When sourcing boat cushions, the most critical factor is the marine-grade vinyl (PVC) or solution-dyed acrylic (like Sunbrella). The material must have a UV resistance rating of at least 1,000 hours to prevent cracking and fading. For the interior, ensure the use of high-density open-cell foam or reticulated filter foam, which allows water to drain through quickly, preventing mold and mildew growth. The thread used for stitching should be anti-wicking bonded polyester to ensure the seams do not rot under saltwater exposure.