I have a 1980 Cherubini Hunter 36. A few months ago, I tightened all of the hull/deck bolts (i.e. the toe rail bolts that others have already mentioned). Reason was that my boat was leaking in the bow/V-berth area. I went to the boat during a rain-storm to investigate, and from the inside I could feel wetness along the hull/deck joint at several places. I have read that a proper fix is to remove the toe-rail, separate the deck to hull joint, put in new sealant and then tighten. But this is a big job, so I figured instead to first just tighten the bolts/nuts.
If the toe rail bolts have never been tightened on your boat, its something that probably will be useful. After 28 years, most of my toe rail bolts were no longer even close to being snug. Assuming that a 1980 H30 has the same toe rail and deck joint configuration as a 1980 H36, the tightening process is have one person on deck to hold the bolt from turning with a Phillips screw driver (to minimize damage to the caulk seal by the turning screw) … as the second person tightens the nut underneath. I didn't have a second person, so my solution was to clamp the screw head with a vice grip; aligning the vice grip in a manner that that it rests against the toe rail as the nut is tightened. You will need an extended length socket. Because of different accessibility positions for each location, you will also need several different lengths of socket extenders, and an universal swivel joint. Also for a few of the nuts, I needed to use a socket set fitting that looks like an open ended box wrench (sorry I don't remember what these are called).
My boat remains dry now during rain, even this week after the +/- 5 inches of rain we received in the San Francisco area over the past several days. One item that surprised me as I tightened all my toe rail nuts is that still pliable caulk (or butyl tape?) was squeezed out from under the toe rail edge on the deck. “Still pliable after all these years”. Another benefit for me after tightening the toe rail is that I no longer have what sometimes were alarming cracking and popping sounds from the hull/deck when I winched the jib sheets real tight. My jib sheet blocks are snatch-blocks attached to the toe rail.