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  • Building WiTHiN

    boat building
    1st May 2009 - By adventuresofgreg
    Building Ocean WiTHiN – a human powered ocean crossing boat

    My last blog post called “how it’s done” was a step by step attempt to show you how we are building Ocean WiTHiN and it was received with a bit of confusion. I realized that I could do a much better job, so after four more days of panel making, and way more photos taken, here is a much more thorough explanation of what we are doing.

    Design:

    The illustration above is a computer rendering of Ocean WiTHiN – a pedal powered boat designed for me to human-power across an ocean with. The ocean in question will either be the Pacific ocean via a route that has never been ‘human powered’ before – from Vancouver Island Canada to Hawaii in June of 2010, or a speed record attempt across the Atlantic ocean in less than 40 days from Canary Islands to the West Indies in December of 2010.

    Ocean WiTHiN was inspired by the prototype version of WiTHiN shown in the photo below taken near Tofino off the west coast of Vancouver Island. Sea trials video here.

    WiTHiN prototype was designed by myself and human powered boat guru Rick Willoughby and build by myself and my friend Ben Eadie. She is made of fiberglass using a double kayak hull as a base which was kindly donated by PedalTheOcean sponsor and advisor Steve Schleicher from Nimbus Kayaks.

    The new boat – Ocean WiTHiN was designed by myself, Rick Willoughby and world record winning naval architect Stuart Bloomfield. Ocean WiTHiN is made from flat carbon fiber panels that are stitched together to form the basic hull.


    The above illustration shows some of the hull panels, and interior seat and bulkhead panels

    This is a paper model assembled from printing and cutting out the individual panels. This method of construction is called developable panel. An advantage of developable panels is faster and less expensive fabrication process. According to Ricks calculations, the efficiency differences between a smooth contoured moulded hull (like the prototype) and the square flat panel hull is minimal.


    How we’re building it

    The drawing above shows the layout of some of the individual panels that will form the hull. Each panel is made from 1/2″ thick Corecell foam board covered with 2 layers of carbon fiber on each side – called a sandwich panel. We are making all of these rectangular sandwich panels in advance, then tracing the outlines of each panel part and cutting that part out with a saw.

    Each panel was printed onto paper using a large format plotter. This photo shows two panel drawings on our giant layup table.

    1. The first step is to cut and assemble 1/2″ thick Corecell boards to make the first panel. The Corecell boards are joined together using an epoxy/micro balloon mix, then sanded flat and smooth.

    2. We roll-out a long sheet of poly (Plastic drop sheet) and tape it down to our layup table. The poly is twice as wide as shown in the photo and the second half is folded down over the left hand side of the table. The poly will form a bag that will eventually cover the entire panel. The Corecell panel is placed on top of the poly.

    3. The first layer of carbon is 6 oz unidirectional carbon fiber. Unidirectional carbon is a fabric consisting of thousands of thin carbon fiber threads all running longitudinally and held together with a fine thread. Unidirectional carbon is very strong in tension longitudinally and has zero strength width-wise. The carbon is 12″ wide and comes on a roll which we roll out to the length of our panel and cut.

    4. The unidirectional carbon strips for BOTH sides of the Corecell panel (2 strips on the top side of the foam board and 2 strips on the bottom side) are rolled up and stored at the back of the table.
    5. The second layer of carbon to be applied to each side of the core is 6 oz bidirectional weave. This is a weave with threads running both horizontally and vertically. It is cut and applied to the foam board such that the fibers are running at 45 degrees to t
    he length of the core (and direction of the unidirectional). These sections of fabric are cut to size, rolled up, and stored at the back of the table.

    6. Absorbent blanket material is cut to fit over the length of the Corecell board. This material will soak up excess epoxy – more about that later.

    7. Strips of ‘peel ply’ fabric are also cut to fit each side of the panel and stored along with the blanket and carbon at the back of the table. I’ll explain what the peel ply is for later.

    8. This is a picture of Ken weighing each roll of carbon. We will be wetting-out the carbon layers on the Corecell with epoxy resin and we use the weight of each layer of carbon to calculate the exact amount of epoxy to apply.

    9. We mix a pre-calculated amount of epoxy resin required to fully cover the Corecell foam board. This epoxy is poured into the foam board and then spread evenly over the board with squeegees. I don’t have a photo of this process. After the board is fully saturated with epoxy, we roll on our first layer of unidirectional carbon fabric.

    10. A pre-calculated volume of epoxy resin is mixed and then poured in an even line down the middle of the carbon on the Corecell board and then spread evenly over the surface with the yellow squeegees shown above.

    11. After the unidirectional layer has been fully whetted out with epoxy, we roll on our bidirectional carbon weave. (There’s always a clown – hey?)

