diagnose. These boats usually have two lines of defense. The hull skin itself is the first defense and is usually a very thick layup at the leading edge and keel bottom. Given that boats with deep keels do occasionally run aground, the builder will usually cap the ballast with a secondary glass layer across the top of the keel. This secondary defense forms the floor of the bilge and will keep the boat dry in the event the hull skin is holed. It's safe to assume that if there is a leak at the inner skin, there must also be a leak at the outer skin.
Powerboat hulls, too, can often hide problems. Many have a double bottom filled with flotation foam or arranged with liners so that the inner skin of the hull cannot be seen without destructive measures. If the leak's origins are truly hidden, the best option is to haul the boat and search the outside of the hull for damage. It helps to leave the bilge full of water and look for the telltale trickle of water leaking out.
Fixing Leaks
Leaks at hull fittings, such as seacocks, valves, hoses, instrument senders, and running gear, are common and usually straightforward to fix. Generally, any leak at the bedding compound sealing a thru-hull or hardware bolted through the hull requires hauling the boat and complete removal and reinstallation of the fitting. Attempts to add "goop" to the outside perimeter of the fitting, or the inside, rarely succeed. Unfasten and remove any hoses or valves and then unscrew the clamp nut or individual fastening bolts securing the fitting. After cutting away as much old sealant as possible, a thru-hull can usually be pushed or knocked out from inside the boat. The old sealant will probably have a strong grip (even though it's leaking) and it may be necessary to "gently" break the fitting loose with a dead-blow hammer. This can be a wood mallet or even a small sledge, provided you use a softwood block between a steel hammer and the fitting.
Through-bolted hardware with an external flange such as a rudder port or prop shaft strut will probably need to be wedged and carefully pried loose. A two-inch or wider chisel works well for this. After removal, clean all the old sealant off the hull and fitting. Check the fitting carefully for cracks or corrosion. Proper reinstallation requires lots of polyurethane sealant under the outside flange, on the edges of the hull opening, and on the inside of the hull under the backing block. Replace any old wood backing blocks with new wood or, even better, a piece of UHMW polyethylene or some StarBoard scraps. Replace any corroded fasteners with new ones.
While you're at it, inspect the hose connected to the thru-hull. Replace any cracked, weathered, or substandard hoses and inspect hose clamps, too. If there is a garden-variety gate valve on a thru-hull, replace it with a quarter-turn ball valve or seacock that meets the material and testing requirements of ANSI/UL 1121, as specified by American Boat and Yacht Council (ABYC) standard H-27.5.2.
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Nick Bailey
Contributor, BoatUS Magazine
Nick Bailey has more than three decades in the boat-repair business and is service manager of Bristol Marine in Mississauga, Ontario.
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How to Prevent, Find, and Fix Leaks in a Sailboat
Sailboats are prone to leaks, which can be a frustrating problem for sailors. Leaks can occur due to a variety of reasons, such as poor maintenance, natural wear and tear, and harsh weather conditions. However, with proper care and maintenance, you can prevent most leaks from occurring. In this blog post, we will discuss the causes of sailboat leaks, how to prevent them, and how to fix them in the middle of the sea.
Table of Contents
Causes of Sailboat Leaks
- Age: The older a sailboat gets, the more susceptible it becomes to leaks. This is because the materials used to build the boat start to break down over time.
- Poor Maintenance: Regular maintenance is essential for the proper functioning of any vessel, including a sailboat. If a sailboat is not maintained properly, leaks can occur.
- Harsh Weather: Harsh weather conditions, such as high winds, heavy rain, and rough seas, can cause leaks to develop.
- Hull Damage: Damage to the hull, such as cracks or holes, can lead to leaks. This can happen due to a collision, grounding, or hitting an underwater obstacle.
- Deck Fittings: The fittings on the deck of a sailboat, such as hatches, portholes, and cleats, can also be a source of leaks.
