Modernized Pearl Diving Boat

Discussion in 'Boat Design' started by minno, Aug 14, 2014.

  1. minno
    Joined: Aug 2014
    Posts: 90
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Canada

    minno Junior Member

    Hi All :)

    I'm planning on using this thread as sort of a project journal, all constructive criticism and Ideas are welcome. :cool:

    I've been playing around with the idea of building a small rowing boat for rowing, snorkeling, and freediving and thought a redesigned pearldiver would be perfect.

    I'll be using it in a fairly sheltered area between Saltspring and Vancouver islands so it doesn't really need to be able to handle high winds or rough water.

    I thought I'd row instead of paddle, and use a round bottomed hull for the least water friction when rowing and an adjustable outrigger that can be deployed wide and low for max stability when swimming, and then pulled in out of the way of the oars, and up for minimal drag when rowing, also for wheeling to and from the water.

    large fore and aft flotation chambers, safety first :)

    Design criteria:
    - Light, 75 pounds max, I'll be handling it alone and wheeling it about a half mile one way every time I use it.
    -VERY Stable I'll be climbing in and out often and will have a fair amount of gear in the boat so bottoms up isn't an option.
    -Easy to row I'm much more likely to use it if I get the most miles on the least number of strokes.
    -Inexpensive 'Cause I'm cheap :)
    -Unsinkable did I mention I'm cheap :)

    I thought I'd make the hull from a single sheet of 3/8 BCX spruce cut like in the attached drawing, the stern and stem stitched and glued as round as possible and joined with a butt block on the inside which will form the base to attach the rear bulkhead/flotation chamber. I built a 1:12 cardboard model and if my math is right the dimensions should be 10'6" long, by 36" wide, by 14" deep if I make the zigzag cuts 36" long. I could make the hull longer and narrower with a longer zigzag or shorter and wider with a shorter zig zag.

    Both the fore and aft Flotation chambers will have storage compartments with water tight hatches, probably a cooler/anchor storage forward and gear/anchor aft.

    Of course this hull will be pretty tippy (I'm a nOOb, in a year or two I'll start saying tender :) ) and pretty much impossible to get in and out of, so it'll need an outrigger, maybe two.

    Outrigger Design Criteria:
    -Light
    -Lots of flotation, I'll be entering and exiting the boat between the outrigger and the hull so the outrigger needs to displace at least ~200lbs/3.1 CF of water.
    - Adjustable, I need to be able to be able to move the outrigger from a wide and low position for swimming to a narrow/high position out of the way of my oars when I'm rowing.

    - If I end up using two outriggers they could be used as steps to get in and out of the boat and wouldn't need to adjust wide and narrow but should still be adjustable up and down.

    -Outrigger/s will have a waterproof cap on the rear and be used to store pole spears, speargun spears, ect. basically anything long that might poke holes in the hull or operator.

    At the moment I'm thinking 4" sewer pipe for the outrigger/s, no idea how I'm going to attach it/them to the hull yet but planning on skookum forward and aft bulkheads to mount it/them on.

    That's about as far as I've gotten, esthetically it'd be nice if it turned out purdy, but I'll take a sweet personality over looks any day :)

    y'all stay safe

    minno
     

    Attached Files:

    • boat.jpg
      boat.jpg
      File size:
      103.8 KB
      Views:
      309
  2. Russ Kaiser
    Joined: Jul 2009
    Posts: 119
    Likes: 2, Points: 0, Legacy Rep: 35
    Location: Winston-Salem, NC

    Russ Kaiser Exuberant Amateur

    Just a quick comment about your panel joining technique. I have seen interlaced joints in "kit" boats (made by a CNC cutter) but imagine puzzle piece tabs rather than sharp points. Plywood doesn't do sharp pointy shapes very well, especially cheap plywood.

    Of course, you don't have to join wood that way at all, a normal scarf joint will suffice.
     
  3. Russ Kaiser
    Joined: Jul 2009
    Posts: 119
    Likes: 2, Points: 0, Legacy Rep: 35
    Location: Winston-Salem, NC

    Russ Kaiser Exuberant Amateur

    quick math: 200 lbs. of flotation displaces approximately 3 cu ft. of water.

    A 4 inch pipe has a cross section of 12.6 square inches.

    3 cu ft. = 5184 cu. inches. 5184 / 12.6 = 411 inches, that's quite a bit of pipe.
     
  4. minno
    Joined: Aug 2014
    Posts: 90
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Canada

    minno Junior Member

    lol, maybe a raft :D,

    Definately gonna have to put more thought into the outrigger, 200lbs is way high now that I think about it, if I'm pulling myself up at the gunwale, 15" from the centerline and the pontoon on the outrigger is 45" from the centerline, it only needs to support ~70lbs, still too much 4"pipe.

    I'm not sure I wanna tackle a complex scarf joint on my first boat, stitch and glue seems a bit more forgiving.

    If this boat turns out well I'll probably start on another one using better materials, and since I'll have this one to use, I'll take the time to do things like scarf joints.

    minno
     
  5. messabout
    Joined: Jan 2006
    Posts: 2,996
    Likes: 199, Points: 63, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    A scarf joint is not complex. It is much easier and more reliable than finger joints in ply. Butt blocks are also an option.

    If you want to keep it light, then big box store plywood ain't gonna get it. There are several ways to go, but if ply is your choice, then bite the bullet and get BS1088 okumee. It weighs one third less than fir ply. Finishes more easily and is not inclined to check as fir ply will surely do. You could do a skin on frame for ultimate lightweight. SOF is cheaper too.....(you said you were cheap.)

