Humidity found in the amas of a Racing-Cruising Trimaran...

Discussion in 'Wooden Boat Building and Restoration' started by Skip JayR, Nov 12, 2015.

  1. Skip JayR
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    Skip JayR Tri Enthusiast

    Thats already on my radar scan and I do this generally as first calculations (writing long, long excel sheet tables). Luckily this boat has everything from 2x anchors to LED lights, solar, radar, VHS/AIS, pump system, deck shower, toilet, holding / black water tank (beside regular fresh water + diesel tanks), life raft, epirb and escape hatch to electronic navigation systems + autopilot. It has enough winches (9 in total) around the central cockpit to sail it short or even single handed. Sails are well balanced with 3 reef main, jib (furling), spinnaker, screatcher (top down furling) and storm jib.

    Electrics and engine plus trampolins had been refitted in 2011/2012. It has enough power with an 18 hp Volvo diesel engine.

    So the list of "to does" for now (beside the ama refitting) is very short: actually the boat has a kitchen with sink/water pump and refrigerator, it just would need a stoven (as it has a two flame spiritus cooker for now), a (winter) heating system (e.g. a Refleks with gravity pump), watermaker and a sprayhood/bimini plus outborder for the dinghy. Maybe a Genoa sail beside the jib. And I'd take a new antifouling which has a living of 10 years, e.g. CopperCoat.

    In total a short list I would say.... rarely seen such a complete trimaran. Thats the relevant reason behind why I think about a refit of the amas... most trimarans I have looked at (for now round 10 boats) I'd have to invest a lot into the equipment quickly 40-60 Thousand extra.

    The upper described boat more needs the bigger investment for the refit of the outriggers. Completing it with some extra equipment at max. 20-25,000.

    I'd exchange the spiritus 2 flame cooker with a propan stoven and in combination use a small propan therme for creating hot water (e.g. as known from Tiny House projects, see vid), so it is not needed the diesel engine.
    https://www.youtube.com/watch?v=cVgSKzRwTBA
     
  2. Skip JayR
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    Skip JayR Tri Enthusiast

    2nd part... portside ama...

    okeys... we have looked at the starboard ama with humidity from outside and inside. Now comes part 2: the portside ama.

    With some photos I received of the trimaran I have noticed something. Over last months I have looked hundreds of photos documenting different trimarans. But never I found it on any Trimaran.

    Maybe its the special light during the photos had been made. So lets take a look at. As I am not a boat builder, pls give feedback what you see.

    [​IMG]

    (Rec.: I have marked it with "blue doted lines". Pls click on the attached image or PDF so you get it in "high reslolution".)

    Regularly every hull of a sportive yacht should have a very plane surface.

    in wooden boat building, it is a method called "fairing" which means: all little nuances of uneveness, wrinkles and bumpyness are being corrected during the planking (e.g. by slicing) to get a plane surface as the boat material itself (wood) has a natural shrinking process by drying.

    In the photos we see the "frames" shining through the painting. This isnt "normal". Not on a Trimaran. - The ama port side from bow to stern has a "wave structure" horizontally and vertically.

    So I ask myself: why isnt the surface plane ? - Was it already a mistake by the boat builder (16 years ago) ? - Which then even might be the reasons for the humidity and water inside the starboard ama, too.

    I only know this battered surface from steel ships being produced by welding of metal plates because the high temperature evokes such "waves".
    [​IMG]

    A fast cruising-racing trimaran should have plane surfaces ! Did the boat builder make the mistake to use "not completly dried" planks ?

    Tks in advance giving feedback !
     

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  3. PAR
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    PAR Yacht Designer/Builder

    The images shows "oil canning" and likely because the bulkheads and internal furniture wasn't bonded to the hull over foam spacers, before the tabbing went down.
     
  4. Skip JayR
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    Skip JayR Tri Enthusiast

    Tks Par ! I first had to learn what the "oil can effect" means. :) I got it. Remembers me "sub marines" diving too deeply. - And yes, its very logically... simple "mechanics".

    Some interesting input I found here too for understanding the "foam spacer" thing... http://www.yachtsurvey.com/HullFailP2.htm

    About this picture:
    [​IMG][​IMG]

    So then I would say the port side ama (and probably same the starboard ama + main hull) have been produced all in "bad quality" and the whole boat has a bigger structural problem.

    Very, very pitty.... for this beauty. I dont like to say it, but it more now looks like a "wreck" with a total damage. Right ?
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    These things can be fixed, but it's a commitment. Tabbing isn't more flexible, so much as it makes a gradual transition from one plane to the other, so point loading and stress risers are eased considerably. The best way to think of this is "density change". The density of the hull shell is consistent, but the abutting structures, dramatically increase this density locally, which creates a hard point where stress concentrates. If the bulkhead or furniture has tapered tabbing, up to and proceeding away from hard points along this panel, the density change is gradual, so less impactful on the hull shell's ability to transmit loading strains.

    I'ts likely the bulkheads/furniture didn't fit the hull shell very well or were not placed very well, maybe slid off to one side more than it should have been, before the tabbing was placed. Foam (and other) spacers help eliminate these issues, before the tabbing is applied. I've used tile floor spacers previously for this reason.

    The solution is to cut the tabbing off one side of each offending piece, back cut under these offending boat bits, foam if desired (not not entirely necessary), then re-tab the side that was cut. Yeah, a bitchy thing to consider, though a huge bargaining chip with the owner once pointed out, possibly enough to make repairs worth it.
     
  6. rwatson
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    rwatson Senior Member

    Is it my eyes, or are the 'hard spots" indented ? This would mean that the bonding on the frames is holding on to expanded plywood sides.
     
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  7. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    The floats look like cylinder molded rather than tortured ply. If they are suspect I'd look to make new ones rather than restore. If you were looking for a professional quote you could contact Thain boatworks they have built some big CM hulls of recent times and their staff are familiar with the technique.
     
  8. Skip JayR
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    Skip JayR Tri Enthusiast

    Yes, I know Thain boatworks... its the warft which built Kurt's Ferry cats for Africa.

    Does exist a video tutorial which compares both methods...

    / CC - Constant Camber by Jim brown
    / CM - Cold molded (or VFP - Vacuum formed Plywood) by Kurt Hughes

    [​IMG]
    Some basics are described here on Small Trimaran Design Website:
    http://www.smalltridesign.com/Trima...-Methods/Cylinder-Mold-Hull-Construction.html
    and on Kurt's website:
    http://www.multihulldesigns.com/pdf/cm/CYLINDER MOLD MULTIHULL CONSTRUCTION.htm

    The CM method I only know from smaller hulls, e.g. building Kayaks and Canoes.
    [​IMG]
    [​IMG]

    Hard to imagine, that it works on big 38-41 fooot long floaters. :) - In the Wooden Boat Forum they have discussed some projects building bigger hulls in the range of 60-70 ft.
    http://forum.woodenboat.com/showthread.php?117995-Cylinder-Molding

    If I'd start such a project, I'd first would build a canoe/kajak from self building sets to get confidenced with... Chesapeake Light Craft has good plans and sets.
    http://www.clcboats.com/shop/boat-plans/kayak-plans/

    CLC has an excellent video series demonstrating the whole procedure of building a 16 foot Kajak hull.
    https://www.youtube.com/watch?v=mPG6asQ82lQ


    it is built in 40-60 hours roughly so it would give me the self confidence, that I have understood all steps... and then overtaking the experience to build a bigger Trimaran hull.
     

  9. Corley
    Joined: Oct 2009
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    Location: Melbourne, Australia

    Corley epoxy coated

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