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Nacra 5.2 Possible Structural Issues  Bottom

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  • One advantage of that location is it is not very visible when you're done. That support stringer provides longitudinal strength and rigidity to the hull, and there is a lot of stress in that area. It might be easiest to pull the front deck to carry the repair forward rather than cut a port which could weaken the bow. Lots of pictures of the deck structure in the archives.

    --
    Tom
    NACRA 5.7 (1984 Sail 181)
    Pennsylvania
    --
  • You are cooking with gas now. Since you need to work the repair on both sides of the bulkhead you need to decide how you want to gain more access. First breath a couple of times, then decide if you want to add an inspection port forward of the main beam and work through it, or to slip off the forward deck and have lots of room to work. There are lots of good and recent posts and images in the gallery on the process of taking the deck off looks like. The work can be done either way. You may also want to invert the hull so that gravity helps with your layup work. That seems a little awkward, but wet glass wants to move.

    The existing glass tube was formed around cardboard, so foam pipe insulation or something similar would provide the form you need to glass over. Then an idea I just had may be of interest or an option to consider and that is to use clear packing tape stretched over your newly cut hole on the outside of the hull. Then working from the inside layup a very light 6 oz. over that tape and let it cure. Once that has cured you can remove the tape and you will have something firm enough to let you do the rest of your glass work followed by fairing. Don't worry if this first layup is a little irregular, you can sand out any bulges and just keep reducing the size of any holes that might open up.

    The final glass work around my cradles (which only had cracking issues) probably extends about 4" beyond the cradle, the fairing in my case extends 8" or more. With my shiny new paint if you are looking straight down the length of the hull you can see this fairing. I would expect that your final repair with fairing would extend in the 10"+ range. It depends on which side of the hull you do most of your reinforcement. I decided that working on the outside was massively easier and that I could live with the fairing.

    I think I would also suggest that the repair be done using epoxy. Bond strength is really important in these kinds of repairs and there is lots of good information about this kind of repair using epoxy.

    You are on your way, making that first cut was the hardest part. Save that little bit of stainless plate that tried to save your hull from the hole you are now dealing with. You are going to want to reinstall it.

    --
    dg
    NACRA 5.2 #400
    This End Up
    Original owner since 1975
    --
  • dmgbear55Save that little bit of stainless plate that tried to save your hull from the hole you are now dealing with. You are going to want to reinstall it.


    I did - I took it straight into the shop and tapped it back to flat, then set it aside for reassembly.

    So I stopped by West Marine this afternoon with the family to pick up the items I needed for the fiberglass repair. I was completely unprepared for both the variety of items offered, and the price of all those items. I quickly grew overwhelmed since I was under a time crunch and left without having bought anything. I'd appreciate getting some help from you guys making sure I get everything I need. I seriously thought I could get this repair done for $100 in materials. That's looking very unlikely now.

    Here's what I think I need:

    Fiberglass Repair
    West System 105 Epoxy Resin ($48)
    West System 206 Slow Hardener ($25)
    West System 300 Mini Pump Set ($17) optional
    West Marine Fiberglass Cloth 1 sq. yd. ($20) right? Can I use the Mat, or do I need Cloth for all this? Is a square yard enough?
    2 pack Resin Spreaders ($6)
    Resin Roller ($25)
    West System 800 Epoxy Roller Covers ($9)

    In addition, I'll need a grinding wheel or two for my angle grinder, and I assume some grades of sandpaper for my orbital sander - what grades should I get? Also a quart of Acetone, which was $20 or so.

    Gel Coat-
    West Marine Finish Gel Coat ($65)
    Cheapo HF HVLP spray gun ($16)
    ... and more sandpaper.

    First question is whether that covers everything, or if there are steps and items I'm overlooking.

    Second question, just the numbers specifically mentioned above have me up to $250. Is that just the cost of doing fiberglass and what I should expect to pay?

    --
    Erik
    1979 Nacra 5.2
    Central Virginia
    --
  • I have done much better getting materials at Discount Marine http://www.discountmarinesupplies.com/. Same stuff, but much lower prices. You need fairing compound which can be simply glass micro fiber mixed with epoxy. Look for West Systems 403 micro fiber http://www.discountmarine…em_403_Microfibers.html. For fairing a project, I like a long flat sanding board. Only $8.00 at Harbor Freight http://www.harborfreight.…dy-hand-sander-1727.html

    To build up the repair, you need woven mat for strength and rigidity. Chopped strand is okay for outer layers and finishes reasonably well, but this should do most of the repair with good Epoxy http://www.discountmarine…erglass_Cloth_Packs.html

    You can skip the sprayer for gel coat. It would be easier to roll on, then blend with 120-800 progressive grit paper and finish with polishing compound.

