Need advice to repair hole in hull at front of centerboard trunk

goodmdo1

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Friend gave me a sunfish, said it leaked a bit. Took it out yesterday and noticed water draining from the bottom when the boat was back on the boat lift. Inspection revealed the hull was half full of water. Inspecting it I see a hull gap right in front of the centerboard and about a 1/4 inch hole clean through. Looks like the patch from an earlier repair came out. This is just a fun boat so a perfectly faired hull repair is not needed however I have not done any fiberglass work and would like advice on what to get; how to do it, and particular advice on the location since it is so close to the centerboard trunk and widening the hole needs care. Thanks in advance
 

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Looks like the daggerboard trunk has been repaired before--then given fresh paint. The puncture, however, suggests a "hit" from the trailer. :oops:

You're going to have to sand inside and out locally until you've established the limits of damage. (New and old). If you extend the damage with your work, that's not a bad thing...:cool:

Start by getting the interior extra dry, borrow an orbital sander, buy a pint of epoxy (or polyester) resin w/hardener, and 8-oz fiberglass tape in widths needed to overlap the damage. (There are inexpensive kits that may do the job for you).
 
Friend gave me a sunfish, said it leaked a bit. Took it out yesterday and noticed water draining from the bottom when the boat was back on the boat lift. Inspection revealed the hull was half full of water. Inspecting it I see a hull gap right in front of the centerboard and about a 1/4 inch hole clean through. Looks like the patch from an earlier repair came out. This is just a fun boat so a perfectly faired hull repair is not needed however I have not done any fiberglass work and would like advice on what to get; how to do it, and particular advice on the location since it is so close to the centerboard trunk and widening the hole needs care. Thanks in advance
How did you get inside there? Is the already an inspection port or do you have an endoscope? If it’s the former, then see response #1 above. If it’s the latter, then install inspection port and then see :)
This spring I was a total newbie at repairs like that. As of today I’m a beginner still but boy oh boy have I learned a lot here. Go slow, do your research. Ask questions!!!! Watch YouTube videos. Then break open your piggy bank, buy good resins and glass and go for it!
 
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Easy fix. Photos look like the damage extends to the trunk interior. This is a common oops from grounding the board at speed.

REF Below is taken from a previous post of mine.

Your port give you excellent access to lay up a proper glass-epoxy patch and reinforcement.

use painter tape all around the openings to keep the epoxy off the hull

scarify the interior to get a good bond.

I use only US Composite 635 THIN resin. On line purchase. Buy the dispensing/measuring pumps. Excellent wet-out, slow cure, long working time, zero blush so multiple layers are easy. soap and scrub clean up but wear gloves. I get 9 mill pro gloves at Harbor Freight, durable and affordable.

for your repair I would apply serious layers inside and a pretty large area. Use a 1” throw away chip brush for mixing and applying. Use the brush to smooth out the patch and to exclude the air. Pre-wet the surface before the first layer. Pre-cut all planned patches before starting.

when the inside is done, flip the hull, grind a tapered depth into the broken old fibers maybe 2 inches either side of the crack. Fill with glass mat and epoxy. You can promote a smooth finish by pressing a thin polyethylene film sheet onto the surface. Stretch the film flat and painter tape the edges to make the film stay flat. If you do this carefully the surface will be nearly glossy when the film is pulled and near net shape. Work the air out. Later, If you need fairing, mix in 3-M micro balloons from US Composites to a stiff creamy consistency. Easy to long-board.

cure time on the resin is 2-3 days for sanding. I said it was slow. Working time is 2-6 hours depending on temperature.
 

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Easy fix. Photos look like the damage extends to the trunk interior. This is a common oops from grounding the board at speed.

REF Below is taken from a previous post of mine.

Your port give you excellent access to lay up a proper glass-epoxy patch and reinforcement.

use painter tape all around the openings to keep the epoxy off the hull

scarify the interior to get a good bond.

I use only US Composite 635 THIN resin. On line purchase. Buy the dispensing/measuring pumps. Excellent wet-out, slow cure, long working time, zero blush so multiple layers are easy. soap and scrub clean up but wear gloves. I get 9 mill pro gloves at Harbor Freight, durable and affordable.

for your repair I would apply serious layers inside and a pretty large area. Use a 1” throw away chip brush for mixing and applying. Use the brush to smooth out the patch and to exclude the air. Pre-wet the surface before the first layer. Pre-cut all planned patches before starting.

when the inside is done, flip the hull, grind a tapered depth into the broken old fibers maybe 2 inches either side of the crack. Fill with glass mat and epoxy. You can promote a smooth finish by pressing a thin polyethylene film sheet onto the surface. Stretch the film flat and painter tape the edges to make the film stay flat. If you do this carefully the surface will be nearly glossy when the film is pulled and near net shape. Work the air out. Later, If you need fairing, mix in 3-M micro balloons from US Composites to a stiff creamy consistency. Easy to long-board.

cure time on the resin is 2-3 days for sanding. I said it was slow. Working time is 2-6 hours depending on temperature.
many thanks to all for the tips -

Mama ha chicago yes there is an access port in the top side that allowed me to see all the water she took on and take the inside picture.

