Broken Gudgeon Bolts

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=

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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=

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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

A 4" porthole has to be put in behind the rear crossbar.
I went through the suggestions that have been posted & it boiled down to wasted time. Plus once you get the bolts out the plate in the hull will fall out & you will have to put in a porthole anyway. it is a good thing to have the porthole for a spooge to soak up water in the future. Doug

Does the plate have to fall out if you put a bolt back into one or two of the other holes before drilling out the stuck ones? When I replaced the bow handle on a Sunfish (I know, a monodull, but still...) I made sure that I kept one bolt in at all times to keep the plate from falling down.

you can do that but you still end up with the corrosion problem down the road so the port is needed and quite handy to have for storage .

Drill it out and put a thread insert in. The hole location will be in the same place, you can still use a 1/4-20 bolt.

Use loctite on the insert so it's thouroughly attached to the backing plate and put anti sieze compound on the 1/4-20 bolt before you bolt it all back together.

You'll have to slap a little resin on the transom where you drilled oversize for the insert but it'll pretty much all be covered up by the gudgeon anyway

I thought about inserts - I'll have to see what material is available. In addition, it may be possible to simply drill two new holes in the existing gudgeon and drill and tap new holes into the backing plate, leaving the gudgeon in the same position. Not as desireable as using the same holes, but worth a thought. The machinist here at work suggested using a pre-drilled block to guide left-handed drill bits (going from smaller to larger sizes) to drill out the bolts. He said that occasionally the left handed drills will catch in the bolt, and will be turning in the right direction to back the bolt out. The vibration from drilling into the bolt might loosen some of the corrosion, and make taking out the bolt possible, he says. He also added that he only felt that I

might

be able to drill out the bolts. I ordered some left handed bits today - should be here tomorrow. We'll see..............

Peter your spending a few dollars on tools if that doesn't work take it to your local vehicle workshop and they will tap it out for you. It wont cost much they do it all the time on old motors. For attatching stainless fittings to aluminium get a tube of the anticorrosive gunk to put on all your bolts, rivets etc
regards

If it were me, I'd drill the bolt out (carefully) and re-tap with a slightly larger bolt. You'll probably have to enlarge the holes in the gudgeons (or tap them out too).

If that didnt work, I'd put in two port access covers and go back to the original size bolts and add fender washers and nuts on the inside. A little silicone in the holes before assembly will keep it waterproof.

Drilling holes in a new location sounds like a bad idea, lots of opportunity to for mis-alignment.

Bill

Looks like I've got my work cut out for me this coming weekend. I'll pick up some Blaster and my left handed bits and give drilling out the bolts a go. Hopefully using care and some appropriate guide blocks will do the trick, and I'll be able to clean up the threads in the backup plate with a tap and be done. If not, I came across a

broken screw extractor

today which could be used as a last resort. It's essentially a 3/8

diameter hardened steel tube with saw teeth milled into both ends, and it has a bore of slightly more than 1/4

. I tested it, and it does cut aluminum, although because it has no set to the teeth, it has little clearance for the chips and has to be extracted every 5 seconds or so and cleared. Using a guide block with a 3/8

hole, I could cut down around the outside of the bolts, through the glass and the aluminum backing plate, and remove the bolt like a wooden plug in a hole saw. McMaster Carr catalogue has a stainless threaded insert for a 1/4-20 bolt which has an external 7/16

thread, which could be tapped into the hole in the backing plate and epoxied in place. Then I'd theoretically be back in business, once I fill the enlarged hole in the glass back up. But I'd rather go the other route, if possible. I'll let you all know how it turns out. Thanks for all the great brainstorming. This forum is great!

Peter

Got 'em out! PB Blaster and the bolt extractor worked on one of them, once I had a proper hole bored in the end of the stud using a cobalt drill bit. The bit that came with the extractor was useless. The other bolt was a lot more work. Using the broken screw extractor (see earlier post) and a wooden guide block with a 3/8

hole in it, I bored a 3/8

hole around the outside of the broken bolt. Since the extractor's ID is only slightly more than 1/4

, it used the bolt itself as a guide once it got started. I drilled as deep as the aluminum plate. I then cut a length of 3/8

thin-wall steel tube, and inserted it into the hole in the transom, so that it protruded about 1/4

. This gave me a reference fitting for my drill blocks. I set up a fence and stop on my drill press, drilled a 3/8

hole 1/4

deep into the block, and, using the same setup, drilled the guide hole for my bits to drill into the stud, exactly centered on the 3/8

hole. I used my Dremel with a silicon carbide grinding wheel to give me a flat on top of the stud, and used a spotting drill bit in one of my guide blocks to get a start. I then started with a 1/8" bit and worked my way up to a #7, and then cleaned out the threads with a 1/4-20 tapered tap. Trick is to drill SLOW, maybe only 100-200 rpm, with lots of pressure, and cutting fluid. If you build up heat, you'll work harden the stainless. Careful not to let the bit grab and snap off (don't ask). The relief I feel right now is priceless. Now to finally finish off this boat and get it into the water. Thanks to everyone for your ideas and support. Hopefully my experience will prove useful for someone else.

Peter Shapiro
P19MX

Fantastic! Congratulations, and once again we see the truth that persistence, time, and hard work sometimes actually pays off. <img src=

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