5 meter deep-v custom cold mold build

Discussion in 'Wooden Boat Building and Restoration' started by peterjoki, Jul 27, 2014.

  1. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    Hi all,

    In this thread my intention is to share, as well as seek advice on my up coming build over the following year.

    A little background: During my final year studying to become a wooden boat builder I have chosen to build a boat. Although we have covered all traditional techniques, my interest lays in cold molding. It fits my style and is a good method in achieving hull forms that I am most drawn to.

    This project is to act as a portfolio of sorts. I hope that future employers and customers get a good idea of who I am, what I like to do, and how I do it.

    The design of this project was created by TANSL. He has been of invaluable help. I had an idea of a deep-v offshore hull combined with classic runabout looks. After hours of scouring the web for ready plans I gave up and joined boatdesign.net in the hopes that someone could point me in the right direction.

    Due to space restrictions at school the project was limited to a LOA of 5 meters. After briefing TANSL, I was extremely happy with how he adopted my vision and created a design that will be a joy for me to build. I really can't wait to start cutting out frame members. Thank you TANSL!

    [​IMG]

    LOA: 5.16m
    Beam: 1.925m
    Draft: 0.33m
    Disp.: 1110kg

    At this point I am busy researching material options and making decisions.
    Please feel free to chime in, advice, and questions are all more than welcome.
     
  2. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,376
    Likes: 450, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Do you have any other drawings of it to show ? A bit hard to see what you have, from that view.
     
  3. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    I insisted upon a 24 degree dead rise. Spending some years of my childhood in Dar es Salaam I became accustomed to this type of hull whilst spending countless hours playing and exploring in the massive boatyard/graveyard of the DYC yacht club.

    Here in Finland this type of hull isn't very common, certainly not in a boat of this size range.

    This brings back many childhood memories that I am fond of and feel very privileged to be able to build this boat as my first project of my own.

    Here are a couple more images:

    [​IMG]
    [​IMG]

    I have received a very detailed set of drawings. As you can probably understand, I am quite reluctant when it comes to sharing such images to be distributed freely on the internet. Rest assured, photos of the upcoming build will do this boat justice. I hope even for the keenest study of hull lines.

    To my knowledge there is only one boat building company in Finland using cold mold techniques on a regular basis: Red Sky yachts.

    My aim is to make this my niche.

    Up till now I have thought about using a total 15.5mm thickness for sides and 18mm for hull. Composed in the following manner;

    Sides: 6mm okume mahogany ply (beautiful surface inside hull + low weight) + 4mm birch ply (good strength and locally sourced, a little on the heavy side but cheaper) + 4mm birch or okume ply + 1.5mm african mahogany veneer.

    Hull: 6mm okume + 6.5mm birch + 4mm birch or okume + 1.5mm veneer

    I will be adding a layer of fiberglass using epoxy of the outside. Not on the inside as I will laminate over final frames and stringers. Would be a nightmare.
    Will possibly include a first layer of fiberglass between the first 2 layers of plywood.

    Frames and stringers will be made out of American ash.

    So far I am looking at West system epoxy. A little discouraged by the price. I believe SP system is a lot cheaper here.

    I saw an ad for Crestomer 1152 in the most recent proboat. It boasts 100% elongation and have become interested in whether it would be of use in gluing the first layer to the stringers. Any thoughts?

    To make disp. calcs this hull can weigh no more than 250-300 kg.

    If any of you have material suggestions, experiences. I am more than happy to hear and consider your input.
     
  4. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    Addition:

    This hull is to be powered by a 5.7l mercruiser to achieve a theoretical 48 nmh.
     
  5. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,376
    Likes: 450, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Similar concept to a Donzi 16 ? Be tough to better that hull, in this type of thing.
     
  6. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    Very much related to the Donzi 16. I was initially drawn to the Formula 233.
    To be able to build it at school it required scaling down to 5 meters.
     
  7. SukiSolo
    Joined: Dec 2012
    Posts: 1,270
    Likes: 25, Points: 0, Legacy Rep: 271
    Location: Hampshire UK

    SukiSolo Senior Member

    What is wong with European Ash?. We are likely to have to cut almost all the entire stock of UK Ash, because of a specific disease. The timber though wil still be OK to use.

