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bmcminn



Joined: 20 Jul 2019
Posts: 45
City/Region: Bellingham
State or Province: WA
C-Dory Year: 1992
C-Dory Model: 19 Angler
Vessel Name: Polū
Photos: bmcminn
PostPosted: Thu Nov 21, 2019 11:10 pm    Post subject: Holes in the hull Reply with quote

I found four holes that I have not seen before. Ugh.

This boat had a major overhaul before I got it and the previous owner hadn't even used it. He hadn't seen them either.

So it's been in the water about 100 hours total. I'm guessing there was a transducer or something there. The transducer is now mounted on the starboard side on the back not the bottom. It's possible that the person who did the gelcoat had covered them with a plate and it has fallen off but more likely I think that they just never got filled. When I took the pics I didn't think to probe them. I'm getting the boat from storage tomorrow and will poke around and see if they dead end or what.

I guess I fill them and sand it flat, but I'm concerned about what could have happened with it like this. I have two batteries in the starboard lazaret and the boat lists to that quarter a lot, the water line is below water a couple inches there. To get it level only takes a little downward force to the port quarter when I'm standing on the dock, so I think the level is just off from the batts. The holes are on the port quarter, but for all I know water has been pouring into some third-space... I don't know how the hull is constructed on the bottom.







Thanks for your ideas on what I should check or do.
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localboy



Joined: 30 Sep 2006
Posts: 4252
City/Region: Lake Stevens via Honolulu
State or Province: WA
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: 'Au Kai (Ocean Traveler)
Photos: 'AU KAI
PostPosted: Fri Nov 22, 2019 12:15 am    Post subject: Reply with quote

So, first off...Iím no expert. But, Iíve had the boat for a decade and learned a lot from people here. It may not be that bad. The hulls are generally cored with balsa. Youíll have to look carefully. But that portion may be glass only. I donít know on your boat. Poke around a tad. See what you find. Itís a 19 so Iím assuming you wonít have a bilge in the true sense. The hullís interior is the cockpit sole. If those holes donít go thru, I imagine they donít, itís just the exterior layer and core you will have to investigate. Iíd make sure if it is balsa to remove all the wet, rotted wood. Let it dry then. Once you have good dry wood, you can repair the holes. I have a how to somewhere here on the site along with pics in my album of how I repaired holes when I moved my swimstep.

Youtube Boatworks Today to see lots of how to on Fiberglass repair.

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Sea Wolf



Joined: 01 Nov 2003
Posts: 8633
City/Region: Redding
State or Province: CA
C-Dory Year: 1987
C-Dory Model: 22 Cruiser
Vessel Name: Sea Wolf
Photos: Sea Wolf
PostPosted: Fri Nov 22, 2019 12:52 am    Post subject: Reply with quote

Here's a closer look for everyone:






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bmcminn



Joined: 20 Jul 2019
Posts: 45
City/Region: Bellingham
State or Province: WA
C-Dory Year: 1992
C-Dory Model: 19 Angler
Vessel Name: Polū
Photos: bmcminn
PostPosted: Fri Nov 22, 2019 1:01 am    Post subject: Reply with quote

Yes, this is a 19', but I'm not sure if it has the balsa core or foam. It's the first one they made and I think someone told me they used foam back then.
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thataway



Joined: 02 Nov 2003
Posts: 17254
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Fri Nov 22, 2019 8:54 am    Post subject: Reply with quote

My 1993 22 had balsa core. It is possible that this may have been a bracket for a pickup tube, --for bait tank/well, or a transducer. It is also possible that there was some filler put in around were the screws were placed.

I would probe it. Then grind it flat, and dish out a little to allow you to laminate new glass from the outside. From the inside you will have to remove the fuel tanks.

If there is a wet core, I believe you would see water dripping out of the holes.

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Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018
Thisaway 2006 22' CDory November 2011 to May 2018
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localboy



Joined: 30 Sep 2006
Posts: 4252
City/Region: Lake Stevens via Honolulu
State or Province: WA
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: 'Au Kai (Ocean Traveler)
Photos: 'AU KAI
PostPosted: Fri Nov 22, 2019 12:56 pm    Post subject: Reply with quote

Here are the ďinstructionsĒ I wrote up on repairing small holes. Pics in my album.

This tutorial will hopefully help those that weren't able to attend the session @ the factory. I don't pretend to be an expert and I am not responsible for any outcome from the use of this tutorial. I am merely trying to convey, in words, what we all observed/learned. A huge mahalo to Scott for doing this for us. I suggest you read through this AND look at the pictures posted to get a better idea of what I am attempting to describe. Please post any questions/clarification you may require and I'm sure those of us that attended will chime in.

