If you have priced swimming platforms, you know that they are expensive. Small ones in kit form cost well over $100, and the price goes up to $600 or $700. It is not too difficult to build a swim platform for your boat, and you can save a considerable amount of money if you use marine plywood instead of teak or mahogany. Swim platforms on inboard boats are mounted close to the water, about 4 inches above the waterline. On stern-drive craft they are mounted higher to clear the drive unit when it is tilted upward. On a 22 or 24 foot stern-drive cruiser, for example, the platform is usually about halfway between the chine and the rub rail, or about in the middle of the transom. Inboard boats generally have curved transoms while sterndrive boats usually have straight transoms. This project is designed for a stern-drive cruiser with a curved transom that is 7 feet 6 inches wide. It calls for a 7 foot swim platform. But if your boat has a straight transom or a different beam, it will be easy to modify the following construction procedure for your craft.