Hull repair on 1990 boat

Rickmerrill

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Yep, your pic are showing up! I'm a little confused. Are you talking about two separate areas that need fixes? On the hole if you follow Wood's layup you'll have CSM, 1708, 1708, 1708 inside. Plus, I'm guessing he'll say something like 1708, 1708. CSM, CSM on the outside. That's plenty strong. You don't need a fillet there - they are to help cloth go over a 90 degree inside bend. On the outside I see a few places where you should grind your taper a little wider say 3" from the edge of the hole. You want good surface area for bonding and you need enough depth so as you build up layers it't not sticking out past the hull surface. On grinding woven roving I don't know but always wondered, hope you get an answer. I'll throw out a guess and say you need to grind enough so all of the contact area has been scuffed (no shiny spots left). Don't worry about it affecting hull integrity, you'll be restoring it with you're lay ups.
 

500dollar744ti

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Let me clarify. Last year I struck a submerged concrete drain. I fixed it but did not use many layers and I think it cured with some air trapped under the resin.

Two weeks ago I had a crack appear along the same strake as last years' repair, at the edge of where I fixed it. I rushed to repair this new crack because I was taking the boat on a trip. After a few days the same crack re-appeared.,

Now that the boat is on the trailer back at home, I wanted to cut away my original repair, cut out anything that looked compromised and sand it all down.

Looking from the inside of the strake, this is after I ground away all the bad glass and old patchwork:

#1 is my original repair from a year ago
#2 is where the new crack appeared and then resurfaced after I did a poor job patching it.
#3 is where more glass looked compromised, possibly from the original damage or from poor repair by yours truly.
J8u2Sld.jpg


I ground all of it out to start over with more time for sanding, lay-up and quality. I want to make a lasting repair. Even though part of the original repair (#1) didn't look compromised, I didn't want to make multiple repairs in the same area. I thought it would be best to make one large area repair instead of cutting up the 1708 for 2 or 3 different places. It seems to me the repair will be stronger if the 1708 is laid as large sheets over all 3 areas instead of smaller sheets over smaller areas that may be compromised. I would expect that to crack again.

This is all a learning experience for me and I'm hoping to get the skill set needed to refurbish an entire hull at some point.
 
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Woodonglass

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Ok, What is the over all Length of the cutout area? What's the greatest Width of the cutout area? How thick is the hull? What does the hull look like at this time on the Outside? Post a pic of the Outside too, please. All of this information will be very helpful in giving you the correct info on how to do the best layup for a proper and long lasting repair.;)
 

Rickmerrill

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Oh, I agree about one large repair vs three small if for no other reason just to make sure you have a known good starting point. I'm starting to wonder if some damage left unground contributed to the second failure. By two separate areas I was actually referring to the pictures where you said your toolbox may have caused damage and the picture of the stringer. I couldn't place their location in the boat and wondered if they were another area you want to fix but I'm bad about figuring out close ups. I don't think Wood knows that you added new pictures back on page one. Oh, I find this thread interesting because 1. Looks like you did a proper repair but for some reason it failed and 2. I haven't seen that many examples of how to repair holes in the forum.
 

500dollar744ti

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I haven't been home to measure the length but I could tell you exactly this evening after I get home. I would estimate it is about 12 to 14 inches long and 2 to 3 inches wide at the greatest point. The hull appears to be 1/4" thick by estimation but I could tell you the thickness when I get home.

This is what the outside area looks like:
iYeV1ne.jpg


This picture shows about where the stringers are with yellow marks, I'm really hoping I can make the inside part of the repair without doing anything to the stringers!
RqYq0qC.jpg
 
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Rickmerrill

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A ha, i call them bulkheads, is the torn woven roving at the bulkhead forward or the rear of the hole? Can you label or describe what we're seeing in the last two pics in post 14? The yellow lines brought it all together for me, thanks.
 
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500dollar744ti

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Yes the bulkheads then. I measured the length of the hole, its 14 inches with about 2.5 inches width at the widest point. The torn roving is where the bulkhead meets the hull on both of them, in front and behind the hole. The other side of the boat does not have any torn roving or cracks either.
 

Rickmerrill

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I'm thinking with both bulkheads failing at the hull joint that should be the first area of concern. Without that support you effectively have a very large unsupported panel subject to stress due to flexing. Just my inexperienced opinion, hope I'm wrong, but it's time for the experts to chime in on this one.
 

