Help with boat building project ideas

Discussion in 'Boatbuilding' started by DonnellyShard, May 28, 2020.

  1. DonnellyShard
    Joined: May 2020
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    Location: Essex, UK

    DonnellyShard Junior Member

    Hi all. I'm new to the forum. I own a 30ft Springer Canal boat that I got in very bad shape when bought. The entire top is wooden and the lot was rotten, along with it a huge hole in the hull. That was in January and now the Hull has nice new steel and I'm currently awaiting delivery of cladding and glass to finish the exterior. Interior building has already begun in the meantime. I can do a separate thread with pictures of it if anyone is interested.

    Anyway, I have new ideas I wish to do. Obviously this boat was a challenge (especially for my first boat) but I wish to build a boat from scratch. Nothing complicated and one just for residential mooring as I'll be moving onto the 30ft when totally ready.

    Questions I have, I'd like to use either steel as the hull or fiberglass over wood. How do I calculate how high the waterline will be with weight on top?
    Fiberglass over wood would be a good project for me as I love working with wood, but I wish to have a 50x13ft flat bottom hull, then a single storey on top (pretty much a pontoon style boat) therefore my worry would be how it would react to being craned into water compared to steel? Breakages or damage would be a worry.

    Any advice or guidance would be much appreciated
    Thank you
     
  2. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    Welcome. 1 cubic centimeter of water weighs 1 gram. A boat that weighs 1000 kg. will displace 1000 litres of water. If the volume of the 1000 kg. boat is 4000 litres it will still displace 1000 litres of water leaving 75% of the boat above the waterline. I will leave the rest to you to ponder.
     
  3. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Steel is stronger, but wood is more than strong enough. Keep in mind, design is important. Proper construction will make the difference.

    -Will (Dragonfly)
    Wood
     
  4. DonnellyShard
    Joined: May 2020
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    Location: Essex, UK

    DonnellyShard Junior Member

    Thanks for the replies. hoytedow, awesome answer but I will have to get the pen and paper out and figure out the maths of it. I do have the weight of steel in mind per square foot.

    Will Gilmore, what's your opinion on a flatbottom wood hull though and covered in fiberglass. Just wondering how lifting it would work strength wise.
     
  5. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Over a 13' width and 50' length? Study solid frame and stringer construction with 1/2" plywood covered in glass? What are you looking at for rib spacing?

    Let it be known that I grew up wandering around the boat yard of Clearwater Bay Marineways where there were lots of boats built of glass covered plywood. My father's fishing boats, 65' catamaran headboats were built that way, as was our 56'×12' live-aboard schooner, but I was pre-high school age, so my memories are imprecise.

    I am a trained cabinet maker and carpenter for the better part of the last 30 years, so I have a good sense about it. Just, don't take my thoughts as definative.

    I see no issues with the materials, in either case. It's all about construction and design with regards to what you are describing.

    I'm sure you can find pictures, through Google Images, of similar sized boats of wood being travel lifted out of the water

    I think I have one of our schooner:
    20180219_142443.jpg

    -Will (Dragonfly)
     
    Last edited: May 30, 2020
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  6. DonnellyShard
    Joined: May 2020
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    Location: Essex, UK

    DonnellyShard Junior Member

    Thanks for the reply. There was one I was looking at that someone home built using 4 wooden sections bolted together and then built on water. And it has so far been on water for 4 years with no issues. But service wise I'd like to pull it out of water, not to mention one of the mooring sections we have a place in with our current boat it would have to be craned over. Here is a picture of one of the frames that was made from the boat I'm talking about. This was then covered in ply and fiberglass. 4 in theory would be easier to build and just put together but maybe a single one would be more stable? It's just the craning part that worries me. Wouldn't be great having it begin to flex and crack in the air. There are quite a few boats on the yard we are on and plenty of horror stories of home builds.

    Screenshot_20200529_182854.jpg
     
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  7. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Wood Butcher

    Here's a little trick I learned from Angélique.
    If you build from steel and make any closed steel compartments, place a lit candle into the compartment before welding it shut. That depletes the oxygen and prevents rust from the inside.
     
