Reducing Condensation: Insulating the Hull

Reducing Condensation: Insulating the Hull

Posted by BoatRx2 Admin on

When sailboats are built, they are usually uninsulated.  For most weekend sailors, this is no big deal, but an uninsulated boat can be huge hassle for liveaboards in all climates.  The ability to keep your boat warm or cool is incredibly valuable.  What’s even more important is keeping it dry.  We live year round on our boat in Boston, Massachusetts.  When the really cold days come, we usually keep the cabin warm with our diesel heater and some electric space heaters, but the fiberglass hull is cooled by the outside air.  This warm air, cold surface combination is the perfect recipe for condensation.

condensation on hull

Condensation on hull sides

Condensation on hull sides

Condensation inside of hull liner.

We’re lucky to have such a beautiful wood interior in our Tayana, but it makes accessing the hull sides impractical.  I did everything I could to try to disassemble the hull liner, and the backs of the cabinets to gain access, but there just wasn’t a way to take things apart in a non-destructive way.  After some trial and error, the best solution I found was to use a trim router to cut a perimeter around the surface, then use the old material as a template to fabricate a new piece.  This is a time-consuming process.

Disassembling the hull liner

Disassembling the hull liner

more disassembly

Disassembling the hull liner

We decided to focus on insulating the v-berth first.  Lot’s of condensation was forming along the hull side next to our bed.  The moisture would drip down and get the mattress wet.  No fun!

For insulation, I read about a variety of options.  There are three main ways heat is transferred, conduction, convection and radiation.  We need to cover all of our bases.  We used spray foam to make sure everything was air tight (convection).  Reflectix should help reflect heat back into the cabin (radiation).  We were also sure to leave a tiny air gap between the hull and the hull lining (conduction).  I also insulated the v-berth from the cold sail locker forward, by insulating the bulkhead with a combination of a closed cell foam and more Reflectix.  To template this, I used the ‘tick stick’ method, often used by boat builders for templating bulkheads to fit the curve of the hull.  Take a look at our progress in the photos below!

hull liner removed tayana 42 sailboat

Spray foam insulated sailboat hull

spray foam insulated sailboat

reflectix insulated sailboat

router back of sailboat locker

sailboat insulation

hull liner assembly

hull liner spacer tool

sailboat hull liner

hull liner sailboat tayana 42

tick stick method sailboat

v berth sailboat insulation