    --
    Tom
    NACRA 5.7 (1984 Sail 181)
    Pennsylvania
    --
  • OK, you're on a student budget, I get it. Lets shave $110 off the cost.
    First, forget the entire gel-cote business, G-cote is much more skilled than the structural repair. Get a $6 rattle can of "plastic paint", get on the water, decide in a year or three if you want to G-cote.
    Second, forget the rollers & sleeves. They are unbeatable for large flat areas, useless when trying to work small inside corners. Go to your local Dollarama & pick up 2 or 3 packs of paintbrushes, they are packaged about 5 to a pack. Don't bother washing in acetone, use once, throw away. You can push the fabric tightly into the crevices/corners by "tapping" with the end of the bristles.
    Pumps are useful, but not required. Save some flat bottomed yogurt containers, or anything similar. Use measuring spoons to add water,(1/2 oz increments) to the container, then mark it with a sharpie, where the resin should end, & where the level is once you add hardener. I keep a bunch of these in my "fibreglass box", & have only used borrowed pumps twice. You will also need a few popsicle sticks for stirring. Also a dozen pairs of throwaway latex or nitrile mechanics gloves.
    Make sure you have a dust mask & eye protection while sanding/grinding. Borrowing a Dremel tool is VERY helpful for working small spaces inside the hull.
    You will need the acetone, but not very much,(borrow a few oz from a friend). You want to wipe down the area before your first layer, to remove 40 years of grunge that might inhibit adhesion.
    You will need a can of microfibres, mix enough in til the epoxy starts to thicken.

    For almost all the repairs I have done, expoxy can be spread via the paintbrush.
    As Tom pointed out, James town distributors, or others have the cloth pretty cheap. Cloth is the biggest pain for first time epoxy work. It looks easy, but as soon as it gets wetted it wants to start coming apart as you maneuver it. A good deal of this repair can be done using cloth tape, 6" or even 8" pieces. The tape has a woven edge & won't come apart. If you have a shop that does glass work, they will probably sell you a couple of feet. I haven't bought tape in years, a local builder just cuts & sells me whatever I need.
    Remove the hull, & knock together some sort of cradle to hold the hull in a position that lets you work comfortably, & makes gravity your friend for keeping epoxy in place.
    You want to have mentally run through ALL the steps & all the pieces pre-cut & dry fitted BEFORE YOU EVEN THINK ABOUT mixing epoxy. This is the biggest mistake first timers make. Dry run your job 3 times, then mix & go for the real fix. I cannot stress how helpful it is to have a buddy standing by. Inevitably, as soon as you get your hands sticky, you will need something else. Your buddy can cut another piece of cloth, adhesive tape, take photos etc. Time is not a factor with slow hardener.
    Don't forget to taper the edges of your hole, inside & outside, so the patch can progressively build outwards.
    It would have been easier to put Saran Wrap on the hull & make a mold before you cut that big hole, especially as there are complex curves in the area but that's now academic.
    I would make a plug that conforms to the hull shape. Saran Wrap the piece you cut out, paint a thin layer of epoxy, then tap 2 layers,(orientated 45* to each other) of cloth into the resin. When still green,(not totally hardened, still somewhat pliable), peel off the plug & trim to shape with a razor knife or scissors. This plug can now be held in place by Saran Wrap or taping some clear plastic around the outside of the hull, in a position that conforms to the hull shape. Try to leave it a little bit "low", so you have depth to add a final layer of cloth that extends past the patch, into where you beveled the outside of the hull. This is an extra step, but in the end is WAY less work than trying to sand a rough patch into a hull conforming shape. You will inevitably end up sanding through multiple layers of cloth. Once this plug has cured in place, rotate the hull & finish with layers inside.
    Paint the area lightly with thickened epoxy, then add 3 layers of precut patch. Wet the patch with as little epoxy as possible, it will look translucent if wet, white if dry. First time it's a given you will have to much resin. It is easy to place another layer of dry cloth on top, then gently tap it into the resin with the bristle ends.
    Depending on temp/humidity, it can easily be overnight for the resin to really harden.
    You won't need much sandpaper, cured resin cuts pretty quickly. A few sheets of automotive 100 & 200 grit, then 1 of 400.
    Think each step through, allow more time than you think it will take & you will be on the water.
    Alternatively, call Dan Berger, he has ads in classified here & is close to you. See if he has an extra hull, or knows of one...you'd get it for the price of the fix, or less...bolt it on and go!