    12. The epoxy resin is a two part mixture: resin and catalyst which will harden (cure) in about 8 hours.

    13. The bidirectional carbon weave is whetted-out with epoxy in the same way that the unidirectional carbon was – by pouring an even line down the middle, then splitting the line with squeegees from each side pulling epoxy from the middle to the edges and then pressing the epoxy into the carbon fabric.

    14. You’ll be tempted to, but don’t eat the epoxy.

    15. The process of wetting out the foam core, rolling out the unidirectional carbon, wetting out the unidirectional carbon, rolling out the bidirectional weave, and wetting that out is repeated on BOTH sides of the Corecell panel.

    Before the panel is turned over, the wet layup is covered with a layer of peel ply (not shown). This is a fabric that won’t stick to the curred epoxy, but will allow wet epoxy to seep out of the layup into an absorbent blanket placed on top of the peel ply. The blanket strip is placed on top of the peel ply layer, then the whole board is carefully flipped over and the entire process is repeated on the other side.

    The whole wetting out process takes about 90 minutes for each side with two people working. The preparation which includes cutting the Corecell panel, assembly of the Corecell sections, and cutting of the carbon, peel ply, blanket, poly sheet and mixing epoxy takes an additional 3 to 4 hours. So far, each panel has taken 2 man/days to make.

    16. After both sides have been whetted out and the peel ply and blanket have been applied, the other side of the poly sheet is placed over the panel completely covering the layup. The three open sides of the poly are sealed using gummy tape to form an air tight bag.

    17. A vacuum pump is connected to the bag and all of the air is sucked out of the bag. The vacuum process creates very high pressure (about 26″ mercury) which presses the plastic bag against the wet layup forcing excess epoxy to seep out of the carbon through the peel ply and be absorbed by the blanket.

    19. In order for the entire layup to fully cure in 8 hours, it is important for the temperature to stay at or above room temperature. Higher curing temperatures are advantageous because it increases the viscosity of the epoxy allowing more excess epoxy to be absorbed by the blanket. To increase the curring temperature and decrease the curring time, we cover the entire wet layup with electric blankets which keep the panel very warm.

    This photo shown the vacuum tube entering the bag and the electric blankets placed on top.

    20. The entire layup is left to cure under heat and vacuum for 8 hours and then we turn the vacuum pump off, and leave the heat on until morning (total of about 18 hours curing). Then the bag is cut open and the fully curred, hard carbon panel is removed. We store the panels in a curved stand which is approximates the curve that the panel will take when it is used to form the boat hull.

    This is a photo of my 4 car garage which has been turned into a boat making shop.

    21. Eventually, the peel ply and blanket is removed from the carbon, but this won’t happen until the panel shape has been cut out of the panel. The peel ply and blanket protects the surface of the panel until we are ready to assemble the boat. The photo above shows our first two panels (with the peel ply/blanket layer removed) post curring on a warm, heated floor.

    22. The panel drawing is placed on the cured carbon fiber panel. The photo shows the bulkheads drawing on a section of panel with the peel ply and blanket layers removed. Normally, we do not remove this layer until AFTER the parts have been cut out.

    23. The drawing is taped down to the carbon panel by cutting holds in the paper and taping through to the panel.

    The two photos above show the paper pattern taped down to the carbon panel ready for cutting.

    24. I use a jig saw and follow the cut lines on the paper pattern. Since the paper is taped down to the carbon panel, I can cut right through the paper and panel.

    This shows a small panel part cut-out with the paper panel still taped on. Note the nice tight fit between the pattern and the cut carbon panel.

    This is the cut-out top deck panel with the peel ply / blanket layer still attached. We won’t remove this layer until we are ready to place it into the jig because it protects the surface of the carbon.

    25. Ken is building a jig for the top & bottom hull halves. He is starting with a long, straight square box on wheels and the jig stations will be mounted to the top of it and aligned. We will start with the top deck (top hull half) and when it is assembled, we will remove the jig stations and install the jig stations for the bottom hull.



    26    . Here is the completed jig station box. It’s flat and square and very rigid with coasters so it can be moved in and out of the shop.

    27. Ken is tracing the jig station patterns onto some 1″ thick MDF wood.

    28. The jig stations are cut out and assembled onto the box at pre-specified spacing

    29. The jig stations are aligned to each other usi
    ng alignment targets and a tight string.

    30. The carbon sandwich panels are placed into position in the jig. Note that the peel ply and blanket layers are still on the panels. This is to prevent us from rubbing off the peel ply texture which is required for a proper bond and paint.

    31. The edges of the peel ply are ripped off showing the carbon. The panels are screwed into the jig sections using a strip of particle board. This will force each panel to curve into it’s exact position.

    32. The edges of the panels are joined with a radius of micro/epoxy

    33. The joins will be reinforced with a strip of carbon tape. To avoid fraying the carbon, a large sheet is whetted out with epoxy resin first, then cut between 2 layers of poly.

