I have a 1993 C36 with the smaller/narrower walk through transom. One of the stainless steel machine screws that fasten the swim ladder brackets to the swim step broke off about 1/3 of an inch below the surface of the gel coat. I tried using an easy out, but the machine screw is such a small diameter that the drill bit just slips off the top of the screw every time I try to drill a pilot hole into it. There are no nuts holding the machine screws from the bottom. Catalina just screwed them into the fiberglass. As far as I can tell there is no way to reach the screw underneath to try and get it out from that side. I can see it by removing a small board in the rear of the aft cabin, but I can't reach it from there. And I don't fit down the aft starboard lazarette (although there is a slight chance I could get down there if I took the lid off...but I doubt it). Do I need to drill the screw out and fill the hole with epoxy? If so, how do I keep the epoxy in the hole if I can't reach to tape the bottom of the hole? Has this happened to anyone before? Better yet, has this happened to anybody before with my model C36?
All the best--JAS
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
I have the same year/model, but this has not happened to me thankfully. Have you considered using a hole saw and cutting a larger hole around the existing screw? Maybe a 1/2" diameter might do it. Then you might be able to force a cork or something down into the hole to the bottom to plug it in order to refill with epoxy. Just a thought. I can't imagine trying to go head first down into that starboard aft lazarette to get to it that way. Definitely not intended for humans to enter. Someone would have to call the fire department to get you out of there.
Don Lincoln
"Nancy Lynn"
1993 Catalina MK1.5, Hull 1238
LaSalle, MI (Lake Erie)
Universal M-35AC
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Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
Just got off the phone with Catalina Yachts. They tell me they have specially designed 'little people' to work down there. They also told me there is a metal plate layered in near the bottom of the gel coat that is tapped/threaded for the screws to fasten into. So it would appear that drilling it out is a lot more complicated than I thought. We talked about the need to occasionally back those screws out, lubricating, and resealing to keep the screws from corroding. But then you run the risk of breaking off a corroded screw...so obviously must be very careful. Also, I have bumped that ladder more times than I care to remember with my dinghy. Not a good idea in retrospect, given the small diameter of the screws. Looks like I'm going to have to find a little person to go down there. My 16 year old son comes to mind. I will keep whoever is following this thread posted on my progress...or lack thereof. All the best--JAS
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
I bought the following product (Unscrew-UMS) in a last ditch effort to get my broken machine screw out without having to drill it out of the threaded metal plate embedded in the lower layers of the swimstep. I'll keep you posted on the outcome. Wish me luck!
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
Here is a video of the product mentioned above (Unscrew-HMS) in action:
https://youtu.be/m8Al4dYDs60
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
Joel: If that (pretty cool) device doesn't work - you might try using it or a press pin about the size of the hole to act as a guide for your pilot drill.
I also recommend left hand drill bits to get screws out. When they bite into the screw - many times the screw will come out without the use of an easy out.
_____________
Harold Baker
S/V Lucky Duck
Duncan Bay Boat Club
Cheboygan Michigan - Lake Huron
1989 C-36 mkI TR/WK M25XP
That's a great idea...thanks!
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
The next step will be figuring out how to fill the hole with epoxy or some such without blocking the threaded hole, or freezing the new machine screw in place. A friend suggested that I thread the new screw in part way, fill the hole with epoxy, and then keep turning the machine screw back and forth while the epoxy dries (to keep it from freezing to the epoxy). Any other suggestions?
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
I have done this before. Coat the screw in wax and the epoxy won't bond to it. Here is a write-up from the Epoxyworks.com site:
"Fasteners and Hardware
When you want to install a threaded bolt or screw and be able to later remove the fastener, there are a couple easy options. In our boat building class with the Saginaw Bay Community Sailing Association, we keep a wax toilet ring for on the work bench and stick a bunch of screws in it. We just pull these out as we need them. The wax gets in the threads and we can back the screw out easily after the epoxy has cured. You can also put auto paste wax on a piece of cheesecloth, grab the threads firmly below the head and back it out with a cordless drill in reverse. This applies a nice thin coat of wax evenly over the entire thread pattern.
Pam® Cooking Spray is a quick and convenient adhesion preventer. Simply place the fastener on a paper towel and spray the threads, butter the threads with a bit of thickened epoxy so air isn’t trapped, push the fastener into the oversized, partially filled hole and let the epoxy cure. Back it out after the epoxy hardens and now you’ve cast threads in the epoxy.
Polyvinyl alcohol or PVA is a green liquid available at hobby shops and craft shops. Dip the fastener in or brush it on the threads, let it air dry and install the fastener like I just described for Pam.
There are a number of aerosol mold release sprays on the market. A couple we’ve used around the tech shop are Stoner® E-497 and E-499 Thermoset Mold Release. They work well for all thermoset resin systems used in most boats – epoxy, polyester and vinyl ester. They do not contain any silicone, which you want to avoid in any mold release, especially a spray. Silicone aerosol sprays can contaminate the entire shop if you’re not careful.
Another common household product that makes a decent mold release is Aqua Net® Regular Hold hair spray. It is nearly all PVA and works well."
Good luck!
Don
Don Lincoln
"Nancy Lynn"
1993 Catalina MK1.5, Hull 1238
LaSalle, MI (Lake Erie)
Universal M-35AC
Very happy to report Unscew-UMS took out the broken machine screws with no problem at all. It was pretty amazing actually. The drill was spinning in the hole in reverse for 10-20 seconds, and then, all of a sudden, the drill began rising out from the hole and voila...out came the machine screw from beneath the gel coat. I had to drill the hole a little bigger for Unscrew-UMS to get down to the machine screw without mangling the gel coat. When I tried to back out the remaining screws, two of the remaining three machine screws broke off under the gel coat as well. My new tool had them out in no time. I then covered the threads of the new machine screws with toilet ring wax (suggested by Don above), and covered the mating surfaces on the bracket and screws with butyl tape. Down the screws went, with no problems at all. I will wait until something new goes wrong with those machine screws before checking to see if the wax kept the epoxy (six10) from adhering to the screws. But by the looks of the wax in the threads, I don't think I'm going to have any problems backing those machine screws out should the need arise again. I did notice a good sized dab of Six10 that had accumulated on the hull below each screw. That was my fault, I tried to squeeze too much epoxy in each of the four swimstep ladder bracket holes. Long story short, the swim ladder is officially operational again...woohoo!
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California