Preventing Sailboat Leaks
- Regular Maintenance: Regular maintenance is crucial for preventing leaks in a sailboat. This includes inspecting the hull, deck fittings, and other components of the boat for damage, wear and tear, and other issues. Any issues should be addressed promptly.
- Proper Storage: Proper storage of a sailboat is essential for preventing leaks. The boat should be stored in a dry, covered area when not in use.
- Quality Materials: When building or repairing a sailboat, it is essential to use high-quality materials that are designed to withstand the elements and last a long time.
- Hull Maintenance: The hull of a sailboat should be maintained regularly, including cleaning, sanding, and painting.
- Inspect Fittings: Deck fittings should be inspected regularly to ensure they are in good working order and properly sealed.
Fixing Sailboat Leaks
If a leak develops on a sailboat, it is essential to address it as soon as possible to prevent further damage. Here are some steps to take:
- Locate the Leak : The first step in fixing a leak is to locate it. This can be done by inspecting the boat and looking for water intrusion.
- Temporary Fixes : If a leak occurs in the middle of the sea, temporary fixes such as duct tape or expanding foam can be used to seal the leak and prevent further water intrusion.
- Long-term Repairs : Once the boat is back on land, long-term repairs can be made to fix the leak permanently. This may involve repairing or replacing damaged components, such as the hull, deck fittings, or seals.
- Seek Professional Help : If you are not comfortable making the repairs yourself, it is essential to seek the help of a professional boat repair service.
How do you find a leak in a sailboat?
Finding a leak in a sailboat can be a challenging task, but it’s essential to locate and address the problem as soon as possible to prevent further damage to the vessel. Here are some steps you can take to find a leak in a sailboat:
- Look for visible signs of water intrusion: Check the bilge, hull, deck, and interior of the boat for any signs of water intrusion. This could be standing water, damp or wet areas, or discolored or stained surfaces. The location of the water intrusion can give you a clue about the possible source of the leak.
- Test fittings and hardware: Check the fittings and hardware on the deck and hull, such as hatches, ports, and cleats. These can often be a source of leaks, so inspect them for any signs of damage or wear, and test them for proper sealing by spraying water onto the surface around the fitting while someone checks for leaks below.
- Check the hull: Inspect the hull of the boat for any signs of damage, such as cracks, holes, or blisters. If you find any damage, it could be a source of the leak.
- Look at the rigging: Check the rigging, including the mast, boom, and standing and running rigging. Look for any signs of damage, such as corrosion, wear, or loose fittings, that could lead to leaks.
- Use a hose: You can also use a hose to simulate rain by spraying water onto different areas of the boat, while someone checks for leaks below.
- Test with a smoke generator: You can use a smoke generator to pump smoke into the boat, then look for the source of the smoke where it exits the boat. This method can be particularly useful for detecting leaks in hard-to-reach areas.
- Seek professional help: If you are unable to locate the source of the leak, or you do not feel confident in making the repairs, it’s essential to seek the help of a professional boat repair service.
In conclusion, finding a leak in a sailboat can be a challenging task, but with patience and thorough inspection, the source of the leak can be located. It’s important to address the problem as soon as possible to prevent further damage to the vessel, and if you’re unable to locate the leak or feel uncomfortable making repairs yourself, seek professional help.
In conclusion, leaks are a common problem for sailboats, but with proper maintenance and care, they can be prevented. Regular inspections, proper storage, quality materials, and good maintenance practices are all essential for preventing leaks from occurring. If a leak does occur, it is essential to locate and address it as soon as possible to prevent further damage to the boat. With the right tools, temporary repairs can be made in the middle of the sea, while long-term repairs should be left to the professionals.
Mark Alexander Thompson
Mark Alexander Thompson is a seasoned sailor with over five years of experience in the boating and yachting industry. He is passionate about sailing and shares his knowledge and expertise through his articles on the sailing blog sailingbetter.com. In his free time, Mark enjoys exploring new waters and testing the limits of his sailing skills. With his in-depth understanding of the sport and commitment to improving the sailing experience for others, Mark is a valuable contributor to the sailing community.
