Please understand that these are very general instructions and may not be appropriate for your Cushions.

Most or all of your cushions have zippers. There are several ways to clean the fabric, however cleaning the foam may be just as important for an older boat.

As far as cleaning the fabric, here are the basic options. Call a company like Stanlee Steemer, Chem Dry or Service Star to have them do a steam cleaning. It's just like the carpet cleaning, except for upholstery. Make sure that you get a quote first. I have heard that it can be quite pricey, as in several hundred dollars.

The alternative is to remove the covers and wash them in cold or warm water and Woolite and line dry. DO NOT try to speed up the process by putting the covers in a drier.  If you decide to do this, do a section at a time and pay attention to the way the covers come off of the foam and the orientation. This will help when trying to put the foam back in. 

For the ones that have buttons through the cushions, you will have to cut the twine and retie the buttons when the cushions are restuffed. A button needle and some tufting twine will make this much easier. You can either purchase one locally or through JSI.

While the covers are off of the foam, it would be a good idea to clean the foam. If you are sailing in a salt water area, salts from seawater, along with body salts get into the foam and hold moisture. The foam also tends to get a funky smell after 4-5 years. If you have a swimming pool or Jacuzzi, chlorinate the water and insert each piece of foam and leave for 15 or 20 minutes. Remove and stand on edge to dry. Do not lay flat, as it will take longer for water to evacuate when laying in its own puddle. If you have a pool, you likely have a drain around the deck. Stand the foam up over the drain and the water will just drain away. 

If you don't have a pool, go to a big box store and buy a blow up pool. Preferably one that is may 6x8 feet. Fill it with enough water to cover your foam. Pour in a half bottle of bleach and insert a piece of foam. Since you will need to reuse the water for each piece, you will need to try to reclaim as much water out of each piece of foam, rather that sending it down the drain. This will likely cost about $30.00 and take several hours of your time.

It will likely take 24 hours for the foam to dry. Once it has stopped weeping water, you may be able to move it to a climate controlled area. That should help get the last bit of moisture out.

The above process has proven to even get rid of diesel odors.