Nicholson 58 many thanks for the glass work tips - those are going to be very helpful.

Question for all - what about the location near the centerboard trunk : when I start removing bad material how critical is it to stay away from the trunk to avoid creating a larger issue?

And what is the best tool for grinding out the bad material ? Toll wise I have an orbital sander however with the v-shape inside and the trunk there wondering how well that will do. I have a dremel tool but wonder if that would not take forever, also an angle grinder but that is probably too aggressive.

If anyone has pics of what a similar repair looked like after prepping that would be great to see.

thanks again

ps - I hope this is where the friends leakage came from. Prior to finding this hole I had wondered if the seam between the topside and hull was open and it was leaking when heeled over and did not relish the idea of removing the aluminum trim strip and resealing each end like I had seen posts here about.
 
Get a SMALL right angle grinder and use the overlapping flap wheel. There are very affordable grinders at Harbor Freight.

I would cut strips of glass. Start by laying them against the hull and up the trunk. Strips around 1-2” wide are easy to form on curved surfaces. Us the packs of woven glass found at hardware stores such as Home Depot. Use the bent SS medical scissors for cutting. These are excellent with the single serrated edge. Wrap the next layer of strips around the trunk overlapping the flat sides by 5 inches. If usually have trouble making them stay in contact then cut polyethylene film to wrap and cover the entire wet work. Use long strips of painter tape to hold it tightly in place. Next layer is large pre-cut patches against the hull and cut out around the trunk. These several layers should all be progressively larger as they extend into the flat of the hull. Repeat the process until you are satisfied with the thickness and integrity, about 3/16 inch, 4-5 layers.

I also use a Harbor Freight high speed die grinder and carbide burrs for detailed cutting and fairing. I don’t think you need this unless you are a tool hound. The deck joint is a possibility as well but the trunk needs fixing. There is a tutorial with photos on this site for how to attack the deck joint. Basically, drill out the pop rivets and remove the aluminum trim. Spread the joint and clean. Apply suitable replacement bonding material. I’d use 3-M 5200. Permanent and flexible. Wear throw away clothing and gloves.
 

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Get a SMALL right angle grinder and use the overlapping flap wheel. There are very affordable grinders at Harbor Freight.

I would cut strips of glass. Start by laying them against the hull and up the trunk. Strips around 1-2” wide are easy to form on curved surfaces. Us the packs of woven glass found at hardware stores such as Home Depot. Use the bent SS medical scissors for cutting. These are excellent with the single serrated edge. Wrap the next layer of strips around the trunk overlapping the flat sides by 5 inches. If usually have trouble making them stay in contact then cut polyethylene film to wrap and cover the entire wet work. Use long strips of painter tape to hold it tightly in place. Next layer is large pre-cut patches against the hull and cut out around the trunk. These several layers should all be progressively larger as they extend into the flat of the hull. Repeat the process until you are satisfied with the thickness and integrity, about 3/16 inch, 4-5 layers.

I also use a Harbor Freight high speed die grinder and carbide burrs for detailed cutting and fairing. I don’t think you need this unless you are a tool hound. The deck joint is a possibility as well but the trunk needs fixing. There is a tutorial with photos on this site for how to attack the deck joint. Basically, drill out the pop rivets and remove the aluminum trim. Spread the joint and clean. Apply suitable replacement bonding material. I’d use 3-M 5200. Permanent and flexible. Wear throw away clothing and gloves.
I checked out the US Composites site for the resin you posted and that site looks great - I see they have both fiberglass cloth and fiberglass mat. Any downside to using the cloth rather than mat? the cloth looks like it may be easier to work with (saw a video of a repair with mat and it seemed harder to cut and handle).
 
Use woven cloth, thin and light. Mat and heavy weave are too stiff to form around a curve. You could use thin bi-directional stichmat. It is the most flexible of all and can easily do complex curves. Use mat for very large layups and generally flat surfaces.
 
Well got the boat to the garage and started the repair; my goodies from US Composites due today. Just finished grinding and smoothing the inside and wanted to post pictures and ask if you think this is ready for patching.

I see someone did some glass repair before and the surface was really rough. Between my HF angle grinder and dremel tool I worked to smooth the rough cloth surface as much as I could and remove the globs of resin to smooth out what I could get to. Tough working in side there for sure. I found putting dewalt flashlight in the hull laying on its side gave the best light and tried using shop vac hose in access hole to catch some dust.

