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Replacing stringers in a fiberglass boat

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  • Replacing stringers in a fiberglass boat

    Howdy folks.
    I posted a question about fixing a seized MerCruiser 140 a little while ago, so you might recognize that i've got quite a project going on. I did away with fixing that motor and bought one that is also older, but runs like a champ. I really could listen to it run all night long.

    Anyway, my boat is a Marquis V170 Stingray. When I bought it, I knew the motor was bad, and knew the front mount needed to be replaced. When I got down there to replace it, I saw that there was a lot of rotten wood around it. A few inspections and Sawzal cuts later, I've realized that the stringers need to be replaced; front to back. The whole 9 yards. This doesn't bother me that much since I basically only paid for the trailer, and only paid $550 for the motor that is going to go in it, and I was in need of a good project anyway. Today I've started cutting out the floor, and as I go I will probably keep asking questions here but I've got some right off the bat before I really get started.

    There are 3 stringers, all of which appear to go all the way to the front. I can see that I will have to take out the fuel tank to get up there to replace them. So here are my questions about that...
    Am I going to need to cut parts of the "dash" apart in order to get that out, or am I missing something? While it would suck to have to rebuild that Im sure it can be done. I can see where the only part I would have to cut out is about a foot and a half up from the floor, right above the step that goes up on to the front of the bow (this is not an open bow boat, but the window does swing open for you to stand up there).

    I have been reading the guide to replacing stringers in the West System book, and theres something I dont fully understand that I feel is very important...

    "When laying out the layers of fabric, do not allow the tabbing edges to end at the same place. For stress reduction, step the edges of the fabric to create a tapered edge."

    I'm pretty new to this so im not sure what the "tabbing edges" are. From what I understand they have to do with the bulkheads and how they're attached to the hull, but this is talking about the fiberglass...

    So, from what I understand, the process is fairly straight forward, but please correct me if I am wrong or missing something.

    Once all areas are sanded and cleaned appropriately...

    - Cut the wood to the appropriate length and shape/size, and epoxy them into the correct place and make sure to smooth off the epoxy that squeezes out the edges to a rounded edge.
    - Lay out your fabric, using as many layers as needed to reach the original thickness with each successive layer slightly smaller than the last, ending about 2 inches from each side of the stringer.
    - Wet all bonding surfaces with the mixture.
    - Lay on the first layer of fabric, and wet it down. Continue laying on the fabric pieces, making sure that each layer gets saturated.
    Let it cure.
    Pretty close?

    I've been watching some videos, and im seeing guys only glassing about half way up the stringer and using plywood. From what I understand about this job, it is using solid boards, and glassing over the entire board isnt it? At least, thats what I am cutting out...maybe I dont have to do that?

    The only other question I have is what is the purpose for the expanding foam in the hull? I will be sure to replace it, im just curious.

    I know that this process can be pretty difficult and long, but I'm determined to do it my self. Its really just a project for me, and since the boating season is pretty much over up here I'm in no hurry.
    Last edited by Mithories3980; September 21st, 2017, 08:49 PM.

  • #2
    Hi mitho, please post some pics if you can. You could upload them to imagur then make a direct link here so your pics will show as a post instead of an attachment. I'll try to answer some of your questions when I get home from work. mean while the pros here love pics it helps them help you better, and there are alot of nice guys here who know there stuff.
    86 Sea Ray Restoration


    • #3
      woodonglass has an exellent illustration of tabbing, search his name and it should come up
      86 Sea Ray Restoration


      • #4
        I'll tell you how I learned, and he has an EXCELLENT youtube channel about fiberglass, stringers, everything you need to know.. friscoboater Look him up on youtube.. he has the best (as far as I have seen) videos that you can follow along and learn everything.


        • #5
          There are hundreds of threads here on iboats that will answer all of your questions, so start reading and it will help a great deal.


          • #6
            Use the ole... S S S...skim, scan, study. Suck it all in and it will begin to make sense. You can doit!
            WElcome aboard!
            Most times I'm wrong, Most times I stand corrected..But...Sometimes I'm right.
            1983 SportCraft Deep V OSFF 222 Cuddy Rehab


            • #7

              There are tons of threads here on restorations that you can skim through, as stated. Those might be more helpful seeing some real-world situations rather than the textbook style of the West System or other references.

              The photobucket image sharing restrictions make some of the threads less informative, but hopefully you will get plenty of background info. Most folks do not cut the console, but rather suspend it temporarily above the floor.
              Best regards, Ted . . . . Cape Cod, MA

              Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
              Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
              Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

              My Boating Web Pages: http://www.tpenfield.com


              • #8

                like TP said .... you can temporarily suspend with whatever is handy
                86 Sea Ray Restoration


                • #9

                  this may be of some help...
                  86 Sea Ray Restoration


                  • #10
                    here's the complete link by
                    Woodonglass ;
                    1961 Lonestar Flamingo - SPLASHED...Kinda!!
                    Fabricating Decks, Stringers, and Transoms
                    Paint Your Boat with Tractor Paint...Say What!!!

                    Most times I'm wrong, Most times I stand corrected..But...Sometimes I'm right.
                    1983 SportCraft Deep V OSFF 222 Cuddy Rehab


                    • #11
                      I used the stringer revised method without the first layer of CSM because my Douglas fir stringers were very smooth and sanded well. I love 1708, it's amazing stuff. I did however use polyester resins. Good luck and welcome. It takes a long time. I started working on mine in Feb of this year. I have new stringers, transom and deck. Rebuilt the engine and front mount. I'm in the process of testing all my wiring and hydraulics, shift cables, etc. Its a long process for sure.


                      • #12
                        On the note of the consol - unfortunately mine is a little different (of course)

                        It won't let me upload an attachment, but here's a link to a picture of it.


                        • #13
                          Here we go. Got the picture thing figured out. I needed 1 more post
                          Anyway here is my console and why I'm concerned about possibly cutting it. You can see the fuel tank through the hole on the left where I removed the plywood. What was there is exactly the same as what is under the dash on the right side, for reference.

                          I watched the video in Woodonglass's post, and it seemed to make the most sense to me. I assume - correct me if I'm wrong - that even though he used plywood, everything still applies since I am bonding wood to fiberglass?

                          The only thing I really see different I think you solved in your picture above Goldie. The PB under the stringer is what initially binds the stringer to the fiberglass, correct? That picture helped me out a lot as well. Thanks for that!
                          Click image for larger version

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                          • #14
                            Honestly it looks to me like you're going to have to decap the boat unless you can work around it. The cap is attached to the hull at the aluminum rub rail. Pop out the rubber insert, then drill out the rivets securing the two halves. Brace the hull to ensure it doesn't move and lose its shape as you lift off the cap. Once the cap is off you'll have easy access to the deck, stringers, and foam.
                            1986 Bayliner 16' Capri, 90 hp Johnson (sold)
                            1990 Chaparral 2000 SL Sport, 4.3L LX, Mercruiser Alpha I, Gen I

                            Link to Chaparral restoration- http://forums.iboats.com/forum/boat-repair-and-restoration/boat-restoration-building-and-hull-repair/10286641-chaparral-2000-sl-sport-floor-and-more


                            • #15
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                              Ah ok, I didn't realize that was a possibility. Im going to try getting it out that little hole but I dont think it will work. What do you suppose the best way to brace the hull is? Would wrapping a couple ratchet straps around the whole boat and leaving them just barely tight work?