Doral 164 with rotten, well um, everything!

Discussion in 'Fiberglass and Composite Boat Building' started by aktmboyd, Jul 14, 2017 at 12:37 AM.

  1. aktmboyd
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    aktmboyd Senior Member

    So my boat is a rotten old mid 80's built heap of rubbish. But it is all I have at the moment and I have some good bits that go on it, 2000 200 Hp Johnrude, Bobs hydraulic jack plate, Uflex hydro steering. The hull needs stringers, transom and sole replaced which are all rotted and probably were well on their way to being rotten a couple years after the boat was built due to the lack of fully sealing any of the wood inside the hull. Doing the work will not be a problem but I have run into a problem that some of you might be able to help me with.

    The stringers of this hull were never fully encapsulated with goo and were only covered with CSM in 3 broken sections along the center stringers 14' length, so this gave me 4 fairly rigid sections with rotten sections of wood in between. This was also mirrored on the outer 2 stringers giving the hull an accordion effect every time the hull was moved in any sort of way. This was also accentuated by the sole not being glued to the tops of the stringers but rather pinned with steel nails which by the way disintegrated many moons ago. But that probably wouldn't have helped much either seeing how the bottom side of the sole was never sealed any how.

    So how does one go about truing a hull when there is no mold and all the structure inside is collapsed and the hull has been twisted and warped every time the boat moved for probably the last 20 years, or should I even be concerned about it.

    One idea I had to get as close as possible is to drill down threw the strakes at maybe 4' intervals and pass 4" X 1/4" bolts back up threw, put the nuts on and then level from the end of the bolt inside the hull. This should give fairly accurate mirrored measurements from the outside of the hull. but this would also mean about 6 holes in the strakes. But that isn't a big deal seeing how there was already 33 holes drilled in the transom by who know how many different owners. :confused:

    Any Ideas?
     

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  2. Mr Efficiency
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    Mr Efficiency Senior Member

    What's with the breaks in the stringers ? Have you pulled some bulkheads out of there ? So far as getting the alignment trued up, how important that might be could depend on what sort of speeds you travel at, if relatively sedate cruise speeds of around 20- 25 knots are the norm, there is probably some leeway before you get any adverse traits. You could use a spirit level, long straight edge etc to take any twist out of the hull, by strategically supporting it, and having a consistent level across-ways the hull, measured from corresponding points along each side, at all points, whether the chine or sheerline. Once you've done that, you can use some stringlines to look for any irregularities in the bottom, like hollows, that would not be desirable, and not likely the way it was designed.
     
  3. PAR
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    PAR Yacht Designer/Builder

    These were considered "disposable" boats when built, knowing they'd be hammered hard, put away wet and pretty much used up after a few years. This is one reason they seem to have been built so poorly. Another reason was this era is known in the industry as the "dark times" when manufactures had a glut of product and couldn't sell them at half price. This forced most to cut back on materials, quality, resin types, etc., with the end result being a boat that suffered from all sorts of issues in short order. Lastly in this regard, competitive racing usually meant the boat was obsolete in just a few years, so you tossed it, in favor of a newer model, so this planned obsolescence was intentional.

    When it comes to fixing one of these, you're correct, it'll have some distortions, likely from a number of reasons. If you're experienced with these types of repairs, a lot of itching, but manageable. If you're not very experienced, you'd be best advised to find a sound hull and swap out the engine and equipment.

    Your idea of trying to "square up" the strakes is an option, though you could also do this with well aligned athwart supports too. A few holes will be mandatory, if only to "suck 'er down" to a reasonable shape. The real problem is the laminate, which is thin and fairly easily damaged (delaminated). You see, 'glass has a memory and will want to retain it's shape, once cured. This said, if the hull is distorted over time (years), like on a poorly fitted trailer (for example) it can also forget it's memory and learn to accept the new shape (distortion). You can force it back and with enough reinforcement (or time) it'll adopt the new (original) shape again. This isn't as easy as it might sound, as you don't really know when to stop forcing her into the new shape.

    On your boat the back 1/2 will be mostly straight lines, which makes it fairly easy to see where it's wrong (out of shape). Can you provide some pictures of the boat's exterior profile and underwater areas? There's nothing special or valuable about these puppies, so you'd need a good reason to put the effort and money into this restoration. Even if not a full up resto, the work and costs can be hard to justify, unless you have an itching fetish. I find a few dozen of this type of boat each year and 99% of them will fuel the local landfill incinerator before too long.
     
