Hull Repair Needed - Bulging soft spot under bottom paint

[rfdfirecaptain]

While restriping my boat yesterday? after a few weeks worth of a compounding and buffing job, I noticed a problem on the bottom of my hull. About a foot inside my Starboard stern corner I noticed a small bulge or "puffy" spot in the bottom paint a little smaller than a baseball. The bulge is raised no more than a quarter inch. It?s covered with bottom paint so I don?t have a good visual without doing a lot of sanding.

Anyway, I tapped and pressed all around the bulge. The puffy area was spongy. Not so spongy that my finger would push through, but soft enough that I could see it flexing. Other areas toward the stern, gunnel wall and keel were solid and hollow, where it seemed appropriate as compared to the Port side of the boat.

I would like to make the repair from the outside. Actually, there is no other option for me. I would have to dismantle too many things to get to it from the inside.

I just read in another thread http://forums.iboats.com/showthread.php?p=2971091 about an epoxy repair. So, assuming that is the method I will use, here are a few questions:

1. What the largest size hole I can repair using the suggested epoxy method?
2. Would it be advisable to use a hole saw to cut out the damaged hull area? It would certainly make a cleaner and neater hole and probably a more stable area to work within. Thoughts?
3. If a round hole is advised for this repair what would be the largest diameter that the epoxy repair could be trusted to repair? I'm thinking I may have to go anywhere between 1.5 and 3 inches.
4. In the thread linked above Mark42 suggested using ?small pieces of csm?. What is ?CSM??

Is epoxy the only way to repair? Can anyone suggest other ideas or a well established thread with detailed repair information? Thanks!!!

 

[Yacht Dr.]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

Its hard to tell from the discription...could be an old repair just failing..

Id say if you can press and flex it..its not deep.

You could grind it and reglass ( hole saw .... eh..).

Pics again would help ..

YD.

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

YD...

Yeah I know pics are always best. I'm working another 24 hour shift today, so no pics today, sorry. I'll post one tomorrow morning, but you won't see much becasue the bulge is uniformly covered with bottom paint. Once I put the sanding disc to it more will be revealed. I really want to get off on the right foot with this repair since this is a potential boat sinker!

What's your recommendation? I was thinking:
1. Sand off the bottom paint
2. Take pics
3. Post pics and ask for opinions

 

[Yacht Dr.]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

Keith...thats not a boat sinker lol..

If you can push on it..its not that bad

sand the BP off at least 3" on and around your soft spot.

Clean with acetone..Without pulling the paint into your sanded surface..work outwards towards the bottom paint with a clean rag..

Grind out your Blister/bubble ( Im sure its only through the first layer of mat ) then pics .. You will probably get away with a simple mat layup .. 3 layers ...

Wear a resporator please..and some long arm trash shirts

YD.

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

YD...

That may not be the "hole" that sinks it. If I have to start one more thread this month about a problem with this boat, it will be the "hole" from a stick of dynamite that puts 'er under!

I'll have photos on here by tomorrow night. I have church, and a wedding tomorrow, so it will probably be later in the evening before I get them up. If you can take a look and advise me I can work on the repair all day Monday- Wednesday.

Thanks!

 

[ondarvr]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

1. For a hole when only using epoxy and below the waterline I wouldn?t go much bigger than a ? inch, but this depends on how thick the hull is where the repair will be and the exact location of the hole.

2. You almost never want to cut out a section of the hull when doing the repair, mainly because it makes it more difficult to do the repair. Its much easier to grind it down from one side, glass that side, then grind the rest of the bad glass out from the opposite side and glass it too. This allows you to use the original shape of the hull as the form instead of trying to span the gap with something that may not take the correct shape easily. This isn?t always possible though, so you just have to work with what you have sometimes.

3. 3 and 1 appear to be the same question.

4. Chopped strand mat.

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

UPDATE #1

I took a 50 grit sanding disc on a 4.5 inch grinder and lightly sanded down to reveal what you see in the photos.

In the first photo,(not yet sanded) even through the bottom paint you can see a hairline crack that starts in a dark spot on the left and extends all the way to the stern and turns up the stern wall (I will show the stern wall in pic #3). The dark spot is the soft spot to which my thread refers.

