24' Fiberform - Rotten Stringers/Transom

Discussion in 'Fiberglass and Composite Boat Building' started by Ehdrian, Apr 27, 2007.

  1. Ehdrian
    Joined: Apr 2007
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    Location: Nanaimo, BC, Canada

    Ehdrian Junior Member

    Hello Everyone,

    I have been reading this site for while now and have learned allot about stringers and transoms. I was wondering if I could get some tips for my specific issue as I am very new to boat repair. :confused:

    This boat is a 1977 24' Fiberform Cabin cruiser. It has four stringers running from the transom to the bow. The engines rest on the two center stringers. The stringers look like regular 2"x10" fir boards grafted at the top and bottom to fit he hull and furniture (galley/helm/motor mounts etc..). The twin engines are OMC 140's with OMC stringer 400 drives.

    Bad news: All of the stringers are rotten and there is rot in the transom.

    I would like to replace the stringers without removing the engines or the transom the first time through.

    Has anyone replaced stringers without removing the engines? On this type of boat? How?

    Can I just cap the end of the stringer with fiberglass (no wood touching wood) at the transom and replace the transom later so the new stringers are not affected by the transom repair.

    What should I use underneath the stringer to keep it from touching the bottom of the boat?

    Is there REALLY 'pour in' foam that could be used in place of a stringer?

    What are the best tools for cutting out thick fiberglass around a stringer? Right now I'm using a side grinder.

    Thank you very much to all those that help! :D

    -=//-\drian Thompson=-
     
  2. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Ouch.
    I see two ways of doing this. The first is to leave the motors in, glass over the rot, pretend nothing's wrong, and wait for an engine to slam right through the bottom of the hull when you come off a wave.
    The second is to take out the motors and drives, support the hull very well from outside, take out ALL the rotten and/or damaged wood, and rebuild them properly the way they should have been in the first place.
    The stringers really should be glassed to the transom, with some very solid bracing- there's a lot of stress here from those drives. Better to do it all at once.
    I'm afraid I'm not aware of any such product that will hold up to the job structurally, and especially in terms of water damage and deterioration.
    The angle grinder you're using is a popular one and it works. Fibreglass is bloody hard to cut and destroys high-grade saw blades like they were made of plastic.
     
  3. jimslade
    Joined: Aug 2005
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    Location: north Markham

    jimslade Senior Member

    Do it right, if you don't you will regret it!
     
  4. Ehdrian
    Joined: Apr 2007
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    Location: Nanaimo, BC, Canada

    Ehdrian Junior Member

    Ok. I have ripped out one mush stringer and exposed the other three which have 1/16" surface rot on one side and about a 1/4" rot on the other where it touched the bulkhead. The transom needs to be replaced, which I will do from the inside behind the engines.

    I have heard of a product called CPES which might be used to 're-thicken' the stringer where I cut away the 1/16 + 1/4 using sawdust or fiberglass dust as a filler. It is about a 3 1/2ft stretch where this needs to be done. The stringer is bone dry in the middle after a core sample.

    Has anyone fixed a hole 1/4 inch deep and three ft long with this stuff? It is recommended?

    Thanks!
     
  5. eyes
    Joined: May 2006
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    Location: Dominican Republic

    eyes Junior Member

    I agree with theses guys. Do it right, do it once.
    You can check this site, http://classicmako.com , they have a lot of projects going on and finished. Check on the process (pics) and come back post pics of your progres and ask the experts here to guide you trough the process.
    This is a awesome site with a lot of knowledge inside.
     
  6. eyes
    Joined: May 2006
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    Location: Dominican Republic

    eyes Junior Member

    You better think about getting some lifevests if you decide to just repair part of it.
     
  7. Ehdrian
    Joined: Apr 2007
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    Location: Nanaimo, BC, Canada

    Ehdrian Junior Member

    Ok. What should I use or the stringers?

    Cedar, Spruce, Douglas Fir or 2x Plywood laminated together?

    Should I use treated plywood or marine plywood for the transom, decks and bulkheads? Does the epoxy bond well with these? I would like to avoid marine plywood as it is expensive.

    EDIT: Is it OK to use a urethane layup or must I use epoxy? I don't know what the hull is made of.... If the hull is epoxy based, will this compromise the structure of the boat?

    Thanks!
     