    I would not bother putting f/glass between any sheets of ply. No benefit for strength at all, better on the outsides. SG/SD of Okume/Gaboon approx 0.550 + glue for ply. Birch approx 0.660, with Ash only a little more. If you use SP (Gurit) epoxy, I would recommend the 320 or better, not the basic 106 which I have had the odd problem with in the past. The 320 flow coats better too. Worth checking the Araldite range of epoxies and a few others too. If you can get tight joints, perhaps vacuum bagging the ply/veneeers then also commercial Aerolite (urea formaldehyde) resins can be cost effective. You need to be in the 25KG drum sort of quantities but they allow quite a long working time and generally require a modest heat boost to cure - fairly easy to do btw. The resulting laminate can be epoxy sheathed regardless of the lamination resin as long as it is a waterproof glue.

    There are a few 'tricks' to get fractional double curvature with ply especially if you are part making the ply. Maybe a little time consuming but useful to know about when attempting deliberate distortion to achieve better hull form or superstructure.

    Hard to comment on the hull thickness, without seeing a Frame plan, it 'feels' a little on the heavy side. Usual trade off, more ribs and stringers the thinner you can go. The floor ply would be around 10 - 11 Kg per sq meter, just from a rough approximation, and you have a weight aim of 250-300. Once you have the scantlings roughed, it will be worth a weight check. Do not ignore the weight of glue and sheathing.

    Nice looking hull Tansl and Peter.
     
  8. Joris
    Joined: Mar 2013
    Posts: 59
    Likes: 1, Points: 0, Legacy Rep: 18
    Location: belgium

    Joris Junior Member

    As you i was also a bit put off by the prices of West-Systems. (i guess the costs for transport etc to europe adds to the price?)
    After much consideration i went with http://www.hp-textiles.de because they gave me excellent support and even offered to send me samples for testing when i needed a different viscosity for vacuum bagging. As a first time builder with lots a questions that did it for me. I probably saved some money along the line but in the total cost of building a boat this won't be significant...

    very nice design btw!
     
  9. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    There is only one supplier of imported lumber left here in Turku (don't think its worth going on a long drive when such a small quantity is in question). American ash is €200-300 cheaper per m3. As crazy as it may sound.

    The salesman told me that a lot of European lumber is experiencing a huge rise in price due to demand from China

    The hull thicknesses I admit are 'on the safe side'. The drawings call for 10 frames 500mm apart. I haven't decided on how many stringers to use yet.
    What kind of thicknesses would you suggest?

    My aim is to get as tight joints as possible, but am a little weary of vacuum bagging, I was thinking of using staples which will be removed. My training has been very wood specific. The GRP exam which I had to take last year was all basic hand lamination using steel rollers.

    I took a look at all the epoxies that have been suggested. Hp-textiles seem to have a really good variety of products. I would however like to go with something that is available here in Finland. So my choices are limited to Gurit's SP range and the unlikely West system. I think they are so expensive because of their wide advertising campaign and the hype they have created.

    What kind of problems have you had with sp-106? I too have been leaning towards the 320. At least for the fiberglass and topcoat.
     
  10. SukiSolo
    Joined: Dec 2012
    Posts: 1,270
    Likes: 25, Points: 0, Legacy Rep: 271
    Location: Hampshire UK

    SukiSolo Senior Member

    Regarding timber sustainability, I believe that both Finland and the US grow more timber than is removed. However there is very little virgin growth left in the US, mostly 2nd,3rd growth for softwoods. Some of the hardwoods are definitely harvested and grown commercially, we have a lot of US maple, cherry, some oak etc imported into the UK. The US contribitors will have more specific information, so perhaps they can inform you better. These things do change, along with International treaties for protecting species ie C.I.T.E.S..

    I'm sure TANSL would be helpful regarding the scantlings of the craft. You have the choice of a clean interior, but thicker skin, or thinner and lighter hull with more stringers and ribs. Probably need to work up the structure a bit further before coming to a decision. Also depends on enviroment useage, a dirty commercial seaway may need heavier scantlings to allow for hitting UFOs' and the like.

    Do not ignore some of the other waterproof adhesive systems for cold moulding. They are quite a lot cheaper than epoxy, so a combination may be worthwhile financially as well as in engineering terms. The SP 320 is way better for flow coating than the 106 and bubbles/gasses less so for sheathing it is a good resin. One leading UK foil maker swears by it, for coating and buffing to a perfect clear finish.

    This company has a resin range that will be suitable for cold moulding and cheaper than epoxy. I've use the urea formaldehyde resins successfully in the past for cold moulding veneers from 0.5mm upwards.

    http://www.dynea.com/solutions/solution?area=17850331&solution=17850557#

    I'm sure you could contact them and outline your project, to get their recommendation.

