Drilling holes in the cabin roof

[Sea Hunt]

I am getting ready to drill small holes in the cabin roof for the purpose of attaching port and starboard cam cleats for the jib sheets. I have been studying Don Casey's book, Sailboat Hull and Deck Repair.

Mr. Casey recommends drilling the holes "oversize" and then removing core material with a bent nail in a drill. This is then filled with epoxy and a final drill hole made.

My question is: how much "oversized" should the initial hole be drilled

The final hole drilled should be 13/64 according to the Harken drilling guide.

I am thinking of drilling a 3/8" initial hole. Does this seem about right Not sure if I can get a bent nail into that small a hole to remove some additional core material as suggested by Mr. Casey.

I would welcome any helpful suggestions. Never having drilled a hole in a boat before, it is disconcerting.

Thanks in advance,

[moctrams]

I want to install a dorade guard and was wondering how to "cover" up the hole in the liner when I install backing plates.

[mattlydon]

That being said, you don't need to remove very much balsa. You don't want your hole to be so big it shows - not past the hardware you're installing.

The bent nail in a drill thing didn't work too well for me - I couldn't get a small-enough bend in the nail, so I just dug out balsa by hand.

An epoxy-filled area the size of a penny is perfect for a 1/4 " bolt hole.

[sharkbait]

I drill all the way through with the proper size drill bit. Then I drill all the way down to the inner liner with the over sized bit. Then I put a piece of duct tape over the inner hole and pour the outer one full of filler. I use epoxy plus a strength binder. After all has cured I strip off the duct tape and I have a perfect guide to drill the final bolt hole from the inside out.

If I really want to make the area crush proof I will install sleeves of stainless steel tubing into the over sized holes then pour the epoxy filler. Lay a piece of wax paper over the outer surface and set the fitting with the bolts to hold everything in place while the epoxy cures.
After the epoxy cures remove the fitting and peel off the wax paper and reinstall the fitting.

[Maine Sail]

http://www.pbase.com/mainecruising/sealing_the_deck

[sloopjohnl]

sea hunt,

where you drilling you may hit plywood as the core for the aft holes and balsa for the forward holes depending upon the exact location. you may not be able to remove plywood core very easily. this would necessitate a larger hole filled with epoxy followed by a smaller hole for the cleat screws.
mine were installed with sheet metal screws and were not through bolted.

[Markst95]

I would use 1/2" for the hole and try using a tool like a dental pick or ice pick for picking out the balsa before you try the drill. Just check the camcleat and backing plate or washers to make sure it will cover the size holes you will be drilling.

[oldragbaggers]

That being said, you don't need to remove very much balsa. You don't want your hole to be so big it shows - not past the hardware you're installing.

The bent nail in a drill thing didn't work too well for me - I couldn't get a small-enough bend in the nail, so I just dug out balsa by hand.

An epoxy-filled area the size of a penny is perfect for a 1/4 " bolt hole.

Lance and I used a 1" bore to drill out the top layer of fiberglass and starting through the core, but being careful to stop before penetrating the inner layer of glass. Then dig out your core with a screwdriver or whatever works for you, poor your epoxy and then drill your screw hole. 1" should be easily covered by a cam cleat.

Becky

[Sea Hunt]

Maine Sail et al.

I am really a dummy I remember reading you website on rebedding deck hardware, etc. about a year ago when I was thinking of rebedding the winches. Your photos and descriptions are first class stuff. I guess it must be old age forgetfulness.

I did the job today and, so far it came out pretty well.

I measured for the two screw holes for the jib sheet cam cleats port and starboard. I wanted them as far back as possible but as close to "in line" with the jib track. I used a template to get the holes lined up.

I drilled a pilot hole using 1/16" drill bit. The cabin roof is THICK I measured 1 3/4" in total depth with 1/2" fiberglass each top and bottom and 3/4" balsa core.

I then drilled a 3/16" hole (this will be the diameter of the final drilled hole for the #10 screw. Finally, I drilled a 7/16" hole.

I then took a small nail and bent the "pointy end" about 1/4" to a 90 degree angle and put it in the drill chuck. This dug out a good amount of balsa core without touching the fiberglass (at least not that I could see). It all worked very well - at least by my standards.

I taped the bottom of the hole - duct tape of course. I then used West System Six10 Epoxy Adhesive to fill the holes. It worked very well. First time I have ever tried working with epoxy. I taped around the outside of the holes with blue painter's tape to collect any epoxy drippings and removed the tape after filling the holes.

Tomorrow, or Wednesday, I will drill the final screw holes using a 1/16" pilot hole drill and then a 3/16" drill bit for the final.

I have purchased long screws (4" ss), backing washers (ss) and nylon locking nuts (ss) to finish the job.

Maine Sail, next time, before I do anything "intrusive" to S/V Tadpole, in addition to checking with this board I will go to your website (if I can remember to do that ) and see if you have already covered this with great photos and descriptions.

I thank everyone for their suggestions and recommendations.