FIRST A WORD ON SAFETY. Please follow/use common-sense personal safety practices. Use eye & ear protection when using power tools. Use the proper gloves when handling/using chemicals and dust masks when creating dust/sanding/grinding. Properly dispose of any material used in this tutorial. Finally, make sure you have proper ventilation when using chemicals/resins. The filler & resins etc used in these procedures can create heat. Be aware of the possibility that FIRE/BURNS exists if they are improperly mixed. BE SAFE!!!!!!!

REPAIRING THROUGH HOLES:

Per Scott, this repair is for any through hole larger than ~1/2" diameter. It is the most difficult & time consuming, however, this repair is also useful for gouges and small holes that do NOT go completely through. The one caveat is you will only use the steps I will describe from the second Duraglass application on. In other words; for gelcoat gouges & small holes you will fill w/ Duraglass, followed by sanding w/ 600-800 grit using a D/A sander until smooth. From this step on it's a matter of spraying gelcoat and cutting/buffing on ALL repairs, including when you need to remove scratches. I will describe the spraying of gelcoat, cutting/buffing separately.

Materials:
"Duraglas" filler w/ hardener
Polyester resin w/ hardener
Bi-axial 0-45/90 clothe
Matt clothe
36-50 grit discs (for die-grinder)
320 & 600-800 grit discs (for D/A sander)
Acetone
latex/nitrile gloves/dust masks

Tools:
Die-grinder w/ disc head (or electric)
D/A sander (or electric vibrating sander)
putty knife(s)
small metal resin roller
disposable paint brush(es)
scissors

Begin by cleaning up the hole, removing any loose fibers/material etc. If it's a clean hole (drilled) that's good. If it's a structural location, like a transom, or visible on two sides, like a cabin wall/bulkhead this repair must be done to both sides. If not, one need only patch the rear portion with a cloth patch w/ fiberglass. Mix the Duraglas/hardener on a flat piece of plastic or clean wood etc using putty knife according to the instructions. Fill the hole with the mixed Duraglas and let dry/harden.

Once it's cured begin grinding the repair with 36 grit and the die-grinder. This is appears scarier than it is! Take your time!! Scott recommends a 3:1 ratio of repair/patch to hole; for example, if the hole is 1" grind 3" total diameter. You want to end up grinding into the Duraglas & surrounding area to create a ~1/8" concave "mushroom". Clean w/ acetone/rag.

Cut circles of bi-axial clothe starting at the size of the hole then slightly larger. You want two layers of bi-axial, the second slightly larger than the first but not larger than the final layer. Optimally, you make the center layer half of layer 1 and layer 3. The third/final layer is the matting cut to the size of the overall repair/grind-out you created (3" in the above example).

Mix polyester resin according to instructions. Begin saturating the clothe, one layer as you need/install it. Scott used a cardboard box & brush. Begin w/ the shiny side of the clothe down and saturate both sides w/ resin. If you still see white fibers after saturating, it's NOT saturated; brush on more resin. Begin adhering each cloth layer. Scott used a small metal resin roller. Roll across each previous direction @ 90/45 degree angles, varying it to remove all air bubbles. Continue the same with each successive patch. Allow to cure. Remember, COMPLETELY saturate the clothe & REMOVE all air bubbles. Scott impressed upon us that the resin/clothe is where the strength of the repair is achieved! The Duraglas is merely a filler and has no strength. It will crack if not sealed in resin/clothe. When this portion is done, you'll end up w/ ~1/16" high (convex) on the patch vs. the surrounding non-patched area.

Again, using the die-grinder & 36 grit, begin smoothing out the patch to cut down the hardened clothe/resin. You'll want to again slightly concave the patch ~1/16". What you're cutting down will be some of the matting; no problem. You can use a straight edge to make sure you're nice and concave in various directions. Clean w/ acetone.

Back to Duraglas. Mix another batch of just what you need. Fill the patch "criss-crossing" the patch with your Duraglas mixture, making sure it is completely filled slightly higher than the surrounding. Let cure.

Using the D/A sander and 600-800 grit pads begin sanding the patch. KEEP THE SANDER FLAT AGAINST THE SURFACE and take your time. You're complete when it's flat. Best way to check: using your flat palm/fingers, run your hand across the patch in various directions. Doing this w/ your eyes closed will allow you to feel even slight variations in level. Try it.
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bmcminn



Joined: 20 Jul 2019
Posts: 45
City/Region: Bellingham
State or Province: WA
C-Dory Year: 1992
C-Dory Model: 19 Angler
Vessel Name: Polū
Photos: bmcminn
PostPosted: Fri Nov 22, 2019 5:31 pm    Post subject: Reply with quote

Mahalos brother. Shoots, I'll let you know how it goes.
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Micahbigsur@msn.com



Joined: 27 May 2019
Posts: 295
City/Region: Big Sur
State or Province: CA
C-Dory Year: 2003
C-Dory Model: 25 Cruiser
Vessel Name: Sierra
Photos: Sierra
PostPosted: Fri Nov 22, 2019 6:07 pm    Post subject: Reply with quote

