23 Bertram/Carribian Stringers and transom

Discussion in 'Fiberglass and Composite Boat Building' started by crankit, Sep 5, 2012.

  1. crankit
    Joined: Oct 2007
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    Location: Aus

    crankit Junior Member

    A few months back I found rot in a floor on our family boat of 30 years. Initially I pulled out the rotted section and found that a stringer was also rotted. I then did a minor repair and replaced 1 stringer but later after cutting some more floors out I found the rot continued and before long I had all the floors out and transom skinned which revealed rot there. So now all wood is being replaced and I need a little help from the knowledgeable ones.

    Here are the specs of the boat

    Make/Model : Caribbean Crusader
    Year : 1979
    Length : 7.01m, 23ft
    Max Beam : 2.44m , 8ft
    Deadrise : 21 degrees
    Empty Hull Weight: 990kg, 2182.58lbs
    Weight on trailer : 2.4tonnes, 5291.09lbs
    Powerplant : 5.0lx 230hp mercruiser v8 Alpha 1 MR drive.
    Cruising speed: 23 knots
    Max Speed : 35knots

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    The original wood in this boat is Miranti and I’ve been unable to find miranti of the size I need around my area. The first stringer repair was done in hoop pine with ht9000 epoxy and cloth I bought from a local shop. Suffice it to say I’m not happy with the cloth of the first repair (It’s 3 layers of either 4oz or 6oz?) and it seems too thin. I’m considering buying a cloth on eBay, So first Question:

    1. Is this cloth: http://www.ebay.com.au/itm/FIBREGLA...?pt=AU_Building_Materials&hash=item3a7963a357 suitable or is it too thick, what should I use for the stringers and transom of this boat?


    2. The back fiberglass on the transom seems like it wasn’t wetted out properly during manufacture.Should I lay down a layer of fiberglass before installing the transom.
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    3. I’m also unsure what to do here
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    4. should the new stringers be tied to the transom? It doesn't look like they were originally but the rot could be fooling me.
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    I'd appreciate any other tips and suggestions.
     
  2. whitepointer23

    whitepointer23 Previous Member

    stringers are normally glassed to the transom. hoop pine should be okay, i have used an indonesian hardwood from bunnings which is rot proof but i forget what it was called. just about anything is better than meranti. lovely boat you have there, i like the crusaders layout.
     
  3. crankit
    Joined: Oct 2007
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    crankit Junior Member

    I was considering a hardwood but I thought the oils in some might effect bonding of the epoxy. That hoop pine I bought is treated as well but with a water based solution and not mineral based.

    Anyone have any opinions on the eBay link to the fiberglass cloth? If it's good I'd like to get it before it sells out. They say it was used on wind turbine blades so it would be good stuff, But maybe to thick at over 30 oz plus.
     
  4. whitepointer23

    whitepointer23 Previous Member

    there are lots of experts here that can guide you better than me, where are you par. if he doesn't see this just p.m par and he will give you good advice. another option might be full glass stringers and no wood, i think that is how most of the new boats are done. are you putting the cruising layout back in or setting it up more for fishing, you could incorporate a nice fish box and live well into the build.
     
  5. crankit
    Joined: Oct 2007
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    crankit Junior Member

    Whitepointer, I'm going to put back in the teak galley along with table and chairs that it originally had because we like to spend a couple of days up the coast every now and again. Talking about fish boxes! I have been considering joining the two mini boxes at the transom into 1 long box. Those little boxes are not really useful for very much and they've become a waste of space most of the time. At the moment though due to my inexperience I'm going to concentrate on just the transom and stringers for now and sort try of do this with small steps.
     
  6. crankit
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    crankit Junior Member

    I'm surprised I'm not getting more replies! Hope I didn't make that post longer and more complicated then it needs to be. Sometimes you hear people say there isn't enough info.

    I've done a whole lot of reading on which cloth I should use and there doesn't seem to be much of a consensus from whats on the net. My best guess is that 3 layers of 12oz biax for the stringers and the same for the transom but topped of with 6oz for a better finish for painting??
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Meranti is a good choice for your stringers, though pretty much anything can be used, if it's well tabbed.