  4. aktmboyd
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    aktmboyd Senior Member

    Those breaks were where 1"X2" sole supports were once located, they were completely rotted on disassembly. These supports were placed (I believe) prior to the stringers being tabbed to the hull to support the sole plywood and what the manufacturer did was just cut the CSM to fit between them and left large sections of bare wood under them running down the stringer to the hull. 20-25 knots is well below my cruise speed with a 200hp motor with 225hp carbs on it, once on plane I can throttle back to 2000rpm and I am doing 20 mph. I do have to say the boat handled well at those speeds though, but alas I want more.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Problems are much more likely to emerge at 40 mph than 20 mph, for sure, which makes reasonably close preservation of hull shape important. If, as PAR says, the lay-up is modest, that becomes more difficult. If the boat was designed with straight vee sections, as many were, it also becomes easier to create a cradle to support the shape accurately. The apex of the vee, and the chine , will pretty well stay true when internal supports are removed, what is in between less so.
     
  6. aktmboyd
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    aktmboyd Senior Member

    Paul, you always have given sound, straight forward no BS advice to any of the questions I have asked here. I appreciate it.
    I am all to aware of the black days of boat building, and I am a sucker for punishment(I LOVE THE ITCHY'S), I only wish I could have said that with a straight face. "Disposable" boat I kind of choked on my sip of coffee from laughing while reading that, and if I was living back in the south I would have a long time ago carted this heap to the dump and looked for something better. But with my current location boats are few and far between, so I have to make this one better.

    The hull at this time is off the trailer and is sitting on it's keel on a straight 12' 8X8 as a strong back with supports running to the chine and everything is starting to be leveled off of this. I started by leveling off of the inside of the outermost strakes at the transom but as I said it quickly turned turtle and was quite a bit out of level mid way down the hull. With twisting I can bring it near level but what happens when I go too far and try to get it perfect, it starts to lift the opposite side at the transom throwing it out of level and from there I start to chase my tail or I should say chase what is level. I might have to weight the transom from outside the hull and try again. This whole chasing of the level brought in the idea of wondering if I am even working with a consistent level surface on the inside of the hull on opposite strakes due to laminate inconsistencies, so this is where I am thinking of ideas on how to true this hull from the outside with out being able to run a level from side to side under the hull. I might just try again and call it good enough for now, now that the hull has been support by pushing up on the low side for the last 2 weeks in the sun. It looks like it has settled a bit back near level but this is only by looking at the gaps to the bracing at the chine and not by a level. I will attempt again this weekend and see. I just wish our Arctic Sun up here was a little warmer, for some assistance on this matter. Whew that was a mouth full, I hope I worded it in a way you can understand me and I will shut up now.:)
     
  7. aktmboyd
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    aktmboyd Senior Member

    Yah! problems like quartering another boats wake at 40 and not knowing what the Hell the boat was going to do, even with hydro steering it was a white knuckle ride. It felt like I was road racing a 1970's Lincoln Continental with blown shocks and bald tires in the rain at 80 mph. And all the time the sole slapping between my feet and the tops of the stringers. So I could just imagine the flex the hull was under. The hull has a fairly deep vee to it and is built from a pretty heavy woven roving, the bottom will be bulked up once the new stringers and 1700 are laid down with epoxy. I have also kicked around the idea of adding 2 more stringers down the empty strakes that are located between the keel stringer and the outermost chine stringers. That would stiffen the hull up considerably and not add that much more weight and only give a distance of I think 8-10" between each stringer location so the tabbing of the stringers would overlap each other and build a good amount of thickness on the bottom of the hull.
     
  8. aktmboyd
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    aktmboyd Senior Member

    The last pic I posted shows the two inner most strakes that I am considering on adding stringers to. They would be 3/4" like the outer ones, the middle is 1 1/2". All stringers will be built from 3/4" plywood accept for the center which will be a double lam 3/4"ply all scarfed and all with ARK Composites epoxy, It's what I have left from previous and there is 3 gallons sitting on the shelf waiting to be used, I will need to order more though.

    Maybe some can point me in the right direction. The laminate I am thinking should be as follows
    - stringers bedded in a PB, with 3/4-1" radius PB joints
    - 8" 1700 double bias tape for tabbing 2-3 layers
    - 8" 1700 bi-axial tape for a cap on the stringer If I can find a uni tape maybe that instead
    - transom will be built with 2ply 3/4"plywood with a layer of 13 oz uni between hull and plywood and 3 layers of 1700 biax on the inside.
    -sole will be 5/8 ply with 10 oz cloth all round, set in a PB on top of the stringer and tabbed to the hull at the chine with a PB and 1700 double bias tape.

