Damage type
Polyester boat leaking with no visible damage
Water in the bilge and no hole to be seen anywhere. That is confusing, but almost always explainable: it rarely comes through the hull itself and usually alongside something that passes through it. Skin fittings, the propeller shaft, keel bolts, a seam between hull and deck, or a deck fitting that leaks from above and only shows up below.
How to recognise it
- Water in the bilge with no identifiable damage
- Water that returns after pumping out, even with the boat lying still
- Salt deposits or a damp trail around a skin fitting or keel bolt
- A damp patch in the cabin that gets worse after rain: then it comes from above
How we tackle it
- 1
First establish: from above or below
Rainwater coming in through a deck fitting or a window seal looks like a leak in the hull. A simple hose test, section by section, rules that out first. That often saves an unnecessary lift.
- 2
Check skin fittings and keel bolts
Sealants harden and shrink over the years. Around keel bolts, movement in the laminate also creates hairline cracks that water works through.
- 3
Check the laminate for moisture uptake
If water is running into the laminate rather than through it, delamination is usually involved too. That calls for tapping out and a moisture reading before anything is sealed.
- 4
Repair and reseal
Affected laminate around the fitting out, built up again, and only then sealed. Fresh sealant alone postpones a leak, it does not cure it.
Frequently asked questions about leak with no visible damage
My polyester boat leaks but I see no damage. What now?
First test whether it comes from above. Hose it down section by section: deck, window seals, fittings, while someone watches from inside. Rainwater coming in through a deck fitting looks exactly like a leak in the hull. This test rules that out first and often saves an unnecessary lift.
Where does a polyester boat usually leak?
Rarely through the hull itself. Almost always alongside something that passes through it: skin fittings, the stern tube, keel bolts, or the seam between hull and deck. Sealants harden and shrink over the years.
Can I just seal the leak?
As a stopgap you can, but it postpones the problem. If there is affected laminate around the fitting, the water simply works its way past the new sealant again. Repair first, then seal.
Damage to your boat? Send a photo.
A photo and a short description are enough to assess the damage. Then you hear what is needed and get a quote to suit.