Drilling holes in deck

Dean Abramson · Post by **Dean Abramson** » Oct 13th, '09, 11:15

I am relocating my windlass.

I have already "dry-fit" it using holes that are the exact size of the machine screws which secure it. (My boat is now covered and protected from the weather.) My holes already go right thru the vee berth's headliner.

I need to re-drill the holes bigger, fill with epoxy, and re-drill. I have gotten advice from two experienced sailors and from Don Casey's book. Therefore, I have three answers:

Don Casey says use the bent nail in a drill, to ream out core between the two layers of glass, fill with regular epoxy, drain that out while it is still wet, then follow with thickened epoxy.

Mr. X says just drill bigger holes all the way thru, possibly as big as 1" diameter, paint the sides of the bores with regular epoxy, let it set up just a bit, and then fill with thickened epoxy.

Mr. Y says drill all the way thru, but not that big (maybe 9/16"), but then use "penetrating epoxy" initially, then thickened epoxy.

Don's method would leave a smaller scar below and above; but above it will be covered by the windlass, and below by a SS backing plate. (There are already some in this area for my foredeck cleats.) The whirling nail seems a bit imprecise to me, as you cannot see exactly what you are doing.

Mr. X's method leaves the biggest scars, in the slim chance that I would ever undo this job. But that is extremely unlikely. And this method is simple and I already own what I need.

Mr. Y is the only one to mention "penetrating epoxy." Maybe he owns West Marine stock... If I were to use the smaller bore (9/16), I would probably use Don's fill-then-drain-while-still-liquid-method with the penetrating epoxy, as painting in that size hole would be difficult.

All of which begs the question, why not just drill large-ish holes and just fill them with regular non-thickened epoxy? One step.

What would you do? Any input will be appreciated.

Dean

Markst95 · Post by **Markst95** » Oct 13th, '09, 11:26

The bent nail has come up before, I don't think it works very well. I drilled a slightly oversized hole, used something like a heavy duty dentist pick and cleaned out the hole. Remember, its only balsa wood. I didn't drill through the bottom layer of fiberglass, a smaller hole is easier to cover with tape. I then used unthickened epoxy to fill the inside of the hole (unthickened flows better) Drained it and then added colloidal silica and refilled. Then redrill the hole you need.

The Patriot · Post by **The Patriot** » Oct 13th, '09, 11:53

Dean Abramson wrote: ... why not just drill large-ish holes and just fill them with regular non-thickened epoxy? One step ...

I prefer to overdrill and fill with "thickened" epoxy. Then I have the option to either drill to fit a fastener, or drill and tap to fit a machine screw without washers and nuts on the other end. If you cannot reach the inside easily this has an advantage, and it really is quite strong.

However there is a technical reason to avoid "straight" epoxy without filler. Solid epoxy is actually a glass and is quite brittle with comparatively low crush strength. That's why the West System offers such a variety of fillers. I would go with a high density filler from West.

If all else fails you can try to get permission to read some of the articles on this subject written by other board contributors (Irony Alert).

Steve Laume · Post by **Steve Laume** » Oct 13th, '09, 12:27

I have done the hole and nail routine. I have also done the hole with larger sized hole in the top layer only and the bent nail. I never liked the idea of drilling a large hole all the way through or not gouging out some of the balsa around the edge of the hole. I like the idea of having a machanical joint around the hole instead of a straight through core of any kind of epoxy.

I have always sharped the bent over portion of the nail to a chisel point instead of using it the way it is. It does a better job of getting the wood out up against the fiberglass.

Much better than a nail is a key hole router bit that is typically used for making a key hole slot to hang pictures or plaques. I use it in a drill just as you would the nail. It does a really nice job of cleaning out the balsa and is much easier to control than a bent nail.

The nail never seems to stay bent the way you want it, Steve.

Ed Haley · Post by **Ed Haley** » Oct 13th, '09, 12:41

Markst95 wrote:The bent nail has come up before, I don't think it works very well. I drilled a slightly oversized hole, used something like a heavy duty dentist pick and cleaned out the hole. Remember, its only balsa wood. I didn't drill through the bottom layer of fiberglass, a smaller hole is easier to cover with tape. I then used unthickened epoxy to fill the inside of the hole (unthickened flows better) Drained it and then added colloidal silica and refilled. Then redrill the hole you need.

This is the best method for filling in the hole with epoxy before redrilling a smaller hole for the fastener. If the surface is level, I would just fill the opening with unthickened epoxy. If the hole stays full, then I would let it harden and then drill for the fastener.

If the surface is not level or the hole drains with the unthickened epoxy, then I would add thickened epoxy until the hole is full and let it harden for a full 24 hours or more.

The use of the bend nail to clear out a bit of core filling is helpful to add strength to the hardened epoxy plug so it doesn't pull out of the hole.

