Bonding and sealing compound used in fiberglass construction and repair. You don't have it, so you don't need it. You need to seal the edges of the holders to the gunnels, this is called bedding. Some like a polysulfide product, such as LifeCaulk, others use marine grade silicone sealant. Either one is fine for this application. Squirt some on your finger, rub it into the exposed wood grain in the hole, and it will be fine. Try not to overthink boat repairs, like I used to do. The stress detracts from the fun of boating, which is what all this is supposed to be about!