In photo #2 I have sanded the soft spot down to the fiberglass mat. When I rub my finger across the mat there is a small lip in there (about 1/16 inch lip) where it should be smooth, especially after sanding. This is not detectable just by looking at the photos. The lip is in line with where the crack extends through the section that has been sanded to the mat.

Photo #3 is a shot of the stern wall. You see the stainless trim tab on your left. Notice that the crack is continuous from the bottom of the hull and it extends about 8 inches up the stern wall.

I think this means I need advice on two things:
1. How do I repair the soft spot?
2. How do I repair that crack. From beginning to end the crack is about 25 inches long.

I'm off until Thuirsday morning and ready to get busy as soon as you guys tell me what to do.

Just for the sake of knowing.... how serious is this? Is the back corner in danger of breaking off the boat if I get into some rough conditions?

Thanks!

http://s990.photobucket.com/albums/af27/andreawilder2009/Boat Hull Repair/

 

[ondarvr]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

You'll need to start grinding on the crack to expose the laminate, the gel coat will hide the real damage. White glass is bad, fractured, broken, etc, so its easy to see how deep it goes when you start grinding.

 

[gozierdt]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

A good reference is the West System "Fiberglass Boat Repair and Maintenance",

http://westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf

and a companion booklet "Gelcoat Blisters Diagnosis Repair and Prevention" articles on the West System website:

http://209.20.76.247/ss/assets/howto-pub2/Gelcoat%20Blisters%20Diagnosis%20Repair%20and%20Prevention.pdf

They go into a lot of detail on fixing these kind of problems. You don't have to use epoxy, you can use polyester resin and the appropriate glass products with the same techniques taught in these booklets. I prefer epoxy because it's stronger, but in a good repair polyester is plenty adequate.

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

Sorry ondarvr.... I gotta ask a few things for clarification

The layers I see are and in this order: Bottom paint, White gel, Green gel, Glass mat

1. What is "laminate"?
2. What is "white glass"? Why is it "bad"? Do I have white glass?
3. What are some examples of the "real damage" that I may be looking for?
4. Can you be more specific on how to grind the crack? How deep? How wide?

I'm off work for the next 3 days. I'm pretty sure I can get the dirty work done by lunch tomorrow. Then what?

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

gozierdt:

This question may be answered in those links you sent me. I see some of these words you mentioned A LOT in these threads. For the benefit of this thread can you elaborate on a few things? Surely, I can't be the only one who wants to know these things.

1. What is "epoxy" and what is "polyester". Specifically, what products are they?

2. You mentioned epoxy stronger than polyester. Why?

3. Which is easier to use? Does one take longer than the other... to apply, and to cure?

Thanks a lot!

 

[ondarvr]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

This will explain the terms and products used to work with fiberglass, a quick scan will answer your questions.

http://forums.iboats.com/showthread.php?t=286013

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

WOW! You guys have sent me hours of reading. Thanks!

ondarvr thanks for the link to that thread. It answered nearly all of my questions and it defined (very well in fact) 99% of the terminology you guys use so often. Seems like knowing the jargon is 20% of the battle in my situation.

20% = Know the jargon
20% = Know the products
20% = Know the methods of repair
40% = Do the work

I?m still trying to learn more about the epoxy ?vs- polyester thing. That is where I find most opinions differ on this site. This must be decided asap so I can make purchases and get started today.

I?ve successfully used general purpose resin (aka polyester) many times for small repairs, and I am not opposed to epoxy for this repair. I just didn?t find enough information in that thread on ?working with epoxy? to get my comfort level where it needs to be. I guess it?s fear of the unknown (epoxy). The thread kept saying epoxy is ?forgiving? for amateurs, but the guys also stated, ?I'm not an epoxy guy, so I won't give information on it because it may not be accurate.? He was referring to the quality of epoxy brands. Even so, that kinda threw me off.

Here?s where I am right now with this project.
1. I need to decide asap ? Epoxy or Polyester. More suggestions or opinions please?

2. FIRST Big question still not answered about prep work ? When ondarvr said to ?grind? the crack I thought he meant to gouge it out. Now that I know what ?laminate? is I think he meant to just sand off the bottom paint and gel to reveal the laminate. What do I do if the crack persists deep into the laminate?

3. SECOND big question not answered ? will epoxy or poly bond to gel coat? That will determine how far out I have to sand.