    I am thinking this will be more then adequate seeing how the factory used sub par full of knot lumber for the stringers and only 1 layer of 1 1/2 oz CSM (everywhere) broken into pieces with absolutely no radius's or for that fact no complete tabbing to the hull and transom. There are holes and gaps where no glass was ever applied and this heap lasted 30+ years.

    P.S. there will be NO FOAM
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    I sometimes wonder if a better solution to timber or ply stringers, isn't a sandwich construct, using a thickish structural (PVC) foam, and the existing hull bottom as your outer skin. Your inner skin need only be half as thick. Just add some sandwich panel bulkheads to support whatever you will be walking on, screwed down ply that can be easily replaced, e.g. No stringers. And no risk of deterioration of the main structure. You get a lot of advantages, but the execution is a little more involved.
     
  10. aktmboyd
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    aktmboyd Senior Member

    Sorry, I should have clarified the foam thing. I meant no flotation foam is going under the floor. However, I would love to be able to build with the new non-wood materials but due to my location that's out. So wood it is, sealed with the goo. Probably will outlast me when done.

    If I had the availability to the materials it would be cool to do a Coosa transom/stringers and then a composite floor as well.
    I don't think the boat would warrant it, it will never be something special that people would pay large amounts of money for but for my own satisfaction it would be interesting to do.
     
    Last edited: Jul 15, 2017 at 6:03 PM
  11. PAR
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    PAR Yacht Designer/Builder

    Once you start pricing the options to plywood and solid timber, you'll see why they still use wood. Foam core is an option, though rife with a new series of issues and the goo factor goes way up too. Given the boat type, I'd just put wood back in, knowing I'd be sealing it much better than the original manufacture and get at least another 20 years out of her.
     
  12. aktmboyd
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    aktmboyd Senior Member

    My location here is what is the deciding factor to this all, that is why it will be done with wood. It even dictated what resin I am using. Yes I will pay a premium at the store for epoxy but it comes with the benefit of not having a dangerous goods price attached to it to fly it into our location,unlike polyester and/or vinyl ester, with the DG added to the sub performance resins it brings the price of them extremely comparable to epoxy. Now if you take into account the lesser amount of materials and cheaper glass needed to build with epoxy, for me, due to shipping and the DG, polyester resin ends up at the same price as epoxy and vinyl ester resin is actually more expensive. So comparing this all and knowing the strength benefit and better sealing that epoxy has over the other 2 resins, and also taking into account there is no marine grade ply available so I have to use exterior grade plywood for the structures. In the end epoxy is the clear and cheaper winner for my situation.

    Now I full well realize some people are dead set against using anything other than the best of marine grade ply and lumber in their boats and that is fine. But all I have to say is, when this boat was built someone should have told Doral that, and also that there would be no way that their boat would last 30 years using a PT 2x3 nailed with iron nails to an untreated 2x10 full of very large knots (exactly like the lumber I built houses with) for the keel stringer, 3/4 pine secondary stringers(also with a bunch of knots) and an exterior plywood transom, all done with vinylester resin and CSM. Granted as PAR said these where built as throw away boats and yes everything is totally rotten now, but hey, it lasted this long right. Needless to say it was an eyeopener on disassembly. Don't get me wrong if I was able to go to the hardware store and buy some marine ply I would, but now I feel totally confident doing this repair with exterior ply and a much superior resin and glass system than vinylester and 1 layer of CSM. Which by the way held up to my unorthodox driving and a motor that is making almost 250hp, I really don't know how but it did. All I know is on a hard throttle start from a stand still the hull and 3 POB almost clears the water surface and the transom was still attached to the boat.

    Any input on my laminate sched, should I use more of anything anywhere. Or is it workable.
     
  13. aktmboyd
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    aktmboyd Senior Member

    So $1000 just spent on materials, so that gives me about 2 weeks until it is delivered to get the hull in shape and ready to go. I will need to order more glass for the sole but I will have to do that latter, shipping weight was already at almost 200lbs so freight charges are already going to be hard to swallow.
     
  14. aktmboyd
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    aktmboyd Senior Member

    I am thinking on using the 10oz cloth I have for the top of the sole and 6oz for the under side of it, does that sound OK or should I just wrap the whole sole in 10oz.
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    The sole does not need glass on the underside, unless it is a bit marginal for strength. You could seal it with a coat of epoxy, even a couple of coats of suitable paint. Or do what was done back in the day....probably left as-is.
     
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