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How to Prevent Moisture in Your Sailboat
Last Updated by
Daniel Wade
June 15, 2022
Moisture is the enemy of sailboat interiors, causing mold, rot, and other issues. It can also compromise your deck and keel.
In this article, we'll cover why it's important to keep moisture out of your cabin. We'll also show you the best ways to prevent leaks, which are the primary cause of excessive moisture. Additionally, you'll learn how to repair moisture-damaged surfaces.
Proper ventilation is the easiest way to prevent moisture from building up and damaging your sailboat. Moisture can be prevented by regularly inspecting and repairing areas around hatches and vents. A blower or dehumidifier can keep humid climates from negatively impacting your boat.
We gathered this information from sailors and repair companies with years of experience dealing with moisture problems on sailboats. Other sources, such as marine equipment manufacturers, also provided information that contributed to this guide.
Table of contents
What Causes Moisture Buildup on Sailboats?
Moisture buildup in the cabin of a sailboat is more than just a nuisance. It's the main cause of structural damage on many boats, and it can utterly destroy the liveability of your sailboat cabin faster than you'd expect. But what causes moisture buildup on sailing vessels?
The most obvious cause of moisture buildup on boats is a leaky deck or hatch. Counterintuitively, it's not usually the hull of the boat that leaks. Rainwater is the primary culprit, and a very large volume of it can accumulate inside your boat.
The problem is compounded by poor ventilation. A fiberglass boat is a lot like a plastic bag, and water can't evaporate and escape nearly as easily as it can get in. It's also important to note that vents themselves can also be a source of leaks.
What does Moisture Buildup Do?
Moisture buildup has nasty effects on virtually every structural and technical system inside a boat. It can also pose a serious health threat over time. This is especially true in hot and humid climates such as Florida or Hawaii.
Structural Damage
Fiberglass sailboats have a layer of shaped material between the layers of glass. Often, this is organic material such as plywood or particleboard. If moisture builds up between these lasers, it can compromise the integrity of the fiberglass. This can cause the deck to sag, and it will eventually ruin the boat.
Cosmetic Damage
Moisture can cause wood to warp, which will lead to issues such as doors that won't close or peeling veneer. These cosmetic issues are usually relatively easy to repair if the underlying structure remains intact.
The one exception, though, is upholstery, as it can be very costly to replace stained and water-damaged cloth, leather, and foam.
Electrical Damage
Moisture is an obvious threat to the electrical systems aboard a sailboat. Water causes everything from contact corrosion to short-circuits, which can be dangerous and a real pain to repair. If you begin having electrical problems after it rains, moisture is the most likely culprit.
Mold and Mildew
Moll is an extremely common problem on fiberglass sailboats. It grows in dark, damp places with poor ventilation. In other words, the cabin of a sailboat is the perfect breeding ground for mold.
Many kinds of mold are harmless, but toxic mold also grows on sailboats. Mold of any kind is difficult to remove, and it can cause long-term damage to your health.
Mildew, on the other hand, is mostly a nuisance and not as serious of a health threat as the toxic black mold. However, the musty smell of mildew is a warning sign that moisture is building up, and mold could soon follow.
How to Prevent Moisture Buildup
Preventing moisture buildup on a sailboat is the best way to avoid costly interior and structural repairs. The best way to prevent water from entering your boat is to visit after a rainstorm or sailing trip to check if (, and where) water is pooling up inside the cabin.
If you have a leak, look for the source. Portlights, hatches, vents, deck plates, and light fixtures are common sources of difficult-to-find leaks. Once you identify the source of the leak, fix it promptly and ensure the vessel has adequate ventilation to dry the water.
If a leak leaves your upholstery soaked, take it out to dry and promptly clean the surrounding area to prevent mold or mildew from proliferating.
