Fixing a drilled hole with epoxy from a Transducer install

J

joechiro30

New member
We readjusted the old transducer location and when we did that. We did not properly seal the holes so water leaked in from the hole.
We got the boat out as fast as we could and trailered home. A few days later we wanted to relocate the transducer but this time use starboard so that we don't have to drill more holes in the hull in the future if we wanted to change the location of the transducer to optimize the sonar readings.
As we drilled a new hole through the fiber glass. Water came seaping out. Probably from the previous hole that we made readjusting the transducer. I am waiting for the core to dry now before packing in the epoxy.
We predrilled the holes on the starboard hull to install the starboard in which the transducer will be mounted on. We drilled the holes all the way through to the inside of the fiber glass which I told my guy who was doing the job not to do. I see that he drilled the hole all the way through. He filled and packed the predrilled hole with epoxy and sanded it down and it looks great from the outside of the hull. My question or concern is that since there is a hole through the fiber glass on the inside, did the packing of the epoxy from the outside fill in the hole enough so that water will not get in from the inside where the bilge pump sits on the bottom of the inside hull. When it rains or when we wash down our boat water can some times get down there and my concern is that water may seep into the core from the inside. Do we need to coat or fill with epoxy from the inside as well. It seems like it is hard to get in from the inside down to the bottom of the hull where we drilled the hole.
I don't want water to intrude into the core from the inside. There is a bilge pump there for a reason. Water can get in there where the holes were drilled.
The holes that we found dry we began to fill and pack with epoxy and let it dry.
There are remaining two holes that I am waiting to dry, the other drilled holes have been filled and packed with epoxy.
Is there a way to dry the core besides letting it sit on dry land? I believe the core is not a balsa core like the 22 cruiser but it is a foam core. Is it ok for it to be damp before installing the epoxy?
Any advice would be appreciated before we continue with the install

Thank you
 
As you can see by the photo, the core is closed cell foam, not the dreaded balsa core. It should be fine after you seal the hole. Lots of choices for sealing but make it permanent and waterproof!

DSCN0131.jpg
 
Dreamer":1i21tqxd said:
As you can see by the photo, the core is closed cell foam, not the dreaded balsa core. It should be fine after you seal the hole. Lots of choices for sealing but make it permanent and waterproof!

DSCN0131.jpg
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Thanks Roger, do I need to seal the hole on the inside of the hull as well since we made a hole straight through to the inside? If we fill the hole from the outside and pack it tight will that be enough?
 
I think I would use a large syringe to pump some thickened epoxy all the way through that hole. Depending on the diameter of the hole, that may be all that's needed.
 
Dreamer":1nnypp8r said:
I think I would use a large syringe to pump some thickened epoxy all the way through that hole. Depending on the diameter of the hole, that may be all that's needed.
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The holes are less than half inch about 7/16 drill bit we used. Good idea about using a syringe to put the putty in. Is there a Syringe I could use with that size hole it should I make the hole a little larger?
 
Lots of info if you search for it.

This is a current thread, still up on the top page as of today:

http://www.c-brats.com/viewtopic.php?t=24341

In it I detail how to fill holes through the transom that are widened between the glass layers to accommodate fasteners, however you can use the same reservoir technique I posted there. The pics are also in my album.

The method I describe is good for getting epoxy to the top of the hole on a vertical surface like a transom.
 
San_Juans_2011_001.sized.jpg

Here is "local boy's image". How thick was the outside glass on the transom--and are you sure y0u were down to the foam? Different foams have different colors, and certainly foam can be pink.

7/16" is a big hole to drill in a transom for transducer mount. No wonder water came in quickly.

Yes, the interior of the hull should be sealed with epoxy and glass, When "plugging" a hole in the core, it is probably best to undercut the foam/balsa.

At this point, if there is already a plug of epoxy in the transom, but you are not sure if it goes all of the way thru, I would clean the interior surface of the transom (down in the hull) and then get a grinder down in there, do a rough surface grind, and clean off any dust. Then coat that area with epoxy, and before it goes off, get several circles or squares of glass cloth saturated with epoxy, over this area.