    The amount of tabbing is application specific, so just try to bulk up the new tabbing, to be as thick as the old. 3 layers of 12 ounce biax sounds a bit light on your boat. This boat will experience considerable slamming loads, so error on the too much side of things.

    It's difficult to comment on the EBay supplies, as you just don't know what you're getting, so it's a crap shoot.

    Stringers don't have to be attached to the transom and commonly aren't. This permits the bottom to flex, without ripping out tabbing on the transom at the end of each stringer.

    2 coats of epoxy on all wooden surfaces that will be covered with fabric, three coats if not covered. All screw holes, notches, etc. get coated. Stagger the tabbing so the edges don't land on top of each other. Lastly, insure you have at least 6" of tabbing on the hull shell in all directions (both sides of stringers), insuring you spread loads out well.

    The most common reasons for these types of failures is, the factory didn't use enough resin to protect the wood. They all didn't take their time to do a complete job. You can solve these issues by using enough materials to make it bullet proof and with some care, insure no raw wood remains exposed.

    It's assumed you'll use epoxy, as it's the novice's best option. If using polyester or vinylester, then you can skip the biax and just use CSM and roving. Also, if using epoxy, you don't need, nor is it desirable to use mat.
     
  8. tunnels

    tunnels Previous Member

    Whats your motor mount like ?? have you checked that ??:confused:
     
  9. whitepointer23

    whitepointer23 Previous Member

    i didn't realize stringers stopped short of the transom, last time i replaced them i glassed them to the transom. i converted that one to inboard shaft drive so i guess there was no stress on the transom anyway. crankit your fish box idea sounds good, you might be able to add some depth to it at the same time, some insulation and you will have a large ice box for camping trips as well as some where to put the fish.
     
  10. whitepointer23

    whitepointer23 Previous Member

    that dry glass seems to common on factory boats, usually up under the gunnels to, i guess you could clean the area with acetone and then give it a good coat of epoxy. if you get hold of jeff webster book on restoring trailer boats there is lots of info on glassing and stringers etc. most news agents have it.
     

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  11. crankit
    Joined: Oct 2007
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    crankit Junior Member

    Now I'm glad I came here and checked, Thank you for your advice sir.
    I've seen some 17oz biax from a online shop here in oz, would 3 layers of layers of that be enough? The stuff on ebay is around 30oz so I'm guessing that's overkill/

    Those motor mounts are also shot and they will be replaced as well. :)


    Whitepointer they are great magazines! and I have 3 of them. The thing I really like about that publisher is he's not trying to ram sponsored products down your throat that are not necessarily the best. The articles are completely un-biased if you know what I mean
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Biax is reserved for high modulus resins, which polyester isn't. Vinylester can take some advantage of biax, but will need mat to bulk up, while epoxy can take full advantage of biax and doesn't need the mat.

    Tabbing and general laminate thicknesses are application specific. Three layers of 17 ounce biax with epoxy will do, though I'd like to see more if using a different resin system. Insure at least a 6" contact patch on the hull shell, on both sides of the stringers and stagger the layers so the seams don't land on top of each other.
     
  13. crankit
    Joined: Oct 2007
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    crankit Junior Member

    Par,
    I'm using Epiglass ht9000 marine Epoxy for all of this. It's quite a bit more expensive then polyester, but like you said it is more friendly for beginners, And I would hate to come back and do all this a second time. I realize I'm going to need a lot more epoxy then the 8 liters I've already bought.

    Thanks again.
     
  14. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Have you looked into BoatCote? It's a more economical goo and I know many in your country that use it exclusively.
     

  15. crankit
    Joined: Oct 2007
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    crankit Junior Member

    Par,
    I noticed Boatcote in one of the online shops I've been checking out on the net and have been wondering if it's a superior product to the epiglass ht9000 that I've been using.
    The Boatcote product is a 2:1 ratio epoxy and It is slightly cheaper in bulk at 22 dollars a liter compared to the ht9000 which is 3:1 at 24 dollars a litre. Although unless I buy it at a local shop like my ht9000 at that price the ht9000 is cheeper for me.
     
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