Filling holes

[Set2sea]

This is going to sound like boat repair 101 but bear with me for a moment.
I recently filled some 1/4"diameter holes in a inclined surface (cockpit combing) with thickened West epoxy. After they cured, I was underneath and could see that the epoxy only was pushed to about half the thickness of the fiberglass.
Here is my question: Would Marine-tex putty be better to fill the full depth of hole?
In the case I am talking about, the half depth fill was okay, but now I am filling holes that I am going to redrill, so I would like full depth fill.

[KWKloeber]

This is going to sound like boat repair 101 but bear with me for a moment.
I recently filled some 1/4"diameter holes in a inclined surface (cockpit combing) with thickened West epoxy. After they cured, I was underneath and could see that the epoxy only was pushed to about half the thickness of the fiberglass.
Here is my question: Would Marine-tex putty be better to fill the full depth of hole?
In the case I am talking about, the half depth fill was okay, but now I am filling holes that I am going to redrill, so I would like full depth fill.

Paul I'm a wee bit confused - it's a vertical surface, but the mixture filled 1/2 -- 1/2 in depth or 1/2 in height (being vertical) - did it sag?

If you are redrilling then you must overdrill, fill and then redrill to size to seal out any moisture.  Have you read MaineSail's primer on thru fasteners?  If not, do it!

There is no difference between epoxies - it's just how you mix and thicken them.  You can make West as stout as MarineTex (but I would never to fill a hole!)   When you are filling, you need to first wet out surfaces with unthickened mix (to get a good bond), and then fill w/ the thickened mix.   

These are thru holes, and not blind holes? Then there's no reason that West wouldn't fill the entire hole (again, given the viscosity of the mix you make).  I much prefer using microfibers over colloidal silica. 

How did you fill them on a vertical surface?  Did you use a syringe?  How thick was "thick" - mayonnaise? peanut butter?

On horizontal surfaces, I use duct tape below, and fill the hole with a wetter mix.  On blind holes, and where I have the underside taped, I use a toothpick to work trapped air out of the hole and then top off the mix. Slightly convex if you like, and you can slice off the surface flush with razor blade after the mix kicks and is in gel state.

Ken

[Ron Hill]

Paul : Does it make any difference if the holes you are filling are not completely filled??

a question

[Set2sea]

Paul : Does it make any difference if the holes you are filling are not completely filled??

a question

Ron,
Yes, I am filling holes where I will be putting a self tapping screws back into the hole.
What I realized is that I should be inserting the thickened epoxy with a syringe. That will fill the hole instead of how I did it by pushing into the hole with a plastic stick.

[KWKloeber]

Ron,
Yes, I am filling holes where I will be putting a self tapping screws back into the hole.
What I realized is that I should be inserting the thickened epoxy with a syringe. That will fill the hole instead of how I did it by pushing into the hole with a plastic stick.

Other options - YBYC --

Option 1

When I have locations where only a screw thread will do (canvas snap studs pulled out, no way to get threaded fastener in there, etc.) I do this:

Overdrill to the largest size you can, so that your new fastener head will just cover the hole and not show anything below.  Consider a larger head fastener if necessary.

With a Q tip (I mean "cotton swab,") wet out the inside face of the hole as best you can with unthickened epoxy (to prime the surface for best adhesion.)

Soak a foam earplug in epoxy (experiment with a little, but not too much thickening additive.)  The foam needs to be "soaked" but not "soaking wet" so that it will run all over.

Squish and insert earplug so that it's nearly flush (protect the surface w/ masking tape around the hole.)  Trim flush with a razor blade after the mix gels.  clean up the gel coat surface with acetone -- carefully -- not to soak your epoxy plug.

Drill for new fastener -- the expanded earplug on the back side becomes a "drywall" anchor that gives a lot more depth for screw-thread grab and support against the inside wall -- so that it can handle a lot more stress without pulling out.

I've also used other foam pieces that work better to soak up thickened epoxy (more "open cells")  --  it doesn't need to be an earplug.


Option 2

Where I have a cavity, (e.g., between liner and coming) I oftentimes use insulating foam in a can (e.g., "great stuff") to fill some of the void.

Then I rout out the filled space with an "L" wire (bent heavy wire coat hanger,) so that there's a good hole to accept thickened epoxy, and then fill to get a lot more area/depth to hold the threads. 


Ken K

PS:  The syringes can be used several times - get several and after use, go to the next one and let the other set up -- the epoxy will pop free from the plastic syringe and then clean off the rubber plunger. 
It's a little tricky to get the plunger to release from the bottom, but it can be done with finesse, rather than brute force pulling.