Filling/repairing through-holes on cabin

[bmacpiper]

Hi all,
I've been searching/perusing the topics on hole repair, and they seem to address holes into the core only. That is some good reading, and a good winter project for my tabs and transducer.

Please redirect me if I've missed it, but I'm looking for an article or information on repairing holes through the cabin, i.e. for relocating running lights, etc. Mostly what I need to deal with is 1/4" or smaller. Mainly interested in how to make a strong repair, and also how to do a professional job on adding gelcoat back on top and/or interior finish. Recommended products, techniques, etc.

Thanks in advance.
Ben

[thataway]

Small holes such as 1/4" are difficult to repair. Really small, re-drill the hole slightly bigger to make it clean. Bevel the edge with a counter sink--more on the inside. Make a mix with mill fibers and polyester resin, and work that into the hole--leave it slightly proud on the back side, and cover with wax paper, duct taped over. On the front, you can let this set up, you may need to put a small amount of thickened resin to smooth the area, sand flush, then gel coat. Spectrum color has a kit of small amounts of gel coat. The C Dory has a slight amount of yellow and brown pigment if you want to buy white gel coat and mix your own gel coat to match. White is hard to match. Gelcoat can be painted or sprayed on. It may have to be sanded out with wet sandpaper thru progressively smaller grit (up to 1200, then worked with a compound, such as 3 M Finesse it.

Larger holes may require a backing of cloth and matt to give strength, do a small taper grind on the back side to spread the repair over a larger area to get a better bond. Grind out about 1 1/2" for a 1/4" hole (which you have freshened up the edges, and counter sunk the outside slightly. I often use epoxy for larger repairs because it has a better secondary bond than polyester. With polyester resin I lay in a circle of mat after coating the ground out area with resin, then a wetted circle of cloth, then mat and final layer of cloth. From the outside work in some short fibers of glass and fill with thickened resin. and mill fibers. Finish off as above.

Here is a link to one person's way of repair by West Systems--with epoxy
http://www.westsystem.com/ss/repairing-machined-holes-in-fiberglass/

There are several tutorials on this site which give more details on gel coat. If someone does not find it, or I don't find it, I'll post more on the Gel coat covering later. Some use MarineTex, an epoxy compound. That is OK in some places with small holes, but it not match the gel coat color and will often yellow with age.

Where are you moving the lights to?

[bmacpiper]

Thanks Bob, I'll look at the link.

Long story on the nav lights, but basically the first owner put them on quarterboards on the roof; I added newer/brighter ones near the original location, then found glare on the deck in front of me at night. So I'm likely putting the new LEDs on the quaterboards, and then sealing the holes from the new ones down below. Three holes per side, about 1/8" diameter each.

best,
bmc

[hambone]

Here is Spectrum color link for C-Dory
http://www.spectrumcolor.com/Items.aspx?key=cat&code=K&manu=C-DORY&incl_m=F

[bmacpiper]

Thanks Mike!
bmc

[redbaronace]

[thataway]

If you are building up the hole with a glass repair on the inside= larger hole, then let that go off first---or at least get pretty firm. The rest you can do fairly quickly since if you are using fiberglass and polyester resin the kick off time will be fairly rapid. (20 to 30 minutes working time) Use the "normal" amount of catalyst (12 drops MEKP/oz polyester). Since you are doing all of the holes at once, you don't want the mix to be too "Hot". Go with small amounts of resin mixture to start with. You want it to be kicking off in Polyester resin curing time is dependent on the amount of catalyst (Methyl Ethyl Ketone peroxide). You can also keep the resin cool and then warm it with a hair dryer after all is put together. Epoxy you must use the correct amount of catalyst---there are fast and slow hardeners, thus you use a different hardener if you want fast or slow cure time.

I would want the underlying glass to be cured (with laminating resin it will still be tacky on the surface) and not still hot when putting on the gel coat. I assume that you are going to use non waxed laminating resin. If this is the case, you may want to spray the inside repair with PVA (Polyvinyl Alcohol) as a curing agent. Another way to get the resin to cure is put wax paper over the inside circles of laminating resin and cloth. The resin has to be occluded from air to cure--the wax floats to the surface in finishing (waxed) resin to give that occlusive property.

If you have to sand the repair--you want the resin to be fully dry--and that may mean that you will put occlusive material over the area to be gel coated, and then let it dry at least 6 hours before sanding. So that may take it to a second day, for the gel coating.