Sweet dreams

Foam mattresses If you like your dreams tickled by exotic pudding fantasies, make sure your berth offers the right support.

In my offshore yacht racing days there were no foam mattresses. It was either stacked up to windward like a sardine in a canvas cot or sleeping on the sails dumped on the cabin sole. After much testing I preferred the No 2 genoa over the lumpier No 3 jib.

As age and wisdom has descended I now prefer cruising. The foundation of cruising is a good night’s sleep and the foundation of that is a good mattress.

THE MANUFACTURING PROCESS:

For most marine applications mattresses are made out of polyurethane foam of varying densities. The production of polyurethane foam is a simple three-step process: • MIXING: Polyurethane foam is formed by a chemical reaction between polyol and diisocyanate; both products derived from petroleum. A typical ratio of polyol to diisocyanate is 1:2. The ratio can be tweaked to provide an infinite variety of characteristics and densities to the foam. While the raw ingredients are toxic, this is neutralised by the chemical reaction that occurs in the process so that the final foam is safe for human contact. • REACTING: The raw ingredients are passed through a heat

exchanger as they are pumped into pipes. The exchanger

adjusts the temperature to begin the chemical reaction. By the time the polymerizing liquid gets to the end of the pipe, the polyurethane is already forming. • BLOWING: The dispensing head is hooked up to the processing line. A roll of baking paper is spooled at the start of the processing line and is moved along a conveyor under the dispensing head. As the paper passes under, polyurethane is blown onto it while being mixed with carbon dioxide, which causes it to expand. Once the foam has cooled it is cut into standard lengths.

While the production of polyurethane foam is simple, the different densities of foam this process produces can lead to endless arguments as to what constitutes comfortable. Just Google ‘best foam for mattress’ and you will see what I mean.

The core of all the argument is that different kinds of foam have differentdensities(measuredinlbs/ft3)andfirmness(indentationload Deflection–ild)ratings.forthisreasonsurfacefirmnessisindependent of foam density.

To add further fuel to the argument firmness (ILD) is not to be confused with support, which is the foam’s ability to push back against weight and prevent the foam from bottoming out. This sounds like an argument with myself and I would highly recommend ignoring the lot and doing it all by what feels right.

Generally speaking, comfort from a foam mattress comes from layering. For a 150mm thick composite construction mattress the following proportions would work:

• Quilted knit fabric with 20mm pillow soft foam. • 30mm elephant foam 28/130 grade • A base of 100 mm firm foam 22/150 grade

Having congratulated myself that I now have comfortable layers and I am no longer sleeping on the No 2 genoa, I realised that there is even more comfort to be had from a mattress.

A phone call to Stuart Reed of The Bed Factory revealed a whole new level of luxury in its range of custom-made, pocket-sprung mattresses. The description for a 200mm thick mattress sounds like a recipe of a triple-dip, fudge ice cream on a hot day: • A top quilt of 20mm pillow soft foam quilted on a

knit fabric • Pocket springs 135mm high and 60mm in diameter

made in 1.8 gauge wire • A comfort layer of 30mm elephant foam 28/130 grade • A breathable base layer of 20mm coconut fibre pad sprayed with latex All edges finished in 70mm high density foam All layers are bonded using hot melt glue.

If you are having trouble sleeping or trying to convince someone else to sleep aboard, then the pocket-sprung mattress is your trump card. Alternatively, you can regale them with stories that start with “In my day we slept on the sails,” or perhaps, your theories on indentation load deflection ratings. B