4. It looks like this repair is going to be about building a ?bridge? over the crack. How many ?layers? would be advised? I?m thinking 3 layers (maybe more) over the soft spot, then 3 staggered and feathered layers over the crack to build the bridge.

5. To build the bridge, which is the best glass to use - Mat? Cloth? A combination of both with cloth used for the top layer? If I can find carbon fiber I may use that.

6. Suggestions for the width of the widest part of the bridge? I?m thinking 6 inches wide.

7. After sanding the bridge down do I need to coat with gel coat before I recoat with bottom paint?


Sorry gang I know that's a lot.... just trying to get my game plan together so I can get on this thing today.

Here's the photo linkl again
http://s990.photobucket.com/albums/a...Hull Repair/

 

[ondarvr]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

I don't have a great deal of time right now so I'll get to the polyester vs epoxy issue

Epoxy is better in almost every way, stronger, bonds better, more waterproof, etc. It does cost more and can be a little more difficult to work with. Gel coat and polyester won't stick well to epoxy, but epoxy does stick very well to polyester. Epoxy can be more toxic, but polyester smells worse.

While Polyester doesn't have the same physical properties as epoxy, 99.999% of the boats are made from it and the polyester holds up fine, its the wood that rots and fails typically due to workmanship. So the wood will rot in the same way no matter which resin is used.

Again 99.999% of the repairs done by professionals are done with polyester...why...because even though epoxy is stronger, polyester is more than up to doing the job very well.


In that link I said I'm not an epoxy guy because in 40+ years of doing repairs on fiberglass, I've never found the need to use epoxy for a successful job. There are times when epoxy would be nice to use, or if you?re doing other things that may need the bonding strength, but in a normal repair polyester does a good job. The other reason is that I know polyesters and their properties very well because of the job I have, I don?t have the same knowledge of epoxies, so I can?t get into great detail on the chemistry or differences between formulas.

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

On spot ondarvr; thanks!

Going shopping asap to get materials. I'll have to wing some of this on my own I guess, but I know more now than I did last night. I'll try to get it sanded down and layered today.

Please don't forget to let me know about the need for gel coat on top of the layers, before I recoat with bottom paint.

 

[gozierdt]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

1. Ondarvr gives you the details of epoxy vs polyester above. The only thing I would add is that if you decide to use polyester, you need to be aware of "waxed" vs "unwaxed" polyester resin. The unwaxed resiin stays sticky on top, allowing you to lay another coat of resin or resin/glass on top with good adhesion between layers. the waxed resin has a wax in it that rises to the top of the resin as it cures, giving a hard surface to that layer- the resin doesn't cure completely unless it is protected from the air, that's what the wax does. You can remove wax by wiping with solvent and sanding, but if you're doing multiple coats, it's easier to use unwaxed resin until the final coat.

2. You need to get to the lowest layer that isn't cracked to really fix the crack. So you need to grind the material away until you get to the bottom of the crack. If the crack goes down into the laminate layers, it will show as white "splotches" in the laminate where the glass fibers are broken. You need to keep grinding away until all the broken, white fibers are gone. If it looks like you're going to have to grind all the way through the hull, you should only grind about 1/2 way from the outside, do your patch, then grind from inside the hull to the patch, and finish the patch from that side. I don't think your crack looks that bad, just for information. The recommendation is to grind 8:1 for width, in other words, if the crack is 1/4" deep, grind a bevel 2" wide on either side of the crack. Then fix with multiple layers of glass/resin until you're just below the surface, and finish with your surface layer, no glass.

3. Answered by Ondarvr and the link he gave you.

4. Yes, you've got the idea. Each layer will be about 1/6" to 1/8" thick, depending on what glass you're using. Build it up with wider and wider pieces of glass so that the strength builds up gradually across the width of the beveled area.

5. I wouldn't use carbon fiber. You want to match the strength of the existing hull, not create a stiff spot. What I've read and used is mat for the inner layers of the patch, light weight cloth for the outside layer (fixing a 1/4" deep crack on a 20' hull). Make sure to get each layer wetted out well with no air bubbles. You can tell where there are bubbles- they'll show up white. When the glass is well wetted it gets almost transparent- that's what you want. Get a fiberglass roller, or use a stiff brush and work the glass until all the white fibers go transparent. You won't have a lot of time to do this with polyester, the resin will kick off in typically 5-10 minutes at 70-75 degrees temp. That's from when you start mixing the resin and hardener.

