Today I was trying to do a little preventive maintenance on the P19 I'm restoring, removing the SS 1/4-20 bolts which hold the gudgeons on to check for corrosion, and, of course, the last two bolt heads twisted right off as easy as pie, leaving their threaded portions still inside and flush with the outside of the transom. Am I completely screwed, or is there a reasonably non-destructive method to remove the bolts? Digging around the bolts to allow for a pair of vise grips has already occurred to me, but I'm hoping for a more elegant solution.

You need a dremel to cut a groove for a flat head screw driver. If the bolt has'nt moved you will need to tap with a hammer to loosen the bolt a little. You can drill and retap but its allmost impossiblle to get the dirll bit straight down the hole without damaging the thread. A small hole with a reverse thread tap could also work..

Easy--go and get a bolt extracter set. If you have a Harbor Freight nearby, they have a set for around $10. Home Depot will be higher, but still the worth the money. Basically, you drill a small hole into what's left of the broken bolt and then insert a reverse threaded bit that bites into and backs out your broken bolt. (The set will have various sizes to use.) Might seem like a disaster to you now, but it's really no problem with the right tool.

Thanks. I've calmed down a bit, and will try these approaches tomorrow. The Dremel I've already got, and Home Depot and Harbor Freight are within reach. Thanks again.

Peter
P19MX

Does the P19 have threaded plates molded in the hulls for the gudgeons? All the other Performance Cats (Nacra, Inter) have nuts and big washers (through drilled aluminum plates) that are loose on the inside of the hulls. Nothing is actually tapped and/or molded in the hull for the gudgeons so the hulls just have through holes.

You've checked to make sure there are not nuts on the inside right?

Older threads on this forum have said that the P19 has threaded backup plates, so I'm going on that assumption. The 6 other bolts came out cleanly, and then snugged up tight when I ran them back in. The heads of the last 2 came off almost immediately when trying to back them out, so I'm thinking either they were torqued down way too tight by the previous owner, or they have seized on the aluminum, due to no grease being applied to the threads (hopefully the former). You're right that nuts on the backside would make removal of the bolts easier, but there's a bulkhead in the way between the inspection port and the transom, and I'd like to avoid cutting through that, if at all possible.

"Use the bolt extractor set, Luke. Just let the bolt extractor set work through you..."

Well, it's a no-go, I'm afraid. The dremel slot method and the bolt extractor only lead to the bolts continuing to self destruct. It seems as if these bolts are seriously seized into the back-up plates. I'd be very grateful for any other solutions other than tearing into the transom itself, if there are any out there.

Can you post a picture for us?

If I had gotten to this thread earlier, I would have suggested a liberal dosing of PB-Blaster to the bolts before you tried any kind of extraction. Sorry I didn't get here sooner.

ALWAYS try to get penetrating oil into seized bolts before trying anything.

PB Blast is simply incredible stuff. I've had it take a seized bolt to being able to unscrew by hand just by soaking the area thoroughly overnight.

I'm afraid my kids have destroyed the digital camera, but if you can picture the ends of the stems of two 1/4-20 bolts, considerably chewed up, slightly below the surface of a P19 transom where the gudgeon used to be, then you've got the idea.

Thanks for the idea. I suppose I could drill a small hole down next to the bolts, to the backing plate, and squirt a bunch in there, and try again to back the bolts out. If worse comes to worst, then I'll have to make a clean cut-out around the bolts and try more mechanical means to get them out, and deal with fixing the transom.

I ran across the same problem on my P-19 MX... Take your dremel with a small routor bit & route around the bolt . I mean right up against it. Go all the way thru the hull. Fill the holes back with epoxy . Drill new holes & replace the the bolts with new stainless bolts & nuts. You will have to drill the holes out in the plate . Dont use the same set-up ... The corrosion problem will happen again. Stainless & aluminum weld together after awhile in the salt. If it's not clear on how to do this just let me know. Doug <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

Regarding PB Blaster, it's good stuff but I haven't found it to be a panacea. I had several stuck bolts on my recent catamaran restoration project and literally kept them bathed in PB Blaster for 1 or 2 days, yet to no avail except for one of the bolts (which still came out really tough!). At any rate, I wouldn't do anything based on just getting PB Blaster to the site and count on that to fix it (though it certainly might help). It sounds to me like Southern Cross's idea would be best, although you might want to consider the possibility of putting an access portal on top of the hull toward the transom and coming at it from that angle. Bummer of a situation, that's for sure.

Oh, regard the camera, my dad always said that you can't have anything good with kids around... <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

The bolts are frozen, so slotting and using a screw driver is unlikely to work (the socket wrench did not). If you centerpunch the stud remaining(grind a flat face on the stud if possible) and drill dead center down it, and then keep increasing your drill size to the next bolt's drill tap size (consider a metric bolt too) you may re-tap to a reasonable bolt size. Failing this, perhaps you could move all four holes down slightly and drill and re-tap all back into the glassed-in plate. I don't know exactly how much clearance the rudder tiller arms have to the stern etc, but 3/8 of an inch...should work.
The Hobie 16 has those metric cast gudgeons where you re-tap the sterns to suit...that works.

If you have some decent drill bits, try drilling through the bolt itself with a small bit and then work your way up to a larger one.

Sounds like a do-able fix. I have a couple of questions, however: 1. I assume you routed down to the aluminum plate, and then drilled through the plate, but did you cut off the bolt flush with the plate first, and if so, how? 2. My boat has a bulkhead between the access port and the transom. Did you cut through that with jig saw or large hole saw to enable using nuts on the back side of the aluminum plate? And would locknuts be the call in this situation?
Peter

I may try the gradually increasing drill bit fix first, before going to the routed hole and bolt method. That may be the one I have to use, but hope springs eternal, so I'll work my way up through these less invasive fixes first. I'm going to look into cobalt drill bits to tackle the stainless - the cheap bits I have at home now won't cut it.

Personally, I would probably do what others have suggested which is to try to drill out the old screw. Grind the frozen stud down to a flat surface. Center punch the stud- do a light punch first to insure that you're on center, then re-punch for a more defined dent. Get a good set of sharp drills and drill it out. Re-cut the threads or go to the next size up if necessary.

If that doesn't work, you might consider going to a weld/machine shop and having a custom gugeon made up with a new bolt pattern. I would look into the cost of that before monkeying around with cutting holes in the boat etc.

sm

make sure to liberally apply cutting oil (3in1 household oil) when drilling through the metal