Woodonglass

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Ok, now it's all making a bit more sense. You must have hit that concrete thing a pretty goo blow. Do you see any noticeable deflection in the hull? The inside and outside areas all need to be ground back a lot more than what they currently are. you want at least 8-10 " all the way around the area. You then want to grind the glass towards the hole so it's feathered or tapered so the edge at the hole is almost razor sharp. This grinding is on both the inside AND the outside. This Grinding is very important and is what will ensure proper bonding of the new glass to the old. You will then use some heavy plastic and tape on the outside to seal it off. Then you'll do your first repairs on the inside. Since its on the strake it's a bit more challenging. I'd recommend using some slab foam to create a "form" that mimics the shape of the strake line and tape it to the outside so your inside repair will conform to that shape. It will take a bit of doing but the time you spend making that will really save you shaping the outside repair later. The fractured glass on the Bulkheads needs to be ground away as well so new tabbings can be applied .

The first layup on the strake repair should be 1.5 oz csm and should be about 2" larger than the existing hole. Once it starts to tack up in about an hour the first layer of 1708 goes on and it should be 2" larger than the 1st layer of CSM. In an hour put another layer of 1708 on that's 2" larger than the previous one. And finally an hour later put one more layer of 1708 on that's 3" larger than the previous one. If you're careful and Dab with a brush from the center out towards the edges you should be able to avoid air bubbles. The repair on the outside is a bit different CSM first, then a layer of 1708 then 2 layers of CSM Same dimensions as the inside however. You'll need some fairing material and gelcoat too.

Keep posting pics and we'll be here to help when and where you need it. This is NOT the easiest of repairs. Strakes are tricky but with patience and perseverance I think you can do an acceptable job. Sanding, Acetone Wash down,Good Resin, and Good application is the key.
 

500dollar744ti

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Ok, so this is interesting. It seems that most of the woven roving I'm trying to sand away has already delaminated from the hull. Maybe that's why the stuff flexed so much, and maybe that's why my original repair didn't work. On the original fix, if I was glassing to roving that had already delaminated from the hull, that would certainly be weak.

Here's some pics of the delamination. The roving that I've been picking away by getting under it with a screwdriver and prying up by hand is the same stuff I had sanded down and trusted my original repair to. :facepalm:
pOUEHVb.jpg

qmBvvDO.jpg

lA8aBN7.jpg

OR4WDTG.jpg

lDvis68.jpg
 

500dollar744ti

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Rick wanted to know about the bulkheads to get an idea of where I took the previous pics. I am looking down through the floor section I cut out in the left lower cabin area of my boat. Looking in, this is the bulkhead forward of the hole:
VhjYBd5.jpg


This is the bulkhead aft of the hole:
K9DqedA.jpg


This is the view looking at the stringer that runs forward to aft that the two bulkheads are butted against. I think that's the proper terminology. :lol:
ChKExqn.jpg


In the compartment just forward of this section I'm repairing, is where I had my spare starter and tool box stored. These items are quite heavy and in my early boating ignorance I didn't realize they were sitting directly on the hull, bouncing around. :facepalm: See now the other side, which I may add has no issues, not even a hint of cracking, is where I store my extra dock lines.. hmm maybe that's why it's still okay.

So, now my plan is this.. I want to remove all the bad roving down to the bare wood where there's wood and down to the bare hull elsewhere. Then I want to make my repair to the hole in the strake, inside and out since it would have to be laid before tabbing the bulkhead which will overlap. Once the hole in the strake is repaired, I want to re-glass all the areas where the woven roving used to be. I'm not quite sure how to do that but I was thinking of filleting the areas where the wood meets the hull, then laying up multiple layers of CSM and 1708 to make new tabbing from the hull to the bulkheads and the one part of the stringer.

Does this make any sense?
 

Rickmerrill

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Wow! So do we think the original hit caused all that damage or did using the boat after the damage caused more damage or was there a defective layup and the hit just happened to be in that area and made things worst? Or will we ever know? Hard to believe from the outside damage it did all that! Well, at least it's all fixable. I'm learning a lot on this one.
 

kjsAZ

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That looks really bad, sorry! These stringers have completely separated from teh hull and should be seated back with PB and then glassed in again. That's LOTS of work. My fear is that you won't be able to fill everything underneath well enough short of taking the stringers completely out.

It almost looks like the manufacturer did cut some corners and the impact then fractured the glass...
 
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Rickmerrill

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Thanks 500 for adding those pictures, helps a lot. Looks like that aft bulkhead wasn't even tabbed in. I know Wood says the CSM on the back of 1708 is sufficient for lay ups so you may not need any CSM but he does say, when installing stringers, if the area is rough to put a layer of CSM on first. Not sure which way he will go in this one. But after the first layer you get a lot more strength from the 1708 vs CSM. Make sure to wet out that bare wood and let it start to tack before laying any glass on it, learned that the hard way, and it would be better if you can lay the glass on it fairly soon after it tacks up so you get a nice chemical bond. After all this I don't think you'll have anymore problems with this fix. Oh, and you want to mix up some PB and put a fillet in that area between bulkhead/stringer and the hull to get that glass to lay down on the inside corner.
 

