Gudgeon bolts rusted out: how to extract?

Webfoot1

Active Member
#22
The new or the old boats? There was a switch to stainless at one point, probably
when Lazer Performance took over. Before that all the blocks were wood with exception
of the backing plate for the new rudder. The boat I have is mid 1970's something so I'm not
expecting much. It does have screws holding on the Gudgeon so it tapped into something, or
they just used a wood block with bolts and nuts. I'll try removing the screws tomorrow and
see what happens.
 
#23
My '82 Sunfish has a rear inspection port. I reached in with a rare earth magnet and ran the magnet all over the glassed-in pintle backing plate--no noticeable reactivity (& the plate is clearly metal). When I moved the magnet away from the plate (still inside the boat and tight against the transom) the magnet easily held a big steel washer laid against the outside of the transom (so the magnet should have reacted with the backing plate if the plate is plain steel). There is always the chance the plate is aluminum (which might help explain the failure of Jack's ss screws due to dissimilar metal corrosion if the backer in his boat is aluminum), but the backer in my boat is not plain steel.
 
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Thread starter #24
Still haven't been able to fix my gudgeon, despite buying new drill bits (both right and left handed) that are supposed to be able to cut stainless steel but no luck; I simply cannot drill out these old bolts.

So, before I hire a professional, I had one more idea to run by the group. What if I were to take a router and cut out a rim of fiberglass around the corroded bolts that are flush with the transom, thus giving me room to gain purchase on the embedded bolts with a pair of pliers, then remove the bolts and use West System epoxy to fill in the defects after the gudgeon is bolted back properly?

I appreciate all suggestions so far. Since the rudder is obviously critical to the function of the boat, I don't want to screw it up!
 

Webfoot1

Active Member
#25
Keep it simple, put a inspection port on the back deck. May
not seem simple now but you'll see how easy it is after you
finish. Knock the backing plate out and order a new one, they
are really cheap. You can do the entire job in couple hours
and go sailing. You also get the benefit of a storage place
for you wallet, keys, etc. I don't think Sunfish were manufactured
with the intention they would still be sailing 50 years later so
a few changes are needed to keep things going.
 
Thread starter #26
Thanks, webfoot, for the suggestions. Any idea where I can order a new backing plate? Also, does anyone have a preferred brand of inspection port to install?
Finally, I'm assuming the backing plate is held in place with epoxy and/or fiberglass. Any tips for knocking that off without damaging the transom?

For those of you who are used to working on these boats I'm sure many of these questions seem basic but it occurs to me that there is a real possibility of creating significant damage if I don't think this repair through properly ahead of time.
 

Webfoot1

Active Member
#27
Flat backing plate:
Sunfish Direct is $33
EBay is $15

I get my ports at West Marine. Bigger 6" for
me, others use a 4" inspection plate. Place 4 inches
from the rear of the deck edge with the rear of the
inspection plate ring on the 4" line.

Plate is held on with a fiberglass strap. After
all these years it should be easy to pull the strap
off. Plate should fall off.

It will take 2 saber saw blades to cut one hole.

Total difficulty level: 2 out of 10.

Good luck, Sunfish are as much fun to fix as they
are to sail. Something about low initial investment.
 

L&VW

Well-Known Member
#30
"There is nothing - absolutely nothing - half so much worth doing as simply messing about in boats."
—Kenneth Grahame
;)

I had advertised for sale my collection of inspection ports—the following are about half of what I still own:

P8100014.JPG

I agree with the 6" port. The optional internal water-resistant storage bag can be added later.

The gudgeon symptoms suggest that your bridle-attachments may also need attention—and it's a long reach! :confused:

Sketches of inspection port installation process:
How to install an inspection port.

Factory photo shows what's under the deck near the transom—far left:


But your boat could be different! :oops:

Use nuts and bolts, but consider replacing the metal backing plate with a hard plastic cutting-board section: 'easy to drill and cut, cheap, no corrosion problems—and plenty strong. :cool:
 

L&VW

Well-Known Member
#31
A cobalt drill bit (M35 or M42) at slow speed w/ lube is the machinist's preferred way to drill stainless steel. Note: there are quantities of cheap, fake, "cobalt" drill bits on the market. A drill bit with "cobalt nitrate" coating is not the same as an M35 or M42 cobalt bit.
I think you meant, "Titanium Nitride". (Or, TiN).

As a "wear-proof" coating, it's a pretty color. ;)

It's really finicky to try to drill out small broken bolts or screws, even if the part holding the screw can be clamped on a drill press table. Stainless steel can be an especially tough material to drill.
You got that right!!! :eek:

"...Personally, the easy way is to just put
in a inspection port, knock the plate out and buy or make a new one. Use bolt and locknuts,
pop-rivets, a metal tap or whatever you preference is. It's all good.
The hard way, would be to take a Sawz-All to the transom, and repair it from the inside-out. :eek:

Bond ¼-20" bolts to the inside plate—return the failed drill bits, buy cobalt drill bits—enlarge the gudgeon holes to fit the ¼" bolts, seal with silicone sealer, and fit Nylock ¼-20" nuts to the outside.

Use West System epoxy and bond everything back together. Better'n new! :)

'Course, isn't "easy" starting to look good? :confused:

.
 