I realize that this may be hard to do. But I know of one large racing boat which failed to do this, and almost sunk. I doubt that the Tom Cat will sink or that the plug will come out, but you want the best repair you can do under the circumstance.

I would want the foam dry before putting any epoxy in place. Epoxy will stick to clean surface which is wet, but the bond is not as good.
 
thataway":388y4kb8 said:
San_Juans_2011_001.sized.jpg

Here is "local boy's image". How thick was the outside glass on the transom--and are you sure y0u were down to the foam? Different foams have different colors, and certainly foam can be pink.

7/16" is a big hole to drill in a transom for transducer mount. No wonder water came in quickly.

Yes, the interior of the hull should be sealed with epoxy and glass, When "plugging" a hole in the core, it is probably best to undercut the foam/balsa.

At this point, if there is already a plug of epoxy in the transom, but you are not sure if it goes all of the way thru, I would clean the interior surface of the transom (down in the hull) and then get a grinder down in there, do a rough surface grind, and clean off any dust. Then coat that area with epoxy, and before it goes off, get several circles or squares of glass cloth saturated with epoxy, over this area.

I realize that this may be hard to do. But I know of one large racing boat which failed to do this, and almost sunk. I doubt that the Tom Cat will sink or that the plug will come out, but you want the best repair you can do under the circumstance.
I would want the foam dry before putting any epoxy in place. Epoxy will stick to clean surface which is wet, but the bond is not as good.
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Thanks for the input Bob

The hole was drilled to mount a piece of starboard to the transom where we will attach the transducer to. I am sure we drilled through the hull because I can see the hole from inside the hull. It will be difficult to reach down there to do the repairs. What type of epoxy should I use with the fiberglass. There are so many out there and unsure of what to get.

Is this a job I could do myself? Or should I get a professional. I am not very handy.
 
I know how hard it is to get down in there. My concern is that apparently the plug of epoxy put in, did not complete seal off the core, from the bilger, where the bilge water may collect--thus more water can get into the core. This makes delimitation of the transom more likely to occur--I cannot say how likely this is, but the structure intregtity depends on a certain amount of adherence of the foam to both fiberglass inside and outside of the transom.

I have been working with West Systems Epoxy for a number of years, and am most comfortable working with it. There are a number of good epoxy systems. I would use "normal' hardeners to give a pot life of 20 to 60 minutes.

I see two possibilities at this point--one is to drill out the plug you put in, and then fill the entire depth of the transom with epoxy--I don't know exactly what technique was used previously in the attempted repair.
He filled and packed the predrilled hole with epoxy and sanded it down and it looks great from the outside of the hull. My question or concern is that since there is a hole through the fiber glass on the inside, did the packing of the epoxy from the outside fill in the hole enough so that water will not get in from the inside where the bilge pump sits on the bottom of the inside hull. When it rains or when we wash down our boat water can some times get down there and my concern is that water may seep into the core from the inside.
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#1: Kushtaka has given you some ideas on how he fills voids in the transom. I have used a thickened epoxy mixture, and packed it in with wooden "tools" made from popsicle type of sticks.

#2: However, now that the holes are drilled thru the entire transom, you need to seal the inner skin. Normally one would grind out a 6:1 ratio, and build back up the glass to the original thickness. I don't believe this is necessary, and a couple of pieces of glass cloth will be fine. I would get as much access room as possible--this may involve undoing hoses and ables to get the access to the bilge pump/macerator pump, etc area of the aft bilge. (Sorry I don't remember the exact configuration in this area), but the idea is to get a grinder or sander down around the hole: for example even the triangular type which goes on the Fein type of tool, or a flexible shaft tool.--I believe that a 4" Milwaukee grinder I have probably would fit down there. Then you can shop vac out any dust--use a small roller on a handle to put the first coat of epoxy down--then work the glass saturated with epoxy down in place with batten type of sticks maybe even paint stir sticks. I would probably use 1708 cloth just because I have some, and it works well with epoxy. The mat is stitched in place and does not rely on binders which might not be compatible with epoxy. The matt side is toward the inner side of the transom, the second piece is is mat toward the innersole also. After this is in place, then another roll over with the small roller and epoxy--and you should be done...
 
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