Looks good, except for better adherence to old fiberglass I prefer epoxy resin with measuring pump cans.
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localboy



Joined: 30 Sep 2006
Posts: 4252
City/Region: Lake Stevens via Honolulu
State or Province: WA
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: 'Au Kai (Ocean Traveler)
Photos: 'AU KAI
PostPosted: Fri Nov 22, 2019 11:11 pm    Post subject: Reply with quote

Like I said, Iím not expert. But I believe in the do it yourself when you can philosophy. I learned and asked and did what I could. So can you. Cool
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bmcminn



Joined: 20 Jul 2019
Posts: 45
City/Region: Bellingham
State or Province: WA
C-Dory Year: 1992
C-Dory Model: 19 Angler
Vessel Name: Polū
Photos: bmcminn
PostPosted: Sat Nov 23, 2019 12:33 am    Post subject: Reply with quote

Well, so there's wet core. When I sound it I can squish out salt water and if I jam some copper wire into them I can get out some wet wood chunks. The two closest to the edge may be partially sealed but I can feed a couple inches of screwdriver into the two inside ones. They are 2.75" apart and 2.75" from the edge. I slid the gas tank out of the way and they don't go through to the cockpit, so I guess they are within the depth of the transom. I'll look up digging out balsa but any more ideas about that are appreciated.

Thanks.
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bmcminn



Joined: 20 Jul 2019
Posts: 45
City/Region: Bellingham
State or Province: WA
C-Dory Year: 1992
C-Dory Model: 19 Angler
Vessel Name: Polū
Photos: bmcminn
PostPosted: Sat Nov 23, 2019 1:32 am    Post subject: Reply with quote

I decided to drill some holes. 3/8", one in the center and two more towards the centerline, out to about 3". Wet core, but the last one seemed to have some solid material near the top. The others were mush.



Not sure if I'm supposed to cut this out from the outside or inside, though the holes don't go through to the cockpit, so not sure if that should be left intact.

I'll call NMI down in Fairhaven on Monday and see if someone there wants to take a look and give me some in-person advice.

Bob, I read your post about replacing the floor of your cockpit. I guess you just use a cutting wheel of some type to remove the rectangular piece. I have a electric cutter. Do I save the piece and use it again? You suggested a different core material, Nida-core...

Oh man I got a lot to learn and no time.
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Micahbigsur@msn.com



Joined: 27 May 2019
Posts: 295
City/Region: Big Sur
State or Province: CA
C-Dory Year: 2003
C-Dory Model: 25 Cruiser
Vessel Name: Sierra
Photos: Sierra
PostPosted: Sat Nov 23, 2019 2:26 am    Post subject: Reply with quote

You will get a lot of suggestions, search back through the old posts, some will help.
I see 2 ways to go.
The fix it and pray for the best method...
Dig as much of the mushy core out that you can. Tape a little plastic tent/enclosure down from the hull, put in a little heater, not too hot and try to get it dried out over a few days. Fill with expanding spray foam or or acraglass whichever looks like it would work out best then glass over as in your earlier post.
If the hull and interior don't seem soft and flex under a rubber hammer before you start this could be all you need. Use epoxy resin.

The next fix is if you feel that the bad core has spread far enough that tapping with the hammer and it sounds "dead" and flexes away from the holes after drying and you want a good fix and feel confident in your DIY skills.

Laminate over the holes as above.
On the interior which is hopefully accessible, using a small grinder with a diamond blade cut away some of the laminate above the bad area, cut a small square and pry it out. Keep expanding the area until you find the edges of the good core. Scrape out the bad core and lightly sand/grind the bottom laminate. Straighten and even out the perimeter of the excavation. OK, now you need new core, foam or balsa of the same thickness from a fiberglass supply (on line) cut it for a tight fit in your hole. Cut a piece of 1.5 oz. Fiberglass mat to fit in the hole paint the bottom laminate liberally with resin, put the mat in. brush resin liberally on it and work out the air bubbles with the brush tip. Paint resin on the bottom of your replacement core place it down in against the wet glass on the hull, weigh down the core with weights like bricks to press the core into the wet layer of glass. After cure grind away and taper the area of the surrounding laminate out 2 or 3 inches, the core and surrounding laminate should be a nice smooth surface. Laminate over the area you have ground down with small to larger glass pieces to fill the area with a tapered patch. Use alternating layers of mat and e-glass or biaxial cloth up to the original glass thickness. Epoxy resin is much better, I use West but others are fine as long as they have measuring pumps for the cans. Try to find glass mat that has a binder that is compatible with epoxy.
This is only a very basic outline, but using common sense and if you are used to building and crafting things in general, if you take you time and think things out, do a little studying on line, you can do this. It is actually pretty simple if you are handy.
I'm sure others will chip in with good ideas also.
Good luck.
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Micahbigsur@msn.com



