Finding And Fixing Leaks In Your Aluminum Boat

Owning a boat can be a lot of fun, but it also comes with its fair share of maintenance and repairs. One common issue that boat owners may encounter is a leak. While leaks can occur in any boat, including aluminium boats, there are several methods to detect and fix them. Some techniques to find a leak include filling the boat with water, using air pressure or vacuum tests, employing light to detect pinholes, and drying the boat completely before relaunching it to identify the source of the leak. Additionally, it is important to check for water accumulation in the bilge and monitor for any changes that could indicate a leak.

Check for water dripping from an old hatch

If you suspect that an old hatch is causing a water leak in your aluminum boat, there are several steps you can take to check for dripping and identify the source of the leak.

First, thoroughly dry the boat and then relaunch it on the water. Keep a close eye on the suspected area to see if you can spot any water coming in. If the boat is in the water all the time, as mentioned in your case, you may need to take it out, dry it completely, and then relaunch it to effectively identify the source of the leak.

If you are able to locate the suspected area, such as an old hatch, you can proceed to strip off any anti-fouling paint or coating in that section. This will allow you to inspect the underlying structure for any signs of damage or cracks that could be causing the leak.

In the example provided, after stripping the anti-foul coating, a cracked weld was discovered along the edge of an old patch. This crack was identified as the likely source of the leak.

It is important to note that this process may not always reveal the exact location of the leak, especially if there are multiple leaks or if the boat has complex structures. In such cases, you may need to explore other methods, such as filling the boat with water or using air pressure tests, to pinpoint the exact source of the leak.

Additionally, you can employ the use of dyes or food coloring in the water to make the leak detection process easier. By adding a dye or coloring to the water, you can more readily identify the origin of the leak by observing the colored water as it leaks out. This technique is especially useful when combined with methods such as filling the hull with water or pressurizing the hull.

Look for wetness on the inside skin of the hull

When looking for a leak in an aluminium boat, it is important to first check the inside skin of the hull by hand for any wetness trickling down from any thru-hull, rudder port, the shaft log, stuffing box, and strut fasteners. Use a paper towel to dry off the hull and the fitting, and inspect closely using a flashlight. Look for the first appearance of a trickle or drip. Dry it again and verify you are seeing the first point of emergence.

If you have checked the bungs and they are not the issue, check along the underside for any cracks. Also, check any water pick-up pipes for fish boxes or water pick-up lines as these may be a flush flange that has come loose. If nothing is obvious, carefully flood the bottom of the hull in stages, being mindful of the weight that your trailer is carrying.

Another method is to put water in the hull and add a significant amount of food colouring until the water is very dark. Move the water around by moving the boat up and down on the jockey wheel. If you see coloured water leaking on the bottom, it is easy to find the spot.

Use a flashlight and mirror to inspect hard-to-see areas

If you're having trouble spotting the leak in your aluminium boat, a flashlight and mirror can be used to inspect hard-to-see areas. This method can be especially useful if you suspect the leak is in a tight or confined space.

Firstly, thoroughly inspect the underside of your boat for any cracks or signs of damage. Pay close attention to water pickup pipes, as these may be a source of leaks. If you don't spot any obvious issues, try the following method: carefully fill the bottom of the hull with water, being mindful of the weight on your trailer. You can also add a few drops of food colouring to the water to make it easier to spot any leaks.

Once the hull is filled, use a jockey wheel to move the water around and look for any signs of coloured water leaking from the bottom of the boat. This will help you pinpoint the exact location of the leak. If you suspect the leak is in a hard-to-reach area, that's where a flashlight and mirror come in handy. Use the flashlight to illuminate the suspected leak area and the mirror to reflect light into tight spaces, allowing you to get a better view.

By combining the use of a flashlight and mirror with the water-filling method, you can more easily identify the source of the leak in your aluminium boat, even in those tricky, confined spaces.

Differentiate between routine drips and sinister leaks

When it comes to differentiating between routine drips and sinister leaks in an aluminium boat, there are several factors to consider. Here are some guidelines to help you identify and address these issues:

Routine Drip vs. Sinister Leak

• Routine Drip: A slow drip that occurs at regular intervals and is often expected by the boat owner. For example, a stuffing box that drips every 15 seconds, yielding about a quart of water every three days, is considered a routine drip.
• Sinister Leak: An unexpected leak that cannot be easily identified and may indicate a more serious issue. This could be a result of a critical component failing or an unknown source of water ingress.

Identifying the Source

• Hull Fittings: Leaks at hull fittings, such as seacocks, valves, hoses, instrument senders, and running gear, are typically easy to find and fix. Check for wetness or trickles using paper towels, a flashlight, and your fingertips.
• Rivets: Most leaks in aluminium boats occur at rivets rather than punctures. These leaks are usually caused by rough handling or impacts with submerged objects. While the source may be challenging to find, rivet leaks are generally easier to patch than gashes.
• Keel Bolts: To find a leaking keel bolt, ensure the bilge or keel sump is completely dry, then watch for the first drop of water welling up from under a backing plate or a crack.
• Transom: Livewell pumps on the transom can be a source of leaks that are hard to identify.
• Below the Waterline: If all the below-waterline fittings check out as dry, but the bilge is filling with water, detective work is required. Pay attention to when the leak occurs (only when underway, during specific speeds, etc.) and where it originates (port, starboard, forward, or aft).

Temporary Fixes

• Routine Drip Adjustment: A routine drip at the packing gland of a stuffing box or rudder port can often be controlled by adjusting the stuffing box nuts.
• Sealants and Epoxy: Various sealants and epoxy solutions can be used to address small cracks, holes, and rivet leaks. Ensure the surfaces are clean and dry before application.

Permanent Solutions

• Replacement: For broken or corroded parts, the best solution is often to replace them. This includes items such as hoses, valves, fasteners, and hose clamps.
• Re-riveting: If several rivets are problematic, consider re-riveting the affected areas. This process requires a rivet gun, a through-hull marine adhesive sealant, a power drill, and new rivets and burrs.
• Consult a Professional: If the problem is challenging, consider consulting a professional boat repair service. They have the expertise to properly identify and fix the issue, preventing the need for repeated repairs.

Dry the boat completely and relaunch to see if it stays dry

Drying your boat out completely and then relaunching it is a good way to find a leak. This method is recommended by Dangar Stu, a commercial boat skipper and mechanic. He suggests that if your boat lives in the water, the float switch on the bilge pump won't pick up the last few centimetres of water, so it's a good idea to dry the boat out completely and then relaunch it to see if you can spot where the water is coming in.

Drying your boat out completely will also help you to identify whether the water you find after relaunch is new or old. If you're confident that you've dried the boat out completely, any water you find after relaunching is likely to be a new leak.

Before drying your boat, you should check the normal bilge water accumulation for your boat. You can then assess whether the water you find is a normal amount or indicative of a leak.

Once you've dried your boat, you can also use soapy water and a spray bottle to check for leaks. Spray the soapy water onto the suspected leak and see if bubbles start to form.

If you're going to dry your boat out completely, it's important to be mindful of the weight of the water when you're filling your boat to find the leak. If the leak is low down, you can fill the boat with 10cm of water. But if the leak is higher up, you should be careful not to fill the boat too much, as this could damage the hull or trailer.

Frequently asked questions