    Edited by Edchris177 on Apr 23, 2017 - 11:37 AM.

    --
    Hobie 18 Magnum
    Dart 15
    Mystere 6.0XL Sold Was a handful solo
    Nacra 5.7
    Nacra 5.0
    Bombardier Invitation (Now officially DEAD)
    Various other Dock cluttering WaterCrap
    --
  • QuoteIMHO - Pumps are useful, but not required. Save some flat bottomed yogurt containers, or anything similar.

    if using the west system ... save yourself time and hastle and get the pumps - for $18 beats measuring and preping yogurt cups.

    also - when using west system epoxy - its ok to use plastic containers... but if your using gel-coat... you have to be sure your container wont melt from the chemicals (same with your brush and stirrers) PS never use glass either - this stuff gets hot, esp in a small container



    Edited by MN3 on Apr 24, 2017 - 10:13 AM.
  • Going back to EdChris's idea of a mold, you could take a 1-2 layer mold of the other hull, and it should be close in shape to match the compound curves on the one being repaired. You would be swapping front to back, but it is going to be close enough. This assumes you fasten your mold over the outside of the hull and layup from the inside. You will need a release agent/wax on the mold.

    BTW mask everything you don't want coated with epoxy. This stuff runs all over.

    --
    Tom
    NACRA 5.7 (1984 Sail 181)
    Pennsylvania
    --
  • Quoteif using the west system ... save yourself time and hastle and get the pumps - for $18 beats measuring and preping yogurt cups.

    I agree, $18 is what we spill in beer on a good weekend. However, the OP is a starving student, & concerned about $250 vs his initial thinking of $100, therefore $18 might better be spent elsewhere. West specifically mentions you should calibrate the pumps, especially if they have not been used for a while, so you are measuring once anyways.
    I have some shallow plastic measuring cups, sort of like miniature frying pans, that I have etched markings in. After use I just peel the remaining film of resin out & re-use. Had them for years, they allow me to mix down to 1/4oz batches very accurately. resin is expensive, I try not to waste any.

    --
    Hobie 18 Magnum
    Dart 15
    Mystere 6.0XL Sold Was a handful solo
    Nacra 5.7
    Nacra 5.0
    Bombardier Invitation (Now officially DEAD)
    Various other Dock cluttering WaterCrap
    --
  • QuoteI agree, $18 is what we spill in beer on a good weekend

    that's why i drink rum... to precious to spill :)

    Quote$18 might better be spent elsewhere.

    I totally get it, saving everywhere is important
    i just personally feel the hassle of measuring, with the possibility of getting it wrong, or spilling coupled with the need to open and close containers to mix another batch....

    all good advice - ymmv



    Edited by MN3 on Apr 24, 2017 - 11:27 AM.
  • Wow, that is turning into a major repair--but you can do it. I would go to West Marine and get some of their 2 part epoxy and some woven glass sheets. I would pick up some filler/bonding agent, too. I don't think you would need more than a quart of the epoxy. West sells pumps for the epoxy and hardener that give you the precise measurements and makes it very easy to get the ratio correct. You can always add a little more hardener to make it kick off faster.

    There is a good article on fiberglass vacuum bagging work: http://www.westsystem.com/ss/assets/HowTo-Publications/Vacuum-Bagging-Techniques.pdf

    I don't think you would need to vacuum bag, but there is a lot of good info on general fiberglass work in that pdf.

    You are going to have to cut an access port in the deck in front of the beam to get to the back of the fix in front of the beam. I believe the deck piece is only to make the boat water tight, I don't think it is structural. If I'm wrong and it is structural--and you then wouldn't want to install an inspection port, you can pry the deck off by getting a sharp chisel under it and working your way around. When you are done, you can clean it up and use 3M 5300 to glue it back down. Someone check me on that--it might be 5200. I have found that an excellent bonding agent is that filler/bonder that West sells. I'll get you that item number tonight.

    So, set yourself up with some glass sheets that you can glue in behind the cut out area. You will need one for the reinforcement running down the hull, one for the top including the cradle and one for the side of the hull. You will probably need more for the other inside places as well.

    What you are doing is building a backing so you can build up glass on the outside. You can do most of it through the opening, but you will end up needing to get at the back of it once you have closed everything off.

