Investigating hull rot, 350lb list

Discussion in 'Boatbuilding' started by Businessjeff, May 3, 2019.

  1. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    Ill make this as brief as i can.

    I have a 1993 formula 31pc. Its listing port side high about 4-5 inches. Adding 55 gallons of fuel to port tank leveled the boat. So i have around 350 lbs of weight sitting somewhere starboard side.

    Id love to hope its soaked foam and that i can open up cavities, remove foam, repair. Meaning, not touch or worry its structual or wood soaked.

    Its my theory that theres far more volume of chamber space (foam) than overall wood (stringers, members..) so finding my rouge 350lbs is more likely the foam.

    In your experience, how heavy can rotten stringer possibly be? Mind you this is looking at starboard side only.

    Am i accurate in thinking, 1 cubic foot of wood stringer can only hold 1 cubic foot of water if 100% saturated?
     
  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Welcome to the forum.

    Chasing down hidden water weight is challenging. Second only to fixing an intermittent electrical issue.

    Good luck.

    A cubic foot of stringer can never hold a cubic foot of water. The wall thickness alone occupies some space. You have to use the internal dimensions not the external. Unless the wood was 100% rotted away, it's fibers would displace some water.
     
  3. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    Well yah. I was just trying to confirm my point that soaked member would not be as much weight as soaked foam chambers. Seeing that im looking for a large ammount of rogue weight here and hoping its not sitting in members
     
  4. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    Has anyone ever removed a 300 lb stringer? Mine is about 6’ long 10” high probably 1-1.25” core
     
  5. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    I have done some structural repairs on my 2 Formula's . . . a 330SS & a 242SS. One of my forum buddies have done similar work on a Formula 27 PC. Your thought process is correct, much of the water weight will be in the foam or any chambers that can fill. The results from water saturation may be the more concerning issue rather than the weight itself.

    I assume the stringer(s) that you are talking about are the ones leading forward from the main bulkhead, which is in front of the engines. I would not count on those stringers being fully encased in fiberglass. It is more likely that they are relying on the wood itself for much of the strength. So, if the wood is compromised, so is the boat.

    Formula foams in the fuel tanks on most of their boats. The PC's typically have foam underneath the tank(s), but not as much on the sides. So, water could be sitting in the foam under the tanks. Sort of depends on exactly where they are in the structure . . . presumably under or along side the aft berth. The larger foam filled compartments will be outside of the main stringers, where much of the engine compartment 'stuff' is mounted.

    The main bulkhead is typically the weakpoint on the boats, as it can be the first thing to absorb water. Then it spreads to the stringers going both forward and backward of the bulkhead.

    Have you taken a detailed look at the 'guts' of the boat? Removed the aft berth? etc.? Got any pictures to post?
     
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  6. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    The tanks are not foamed in. They sit on a shelf from hull to outer stringers, transom to aft bulkhead. On the heavy side i had already opened said shelf removed soaked foam. This shelf is rather large, id guess 80-90 lbs of water and foam removed.

    Either way, that cavity has been cleared. Beyond bulkhead into aft cabin there is more potential to discover yes.
     
  7. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    Are you fixing this yourself or planning on having it done?

    Post pics when you can
     
  8. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    Just depends. Glass work is a new animal entirely for me. I do everything myself normally but really dont have the desire to learn and tackle this. I do have pics but will have to post them tomorrow.
     
  9. tpenfield
    Joined: Dec 2016
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    Location: Cape Cod, MA

    tpenfield Senior Member

    Usually the issues are about 3X what they originally appear to be, once you open everything up. So, if you are not up to doing glass work, then maybe start searching out some shops in your area.

    On my 330SS, I originally thought that I would be replacing the main bulkhead. Once it was removed, I realized that the fuel tank had separated from the foam and was collecting water in the foam :eek:.

    So, out came the fuel tank. With the fuel tank out, I could see that the moisture had gone forward beyond the fuel tank bay into a storage area under the helm :eek::rolleyes: . The floor and ribs under the storage area were soaked. I cut those out to replace it all. :mad:

    The moisture finally stopped at the cuddy cabin bulkhead . . . about 12 feet away from the original problem :rolleyes:
     
  10. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    I have a very good glass guy in my area. So good you cant afford or ever book him!

    My tank is not foamed in but was leaking. Shelf it was on was soft and full of soak foam and gas. Opened shelf up fixed it all. All the structural member looked good. I added some more tabbing to be sure.

    Thats what i can handle. My question is, how to determine whats structual or not? Example, a boxed shelf made for aft cabin seats? Its all glassed but is it part of member support by that point?
     
  11. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    Heres in the floor of my aft cabin. Pulled out the table post, free hole. All foamed in, pretty soaked.

     
  12. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    4D739570-8B9B-4675-96D5-619F6F78E7C5.jpeg 414B496F-4568-4FED-A9A4-6A358BDEC656.jpeg 4259268E-7CEF-4539-BBC2-490F5F3A3343.jpeg Ok finally got my pics working. Heres the shelf in bilge i tore out and redid.

    This is my question. The top ply of this shelf bonds the outer engine stringer with the hull. Would this then be structual? Giving the stringer more support?
     
  13. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    AD705F5E-1525-4973-A5FA-6D30D6B7C674.jpeg BE086E0F-BADF-4A6B-B593-B3F663BCD942.jpeg

    How do the members look? A bit swollen but i reinforced the tabbing to the hull and called it good. Added weep holes and epoxy coated them so now any water can drain into bilge properly.
     
  14. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    5F76C016-7E0F-40DE-BBCD-ABA6C635E8FA.jpeg 53A1FDBC-0B0A-4277-8D1B-F89D80B9DBFC.jpeg

    This was just test fitting but i fully glassed these sheets before i screwed and tabbed them in.

    Im aware of the grades of ply. More of my structual question here. I just used home depot ply for this shelf. Would this be a wrong material choice? Should it of been a lvl type and paid attention to the orientation of grain within the laminate layers?

    Or is that only important when building stringers or members?
     
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  15. Businessjeff
    Joined: May 2019
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    Location: Mi

    Businessjeff Junior Member

    Anyway... so the tabbing sepetrated along the aft cabin bulkhead and along hullside. Additionally screw holes allowed water intrusion down into shelf top and foam. Also also, leaking fuel tank added gas into the soak. Im now finding/guessing more water intrusion on other side of bulkhead.

    Overall in this whole repair, the 3 cavities i removed roughly 80-90 lobs of soaked foam and 25 lbs of soaked shelf rot. This is a large area compared to whats left on this side of the boat aft the bulkhead.. keep in mind im hunting down 300-350lbs.

    Is this just foam or bad soaked members... i hope just foam
     
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