  8. Will Gilmore
    Joined: Aug 2017
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    Will Gilmore Senior Member

    Very interesting idea.

    How do you maintain the vacuum before the welding is done? Leave the candle burning inside and let the vacuum hold the last panel in place? Certainly it would serve well to also dry the air and that would also be beneficial.

    I'm just beginning to learn about the complex world of corrosion. So complicated.

    -Will (Dragonfly)
     
  9. DonnellyShard
    Joined: May 2020
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    Location: Essex, UK

    DonnellyShard Junior Member


    Very awesome idea! If I were doing a type of barge though I'd have it accessible for ballast if needed in area and not to mention the extra storage for tanks and pumps
     
  10. hoytedow
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    hoytedow Wood Butcher

    Clearwater Bay Marine Ways was for me an inspirational visit almost 50 years ago. They were building a plug for making a mold of a sailboat hull. It was beautiful.
    I don't think a vacuum is involved in the candle oxygen depletion method. Until the compartment is sealed it shares the same atmosphere as the exterior until it burns the oxygen becoming CO2 rich. The other main product of combustion is actually H2O. So technically the air in the chamber would be wetter, but harmless.
     
    Last edited: May 29, 2020
  11. Will Gilmore
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Could have been for the ComPac 23. That's about when I saw the plug at a boat show in Tampa. Although sailboatdata lists the first one built in '83. The plug I saw was some where around '73 (I was about 10). I'm pretty sure it was the plug for the ComPac 23.

    -Will (Dragonfly)
     
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  12. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    I found this quote from a NACE engineer,
    "Carbon steel (CS) is the primary material for constructing CO2transportation pipelines. CO2 dissolves in water to form carbonic acid, which is corrosive to CS. The rate of corrosion or weight loss depends on the formation and stability of iron carbonate that is formed as a consequence of corrosion of CS in carbonic solution. Corrosion of CS in aqueous CO2 has been an active field of study for the last 50 years. The corrosion rates reported in the studies can vary by four to six orders of magnitude."
    Pipeline Corrosion Issues Related to Carbon Capture, Transportation, and Storage http://www.materialsperformance.com/articles/material-selection-design/2015/08/pipeline-corrosion-issues-related-to-carbon-capture-transportation-and-storage
    The subject of corrosion, I'm finding, is broad, complex and unsettled.
    Not being either a chemist nor a materials engineer, I am finding the subject eye opening.

    -Will (Dragonfly)
     
  13. hoytedow
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    hoytedow Wood Butcher

    Once that minute amount of carbonic acid reacts with a minute amount of steel it is neutralized and no more corrosion.
    '73 was about the time I went there(CBMW).
     
    Last edited: May 29, 2020
  14. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Donnelly, I would be a bit concerned about you building a barge as per the 3-D shown in post 5 - if you are going to go to all that effort for such a big vessel, then it would be worthwhile building something a bit more seaworthy?

    You mentioned :
    "Questions I have, I'd like to use either steel as the hull or fiberglass over wood. How do I calculate how high the waterline will be with weight on top?
    Fiberglass over wood would be a good project for me as I love working with wood, but I wish to have a 50x13ft flat bottom hull, then a single storey on top (pretty much a pontoon style boat) therefore my worry would be how it would react to being craned into water compared to steel? Breakages or damage would be a worry."

    Click on this link, and scroll down to the 45' Teign Motor Barge - could something like this be suitable for what you have in mind?
    Motor Boats over 30' http://www.selway-fisher.com/Mcover30.htm
    The cost of the plans is GBP 450, but it would be a tiny percentage of the cost of the materials that you will buy to build the boat with - it would definitely be false economy to try to design it yourself.
     
    Last edited: May 30, 2020
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  15. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    bajansailor makes a good point. For such a large vessel use a tried and true design.
    Do not be dismayed, however. You will need a tender or auxiliary vessel and that is a good candidate for a diy wood dinghy or skiff.
     
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