If humidity is the problem, you may want to consider adding active ventilation to prevent musty air from becoming stagnant. Even a small amount of active ventilation can prevent or reduce mold in humid environments.
Active Ventilation vs. Passive Ventilation
The difference between active and passive ventilation is important to consider when equipping your boat to deal with moisture buildup.
Active ventilation uses a powered fan or blower to artificially induce a draft inside of the boat. Many sailboats utilize solar-powered deck vents as a low-maintenance and self-powered form of active ventilation.
Passive ventilation simply refers to deck cowls, open windows, or any other ventilation system that doesn't utilize a fan. All sailboats should have at least one form of ventilation that's open all the time.
Active ventilation is better for reducing moisture, as it pulls a much greater volume of air through the cabin almost all the time. Solar vent fans are an excellent choice for this. However, the ideal combination of vents includes both active and passive vents.
Dehumidifiers
Dehumidifiers have long been used as part of the HVAC system on larger commercial vessels and yachts. In humid climates, even sailboats larger than 30-feet in length could benefit from a dehumidifier.
This is especially true for liveaboard sailboats , as the addition of a dehumidification system can make the cabin much more comfortable. A typical home dehumidifier will work, but it's not the best solution.
This is because home dehumidifiers are bulky, and their water containers often don't seal completely. The last thing you want is for a passing boat wake to topple your dehumidifier and spill the water right back into the boat.
A marine dehumidifier is a better option, and there are many options available for larger family sailboats. Dehumidifier units are also available for small boats, and they typically run on 12-volt DC current. These smaller units are self-contained and portable, allowing you to run them periodically when you're not aboard.
Dehumidifiers are an excellent option for sailors who don't use their boats often, as they're an inexpensive way to keep your boat safe and dry. For long-term use, consider installing a permanent dehumidifier as an integral part of your ventilation system. These units don't have drainage tanks, as they drain excess water directly out of the side of the boat.
Tips for Repairing Moisture Damage
Moisture will always be a problem that sailboat owners have to deal with. As a result, there's a good chance that you'll have to deal with moisture damage at some point in your sailing career.
When dealing with suspected moisture damage, it's important to determine the actual extent of the damage. If you notice a peeling cabin board, don't just replace the veneer. Make sure that the wood below hasn't begun to rot, and make sure that surrounding areas are free of mold. The same applies to upholstery, as cloth can trap moisture for long periods of time and dramatically accelerate wood rot below it.
If electrical systems are involved, hire an electrician to get an accurate picture of the extent of the damage. In many cases, simple wiring can be saved, but any circuit board-used electronics are usually toast.
It's important to use extreme caution with electrical systems, especially any system that uses 120-volt AC power. DC systems are a bit less hazardous, as they typically use much lower voltages and amperages, which reduces the risk of a dangerous shock.
Upholstery can usually be cleaned after sustaining moisture damage. If the smell of mold or mildew remains after a thorough cleaning, you may have to replace the foam inside the covers. When mold is involved, you may be best off replacing the non-washable materials regardless.
Always wear gloves and a respirator when dealing with mold. A standard painter's mask probably isn't sufficient, as industry professionals recommend a full respirator with filters designed to capture mold spores. For the best protection, use a respirator with P100 filters, such as those certified by the EPA for lead paint, asbestos, and mold.
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Yachting Monthly
- Digital edition
How to repair yacht hatches and windows
- Duncan Kent
- June 8, 2023
Leaky yacht hatches and windows can make life down below miserable. Duncan Kent explains how to ditch those drippy blues forever
Every boat I have ever owned has had at least one leaking window or hatch at some point and, from experience, no amount of temporary bodging has ever succeeded in fixing it for longer than a few days. In the end, the only way is to do it properly. Despite taking longer, there’s nothing better than knowing you’re leak-free when the skies open or a huge greenie comes rolling down the sidedeck.