  8. tja
    Joined: Sep 2004
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    Location: canton oh

    tja Senior Member

    Tja

    The hull is made with polyester resin. Stick with that. It's easier to work with and you won't like the cost of epoxy. For plywood i'd look into Greenwood products XL panels. Alot of good boat yards and manufacturers use it and will sell you what you need. It is guarenteed not to rot or delaminate for life or they will replace it including lobor. If it's worth doing it's worth doing right. Before you tear out too much sit down out make a plan and don't exspect it to go according to what time you think it should take. It will most likely two to three times longer. Good luck. Tom.
     
  9. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There isn't any wonder goo in a can (Smith's CPES included) that will restore rotted sections of wood. Small, well isolated pockets of rot can be "treated" with epoxy (CPES is epoxy), which will harden the general area, but larger voids, clearly deformed or rotted sections of wood must be removed and an affective repair made.

    Your repair area sounds like a pitch pocket that has rotted away or moisture got trapped under a delaminated sheathing or tabbing (most likely). This has reduced the load bearing ability of the stringer. You also very likely have rot in other, internal areas, that you haven't found or can't see. You already have one spent stringer and three others in need of repair. Do you want to perform a Dutchman kind of thing or would you prefer not to have to gut the boat again?

    Fiberform was one of the many low end boat builders, that went belly up during the glut years of the late 70's. They built as many as they could, as quickly and inexpensively as possible. This manufacturing method doesn't lead to long lived yachts, but does show a profit in the short term (until your company reputation takes a whipping). This was the common thinking and manufacturing practices of the era, in many of the low end production companies.

    Their boats were original pretty heavily laid up, but the chopper gun method, resin choices and poor craftsmanship caused repair, durability and resale value issues that killed the company. Fiberform ceased to be in 1982, when Bayliner bought all, part or it's inventory and equipment. It had been in trouble for several years prior. Bayliner refuses to discuss it's Fiberform purchase.

    Your boat is experiencing some of these corporate choices. Poor wet out under the stringers, less then satisfactory tabbing, insufficient wood saturation and sheathing to prevent moisture ingress, etc. have worked their magic and caused some problems.

    Now for the good news, your boat is repairable, though you have to ask yourself if it's worth the cost, effort and time. This is a tough decision, but a necessary one. Transom replacement, stringer and sole replacement, so far as I understand it now. That's a lot of work on an old war horse, like yours. Keys to answering this question are: do the engines run and have reasonably low hours, is the hull shell distorted from being on the trailer or having damaged structural pieces, good electrics, plumbing, electronics, etc. If you can tick off most on the list of things that make the boat work, then you have a good candidate. If the engines are blowing oil and smoke, the electrical looks like spaghetti, the plumbing isn't reliable, the electronics include a Loran and the transmissions grind going into reverse (when they do) then maybe you should salvage what you can and find another boat to work with.

    Polyester is the poorest choice for this repair. It's used in the industry (and being phased out, guess why) because it's cheaper then the better products. Vinylester is a better choice with epoxy being the best route to go, in these types of repairs. The polyester failed once already, you can use this resin if you want, but you probably have the same problems again in the future.

    There are many transom and stringer replacement threads, on this web sight and a search will offer much information, for you to cruise through.

    If you've decided to save this boat, then gut it. Remove the engines, transmissions, tanks, etc. Anything in the way, so you can get in there with some tools to cut back tabbing and bad stringers or transom. A reciprocating saw (my favorite), angle grinder, big buffer with cutting wheel, Roto-Zip, chisel and a jig saw are typical, heavy stock removal tools. Cut out the suspected areas of rot, insuring that you've gotten back into good wood, by a fair distance (at least a foot in each direction, with exception of the transom which should have all it's wood removed). Grind all exposed 'glass clean with 36 grit (or less), so you have a good "tooth" for the repair to bond to. Cut your repair pieces to fit snuggly, then give them three coats of unthickened resin, which will seal them when cured. Then bond the repairs into the boat, using plenty of fabric. Don't skimp on the protective coatings and fabrics, this is why the pieces failed in the first place.
     
  10. TerryKing
    Joined: Feb 2007
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    Location: Topsham, Vermont

    TerryKing On The Water SOON

    A little Info..

    For some info on treated plywood, adhesion etc., see:
    http://www.boatdesign.net/wiki/MaterialsForBoatbuilding#PRESERVING_WOOD_AGAINST_DETERIORATION
    (This Wiki section is incomplete, but some of the questions are addressed there).

    I would want treated wood in a transom; they always seem to get water intrusion sooner or later.. I used well-dried 3/4 inch Pressure-Treated plywood in a transom replacement 6 years ago, and everything bonded well.
     
  11. Ehdrian
    Joined: Apr 2007
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    Location: Nanaimo, BC, Canada

    Ehdrian Junior Member

    Thank you for the replies!