#32
My point re: "cobalt" drill bits was:
• there are bits made of cobalt steel
(a molybdenum series high speed tool steel alloy with an additional 5-8% cobalt)
• there are many fake cobalt bits
(bits of unknown quality steel with a cobalt surface treatment sold as "cobalt" bits)

Cobalt bits may or may not be TiN coated (titanium nitride surface treating applied by physical vapor deposition).
If not TiN coated, the cobalt bit just looks like tool steel (which is why the fakes are easy to pass off).
Uncoated cobalt steel bits will drill extremely tough, hardened materials.
If the cobalt bit has been TiN nitrided it will look like the commonly available (big box) TiN steel bits (iridescent gold in color).
TiN coated cobalt bits are superior to uncoated cobalt bits (until the bit is sharpened and/or the TiN wears off).
 
Thread starter #33
So the bits I bought to drill out the old corroded bolts were supposed to be cobalt bits; purchased from my local Home Depot. An online search re cobalt drill bits results mainly in confusion. Can anyone recommend a reputable brand of cobalt drill bits?

So I dropped by my local West Marine on the way home and bought a 4" inspection port, mainly because the color on that one seems closest to my white gel coat on the deck. I'm hoping that will be big enough to do the repair, but if some of you have experience with this and are convinced it's too small please let me know and I'll get a bigger one.
 
#34
So the bits I bought to drill out the old corroded bolts were supposed to be cobalt bits; purchased from my local Home Depot. An online search re cobalt drill bits results mainly in confusion. Can anyone recommend a reputable brand of cobalt drill bits?

So I dropped by my local West Marine on the way home and bought a 4" inspection port, mainly because the color on that one seems closest to my white gel coat on the deck. I'm hoping that will be big enough to do the repair, but if some of you have experience with this and are convinced it's too small please let me know and I'll get a bigger one.
I used a 4" inspection port, and it worked fine for me. I personally don't like the large port in the stern area, but some people don't seem to mind/care.
 
#35
Cobalt drill bits:

Grainger is probably the most accessible source for a bit or two:
Cobalt Drill Bits - Grainger Industrial Supply

Precision Twist is a well known brand used by many machinists, but it's harder to source single bits.
Precision Twist

Is there a machine shop in your town/city? Stop by & chat them up with the story of what you're trying to do. They may *give* you a used, re-sharpened bit or two. Buy 'em coffees & a dozen doughnuts. The pretty much standard grind is 135° point angle (they'll know).
 
#36
When drilling hard, tough material the keys are slow rpm, high feed rate, and lubrication. For a 1/4" drill bit aim for something like 300-400 rpm (slower = cooler). Higher feed rate means loading the bit by pushing it into the material (the bit should be cutting, not just spinning in the hole). Lube is usually a high sulphur cutting oil, but you can use any petroleum-based oil you have on hand (but not WD-40 which is too light-weight and evaporative).

As noted earlier in this thread it can be a little tricky to freehand holes in hard stuff with a small hand-held drill.
 

L&VW

Well-Known Member
#37
So the bits I bought to drill out the old corroded bolts were supposed to be cobalt bits; purchased from my local Home Depot. An online search re cobalt drill bits results mainly in confusion. Can anyone recommend a reputable brand of cobalt drill bits?

So I dropped by my local West Marine on the way home and bought a 4" inspection port, mainly because the color on that one seems closest to my white gel coat on the deck. I'm hoping that will be big enough to do the repair, but if some of you have experience with this and are convinced it's too small please let me know and I'll get a bigger one.
Plastic doesn't hold up to "the elements" very well. Each of my new ports gets a coating of Rustoleum spray paint before it goes on.

Granted, the following unpainted port could be 50 years old, but it's been degraded by the sun, and could actually crumble when I replace it:

P7170101-001.JPG

.
 

L&VW

Well-Known Member
#38
'Still mulling over this repair. :confused:

Sand off the gelcoat behind the gudgeon, leaving the darker fiberglass (roving) exposed. Layer-up a replacement external fiberglass plate about 3/16" thickness, and trim for fit and appearance. Bond a [preferably] perforated metal plate to the back of it, recess (countersink) flat-headed s/s bolts to align with the existing holes in the gudgeon. Epoxy the new homemade panel to the transom--inserting another layer of fiberglass--place the gudgeon onto the new bolts, attach s/s nylock nuts.

Go sailing! :)

.
 

L&VW

Well-Known Member
#39
So, before I hire a professional, I had one more idea to run by the group. What if I were to take a router and cut out a rim of fiberglass around the corroded bolts that are flush with the transom, thus giving me room to gain purchase on the embedded bolts with a pair of pliers, then remove the bolts and use West System epoxy to fill in the defects after the gudgeon is bolted back properly?

I appreciate all suggestions so far.
Somehow, I missed your idea--above.

'Good approach, as it can be fixed if it doesn't work out. Suggest you inject some WD40, Kroil, CRC, Liquid Wrench, or PB-Blaster to loosen those machine screw's. corroded grasp on the backing plate.
 

L&VW

Well-Known Member
#40
Just one more thought:

A hole saw kit is available at low cost.

Discarding the pilot-drill part, use the smallest hole saw to make a deep cut around the unwanted machine screw. Then use a thick washer to shield the surrounding fiberglass from heat, and use a propane torch to melt/burn access to the defective machine screw. (Vise-grips are made in a needle nose configuration).

My first choice, however, would be to use a narrow chisel to chip-away around the unwanted machine screw. (After using the hole saw). Of course, epoxy containing a filler material would need to be bonded to that repair (West System's 403, was it?) :confused:

BTW: eBay is showing for sale, ONE replacement metal backing plate! :)

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