some parts of Stringers Rotten

Discussion in 'Boat Design' started by Palmeroni, Aug 21, 2018.

  1. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member

    Hi,

    I have bought and old river cruiser 28 ft ISIS 700 built in Northern Ireland in 1999. she is in fairly bad nick but hull is perfect bar few marks. she was sunk due to filling up with water and no bilge pump. so the front was underwater for a while while the back stayed tied up to harbour.

    So after cleaning her up i found someone had started to drill holes in stringers to add epoxy but never done it. Some are slightly damaged and others the top 1/4 is rotten in places. my main worry is that i can stick a screw driver from below one of the stringer into the keel by the looks of it but it does not come out side the boat.

    so my questions are.

    1: for this hole into kell (i think) can i just inject resin into it?

    2: Some of the strings i will inject resin into soft spots for the damaged ones with small holes can i use P40 fibre glass filled and then fibreglass over it?

    3. Also Can i just run a new stringer alongside a stringer and fibreglass over the new and old to create an wider stringer?

    some images attached.

    Yellow lines/Arrows where i will fill

    red is where i want to add new string part to run along side old one

    blue is where i found small hole i can stick flat head screw driver in

    thanks in advance guys
     

    Attached Files:

  2. JamesG123
    Joined: Mar 2015
    Posts: 271
    Likes: 29, Points: 28, Legacy Rep: 10
    Location: Columbus, GA

    JamesG123 Senior Member

    Probably done for. You could patch it up to keep it going for a few more years, but even the areas that seem firm have been compromised by moisture and rot. You should probably replace all of the stringers. And I bet you will need to replace the hull bottom core as well if there are holes to it. You have to consider if the investment in time and money is worth it...
     
    Last edited: Aug 21, 2018
  3. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member

    Thanks for the reply James , the Hull seems 100% from outside and boat builders are saying it is one of the best types of hulls (I don't know the difference tbh) image of original mould attached. the old hole was back at angle for stringer underneath it.

    By adding stringers each side of the old ones and fiberglassing over all, will this help or am i wasting my time ?

    Thanks
     

    Attached Files:

  4. JamesG123
    Joined: Mar 2015
    Posts: 271
    Likes: 29, Points: 28, Legacy Rep: 10
    Location: Columbus, GA

    JamesG123 Senior Member

    You'll be better off cutting open all the old stringers and ripping out the old wood and replacing it with new making sure the bottom is intact and sealed and then glassing the whole thing over again.
     
  5. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member

    Thanks James , I will take your advice on this.

    And post updates on this thread
     
  6. Blueknarr
    Joined: Aug 2017
    Posts: 275
    Likes: 23, Points: 18
    Location: Colorado

    Blueknarr Senior Member

    Palmeroni,

    Welcome to the forum.

    Great to have someone seek advice before they make an awful mistake and rip everything out. Then call for help putting it back together.

    Some points to rember while replacing stringers

    +keep boat fully supported and squared so finished vessel is same shape as originally built without lumps or sags.
    +remove and replace one stringer at a time. Even half dead stringers provide more support than no stringer.
    +leave fiberglass from one side of stringer intact until core wood is tacked in, them remove second FG side wall and glass everything in. -greater structural retention through our process and preserves information of height and were other things attached to stringer.
    +re-glass to same strength as original
    +read the many threads on this forum which relate to stringers. You might not have to repeat the mistakes others have made.

    Good luck
    I'm looking forward to the progression updates
     
  7. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member

    thanks for the welcome Bluenarr,

    yes i am looking for the most advice possible as this boat project is 10x bigger than any boat i done before (normally small fishing boats or small sailing boats) and i want to do right once rather than many times badly :)

    I have been reading up on many threads on this forum and others so i think i roughly know where to start. and will keep posting my progress and updates / failings here

    re the fibreglass on the stringers can i just remove one side and keep the other and re glass over it to reinforce it?
     
  8. fallguy
    Joined: Dec 2016
    Posts: 1,048
    Likes: 35, Points: 48, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    To your original questions.

    No
    No
    No

    To your last question.

    No

    Often when stringers are rotten; so is transom. The repairs to the transom lead the project as stringers and/or engine ways are tabbed to the transom.

    There are no shortcuts. I have seen people try to save the old fillets at the stringer bottoms, but it seems silly to me. They basically save the stringer channel, but then the new stringer must be fitted to the groove.

    Replacing one stringer at a time is advisable. The other stringer canbe used to help get things level and help avoid the hull becoming misshapen during the repair. Other precautions are also taken if you replace the transom. And the transom repair is best done from the inside, imo.

    Verify transom integrity before proceeding.
     
  9. fallguy
    Joined: Dec 2016
    Posts: 1,048
    Likes: 35, Points: 48, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    If the hull is balsa cored; the boat might be fully rotted out.

    You can determine a rotted core by pushing and banging on the hull and watching for movement or what might appear to be like a liner, which is really delamination.

    Core rot is very painful to repair and not worth it if extensive.
     
  10. fallguy
    Joined: Dec 2016
    Posts: 1,048
    Likes: 35, Points: 48, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    The blue line is a transverse support or a floor. Those need to be replaced as well if they fail screwdriver test.

    I did not see the telltale signs of a core in the boat which is a 2x2 square pattern under the hull glass, but so much blackness hard to be sure.
     
  11. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member

    Hi Fallguy,

    thanks for the reply and advice.

    the ransform is the main runner in the middle yes? sorry if stupid question. if so this seems solid and i done a few test drills and timber is solid on top anyways (i did not drill all the way down)

    re core rot, the hull from outside seems strong and no weak signs as such.

    what is best way to determine if this is worth my time and money ? as in core rot and transom integrity

    thanks
     
  12. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member

    @fallguy

    "The blue line is a transverse support or a floor. Those need to be replaced as well if they fail screwdriver test."

    i drilled the top and side sections in places and checked it seems strong and dry the timber under the fibreglass , but in 1-2 spots i found little holder under it that goes down 3 inches

    I did not see the telltale signs of a core in the boat which is a 2x2 square pattern under the hull glass, but so much blackness hard to be sure.

    no there is no sign of 2x2 square pattern
     
  13. The Q
    Joined: Feb 2014
    Posts: 126
    Likes: 4, Points: 18, Legacy Rep: 21
    Location: Norfolk, UK

    The Q Senior Member

    It's doubtful a boat of that type in the UK would have had any "core" to the skin. As a river cruiser it's probably a heavy solid layup for the Bottom and transom, (as my 1969 27 footer is, though not the same make) although a jusdicuious test may be an idea.
     
  14. Palmeroni
    Joined: Aug 2018
    Posts: 24
    Likes: 1, Points: 3
    Location: Ireland

    Palmeroni Junior Member


    thanks for the reply The Q , yes this is a river boat but the original boat builder said the mold for them came from USA and was one of the best he had seen to be used on Shannon system in Ireland.

    re the jusdicuious test : I'm not 100% sure the best way to carry this out any pointers?
     

  15. JamesG123
    Joined: Mar 2015
    Posts: 271
    Likes: 29, Points: 28, Legacy Rep: 10
    Location: Columbus, GA

    JamesG123 Senior Member

    The transom is the "back" of the boat, or the aft most structural member. What he means is that boats will often get rot at the bottom joint where the transom meets the lower hull.

    By "judicious" he means NOT by drilling a hole thu the bottom of your boat. ;D
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.