Questions then:
1. does this look good enough and ready for patching?
2. do Ineed to clean the surface with acetone prior to patching? (used shop vac to try to clean dust out)
3. How do I best 'plug' the hole from underneath to keep the resin from dripping out (ordered US Composited 635 2:1 as recommended and know it is lowest viscosity and did not want to use a plastic or tape that the resin will dissolve!)

thanks,
Don
 

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Is that daylight I'm seeing? :oops: No wonder, your boat took on water!

You can tape over that potential leak with Duct-tape or any plastic tape outside, or use a medium-firm plastic (using tape or Shoe-Goo), to reduce run-through. The excess can always be sanded away.

Would it help to bag your board with plastic to prevent a firm obstacle from accidentally forming?

Bi-axial tape is a good choice, as mentioned above. A lighter grade of 4-oz tape for the first few layers, then standard 8-oz for the rest. Try to complete this repair in one operation, using slow-set hardener. Use a stiff-bristled "flux brush" to poke out the bubbles and other "transparencies". Your future leaks are at stake. :confused:
 
Thanks for the advice - yes once I got a light inside the hull I saw all the prior patch work done around the trunk.

last week I saw additional advice from Nicholson58 in another repair thread where he spoke about various strips -
1. first strips 1-2 inches wide against the hull and up the trunk followed by a
2. strip on the flat sides overlapping 5 inches.

I have tried to depict my understanding in this image and wanted to check it please
do the red lines represent what is meant in number one above then
does the blue rectangle overlapping the red right angle strips capture what is suggested?

Then I assume I build up several layers in the area where the hole is?

Since this will be several layers of cloth and resin is there any benefit to doing the red and blue work, letting that cure then coming back and building up layers in the hole area or just do it all in one pass recognizing there may be 4-5 layers over the hole area?
 

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This is not a repair I've done; however, my approach elsewhere is to avoid the necessary sanding after each full curing. (Different resins have different post-curing requirements). Other factors can enter here, such as personal fatigue, weather, too-fast curing, etc., but One Big Effort works for me. :)

It's important to have all the tape/cloth cut in advance; otherwise, the curing process gets messy and advances too quickly to catch up.

Yes, I like the "band-aid" approach (red). I'd make several layers and finish with "leftover" big pieces (blue) to cover the band-aids.

The daggerboard trunk typically takes a beating, so I don't think you can overdo the layering--especially the fore and aft curves.
 
Disclaimer - I am doing glass work for the first time - thought I'd post a few more pics for other novices - may help (and I can also get advice on what I did wrong :) )

As suggested, I got various supplies from US Composites – great stuff, packed very nicely ( be nice if their shipping costs were cheaper). I bought a strip of 6 in by 3 ft woven fabric with glass fiber backing and should have bought more. To ensure I had enough for both the inse and the outside of the hull and the help pre-cutting pieces I first took a large sheet of packing paper and used that to cut out templates for the pieces I planned to glass out. Then used these to minimize waste and mark the fiberglass cloth. Attached are pics of the laid out pieces and then the cut out pieces numbered in installation order.

Before mixing the resin I also cut out the pieces of mold release fabric. A pic of the final install with the mold release fabric on also attached. Assuming I did an ok job getting the air bubbles out I think it turned out well.

A comment – I bought the pumps for the bottles and like a dummy did not think about the amount of hardener the pump itself would displace – did not get it very far into the bottle before I had a puddle on the workbench! Needing so little epoxy I ended up just pouring and using the 6 oz measuring cup I got from USComposites – point being if you are not going to first use a lot out of the bottles don’t buy the pumps. I don't expect to use enough to be able to put the pump in.
 

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I think you're well on your way! We'd grind out the bottom of the keel a tiny bit to make sure we were grafting into good fiberglass, with the end goal being to not have a fiberglass bandaid bump on the keel (like I did with my rookie repairs back in 2001.

We use fiberglass woven roving, which is the open weave material you're seeing inside the boat, for the interior repairs and as internal backer patches. On the exterior we like to build 4 oz fiberglass cloth layers with thickened epoxy until just shy of level, then fair to level with our favorite, TotalBoat Total Fair epoxy based compound. If a gelcoat finish is planned, then a primer must be put over TotalFair as a bridge, but that's also true for most final finish paint systems as well.
 
A common mistake with glass work is not feathering back so there is surface area for structural adhesion. That is they just fill the exiting hole.

The course weave glass inside the hull should be sanded down to level or sanded some and a layer of matt before laying in the woven. The matt glass conforms better for the woven. That being said, it is really not important.

The classic failures are from not having a good sanding with like 80 grit and too much resin. Either makes for poorly bonded patches that come off easy.

The hull bottom just needs to be sanded down well with a taper and build it back up.