Yacht window repairs
Scraping and back-filling will only last a short while, especially when the old sealant holding the glass in the frame has deteriorated beyond all recognition. The typical butyl sealant used for sealing glass into frames and frames to the cabin has a working life of around 20 years maximum. The first bit to go is usually the top strip, where the strong rays of the sun break down the butyl into a crumbly, powdered mess.
Adding sealant after a new hatch has been dropped into place and screwed down
No matter how experienced you might be at removing windows and hatches it always turns into a long, tedious job, so make sure you put aside a few days and do them one at a time to avoid having to tape tarps all over the boat.
If you do plan to remove them all at once, do mark all the components of each window and hatch with numbered tape (including any fixings) as it’s very likely they’ll all be a slightly different size or shape, so you don’t want to muddle them up. Also, mark the orientation of each frame so that it goes back in the same way, ensuring the mounting holes will line up.
Windows will be bedded into a frame which, though also sealed to the coachroof/deck at the end, will almost always be mechanically attached to the boat in some way. Although butyl sealant isn’t particularly adhesive, after 25 years you can guarantee it’ll be well stuck to the coachroof, and it’ll be much worse if someone has used an adhesive sealant on them!
The only way to remove them is by sheer hard graft unfortunately – sliding a sharp blade or sharpened paint stripper blade all around the seal (trying not to damage the boat) until enough of the old seal is broken to allow you to pull/push the window out.
Then a similar process has to be carried out on the frame to remove the glass or Perspex, whichever you have. The frame will usually be in two halves, joined by screws or clips with a backing plate, which will need to be cleaned up and resealed before reassembling.
One word of warning: the frames, commonly aluminium, often distort or even spring apart once you’ve removed the joiners, so it’s best to find a way to retain its shape (template or similar) so that it’ll slip easily back into place once you’ve sealed in the window. I’ve seen people make the mistake of sealing the pane into the frame and leaving it to go off before offering it up to the window aperture, only to find it no longer fits and they then have to either disassemble it all or start grinding out the aperture to match.
Once you’ve dismantled the window and hatch you must remove all trace of the old sealant and clean the frame and glass by rubbing alcohol or a similar non-oil-based product. Beware: some plastic panes, polycarbonate (such as Lexan) or acrylic, for instance, can be damaged when they come into contact with certain solvents, acetone or acids. All components must also be bone dry and solvent-free before you reseal them.
There’s a plethora of different types of adhesive and sealant available today but not all are suitable for every job. For instance, some of the well-known Sika brands of adhesive sealant will stick stuff together forever, which might sound great unless you need to change it a few years later and you have to chisel the component out of the GRP boat!
In rough seas any leaks in the windows will become all too apparent. All windows and hatches will need re-bedding sooner or later
Window and hatch glass is usually bedded in using butyl non-adhesive sealant as it will normally be held firmly in place by a frame, which in turn will be fixed to the boat using screws or bolts.
Butyl sealant is a mildly adhesive blend of butyl rubber and polyisobutylene. It is easy to apply and, remaining flexible, allows plenty of room for adjustment when the surfaces are mated together, unlike some quick-setting products.
In effect, it is used to simply create a waterproof, flexible gasket. Available in both cartridge form or as a tape, it is not unlike putty or chewing gum in feel and appearance, and is easier and far less messy than squirting sealant using a pump gun, although the latter is also available for other jobs.
One advantage of butyl is that it’s fairly easy to remove without the risk of surface damage at a later date, should it need redoing. The not-so-good news is it can be susceptible to UV damage, so in the case of some window areas that are regularly in full sun, it isn’t always the best solution.
An alternative product is silicone, which is an elastic, hybrid polymer. It has all the useful attributes of butyl sealant, while being UV and heat resistant too. Like butyl, silicone doesn’t have aggressive adhesive properties, so it’s important to only use it where there is some form of permanent physical support or fixture.