    See if you can make a mold of the curved surfaces and cover that mold with wax paper or saran wrap. lay down sheets of glass and add epoxy between layers. I'm thinking 3 layers would be sufficient. Then, sand the glass mold with 40-60 grit and sand the inside of the hull. Clean thoroughly with Acetone. Then, mix up a thick mixture of epoxy and that bonding stuff. use that as a glue to glue the mold to the inside of the hull. When it has cured, you can then start building up glass on the outside and make sure that you taper the glass on the hull around your cutout so that it has something to bind to. I would add one more layer of glass on the back of your backing plate (if you can get to it) to make sure that the edges will adhere to the inside of the hull.

    You should do that for all the surfaces you need to build up.

    I'm working on a similar issue, I'll be posting my progress. My issue is a crack in the hull, I don't have all the contours you do..

    If you want help on it, you can drag it down to my house and we can get you started!
  • I'm sure this counts as thread-necro, but I though I'd give you all an update since for the first time in two and a half years, I've made some progress. I got to go sailing in the Chesapeake Bay on Friday with some friends on a 40' coastal cruiser, and it made me realize I needed to just suck it up and get to work on this Nacra.

    So, yesterday I took a chisel and hammer and removed the front deck of the hull, using the method I read about in here. It took about 15 minutes, but it came right up. I now have access to all three sides of the repair area. Next step is to grind the glass. I've heard this is misery, but I may tackle it tomorrow, with a respirator, goggles, and a Tyvek bunny suit.

    https://i.imgur.com/UYd7M8P.jpg
    https://i.imgur.com/rlnAxYK.jpg
    https://i.imgur.com/0yqdxLD.jpg
    https://i.imgur.com/0LHuh0U.jpg

    --
    Erik
    1979 Nacra 5.2
    Central Virginia
    --
  • Nice, glad to see this and I could totally relate. I went thru this hmmmm not 2 years ago in my 5.2 restoration. Not exactly what you have but rather the cracks around the bolts up top and had cracked down to bottom of well.

    Once I got going, had some tunes going, had a plan, it took me a day or two, mostly to wait in between fiber applications for res to dry. Go slow, start coarse, make it stronger than original, think multiple fiber applications, keep going till it looks as good as you'd like. You might discover exactly how much you love this boat in this part of the job.

    Once demo was done and the edges were clean, I started inside with a big flat piece of 1 inch closed cell foam that I had laying around from a shipment or something. Figured out how to jam it up against the inside part of the damage and prop there.

    I disassembled and took foam back to work bench, add a layer of wax paper over the foam, cut the first piece of cloth and lay on wax paper, mix first batch of res, soak edges of cloth on the wax paper (I found large areas are easier to cross if I don't put heavy res in the middle of the cloth that is just hanging out in space), pick whole piece of foam/wax/cloth/res and re-position and prop in the inside of the hull. Should go quick as you'd already worked out how to prop it in there... so prop it in there.

    For me this was the hardest park and also because this had to be done thru a port hole. Everything was easier and down hill after that. One can also put a string thru the foam/wax/cloth/res layers with a stick or something on the inside so when installing, pulling on the string outside of the hull will help hold the mass there while the other hand (in the port hole) grabs the prop and jams it in there.

    For the tube bed, I followed 'This Side Up' video/pics and filled in with globs of filler, then a layer of wax paper, then laid the tube into the bed as would be final assembly. Once dried that tube has such good contact with the hull I've often thought about doing all the others like that. I'm guessing the stresses are better distributed in that area because of the perfect fit.

    In any case looking forward to more posts!

    --
    Piatro

    Nacra 5.2 ("HazCat" 1976)
    Nacra 5.5 ("Crazy Horse" 1989)

    Colorado
    --
  • Well, I went for it. I bought a Tyvek suit and some grinding wheels and ground down the hull.

    First step was to finish taking the boat apart. I removed the rear beam and the remaining rigging, then laid each hull on its side to make the grinding easier.

    https://i.imgur.com/HZJGoV8.jpg?1

    Then I ground down all the surfaces I could get to. I used a file as well to get to some of the areas that the grinder wouldn't fit. Here's the end results:

    https://i.imgur.com/iqDg5gR.jpg?1

    https://i.imgur.com/UyklrQ5.jpg?1

    The plan from here is to lay a layer on the internal beam stringer to get that started, then do a single thick layer on the main side of the hull. Then I'll flip over the hull and add structural layers inside the hull to build back the bulkhead, stringer, beam pocket, and side of the hull. By the time I'm done there, all I'll do is add a couple more layers to the exterior to even the hull back out.