Joined: 27 May 2019
Posts: 295
City/Region: Big Sur
State or Province: CA
C-Dory Year: 2003
C-Dory Model: 25 Cruiser
Vessel Name: Sierra
Photos: Sierra
PostPosted: Sat Nov 23, 2019 3:02 am    Post subject: Reply with quote

Diamond edged blades that fit grinders are sold for cutting tile at a building supply. They work great on fiberglass, buy dust masks.
They should also have coarse 36, 50 and 80 grit disks that with a rubber disk back will fit on your small grinder for sanding and grinding fiberglass
I do this on my phone, please excuse brevity and typos.
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thataway



Joined: 02 Nov 2003
Posts: 17254
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Sat Nov 23, 2019 9:35 am    Post subject: Reply with quote

bmcminn wrote:
I decided to drill some holes. 3/8", one in the center and two more towards the centerline, out to about 3". Wet core, but the last one seemed to have some solid material near the top. The others were mush.


This finding illustrates why it is so important to have a survey before buying a boat.

Stop drilling holes in the outer skin--this will compound the repair. The outer glass skin is fine, except where you have holes.

You are going to have to pull the fuel tanks and start sounding (use of small phenolic hammer, plastic handle of screw driver etc) the floor to estimate the degree of water infiltration from the inside of the hull. --If the rest of the inner hull floor is dry, then use of a moisture meter to be sure that there are no more wet areas. (That is a whole different subject)

Quote:
Bob, I read your post about replacing the floor of your cockpit. I guess you just use a cutting wheel of some type to remove the rectangular piece. I have a electric cutter. Do I save the piece and use it again? You suggested a different core material, Nida-core...


What you read about was the floor of a 25, not the bottom of the hull in a 19 or 22. There were some reasons to use the NadiCore in that application. Some boats are built with Nadicore, although I would not choose it for the bottom of the hull because of mechanical properties of the core product. For the C Dory hull laminate, I would go back with Balsa.

As Micah suggests in his post above, You need to cut out the inner layer of the hull, starting all of the way back by the transom, and work outward. Drilling small holes to assess is one way from above. After you have identified the bad area by sanding. The bad area will most likely be further than you sounded.

You are going to have to then remove all wet core, as accessed from the top. This means cutting segments of the inner hull out, and checking the edges. In this case, I would go back with balsa for the core material. You have to remove all of the old balsa. Agree with Epoxy as being best for bottom. You are going to have to repair all of these holes now--but considering how they are spaced, I would tend to grind down the entire area--tapering to the outside, and lay up glass over this entire area, rather than a group of 7 circular repairs. I would do the same on the inside. The actual schedule of laminates would depend on what thickness you find in the bottom. Details would follow as you reveal the amount of wet core. I would have no problem using polyester resin on the top (replacing the inner layer), But there are excellent arguments for use of epoxy--depending on how you are going to finish the repair. There are ways to get gel coat to adhere to cured, and clean epoxy repairs.

Quote:
Oh man I got a lot to learn and no time.


My advice is to go slow, if you are going to do the repair, get advice before you make any move or drill more holes.

I have used multiple techniques for cutting fiberglass. In this case you want to limit the cut depth. A 1/8" rotozip bit cut adjusted to just go into very top of the balsa core, a carbide or diamond blade in any one of a number of small (3" ) saws--such as by Dremel, or Mikita, A Fein type of oscellating saw, with carbide blade will allow cuts right up to a vertical surface (hull side) IF there is no limit to the depth; I have used skill saw, Sawzall, jig saw with either bimetal or carbide blades, even a chain saw...(these latter do not apply to your use).

When you are building the deck back on top (don't put the old glass back in), you will laminate back to at least the thickness of the original inner hull laminate. That needs to be tapered into the hull inner glass which is over intact core.

Since you are in Bellingham, you have a winter to do the project. Hopefully you have a place indoors which can be heated for the repairs. Go slow and ask for help at each step.

Could you do a "temporary patch" from the outside? Yes, but I would only do that if I had some trip planned, and then were going ahead with the comprehensive repair in short order. You will not dry out the core with heat and dehumidifiers in a few weeks. If you go thru freeze thaw cycles, the delimitation would become worse. It is not rocket science.

Both Micah and I have left out some of the details--and our advice is basically the same. I have walked several members thru this repair, and Micah has apparently done some similar repairs.
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localboy



Joined: 30 Sep 2006
Posts: 4252
City/Region: Lake Stevens via Honolulu
State or Province: WA
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: 'Au Kai (Ocean Traveler)
Photos: 'AU KAI
PostPosted: Sat Nov 23, 2019 1:21 pm    Post subject: Reply with quote

More than fixing the holes, now. Thatís a bummer.

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