There are three seals for the opening hatch: the glass to the frame, the frame to the boat, and the rubber opening seal
Yacht window materials
Older boats often had tempered glass window and hatch panes, but these have since been widely superseded by lightweight, shatterproof plastic in most modern production yachts. The most common types used are polycarbonate or acrylic, available in a wide range of thicknesses.
One of the downsides of using plastic panes is that the material isn’t always very UV-resistant, particularly on older boats, leading them to craze over or discolour quite badly. There is no ‘cure’ for this unfortunately, you simply have to replace the panes with new.
Polycarbonate is a resin-based thermoplastic, which is so tough (around 250 times the breaking threshold of glass) that certain types are regularly used in the manufacture of bulletproof windows. It can, however, be scratched fairly easily and can discolour or craze over in constant direct sunlight.
The frames and aged sealant are removed, with old sealant carefully scraped off using a sharp chisel.
Acrylic plastic is part of the vinyl polymer family, also known as acrylates, or simply, acrylics. It is cheaper, less brittle and a little more UV-resistant than polycarbonate.
Neither, however, get on well with solvents, petroleum products such as WD40, or harsh cleaning fluids, preferring instead to be cleaned using warm water and mild washing-up liquid.
he screws were initially nipped up just a little over finger tight.
Both materials can be safely cut, drilled or heat formed into a curve with the correct equipment, although it isn’t that easy for a DIY’er. Frankly, though it’ll add a little to the cost, I would recommend having them pre-cut to fit.
Acrylic is more flexible than polycarbonate and therefore easier to form into shallow curves.
Fitting and resealing
If your pane fits into a U-shaped frame you’ll need to put rubber spacers between the frame and edges of the pane to ensure it is central in the frame and not chafing against it. These will remain in the frame. Then you’ll need similar spacers to ensure an even gap between the frame and pane is left on both sides to fill with sealant. Carry out a dry assembly run first to get the correct thickness of rubber spacers.
Sealant tape doesn’t work too well inside a U-shaped frame so it’s best to use a cartridge or putty knife to force the sealant into the gap, removing the side spacers as you go.
The frame itself can then be sealed to the hull using sealant tape. Clean the window surround thoroughly and then apply the tape to the hull, ensuring you lay tape all around each mounting screw hole as well. The frame should then be pushed gently back in place, lining the screw holes up, and then tightening the screws little by little, moving around the frame by opposing screws to ensure an even spread of the sealant. Do not overtighten the frame as the idea is to use the sealant as a gasket, not to squeeze all the sealant out of the sides!
Leave it a few days, if you can, before cleaning up any excess sealant from around the frames and make sure you don’t use cleaning products that are incompatible with the type of sealant you’ve chosen to use.
Yacht hatch repairs
Re-bedding the frame.
With hatches, the most common areas prone to leakage are the rubber gasket or the seal around the glass where it fits into the frame, so unless you know for sure that the base plate is leaking I’d leave it in place undisturbed. If you do need to remove and reseal the base it’s a good idea to put masking tape all around it before removing it.
This will make it easier to align the frame after applying the sealant, plus it will be in exactly the right place to protect the deck from sealant overspill when you come to replace the base frame, greatly facilitating the clean-up afterwards.
Carefully cutting through the old sealant around the window from below using a craft knife
To remove the base, you’ll have to either slide a sharp blade, paint scraper or a cheese wire around the existing sealant after removing any screws or bolts. You might even need to remove a trim piece or peel back the headlining a little if the nuts are concealed.
Butyl tape is the ideal solution for resealing hatch bases, although a liquid sealant will do just as well provided you carefully create a ring around each screw/bolt hole and ensure the bead of sealant is higher than any frame lip to ensure good contact with the glass.
Once the frame is in the correct position tighten up the screws/bolts just until the sealant starts to squeeze out, leaving it to be fully tightened later once it has cured. This prevents all the sealant being squeezed out by over-tightening the screws when the sealant is molten.