    34. the carbon tape is placed onto the seam. The epoxy/micro filled radius in the join is semi-curred to a tacky consistency to assure a good bond between the carbon and the micro.

    This shows the carbon tape fully whetted out

    35. The carbon tape is covered with a strip of peel ply and a strip of absorbent blanket, then covered with plastic.

    36. Normally, this carbon tape wet layup should be curred under vacuum, but in this case it would be difficult to obtain a good vacuum due to the seam between the two carbon panels. So, we used about 100 lbs of sand to press down on the wet carbon.

    37. After curring, the sand is removed, and the peel and blanket layers are removed. The inside is temporarily reinforced with wood spacers.

    38. The cabin top is removed from the cabin top jig.

    39. The lower hull jig section patterns are printed and cut out

    40. The jog sections are traced onto 1″ thick MDF

    41. The jig sections are cut out with a skill saw and jig saw.

    42. The jig sections for the upper cabin are removed from the square box, and the jig sections for the hull are fastened into place.

    43. The jig sections are aligned using target holes and a tight string. After we aligned each station, we could peer through a 1/4 inch hole in the end station and look through ALL 15 holes in 15 stations spanning almost 30 feet!

    44. A slot was cut down the middle of the floor hull panel to allow it to bend slightly to fit into a shallow ‘V’ shape in the jig sections. It is held in place temporarily by weights.

    45. The carbon panel is secured to the jig stations with screws and blocks, and the cut is filled with a runny mixture of micro & epoxy

    46. The seem is reinforced with a strip of carbon tape, then peel ply is placed over it.

    47. Sand is poured into the epoxy whetted carbon tape & peel ply to keep the carbon tightly pressed against the panel and the seem.

    I will continue this step by step post as we progress. If you have any question, please feel free to post a comment to this blog post and either I or Ken will respond with an answer.

  • No Responses to “Building WiTHiN”

    • Robert Chave on May 2, 2009

      Hi Greg,

      I haven't seen anything on your site about collision avoidance.

      One of the big problems about being in a small slow moving vessel on the ocean, is large fast moving vessels. :^)

      You know about AIS don't you? You must. Anything larger than 65 feet is required, in many waters (but not universally) to continuously report its position (LAT, LONG), tonnage, heading, and velocity over ground, on one of two VHF Marine bands.

      One of the more interesting (low cost, low power, small size) radios that I have seen for doing this is done by Milltech Marine. They seem like nice people and are located on Bainbridge Island, in Washington. The radios are set up to work with a lap-top which then plots the position of vessels that are near you on which-ever of the common chart plotting programs that you happen to be using.

      Try this URL http://www.milltechmarine.com/SR161.htm which links to their receiver-only, alternating, two channel radio. This is the base model. Of course for much more power consumption there are the two way radios that broadcast your presence to neighboring vessels also via AIS.

      Since WiTHiN sits too low in the water for radar to be of much use, AIS starts to become very important.

      Kind regards,

      Robert Chave

      http://www.chave.net

    • David Tangye on May 5, 2009

      This is absolutely brilliant. I am sure you will find it useful in future too. We always think we will remember stuff, and doing it more in future will help memory. Then we find that we do not actually repeat things like this (ever?) as we imagined we would. So the record becomes invaluable. I never had a camera and was always busy 'doing it'. Now a lot of it is just a very vague memory. (On the plus side of course, 30foot waves are now 60foot :-).)

    • Paul Janson on May 11, 2009

      Hi greg,
      I would love to also make a paper model of your boat, by printing the panel cutouts, but the one in this post does not contain all parts (as far as I could see).

      If its possible (legally due to copy rights) I would love to see the parts in a gif file so I can print them. Maybe fun for school kids too?

      Happy boat buiding Paul

    • Adventures of Greg on May 11, 2009

      Paul:

      Like this?

      http://www.adventuresofgreg.com/HPB/uploaded_images/DSC03859-705316.JPG

      I'll have to check with the naval architect Stuart Bloomfield about
      copyright issues regarding those panel shapes. That's the reason why I
      didn't show all of the panels in that blog post.

      I'll let you know.

      Cheers,
      Greg K

    • Harry on May 28, 2009

      Now that would be an Idea Greg. You can have someone make color printed cutout poster board models that they can cut out at say 1/8th or 1/6th scale of your Within Pedal Boat. Then sell them to augment your money situation.

      Just a thought.

      Harry vS

    • Dave on July 10, 2009

      Have you thought about testing water pressure on the windows you are using for the trip? I don't really know what kind of pressures you will be dealing with but in the event you get nailed by a cyclone it might be wise to set up or build a mock-up and test it out. Equipment failure would really suck out there.

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