Outdoor Renovation

How To Seal A Leak In A Boat


Do you have a leak in your boat? Overtime boats can develop minor leaks whether it be gaps in a seem, loose rivets, or perished o-rings that allow water to filter in.

Selleys MarineFlex is a high performance adhesive sealant that can be used on boats, pools & spas^ (in fresh, salt and chlorinated water) where you need a waterproof seal, even under water*- it can be applied and will cure under water.

Compared to traditional polyurethanes it provides a more durable seal with superior UV resistance.

MarineFlex is suitable for use on most materials# including:

  • Metals
  • Glass
  • Ceramic tiles
  • Sealed/painted timber & concrete
  • Fibreglass/FRP/Gelcoat^
  • Most plastics# (pre-test before use)

Sealing a leak in your boat is as easy as:

  1. First thing you want to do is locate the leak – an easy way is to do this is to get your boat onto land and use a garden hose/other implement to fill the boat with water. Looking at the boat from the outside, you should be able to locate where it is leaking
  2. One the leak is located, ensure the surface of the boat is clean and free of oil, grease, dirt or dust. Note that the surface does not have to be dry as MarineFlex can be applied to wet surfaces and under water, although it cannot withstand strong pressure until it has fully cured.
  3. Cut cartridge tip, fit nozzle and cut to size, then insert into the caulking gun
  4. Apply product to the crack/hole to seal the leak
  5. Smooth off with a cloth (if underwater) or soapy solution before skinning occurs
  6. See technical data sheet for more information

Important Information:
#Not suitable for Polypropylene, Polyethylene or Polytetrafluoeoethylene
*critical seals/repairs underwater should be regularly checked & repaired if required.
^ Fibreglass, Gelcoat, polycarbonate and Perspex should be lightly sanded and wiped with turps prior to product application