500dollar744ti

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Wow! So do we think the original hit caused all that damage or did using the boat after the damage caused more damage or was there a defective layup and the hit just happened to be in that area and made things worst? Or will we ever know? Hard to believe from the outside damage it did all that! Well, at least it's all fixable. I'm learning a lot on this one.

Good question, I don't think we'll ever know, it's probably a combination of those things. I know after I'm done with this compartment it's going to be a glassed in fortress. :lol:

That looks really bad, sorry! These stringers have completely separated from teh hull and should be seated back with PB and then glassed in again. That's LOTS of work. My fear is that you won't be able to fill everything underneath well enough short of taking the stringers completely out.

It almost looks like the manufacturer did cut some corners and the impact then fractured the glass...

Yeah, that's my fear too. I don't know if the manufacturer cut corners or if the guy laying the roving ran out of good resin that day or forgot to mix it right or what. It does seem to be an issue concentrated to this area of the boat.

Thanks 500 for adding those pictures, helps a lot. Looks like that aft bulkhead wasn't even tabbed in. I know Wood says the CSM on the back of 1708 is sufficient for lay ups so you may not need any CSM but he does say, when installing stringers, if the area is rough to put a layer of CSM on first. Not sure which way he will go in this one. But after the first layer you get a lot more strength from the 1708 vs CSM. Make sure to wet out that bare wood and let it start to tack before laying any glass on it, learned that the hard way, and it would be better if you can lay the glass on it fairly soon after it tacks up so you get a nice chemical bond. After all this I don't think you'll have anymore problems with this fix. Oh, and you want to mix up some PB and put a fillet in that area between bulkhead/stringer and the hull to get that glass to lay down on the inside corner.

The bulkhead aft was tabbed in, I had removed the tabbing, and sanded the wood and surrounding before taking the pictures. I thought I better get pics of it all before finishing removal.

I was thinking about doing the fillets, then tabbing with a narrow strip of 1708, then a wider strip, then even wider etc on the bulkheads and stringer.

I'm waiting for woodonglass to respond with his opinion as well.
 

Rickmerrill

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You did a good job cleaning up the wood, fooled me. Are you going to be able to tab those bulkheads in from both sides? I guess you've seen Wood's Decks, Stringers and Transoms write up, if not link below.
 

500dollar744ti

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I can tab the aft bulkhead only on the one side, I can tab the forward bulkhead on both sides, as well as that stringer. In order to get to the other side of the aft bulkhead, I would have to tear the hull down to the point I might as well do an entire rebuild. I plan to keep this boat for a long time so whenever the transom and floors start rotting, I'll be doing a complete rebuild and that's when the aft bulkhead would get done.

I'll probably get to a full restoration within the next couple years. (maybe sooner if this repair fails for any reason. :lol:)
 
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500dollar744ti

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It rained yesterday but it's nice today. I'm going to try and finish the sanding this afternoon and lay my first layer of CSM over the hole to get me started. Then I will probably do another CSM and then a strip of 1708. Probably let that cure and see how it looks tomorrow.

I have my fingers crossed that the repair will be effective even though I don't have much space between the back of the hole and the bulkhead aft of that. :pray:
 

Rickmerrill

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I've been thinking about not being able to tab that bulkhead from both sides it just worries me but given the circumstances I might come to the same conclusion you have. In your first repair I remember thinking you might have skimped on the first layer of CSM, make sure at least the center of it is the full thickness of the Matt. After that I'd want several layers of 1708 on the inside like Wood said. It's the better way to build up strength and bulk. Your hull is about 1/4" (.250") so if you get .040 from the CSM and .050 from the 1708 you have an idea of how many layers you'll need minimum. Keep the pictures coming and good luck working in a confined area.
 

500dollar744ti

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It looks like some of the old roving was saturated alright but the layer of CSM under it was never wetted out fully and that's why this stuff was coming apart.
IMAG0567_zps952e0b0b.jpg


It's awkward working down in the cabin and I swear it's like 115 degrees even with a big fan running on high.
IMAG0565_zps87cd2115.jpg


I finished the sanding and removal of all the bad roving..
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I put some packing tape on the outer part of the hull to help shape the first layer of CSM..
IMAG0566_zpsc9c18d80.jpg


I cleaned up the area with acetone and glassed up the first layer of CSM..
IMAG0572_zpsa436d3cb.jpg


I'm hoping to start with this small layer of CSM, build another layer of CSM over it, then some 1708. I will be working on it tomorrow, trying to get more layers set up on the inside and maybe further sanding on the outside.
 
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