    A couple questions now that I'm at this point:

    1. How does the plan sound?

    2. What is the dark grey and white layer on the hull? Is that all gelcoat?

    3. Can I overlay mat onto the gelcoat layer, or do I need to keep all the new mat restricted to the areas of exposed fiberglass?

    --
    Erik
    1979 Nacra 5.2
    Central Virginia
    --
  • Edited post, its difficult to see exactly what is going on here. On further review, I think your plan is fine. If possible, I would try to manipulate the stringer cloth to form the backing for the skin repair. Fix that and the bulkhead at the same time, then do all of the skin in one shot. No reason to lay glass over the gel.



    Edited by bacho on Nov 04, 2019 - 10:53 AM.

    --
    Greenville SC

    Offering sails and other go fast parts for A-class catamarans
    --
  • loquinho... do a single thick layer on the main side of the hull.?


    Plan looks sound, but try not to use thick layers. Strength is in multiple thin layers. You want just enough resin to wet the fabric, you should be able to clearly see the structure of the cloth when the resin cures.
    When replacing the decks, thicken some resin with microfibres, (available from West, they come on a tennis ball sized can), make it about ketchup consistency.
    This will add strength, & prevent the resin from running out, (slow hardener is slow), resulting in weak bond, & possible leaks. It may be helpful to cover the deck with a plastic sheet & weigh it down with small sandbags to ensure the lid conforms to the hull.
    Also, you want that beam pocket to conform exactly to the beam. A sloppy fit is weak. You could cut off a section from one of the wrecked beams, wrap in Saran Wrap, & secure in the pocket. Your patch, (started from the inside), will then conform perfectly.



    Edited by Edchris177 on Nov 05, 2019 - 08:02 AM.

    --
    Hobie 18 Magnum
    Dart 15
    Mystere 6.0XL Sold Was a handful solo
    Nacra 5.7
    Nacra 5.0
    Bombardier Invitation (Now officially DEAD)
    Various other Dock cluttering WaterCrap
    --
  • While you are tearing things apart, I would pull the dolphin striker apart and replace the bolts. I had a P-19 that the dolphin striker bolts sheared (3 5/16" hex head bolts). With the age of the boat, I would suggest pulling every bolt and check it's condition; especially ones that are metal-metal.

    --
    Scott

    Prindle 18-2 Mod "FrankenKitty"
    Tornado Classic "Fast Furniture"
    Prindle 19 "Mr. Wiggly" - gone
    Nacra 5.8 "De ja vu"
    Nacra 5.0
    Nacra 5.8
    Tornadoes (Reg White)
    --
  • Well, I am NOT very good at fiberglass work. But I gave it a shot.

    I got the boat apart and the hull on its side to put down the first layer, which was a thick fiberglass mat to be a backbone for the other layers.

    https://i.imgur.com/Xc0IpCJ.jpg?1

    https://i.imgur.com/3dUfTtf.jpg

    Once that layer had cured enough, I realized I needed to get easier access to the inside, so I suspended the hull from some ratchet straps so I could easily rotate it around at working height.

    https://i.imgur.com/nxPSFi4.jpg

    That was the smartest idea of the day. The hull turned so easily in the strap cradles.

    I then layered up the outside, and a little on the inside. Working on the inside of the hull was so much more difficult than I expected. Add to that, I worked with the resin too long, and the final layer I was trying to add inside the hull got so sticky it started pulling the other layers apart when I tried to get my brush back out. I did the best I could, but it really turned out trash on the inside.

    https://i.imgur.com/YdNnzTk.jpg

    The outside, however, seems to have turned out pretty good.

    https://i.imgur.com/Lgey3O3.jpg?1

    This weekend I'm going to sand it down, and see how much thickness I'm really working with. I might try to do one more session with fiberglass before calling the structural work done.

    --
    Erik
    1979 Nacra 5.2
    Central Virginia
    --
  • Duplicate post, sorry.



    Edited by loquinho on Nov 14, 2019 - 09:47 AM.
  • Resin does not form a good physical bond to old fiberglass and is subject to easily peeling off. I'd consider doing the outside repair using west system epoxy and glass applied to a clean surface. A $20 pack of G-Flex would be adequate.
  • traphappyResin does not form a good physical bond to old fiberglass and is subject to easily peeling off. I'd consider doing the outside repair using west system epoxy and glass applied to a clean surface. A $20 pack of G-Flex would be adequate.


    I sanded down the gelcoat to raw fiberglass and used layers of fiberglass mat and totalboat two-part epoxy resin.

    --
    Erik
    1979 Nacra 5.2
    Central Virginia
    --

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