How To Fix Leaking Pontoons

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How To Fix Leaking Pontoons: Step-by-Step Guide

A leaking pontoon can quickly turn your day on the water into a costly and frustrating situation. Whether you’ve noticed your boat sitting lower on one side or spotted water sloshing inside a sealed chamber, acting fast can prevent further damage and extend the life of your vessel.

In this guide, we’ll walk you through the best methods to diagnose and fix a leaking pontoon—so you can get back to cruising with confidence.

Step 1: Confirm the Leak

Before you start tearing anything apart, you’ll want to be sure the pontoon is actually leaking.

Look for these signs:

• One pontoon sits noticeably lower in the water

• Sluggish performance or handling

• Water inside the sealed chamber (audible sloshing)

• Visible dents or corrosion on the tube

How to confirm:

• Remove the drain plug and see if water comes out.

• Tilt the boat to shift water toward the plug.

• Use a soapy water spray and compressed air to locate pinholes (watch for bubbles).

Step 2: Drain and Dry

If water is present, it must be fully drained before any repair is done.

Tips:

• Remove the drain plug and let gravity do its thing.

• Use a wet/dry vacuum or sponge if needed.

• Allow time for the inside to fully dry—moisture will compromise any patch or weld.

Step 3: Choose Your Repair Method

Repairs fall into two categories: temporary patches and permanent fixes.

Temporary Patch (On the Water or Quick Fix)

• Use: Marine-grade aluminum tape or epoxy putty stick (like JB Weld Marine)

• When: You’re still on the water or need a fast fix until proper repairs

• How: Clean the surface, dry thoroughly, then apply product as directed

Permanent Repair (DIY or Shop)

Option A: Weld Repair

• Best for cracks or holes in aluminum pontoons

• Requires TIG welding with aluminum filler rod

• Can be done at home if you have the tools/skills—or bring it to a professional

Option B: Epoxy + Fiberglass Repair (for non-weldable damage or corrosion)

• Clean and sand the area thoroughly

• Use an aluminum-compatible marine epoxy (like Hawk Epoxy)

• Layer with fiberglass cloth or biaxial tape for extra strength

• Fair, sand, and seal with a protective coating or paint

Option C: Internal Bladder or Foam Filler (Last Resort)

• Install an inflatable bladder or pour in closed-cell foam if repairs aren’t practical

• This adds buoyancy but should be a last resort, not a fix for structural damage

Step 4: Test Your Repair

After everything cures or cools:

• Refill the pontoon with a small amount of air or water to pressure test

• Submerge the repaired area or use soapy water again to check for leaks

• Monitor it closely during the first outing

Step 5: Prevent Future Leaks

• Avoid beaching your boat on rocks or rough surfaces

• Rinse saltwater off your pontoons after each use

• Inspect pontoons regularly for signs of corrosion or stress

• Store out of the water when possible

What You’ll Need

Stock up on these essentials for DIY pontoon repair:

• Marine epoxy (aluminum-compatible)

• Fiberglass cloth or tape

• Epoxy putty stick

• Sandpaper or flap discs

• Aluminum cleaner/degreaser

• Protective gloves and respirator

👉 You can find everything you need at Boat Suppliers. We carry top-tier marine resins, fiberglass materials, and repair kits designed for long-lasting repairs.

Final Thoughts

Leaking pontoons can seem intimidating, but with the right tools and approach, they’re very fixable—even for a DIYer. If you're unsure about the extent of the damage or don’t have welding experience, don’t hesitate to bring in a pro. The key is to act early, seal it up right, and keep your boat high and dry where it belongs.

Need help choosing the right epoxy or fiberglass for your pontoon repair? Contact us anytime — we’re happy to help.