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Water seeping in

1982 383 ,after the previous owner snacked a coral reef, she said it hit hard, so I bought the boat on the hard inspected the damage repaired a (what looked to be a hair line crack) at the top of the keel where it forums to the hull in the very front( it's real thick in that area ) after I ground out the crack to soild glass and glassed it back in and and repaired the bottom of the keel, splashed her and found a small but steady flow of water coming in just aft of the other crack.anyway
Does any one know of a problem with 383 cracking in that area or was it just the hard grounding, I'm pulling her out next week for repairs I'm going to grind it thru and splash it .Any other ideas thanks, its going to get itchy. Captain chaz⛵☠⚓



This is definitely solvable; you have the right idea. Unfortunately, this is one of those projects that is going to require some inventive testing/diagnostics or you will be stuck repeating the cycle of doing a bunch of fiberglass (and finish) work before splashing repeatedly. It will continue to seep at a non-zero rate and will slowly worsen until you get all of the microchannels patched shut. If you don’t find the ‘ends’ of all of the cracks, the seeping will continue, and slowly worsen, until it quickly worsens.

These boats are made of a fiber reinforced polyester matrix, which doesn’t have the tensile strength of modern materials - epoxies, etc - we are used to today. The hull layup was definitely not designed to accommodate a major deformation. A hard run aground that flexes the hull enough will cause internal ply delaminations that extend outward from the visible crack, internally along the ply boundaries. The water is finding these areas of internal delamination to flow along. Based on the leaks you describe, the flex was bad enough that these cracks made it all the way through the laminate.

Here are some images I found on google that should help visualize what is going on inside the layup in the affected area:

Basic point loaded delamination:

Buckling/compressive delamination:

Simplified example of internal delamination around a hole. Local surface geometry will affect the shape that the delamination takes:

You will need to make a judgement call based on the info you have. How extensively you ‘address the issue’ given what you know about the incident should be informed by two main factors: how bad you think the grounding was, and what you plan to do with the boat. In order to frame the question properly, it may be helpful to think of these internal de-laminations as “future crack propagation points” because that’s what they are. You say you heard it was bad. If you plan to go offshore, what is the peace-of-mind worth to you?

This may sound dramatic but to solve it properly, you will need to “scarf” the laminate until you have found the extent of the damage. In your case, the scarf will need to extend basically all the way through to the internal leak location:

Conventionally, you scarf back 1/2” to 1” per ply....it adds up. If you can reach from the inside, a double scarf will help reduce the affected surface area on the outside of the hull:

Finally, you lay a few continuous pieces of new glass up the slope of the scarf on all sides and fill the void with successive glass layups until fair:489DBA0A-B0B9-41D7-A689-A7CF80BE106B.png

If this is biting off more than you can chew, consider doing some leak testing on the hard so you can better judge the extent of the damage. The obvious thing would be to leak test from inside. You could plug up the drain under the mast step and fill the forward area with a hose. As the leak reverses, that will tell you where the leak is getting in from outside.

Leak testing from outside would also be informative, but it will be fussier. You’ll need to tape a big bag over the affected area with some heavy duty waterproof tape and fill the bag with water. For bonus points, tint the water with some food coloring to make chasing the internal leaks much easier.

This is all a question of time and patience more than money. May be worth just paying the yard’s fiberglass guy to go nuts for a weekend.
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Thanks for the info, I'm pulling it out Monday I can reach the inside, I can see the leak but I won't be able to see exactly where it is until I grind some of the glass off of the inside, I didn't want to start grinding until it's on the hard,I'm planning on grinding all the way through tapering and build back up with 1708 and epoxy, you think that is the best


Thanks for the info, I'm pulling it out Monday I can reach the inside, I can see the leak but I won't be able to see exactly where it is until I grind some of the glass off of the inside, I didn't want to start grinding until it's on the hard,I'm planning on grinding all the way through tapering and build back up with 1708 and epoxy, you think that is the best
I am not a structural engineer - I just build the things they tell me to - so that question is unfortunately beyond my ability to answer accurately as far as your specific repair is concerned. You should take the following with a dose of skepticality. Definitely get other opinions.

That being said, I am assuming you mean the +-45 degree bias with the stranded mat backing? Most of the vendors that pop up when you google 1708 fiberglass, even some reputable ones, advertise it as a wind blade and marine structural glass. That is probably fine but on the sites that list specifications, it is labeled as an “E-glass”, not an “S-glass”.

Strictly speaking, E-Glass is a dielectric material meant for things like electrical boxes, radar domes, and fairing panels. S-glass is structural-grade. It’s stiffer, and the coatings on the glass are tailored for structural bonding. I would ask a pro but if it were my boat I’d use structural grade glass. Hope that helps.
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Just to understand the difference is e class and s class both biaxal material or is s class ( csm) cut stranded mat

No, that is not quite correct. You are focusing on the weave of the material instead of the type of material that the weave is made of. It’s like a wool knit vs a cotton knit. The patterns may be similar but the materials aren’t equivalent in performance.

So the individual glass fibers themselves come in types. E-glass is the oldest type, chemically suited for electrical applications. S-glass is for for structural applications. Either type can be woven into a fabric (e.g . biaxial fabric), sprayed into a stranded mat, or made into a combination of types together. This is the case with 1708 fabric - it is composed of a +-45 weave on top of a piece of stranded mat

According to the labeling, this 1708 fabric you are planning to use - to fix perhaps the strongest part of the hull - uses E glass, which is not a structural material in the strict sense of the definition.

You choice of fabric pattern is correct. A +-45 degree biaxial weave is designed for for ease of installation with this kind of irregular geometry.

Your choice of material is not optimal for a such an important structural zone. A better choice would be a similarly weaved material that is clearly labeled as S-glass
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Who carries that type of s - glass and what would be the brand names I have never seen s- glass on any video like( boat works ) they talk of csm,cloth,biaxal, roving never hear any one talk about s- glass or e- glass or any data on it or maybe I'm not seeing the right video


Bottom line: Worst come to worst just use the 1708. It is probably fine.

Else try the composites store, cstsales.com, in Tehachapi, CA. They have a website that has the info you are seeking. You can call and tell them you are repairing a boat hull in a location that needs proper structural fabric and that you think you need a “biaxial S glass that is something between 15-20 OSY”. They will know what you are talking about and can help choose. They do a lot of volume and have good fabric sales so hopefully you’ll get a decent deal to boot.

It’s no surprise that companies don’t focus on this, because for most purposes e-glass is sufficient. For structural applications that need to be signed-off by an engineer, you bet that they are going to make sure it’s S glass, not E glass. I only mention it because you are talking about repairing the hull in a critical location.

CSM, cloth(like biaxial or triaxial), roving, etc are just the pattern the glass was made into. As you’ve learned, the weave pattern is important to the process of layup because certain ones do different things better than other ones. This is what most vendors are “selling” to you.

The type of glass, by contrast, has little effect on the layup process, but a large effect on the performance and lifetime of the part.
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Thanks for that info I've been doing glass work on all my on stuff for years and my brother does his repairs on his drag boat's but never had any problems and this is the first time I have heard about e and s glass but thanks for telling me the difference I'm always one to appreciate learning something new, also never did any glass work on a sailboat hull the has had a hard grounding thanks again, Charlie ⛵