Oswego John · Post by **Oswego John** » Oct 13th, '09, 12:58

Yes, I believe that there are more ways than one to skin a cat (and to drill holes in the deck), and they all work. Ain't it grand to have options. Are you ready for my options? Well, here they come, ready or not.

I drill a larger hole in the outer deck but I don't enlarge the lower hole. I guess that you could call me old fashioned because I enlarge the hole with a wood auger bit set in a hand brace. The worm tip of the auger centers itself in the lower hole in the inner deck and the flat bottom of the auger's cutting edge cuts a clean large hole in the balsa all the way to the bottom. I use a shop vac to remove the balsa chips. On second thought, I suppose a spade bit in a drill motor set on low speed would do the job, as well.

I like to use a medium fluid viscosity of epoxy and filler in order for it to flow and penetrate the surrounding balsa filler.

There is one thing that I always try to do that I don't think has been mentioned yet. In order to get the new, wider holes centered in the exact location, before I enlarge the holes, I draw crosshairs on the center of the original holes

After the enlarged holes have been filled with epoxy, I extend the crosshair lines over the new holes and then drill a small pilot hole on dead center. Larger size bits will follow the pilot hole and maintain center.

Good luck and have fun.
O J
PS: A freeze warning called for tonight with possible snow (a four letter word) showers. Alas, 'tis the season.

sharkbait · Post by **sharkbait** » Oct 13th, '09, 13:57

I have to agree with Owsego John. I drill a small pilot hole with the large cross marks all the way through the inner shell. Then I use a spade drill at low speed to enlarge the hole and do not drill thru the inner shell. I fill the hole with West System and high density filler. Then redrill to the proper size. I usually cover the inner hole with duct tape while pouring the filler. This way I have a mark on the inner shell and can drill from the inside out or using the cross marks from the outside in. Sometimes I drill from both sides to keep things really neat.

sfreihofer · Post by **sfreihofer** » Oct 13th, '09, 15:12

To each his own, but here I side with Don Casey and Steve Laume. The bent nail technique has worked well for me, and like Steve, I grind the tip of the nail to a chisel edge. You need a firm grip because the drill will jump around until the wood core has been excavated. It will leave rough surfaces on the interior of the cavity, which is good for bonding.

The key-hole router bit is a good idea, but I still prefer the bent nail because it can cut a deeper cavity, and leaves a rougher surface for bonding.

The reasons I like this method are because the resulting cavity, when filled with epoxy, bonds the two layers of the deck over a larger area, and seals the wood core a good distance from the penetration point of the fastener. It also involves minimal disruption of the original deck, and thus less finishing, if any.

After taping over the 'lower' hole, the unthickened epoxy is used to 'wet out' the excavated core, filling pores, cracks, crevices, gaps, and covering the rough surfaces. I find an epoxy syringe (just 'suck it up') is helpful for this, a small paintbrush, or even a Q-tip. I then mix filler into the remaining epoxy and load the thickened epoxy into the epoxy syringe 'through the bore' with a popsicle stick or similar instrument, and inject it into the cavity, starting deep to avoid air pockets.

When cured, drill the finished hole for the fastener. I can't imagine a more effective or stronger method.

Stan Freihofer
1981 CD 25 #794
Ft. Lauderdale
www.ReefRoof.com

okawbow · Post by **okawbow** » Oct 13th, '09, 18:01

I use a 1/4" allen key with the end ground to a sharp chisel. It doesn't bend like a nail, and is easier to control. You can ream out the hole with a short end on the key first, and then switch to a longer end for a bigger hole.

Dean Abramson · Post by **Dean Abramson** » Oct 13th, '09, 19:27

Thanks so much for the advice, everyone.

It sounds like, as OJ says, there are several good ways to do it. By the way, I have since continued my discussion with Mr. X. I had misunderstood him; he did not mean that I should drill the big bore all the way through the bottom layer.

Since it is suddenly cold here, the job may have to wait until spring to get done.

Can you tell that I have never drilled holes in my deck before? Not so scary now with all of this input.

Dean

Maine Sail · Post by **Maine Sail** » Oct 13th, '09, 20:48

Having done hundreds of these holes feel free to read the article below. I believe I address all your concerns and even some that have not been raised.

Feel free to read this article:

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

mgphl52 · Post by **mgphl52** » Oct 14th, '09, 11:41

Many, many "Thank You"s, Main Sail!!!
I remembered reading your posting some time back but couldn't find it again. I, for one, greatly appreciate all the work you put into a great DIY article!

-mike & Toni

Sea Hunt · Post by **Sea Hunt** » Oct 15th, '09, 22:03

Maine Sail:

I join Toni and Mike's comments. For a guy like me (by most accounts I am dumber than dirt

) your website is the best. Lots and lots of enlarged color pictures and simple worded explanations. Even I can understand most (sadly not all) of your discussions, "how tos", etc.

Thanks

The Cape Dory Board