Re-bedding the glass
If it’s just the hatch gasket or the glass-to-frame bond that needs replacing then the base and top part of the hatch can usually be separated by unscrewing the hinges or just knocking out the hinge pin (it might need some penetrating fluid applied first).
On some older models hinge removal can be problematic and getting spare parts for things like knuckle hinges is now nigh on impossible. In which case it’s better to bite the bullet and remove the whole unit. Hatches with riser supports and/or manual clamps are usually simple to dismantle, allowing you to take the hatch top to the workbench to remove and replace the glass or acrylic more easily.
Remove the glass or acrylic by first cutting around the edge seal with a sharp knife. Remove as much of the old caulk as possible, which will make removing the glass easier. Prise the glass out carefully using one or more paint scrapers or something similar with a wide blade. Avoid screwdrivers as they can easily crack the glass.
Once removed, clean the frame and glass thoroughly with a solvent such as acetone, before re-bedding it onto butyl tape or sealant. After waiting for the sealant to dry, you need to caulk the remaining gap between the glass and frame. To make it an easy job to clean up afterwards, always run masking tape around both the glass and frame edges, leaving the gap to be caulked clear.
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IMAGES
COMMENTS
Here's how I diagnosed and repaired a troublesome boat leak on my sailboat. Spring (and the preceding winter) is the time to prepare our boats for the upcoming boating season. In this article, I will discuss finding and addressing two significant leaks into the aft cabin of my Hunter 410 sloop, Bay Poet.
Some SN members recommended pressurizing the boat's interior with a leaf blower or shop vacuum after sealing any routes where air can escape. At this point, I'm convinced it's the only way I'm going to trace this leak. The design of my boat includes a couple of fairly large passages between the galley and cockpit lockers, which are difficult to ...
I have been wrestling at least one (likely more) cabin leaks on Hunter 376. After picking the brains of my dockmates and swarthy veterans, went about trying to seal and pressurize the cabin to locate the leak. ... I pressure up'd the cabin with my leaf blower and washed the boat down with dishwashing soap. Bubbles popped in quite a few places I ...
After a big storm in 2007 I had some leaks in the areas shown in the attached pictures. There were just a few drops at the location show in the yellow circle. There was about 1/4" of water in the side pocket behind the seat. Solution.....On all port and starboard chain plates I used silicone...
Here we look at leaks below the waterline and how to find and fix them. Use a paper towel to thoroughly dry the fitting and surroundings. Although there are rare examples of the coveted dusty bilge, most owners expect to do a little dewatering on their boat occasionally. However, leaks from above and leaks from below are not created equal.
Rebed with butyl tape, easier and rarely leaks again. Unless we are talking about around hatches and stuff, its likely winches, cleats, spinlocks or fairleads/turning blocks where it leaks, so they'd need rebedded. Chainplates also common source or leaks. S/V "Ragtime," a 1984 S2 7.9 sailing Smith Mountain Lake, VA.
Fixing Sailboat Leaks. If a leak develops on a sailboat, it is essential to address it as soon as possible to prevent further damage. Here are some steps to take: Locate the Leak: The first step in fixing a leak is to locate it. This can be done by inspecting the boat and looking for water intrusion.
Catalina 22 The Harba! NJ. Oct 6, 2014. #2. Sit inside it and have someone spray water over the cabin. Thats the best way to find your leaks. When I first purchased my boat, I was cleaning out the inside when a big storm hit. Drip Drip Drip.... Every screw/bolt/window needed to be resealed...
Counterintuitively, it's not usually the hull of the boat that leaks. Rainwater is the primary culprit, and a very large volume of it can accumulate inside your boat. ... It grows in dark, damp places with poor ventilation. In other words, the cabin of a sailboat is the perfect breeding ground for mold. Many kinds of mold are harmless, but ...