    Bear in mind, that the hull will need sheathing in epoxy, but the actual lamination need not be. I assume you will not have large gaps in the structure requiring void filling adhesives....;)
     
  11. Joris
    Joined: Mar 2013
    Posts: 59
    Likes: 1, Points: 0, Legacy Rep: 18
    Location: belgium

    Joris Junior Member

    Peterjoki,

    may i ask why you are weary of vacuum bagging?
    I used the composite raptor staples that don't need to be removed combined with low vacuum pressure bagging and i feel the results were very satisfactory.
     
  12. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    Hi Joris,

    I have never done it before. Did you use a combination of the two?
    Will give it some research as it would be a great option for the final layer of 1.5mm veneer.

    Checked out raptor staples a couple of weeks ago. They are interesting, what about price? One thing that put me off was that I would need to buy a dedicated gun to accept these staples. Did you find all the supplies and the gun in Belgium? I lived in Brussels for 10 years and my parents still do. Might take a trip down there if you can recommend any stores. Will definitely be cheaper than Finland. As a full time student my labor costs are not a factor. I figured a couple of days of pulling staples are ahead of me if it saves some money :)
     
  13. peterjoki
    Joined: Sep 2008
    Posts: 57
    Likes: 4, Points: 8, Legacy Rep: 14
    Location: Turku, Finland

    peterjoki Junior Member

    SukiSolo,

    I will be in touch with Dynea Finland. UF is definitely something I will consider. Thanks for proposing this option.

    After playing around with the compositions of the hull and sides, I am ready to commit to the following:

    Hull - 4mm okume + 6.5mm birch + 4mm birch + 1.5mm sapele veneer = 16mm
    Sides - 4mm okume + 4mm birch + 4mm birch + 1.5mm sapele veneer = 13.5mm

    Area of hull is 9m2 and sides make up roughly 6m2.

    I might substitute the last layer for 4mm okume to save weight if need be. Cost is something I want to drive down wherever I can, without compromising aesthetics or structural strength and safety.

    You are right about the forestry practices over here. It's sad that a lot of wonderful logs over here are wasted for paper pulp. Mostly older large diameter trunks that large standardized saws cannot process.

    I find that even indigenous wood (furniture grade) is ridiculously expensive over here.
     
  14. Joris
    Joined: Mar 2013
    Posts: 59
    Likes: 1, Points: 0, Legacy Rep: 18
    Location: belgium

    Joris Junior Member

    Hi Peterjoki,

    There were no dealers in belgium for the raptor stuff so i ordered from the states.
    I didn't like the idea of pulling staples (and the pinholes they leave behind) but since i work alone they were a nice solution. They are like the extra pair of hands you need when vacuum bagging.
     

  15. SukiSolo
    Joined: Dec 2012
    Posts: 1,270
    Likes: 25, Points: 0, Legacy Rep: 271
    Location: Hampshire UK

    SukiSolo Senior Member

    Personally I'd be tempted to use a combination of staples and low pressure vacuum bagging. You need the staples to hold one end of the veneer in place but the bag means minimal staples to pull later. Imagine you staple into the 'hog' (inner keel) and lay down say at 45 degrees. Each strip of veneer can be laid in place dry and tacked at the other end. First actual laminate could be say vertical (square across hull), and only needs tacking at the 'hog'. When you apply the vacuum you can feel with your fingers through the bag that all the veneers have settled correctly and there are no overlaps. Very little pressure (maybe 0.1 - 0.25 bar) is required unless you have massive curvature. The base mould/form cannot be too strong, but can be lighter if you use a low vacuum.

    The easy way to get staples out of the second veneer later is if you use a tacking strip of timber about 2mm thick on top of the veneer. When you remove, just lift the strip with the back edge of a 12mm chisel. If the timber snaps the staple is left sticking out and can be pulled with pliers.

    If you use urea formadehyde be carful with the staple material, do not use steel even plated as it will give dark stains because the hardener is an acid which will attack it. Monel and plastic staples are fine, usually these are available for the T50 size staplers. To aid cure, try laying electric blankets at minimal heat over the vacuum bag after ensuring all the veneer is correctly seated.

    Very important to get the glue quantity right. Make some test pieces and get, or make a glue spreader that gives the correct ammount on the surface. You need enough to spread and cover the surface (usually in little Vs') but not so much you get bleed through. This is more important on the thin veneers (0.5 - 1.0mm) so you can be a little 'heavy' with the thicker sizes, but the Sapele at 1.5 could easily get bleed through, so be careful with that layer. If you want you could run the boil test after a few days of curing on a test piece....;)
     
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.