Which foam should you use on your boat upholstery?
It all depends on what you are upholstering for - Inside or Outside ?
Boat Upholstery Foam For Indoor Seating or Cushions
You can use a medium to firm foam.
We recommend a blue foam - V35/V38, a medium to firm one or a firm one. We make them to a 4" thickness but they are available in different thicknesses. Most foam suppliers also cut the foam to your measurements.
The best foam in our opinion is called Reflex, again we use a 4" thickness when we make seating for customers. Our customers absolutely love the comfort of this foam.
You dont need to make the inside cushions waterproof.
For Outdoor Seating or Cushions
There are a few suggestions below on how to waterproof your cushions/seating...
You could use Silk Film - this is like a thin film which you can use to cover the foam. This provides a moisture barrier between the outer fabric and foam. You should then have an underlining at the bottom of the cushion to allow the escape of any moisture from inside.
You could just use a Waterproof Fabric and make sure all the seams are fully waterproofed.
You could use Reticulated Foam - Reticulated foam is a low density and very porous foam. It allows liquid to pass through it freely. This foam literally acts like a sieve - letting water pass through it therefore not retaining any moisture. It is also very quick drying. You should then have an underlining at the bottom of the cushion to allow the escape of any moisture from inside.
It comes in different grades and can be used for all types of boat outdoor seating. We recommend a 30PPi - Pores per inch, which gives you good support for boat seating & cushions.
Other types of foam such as what you would use for indoors tend to absorb water which means they would dry slowly and become very heavy.
They would also break down much faster and deteriorate quicker. This means the foam wears down much quicker and it will need to be replaced much sooner than a porous reticulated foam.