However, you should not try to fix the leak by plugging/filling/caulking the leak from the inside of the cabin. If you do, it is likely water will continue to leak in from the deck, but instead of making it's way into the cabin it will go into the wood core of the deck and cause rot. The proper fix is to remove the hardware and re-bed it on the ...
Candidates for leaks include any piece of metal or wood attached to the fiberglass deck or cabin, and joints in the structure where two parts fit together. Most modern boats can have scores of potential leak points, and finding the source can be incredibly challenging.
All windows and hatches will need re-bedding sooner or later. Window and hatch glass is usually bedded in using butyl non-adhesive sealant as it will normally be held firmly in place by a frame, which in turn will be fixed to the boat using screws or bolts. Butyl sealant is a mildly adhesive blend of butyl rubber and polyisobutylene.
Images: 2. Re: Sealing Cabin Top Leaks. This works well, you can use the exhaust from a shop vac or a leaf blower in the cockpit or thru a port. I use Dollar Store detergent mixed well in a bucket then swabbed all over the house and deck, large bubbles or large groups of small bubbles form at the leaks.
Hey everyone, question 1001... my hunter 40.5 has had a cabin leak since I bought it a few months ago. I thought I solved it since it stayed dry for a weeks of rain without a single drop, however now I came back to the boat and...water again. We first suspected a post that is below the...
Tape the edges of the companionway and blower from the inside, and exit through the forepeak hatch. 2. Seal the deck. Secure hatches. Tape cockpit locker lids. Plug bilge pump through-hulls. Tape, plug or secure a plastic bag over all vents (dorades, engine intake, solar). Seal anchor-chain deck pipes. 3.
Use the 3/16" shims under the edges of the hatch to keep from squeezing all the caulking out when you tighten the screws. After the caulking is fully cured, come back and retorque the screws. If the hatch ever starts leaking again, all you have to do is again retighten the screws and this should stop the leak.
Step 2. Pry up the frame. Place the pry bar between the fiberglass deck and the hatch frame and gently pry. If you can't wedge the pry bar under the hatch, tap the right-angled side of the pry bar with a hammer to drive it in. Slowly work your way around the hatch, to break the hatch frame free from the old sealant.
In all too many cases, the leak is a symptom rather than a problem. The underlying cause likely is that the holes in the monocoque structure create a loss of stiffness, resulting in excess cabin house flex. Rig loads carried to chainplates, mid-boom sheeting arrangements, and genoa track-induced flex can cause significant deflection.
The recommended sealant is butyl tape, used as a gasket. PS Advisor: Goo vs. Gaskets (PS December 2012) This 2012 article suggests several possible adhesive sealants for bedding new hatches, with a big thumbs up for butyl tape (available from Bomar and others). It also suggests sealants to use between the glazing and the hatch frame.
37. Catalina 320 627 Destin, FL. Apr 5, 2020. #1. Hi Folks, 1999 C320 #627 -- I have had a leak in the cabin for over three years, unable to track it down. After heavy rain or a good boat-washing, I find that water has collected in the small compartment furthest aft behind the Portside settee (just fwd of the electrical panel/plotting table area).
The most glaring is water coming into the cabin when it rains. Small leaks at windows/portholes and more severe down the bulkhead just port of the mast. I suspect the water is entering at base of mast and running down bulkhead cavity then down the wall where (I think it called a chainplate) a metal strap is bolted to the wall. ... The boat will ...
leaks I had the same problem with my '88 33.5. Check where the anchor locker box and the deck meet, there was no caulking on my boat so rain and waves over the bow could enter there. Also check the bow pulpit mounts--the stbd. mount has a hole where the wiring for the nav lights exits.
Jul 18, 2011. Messages. 17,846. Oct 31, 2013. #2. Re: Water leak in cabin issue. Pictures always help . . . post some when you can. Headliner material is often glued to a backing board and then fastened, or simply glued directly onto the compartment ceiling. Headliner material can be found online, if you need to replace it.