Missing In Action Finally Gets his Floor Installed

Discussion in 'Wooden Boat Building and Restoration' started by missinginaction, May 9, 2008.

  1. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Well, It's been a while, but I finally built and installed the aft cabin floor on my 1973 Silverton restoration. I've seen so many questions asked about stringer replacement (that's next) that I thought I'd take a few minutes and post this along with a few photos. The floor came out very nice and much stronger than the original. It's a similar process to a stringer replacement so here goes....

    Here's what I did:

    1. Cut out the old stringer with a long sawsall blade bent so that the blade cuts out the floor and rides along the bottom inside of the hull. PAR or Alan White gave me this tip last year, but I cannot remember which one, I'm sure they both know about this.

    2. Use a straight sawzall blade to cut the floor away from the stringers. Then use an angle grinder to smooth out the area and ensure a good bond for the epoxy. I went out about 8" from the old floor with the grinder. I also wiped the area down with acetone just before I installed the new floor.

    3. Trace out the shape of the old floor you just cut out on your new material. I used Owens Corning Formular 250 extruded polyurethane foam 2" thick and then added a 5" beam across the top of the fom to have something solid to attach the cabin sole stringers to. More about that later.

    4. Laminate up a 2" beam to accept the sole stringers. These sole stringers are similar to floor joists in a house and in this design support the cabin sole. I used Araucoply for the laminated beam (total 19 plys across the beam) and entombed the entire beam in three coats of System Three epoxy (initial coating was clear coat and the two following coats were general purpose resin).

    5. Coat the entire new floor with a piece of 6 oz fiberglass cloth (for handling, the foam is fragile and I didn't want to damage it getting it into the boat) and seal up all edges with a couple coats of resin.

    6. Test fit the new floor in the boat. Trim the floor as necessary to get it to the proper height and 90 degrees to the stringers. Recoat where you trim with more resin. I scribed lines on the inside of the hull as a guide.

    Now the fun part.........

    7. Installing the floor was a 7 hour process that went in two stages. I used 1708 biaxle stitch mat for the fiberglass laminate. 4 plys. I looked at the floor and decided that the easiest way to approach the laminating was to look at the floor in 5 sections. If you look at the picture you'll see two stringers either side if the keel line. I decided to cut my glass to fit into each of these 5 "bays" separately and then tab the floor into the stringers using long narrow strips of stitch mat. Since the deadrise is a constant 20 degrees in this area the fiberglass will get cut into a trapazoidal shape and be draped over the floor and tabbed into the hull bottom. If this doesn't make sense to you (It didn't to me at first) it helps to stand over the floor and imagine what the cloth will look like in each bay.

    Once I had the shape in mind and measurements taken I cut out 4 pieces of cloth for each bay. Do a good job on the first piece of cloth and you can use it as a template for the next three and save some time.

    I didn't know how much resin to mix up so I started with about 12 ounces. This was not enough. So I doubled my resin to 24 ounces and found that to be fairly close to what I' d need. Since the glass cloth pieces were larger in the center sections I needed a double batch there so I mixed up two 24 ounce pots. I used a medium speed hardener for the epoxy to give myself some time. If you do this I'd suggest using medium too!

    I laid out heavy cardboard on the back deck and used a foam roller to wet out the cloth. It takes a few munutes to let the epoxy soak in. Once wet, I laid the glass over the top of the floor and proceeded to stick it down with an aluminum laminating roller. Even though the cloth was wet, it didn't want to stick very well and seemed a bit dry. So I mixed up more resin and poured some over the top edge of the floor and worked the resin into the glass with the foam roller and aluminum roller. (this is why I liked the luxury of some time with the medium hardener). This did the trick as now the cloth was resin rich and smooth.

    I proceeded with the next lamination in a similar manner and then moved onto to the next 'bay". After about 10 minutes I went back to the first lamination I'd done and inspected. As it was just starting to cure it developed a couple of large bubbles under the cloth. I worked these out easily with the aluminum roller and that was all the attention needed.

    I worked along in this manner making two laminations in each bay and then left for the evening. The following morning I started over and made the final two laminations finishing the floor. After the cure it is extremely strong and lighter than the original.

    One thing I didn't mention. Before I started the laminations I epoxied triangular foam into the base of the floor, along the side edges. This is important so that the fiberglass cloth makes a smooth turn from the vertical to the horizontal with no hard edges. I also have to cut out a limber hole at the keel. This is easy to do with a Dremel Tool. In the photo there was still some tabbing to do.

    This is the longest post I've ever done. I hope it helps someone who might be thinking of doing a similar project.

    Photo 1 shows the hull after the old floor was removed, 2= what I used as a former for the new floor, 3= top beam for the floor, 4= roughing in the new floor, 4= new floor installed.

    Regards,

    MIA
     

    Attached Files:

    Last edited: May 10, 2008
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