model
Do you have a DS I or II? If it is as DS I the hole goes through to the water beneath the boat. If it is a DS II it would go into the inner hull space (bilge).If you can scan a post a picture, that would help. I am not sure of the purpose of this hole. It would depend on the model. The previous owner may have used it to suck water out of the bilge if it was a DS II. It if was a DS I, it may have been the hole for a self bailer, only the self bailer is missing. The DS have a self bailer, but it is typically placed near the back of the cockpit sole about an inch from the transom. The standard setup is a DePersia bailer. (see photo)