    Engines:
    Run smooth and quiet with no obvious mechanical issues.

    Outdrives:
    Needs new impellers and fluid/seal change - knuckles might need changing soon. Other than that they work as intended (forward and reverse). I need to replace the electric motor that lifts the port side outdrive. I'm going to hire a professional marine mechanic to remove them for the transom rebuild, but I'm going to refurbish the outdrives myself after the service manual comes in the mail.

    Electronics:
    All works, just need some re-connecting in places. The wires are bound and strung nicely from the helm to the starboard side engine. I need to put in a new hydraulic pump for one trim tab (already purchaced).

    Hull:
    No sags, needs to dry out, gel coat is chipped in places, but in excellent condition. There was a 'bulge' on the rear-left side beside the engine that was cut out and fixed already - because it was sitting on dry dock (this is how the rot was found). There are allot of leaks around the hatch and windows, but calking will fix that. I also need to build the engine covers (doghouse) from scratch.

    Plumbing:
    Fresh water pump works and I have a honeypot.

    I think all I have left to do is replace all the wooden parts. :D

    Here is what I am thinking so far, based on the feed back you all have nicely given me:

    Douglas Fir Stringers
    Exterior grade ply for the bulkheads and decking saturated in thin resin
    Marine grade for the transom
    Resin: I'll look into the Vinylester.

    I have a question about the fiberglass sheets though:

    There is a product that has woven roving and mat stiched together. Will this save me some build time, or am I better off just laminating these layers separatly? How thick should I build the lamination around he stringers?


    Thanks again!! :D
     
  12. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    I suspect this would be a pain in the *** to wet out properly. It's a lot easier to get several thin layers to wet out nicely without bubbles, than to get one really heavy layer to do the same. In my experience, two layers of 300 gsm cloth only takes about 20% more time than one layer of 600 gsm, and ends up with much less entrapped air bubbles. Plus the thinner layers handle corners and compound curves a lot better.

    It sounds like you're pretty confident that the mechanical and electrical gear is in reasonable working order, and you seem eager to take on a project. So I say go for it. Just be careful not to delude yourself into believing it will be easy, cheap, or quick. Oh, and if you insist on using poly/vinyl ester resins, buy yourself a damn good fume mask because both stink to high heaven. Epoxy's much more expensive but is a lot stronger, easier to use, and more durable, not to mention less nasty to work with.
     
  13. Ehdrian
    Joined: Apr 2007
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    Location: Nanaimo, BC, Canada

    Ehdrian Junior Member

    Alright! I'll post pictures as I go... if I can borrow a camera off of a friend.
     
  14. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Combi mat will not offer much for you if using epoxy, if using vinylester it can. The mat is a bulking material and adds very little strength to the laminate. It's added to act as a core of sorts, separating the inner and outer cloth layers, which provides a strong laminate. If you can do the laminate in one shot, then the combi material will be helpful, but if you will be putting layers on in succession, then it isn't much help. As a beginner, you're better off not trying to do too much at once, so skip the combi mat and stick with cloth.

    For amateur repairs like this I always recommend epoxy. As Matt mentioned, it is easier to work with, doesn't have the smell (still protect yourself, especially when in enclosed areas) and is a lot stronger. My reasoning for this is simple, back yard, shade tree repairs are not done in the best of conditions, using the proper skills, techniques or methods and epoxy can save your *** with it's extra strength and gap filling properties.

    Be cautious with pressure treated plywood (PT). It comes from the store soaking wet and these goos need 12% moisture content or less to be effective as an adhesive. I've used PT and currently have a small stack in a steel storage shed. It's stickered up with a box fan running all day long. It's about 140 degrees in the hot Florida sun inside the shed, so it'll dry pretty quickly, but it's been there a month and the moisture content is still too high to use. Well saturated (with epoxy) marine grade plywood will be a faster choice.

    You seem to have a good handle on things. Keep reading up on techniques, methods and materials in our archived, previous threads and post some pictures.

    Good Luck . . .
     

  15. eyes
    Joined: May 2006
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    Location: Dominican Republic

    eyes Junior Member

    Take the advice of the experienced people here.
    You can take a look at http://www.rotdoctor.com/glass/GLrotrepair.html for some graphics.
    I would replace all the stringers as i'm doing in a old boat i bought last year. Sealing and stiffing them with CPES is not recomended. Even if you remove the rotten part only moisture will be sealed again inside the wood and might rot in some time. Replace with new dry wood. Do the work one time.
    The tramsom is already explained by others.
     
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