6. Use the 8:1 rule above. Wider doesn't hurt anything, just that you don't get much added strength, need to use more and more materials, and it's harder to match the hull contours easily.

7. If you're using epoxy, you won't need gel coat for the last layer. Just get the contour blended in with the hull. I haven't used polyester much, so I don't know if the recommendation is to use gel coat over the final resin layer or not. It's probably in the recommended reading.

Keep asking questions as they come up. This is a great forum for getting help!!

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

gozierdt: Awesome information about the method!

Ondarvr?s thread schooled me on the wax/non-waxed. That thread recommended general purpose polyester resin for amateurs like me because with that product wax is a non-issue.

Thanks for the detailed grind information. 8:1 was exactly what I needed to know. I guess that means I can grind out a total width of maybe 4 inches. Less work for me!

I have decided to use the polyester resin. That?s because I?ve searched 3 major automotive stores (Adavance, Autozone and Pep Boys) and 2 automotive paint stores (Carquest and Napa) for the epoxy. None have epoxy on the shelves and only 1 place was even aware that epoxy exists. Most tried to sell me a two part glue when I asked for epoxy resin.

OK, I will use chop strand matting for all layers except the top layer. For that I will use cloth.

YEE HA! OK I?m going shopping now and I?ll try to have pics up tonight.

Believe me, I read every word of that thread and I did not see the answer to my gel coat question. I hope I didn?t just miss it. Honestly, I read about 30 pages last night of that westsystems.com page. It was about 100 pages long so I couldn't finish it. Unfortunately, since last night I have not been able to open that site back up. The ?companion booklet? never opened up for me.
So, does ANYONE know the answer to this question? Do I need to recoat this area with gel coat after applying a polyester patch? Or, should I just paint over the polyester patch with bottom paint?

I?m pretty sure the contour of the boat will be slightly different. I don?t see how I can ever level it out without a slight hump running the length of the crack. I can live with that as long as it stops the problem and doesn?t cause any new problems. Thoughts???

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

I just got back from shopping and realized I did not hit "submit reply" for me previous post before I left. I won?t be able to get any pics up tonight becasue it's getting late and the sun will set very soon. Shopping took a lot longer than I anticipated because I could not find the recommended ?weight? mat and cloth.

The recommended weight in all the suggested reading was 2 oz. mat and ? 4 oz. cloth. The ONLY weight I could find (after a total round trip of 117 miles) was: Mat = 9 oz. and Cloth = 6 oz.

Any thoughts on these heavier weights? Suggestions? Potential problems?

I?ll get on this first thing in the am and have pics up by late afternoon

Thanks again for all your help!

 

[gozierdt]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

I'm not an expert on the glass, but I think as long as your layers stay thin enough to allow you to build up less than 1/8" at a time you'll probably be OK, 1/16" is probably better for each layer. How deep did you go in your grinding? That will give you part of the answer. Basically, you want to build the strength of the repair up gradually, so you don't get a "hard spot" from where the glass layers get much thicker all of a sudden. Someone else will need to chime in on how 9 oz mat will work/how thick the layers will be. I think the 6 oz cloth will be ok for the final strength layer under the gelcoat. And I did give an abbreviated answer to your gel coat question- I thought you should use some. But if I remember your boat has bottom paint on it, correct? I think gelcoat (I've used mainly epoxy) is basically polyester resin with a UV inhibitor added. If you're going to paint, I think you're good with your basic polyester resin as a gelcoat layer, then bottom paint over it. But you really should wait for one of the restoration experts to answer, or do some more Google searches (which told me gelcoat is basically poly resin...).

Edit: OK, went back and relooked at your pics. Not sure you have bottom paint, but looks like the outside layer is dark. If that's true, you'll need to add a layer of colored gelcoat to match the patch up with the rest of the hull.

Keep us informed...

 

[rfdfirecaptain]

Re: Hull Repair Needed - Bulging soft spot under bottom paint

gozierdt:

Yes, I do have bottom paint.

Under the bottom paint is 2 layers of gel coat. The first layer is a cream color and the second is the green color that you see on the sides of the boat.

I hope you?re right about the gel coat = polyester resin. If can get away with sanding my patch down then coating with new bottom paint I will be excited.

I'll post photos and an update asap tomorrow.