Cracks in plywood hull

Alistair Edwards · 06 Jul 2009, 08:51

I am having problems with fine cracks appearing in the paintwork on the hull of my Tigress. The cracks occur only towards the bow. They run vertically in straight lines at regular intervals so they are occuring where the ply sheets join. I have tried filling the fine cracks with paint but they keep re-appearing.
Any ideas what could be causing the problem? I am concerned that water could penetrate into the ply. What could I use to fill the paint cracks in order to protect the hull? Presumably it will need to be a flexible filler?

gerry ledger · 07 Jul 2009, 08:59

Hi Alistair, this was a common problem with cold moulded boats and is caused by the wood drying and shrinking. The best way to repair it is to lightly skrape out the crack and fill with epoxy with a filler in. Hope this helps
These cracks were why I sheathed the hull on later boats.
Gerry Ledger

Alistair Edwards · 07 Jul 2009, 07:05

Thanks for the diagnosis and suggested remedy Gerry. On closer inspection today I noticed that there is a slight ridge along the line of the cracks. Is this typical of the cold moulded shrinkage problem that you described?
Alistair

gerry ledger · 07 Jul 2009, 07:50

Yes, probably because once cracked water can entre and the wood swells and has nowhere to go but up, so make sure it is dry before epoxying. The scraping out of the crack helps this
Gerry

Alistair Edwards · 07 Jul 2009, 08:28

Thanks Gerry. It will be an outdoor repair, so I will have to hope for some more hot dry weather in the near future.