Lots of ways to do the repair that all work. Out of many sunfish at my yacht club the repair failures always are not sanded back first or are just layed down with a lot of resin. Both cases the repairs just peel off. Pretty much anything else just keeps working even with lots of abuse.
 
I'd mentioned earlier to reverse the rubber backing of drill-mounted disc sanders to reach the underside. BUT the woven "roving" is not that thick, so a good roughening should do the trick. It's not practical to sandblast, but that's what it needs.

I use 46-grit sandpaper because I have SO much of it. I thought I was buying anti-slip flooring at a yard sale, so 35-feet of it seemed about right. Now I see I've bought a huge roll of belt-sanding replacement that's nearly a yard wide. :confused:
 
Progress update: flipped her and ground and tapered the hull bottom today. Overlapping sanding disc on my Harbor Freight angle grinder made fast work of this, much easier than inside the hull. Note: when doing the hull inside I wore a basic dust mask and felt poorly that night; wore my EM canister respirator for the earlier resin work and today's sanding and definitely feel better. Here is a pic of the ground hull and planned glass pieces to be applied tomorrow when it is in the 60's (just mid-40's today). Going to put the piece closest to the workbench edge inside the trunk then the other three on the hull bottom. Fingers crossed I have sufficient taper so not a huge hull bump when I am done.

There were two places aside from the trunk where the boat had chipped the gelcoat exposing glass matt so when I glassed the hull hole I tried to put a few pieces over these places I had tapered a bit. I tried the painters tape suggestion and man did I have a ridge of resin to sand and tape stuck under the cured resin - a mess! I did not wear gloves sanding and all evening my hands itched so another observation is to wear gloved when sanding cured glass and resin.

Question: is the the final hull patch once cured and sanded ok to leave as is? i.e. no gel coat or paint? I notice prior owner had painted parts of the hull so if the patch needs to be painted any paint suggestions are welcome.

thanks
 

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We always gear up when messing with fiberglass, long sleeves, mask, long pants, goggles, maske, etc...We found some nice goggles by DeWALT that fit over eyeglasses called Concealers. They have vents up top that are shielded. If you're sanding old polyester resin I might go up to the P95 mask vs N95, those fumes are nasty. One other trick is we use wind to our advantage when we can to blow dust/fumes away from us. Shower off as soon as we're done sanding.

Concealer Goggles.jpg


For patches on Beach Bangers (Glos. 2018) we will spot paint with Rustoleum rattle can semi white gloss, a suggestion from Alan G.
6-7 cans will do an entire bottom and it can be touched up each season. For a bottom that only the fish will see.
 
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So about Sandpaper......

Specific grits are called out for different type of 'adhesives' (paint is included). While doing a restoration on a 1931 Model A I learned a bunch of technical things. I called Evercoat and asked about sanding grits. It is recommended to use the high paper grit allowed.

The issue is scratch per inch. A low number grit does not have enough scratch per inch and may not allow for full adhesion. For example guys using 46 grit to prep for normal filler. There is a greater chance for the filler to peel off with the wrong scratch. I witnessed this first hand during my restoration. Some filler came off easy and it was clear they used a low grit paper.

I believe for normal resin its like 80 grit, but I dont know the real numbers. I found some ranges.

It is important to look at the material sheet provided by the manufacturer of the product. Bob down the street might be feeding you a lot of bad information. I had an old timer give me advice on metal work. He had 50 years experience, none of his advice was close to correct once I learn the science behind it all. Based on what the scientists that make the product tell me.

Here is where common sense comes into play. If you have a smooth surface like gel coat you really want the most scratch per inch. This gives the most number places for the resin to hang on to and stay. If you just use the 46 grit there will be a lot of smooth area between scratch and you might not get the adhesion you need.

On the other hand, The area inside the hull kind of has a rough surface as it is. So pretty much your big issue to prevent adhesion is dirt/ contaminates.

Finally, always keep in mind, if the surface has an acid PH the epoxy for resin both cure by adding a base. If you acid treated a metal surface and some acid is left behind then the resin might not cure at the bond layer.

Hope this all makes sense...
 
Update: made patch on prepped hull sunday and it has now cured - hoping the edges sand off and can make a relatively smooth hull for paint. Now have three layers over the original hole from the outside and 3 or 4 on the inside - no doubt not the finest glass work but seriously doubt she will leak through that old hole :)

Thanks for all the help on sanding PPE, grits, etc.
 

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Rapair finished - sanding was interesting, I struggled to get the edges of the patch smooth; seemed the fibers remained jagged. Got it good enough and went ahead and painted it. All in all pleased - perhaps some can post tips on smoothing the outer edges that could help others. Hope my pics and notes help other total novices. Bottom of my hull is far from smooth so I think this repair will work and should not leak.
 

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