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How to repair a leaking hatch

Leaking hatches are a common issue on boats, especially in the late fall and early winter. Everyone who owns an older boat for any period of time will likely have to deal with a leaky hatch at some point.

While it might be tempting to try and stop the leak by adding covers, tape, silicone, and even a tarp, a permanent fix usually involves rebedding the hatch. While it might seem intimidating, it’s actually a fairly quick and easy job if you know how to go about it. 

woman and man inspect a leaking hatch on a sailboat
Robin and I met fellow cruiser in a boat yard in Raiateia. We became fast friends while making mid-Pacific repairs to our respective vintage Dufours.

A version of this article originally appeared in Good Old Boat Magazine.

Is it time to rebed a hatch?

While a fairly straightforward project, you obviously don’t want to rebed a hatch if you don’t have to. Ask yourself:

Is the leak persistent?

Sometimes, at the end of a very dry and sunny season, or if the boat has been kept out of the water, you may discover tiny new leaks after the first rainfall. This is likely because the boat has dried out, resulting in small voids around thru-deck fittings. With the first rain, the deck may swell slightly to fill the tiny voids.

If this is the case, you may be able to delay rebedding.

Where is the leak coming from?

Is the leak coming from between the fiberglass and the hatch? If so it’s likely that the bedding compound has failed and is letting water through.

If the water is coming from the hatch seal (between where the hatch meets the hatch frame) there may be a problem with the hatch itself. Thoroughly inspect the seal for damage and replace it if necessary.

woman inspects a leaking boat hatch
Inspect the hatch so you know where the leak is coming from before you embark on rebedding.

Materials you’ll need to rebed a hatch

Assuming you don’t need to replace the hatch glass, seal, or the hatch itself, fixing a leaky hatch can be very inexpensive. You’ll need:

  • A long-handled square shafted slotted screwdriver
  • A crescent wrench
  • A hammer
  • A pry bar (or two)
  • Sika Flex 291 (preferably white to match your deck)
  • Paper towel and acetone for cleanup

If you suspect that the hatch is affixed to the deck with rusty, seized screws, you may also need:

PB blaster and micro-jet
PB blaster and a microjet torch are handy for removing rusty screws

How to rebed a leaky hatch

Step 1. Remove fasteners

Remove screws with a long-handled square-shafted screwdriver and put them in a safe place. Hatch screws are usually corroded and difficult to budge. We learned a great little trick for removing a rusty screw from Paul Hrabowski at Ocean Rigging & Hydraulics to make the whole process relatively pain-free (see sidebar: How to remove a rusty screw ).

Using a screwdriver to remove a rust screw on a leaky deck hatch
Removing rusty screws from the hatch frame.

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.

Prying up the hatch. A couple of taps with a hammer will help wedge the pry bar under the hatch.

Step 3. Remove the old sealant

With the hatch removed, the fun really begins. Scrape away any only sealant using whatever tool best gets the job done. We’ve found prybars and chisels usually do the trick.

scraping sealant from hatch
Removing the old Sika Flex is the most time consuming part of the whole process.

Step 4. Apply new sealant

Apply the new Sika Flex by filling the screw holes and running a line around the area where you’ll seat the hatch. Don’t be shy with the Sika Flex. When done correctly, it should squish out the sides when you reaffix the hatch. Too little sealant and you’ll risk a small gap where water will inevitably find a way through.

applying Sika Flex to leaky boat hatch
Generously applying Sika Flex to prevent future leaks.

Step 5. Install fasteners

Replace your screws and mop up the bulk of the excess Sika Flex with paper towel. You can use a bit of acetone to clean up any remaining Sika Flex.

Congratulations! You’ve banished your hatch leak. Now you can get back to sailing.

Woman  triumphantly holding Sika Flex sealant after fixing leaky boat hatch
Leak hatches beware! This cruiser means business.