Rusted Bolts

My 1985, 32’ Hatteras has rusted bolts on what appears to be stringer-like supports in the aft bilge, just forward of the transom. The 32 Hatt has prop pockets on each side. To the inside of the prop pocket is this triangular shaped support that looks like a stringer of some nature. It angles upward as it approaches the transom. It has three bolts in it that are very rusted and deteriorated. I would like to replace those bolts but I have no idea what purpose that piece serves and whether it is a structural support (which it appears to be). It cannot be supporting the shaft strut since that is attached under the prop pocket and this is on the inside side of the pocket.

I have questions:
1. What purpose do these stringer-like supports serve and what are the bolts actually securing?
2. I would appreciate any advice you could give me since I'm concerned about the deteriorated status of the three bolts (on each one) and would like to replace them, since I'm also concerned that if I touch them, I may end up with further, unwanted problems.
3. A secondary question would be, what is my risk if I just leave them alone?
4. I assume these are not through bolts and probably are secured to an inside anchor-nut. Can I remove the bolts one at a time to replace each while it is in the water?

Please see the pictures attached. Thanks for your help and time in answering this.

Karl Sydor

I do not have first hand knowledge of what they are used for. I'd be inclined to first ask someone at Sam's to view your photos.

Unless you get a definitive answer, I'd leave them alone. In wood boats such triangular supports were often used to reinforce stern to bottom or hull side to bottom.
Here are a few suggestions: Try holding a magnet close to them..they appear to be rusted ferrous (magnetic) material but I cannot see them clearly enough to be sure. Another option is to wire brush one and see what metal is under. If not magnetic, then for sure leave them alone as a stainless material will last a long, long time. There's a good chance this will last another 20 years anyway.

What's on the other end of these fasteners?? Either they are bolts and the other end must be accessible for a change out, or they are lag bolts (a screw thread) which is less likely. If something was bolted together prior to installation, perhaps by glass encapsulation, you'll not likely be able to get them out anyway...

good luck.