    I think that you will want the boat to be longer than you have suggested and much narrower if you are going to use outriggers. A long skinny boat is easier to propel than a short fat one. (You said you wanted to maintain some paddling efficiency.) Long and skinny it should be.
     
  6. SamSam
    Joined: Feb 2005
    Posts: 3,818
    Likes: 156, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Those big jagged parts aren't a joint, they're going to be squashed together to form the two ends of the boat. The seam is with the two straight edges butted together.

    With such a different type of construction, sort of experimental, I wouldn't put much money into the materials either. The cheap ply will show where the problems will be, and paint will make it last for a few months at least.
     
  7. minno
    Joined: Aug 2014
    Posts: 90
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Canada

    minno Junior Member

    sorry for the confusion, my MS Paint skills end at straight lines or I'd have done a drawing with the bow and stern joined.

    The first drawing shows the 4X8 sheet with cutlines in red and the second shows the pieces ready to be joined. Next time I'll draw it on paper and take a pic, then you'll only have to puzzle out my terrible handwriting :)

    @ Messabout: I would love to go longer but 12 feet is about as long as I want to handwheel down city streets to get to the water, I could certainly build a narrower hull, but I require a fair amount of storage for gear so I don't want to go too narrow or I'll end having to strap gear on. This hull should row easily but not very fast, which is ok, I'm retired so I'm not in a hurry :)

    @SamSam, on the nose m8 :) This boat will never spend more than a couple hours in the water at a time and will be stored hanging on the wall inside when not in use so it should last just fine with paint on the outside and linseed oil on the inside.

    there are plenty of small boats out there built this way, here's one from Hanau's boatyard, the dug, an 18' hull made from one sheet of 1/2" plywood stitched and glued.

    minno
     

    Attached Files:

  8. Russ Kaiser
    Joined: Jul 2009
    Posts: 119
    Likes: 2, Points: 0, Legacy Rep: 35
    Location: Winston-Salem, NC

    Russ Kaiser Exuberant Amateur

    Oh, I get it - I have seen construction like this but he is going to cut the plywood in strips and then glue it back together right? I can't imaging getting a typical sheet of 3/8 inch plywood (that's awfully heavy anyway) to roll enough up to permit the ends to be joined.
     
  9. minno
    Joined: Aug 2014
    Posts: 90
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Canada

    minno Junior Member

    I may have to go with 1/4" plywood, but I'd prefer 3/8" if it's doable for durability, gonna be standing and handling heavy and sharp objects a fair amount, rather not have any impromptu fountains.

    I think that if I stitch it loosely with copper wire I can pull it into shape over a couple days by giving each stitch a twist or two a couple times a day. I don't really want to pull it in too much, I need the room, if I have to, I'll Torture it

    at the moment I'm kind of wondering if I should maybe build two big outriggers and tie 'em together with a platform instead of a hull, a catamaran might be much better for a solo dive boat.

    minno
     
  10. Russ Kaiser
    Joined: Jul 2009
    Posts: 119
    Likes: 2, Points: 0, Legacy Rep: 35
    Location: Winston-Salem, NC

    Russ Kaiser Exuberant Amateur

    Don't be a slave to material efficiency

    I have never been a fan of designs that try to build the most boat out of X sheets of plywood throwing little to nothing away. That said, they're a neat mental exercise and I have played around with a couple one sheet and two sheet concept boats myself. Just because you put it down on paper doesn't mean you have to build it and float it.

    That boat you pictured has a lot of length that isn't doing much for the boat in calm water, it certainly makes it harder (if not dangerous) to store :p

    You'll find that once you start building a boat you're going to dive down a project cost rabbit hole, a hole you won't get to the bottom of until your boat is floating and fitted out exactly like you want. If you get hung up on minimizing material expenditures up front you're still going to spend more than you planned but may end up with something that won't suit your purposes. That would be a shame.

    Rather than deal with a complex outrigger design where the rigger moves in and out, why not burn a few more calories rowing a broader design and enter and exit the boat over the transom? A longer boat should provide enough cantilever to allow you to get up without pulling the bow out of the water and would pull better. A short boat in any sizable chop is going to be miserable to row.
     
  11. Russ Kaiser
    Joined: Jul 2009
    Posts: 119
    Likes: 2, Points: 0, Legacy Rep: 35
    Location: Winston-Salem, NC

    Russ Kaiser Exuberant Amateur

    Here is a two sheet design where all the strakes are the same. It lends itself to butt block joinery because the bend of the strakes is very small. The bottom is made out of whatever is left after cutting the 6 strakes. If memory serves it's about 14.5 feet long and 3 feet wide.

    This design certainly won't work for you, it's seriously lacking freeboard, but designing your hull in this fashion is pretty easy using most drafting software or by modeling in paper.


    [​IMG]PolarArrayBoat by Russ Kaiser, on Flickr
     
  12. minno
    Joined: Aug 2014
    Posts: 90
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Canada

    minno Junior Member

    Well, ya talked me out of it :rolleyes: , I think I'll go with a PVC pipe Catamaran for now, it would be pretty much ideal for what I want to do, I'll put storage aft, probably just a couple of large plastic picnic coolers, a diving deck forward where I can dive or deploy/carry crab/prawn/shrimp traps, a water scope midships to watch the bottom for interesting spots to dive/fish.

    I've got an idea for a folding deck and built in wheels so I can get from home to the water and back easily.

    Thanks for all your help and patience :) once I round up the materials I'll start a new thread with even more nOOb questions :)

    Hope y'all are having a fantabulous weekend.

    minno
     
  13. Nnnnnnnn
    Joined: May 2012
    Posts: 60
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: MOW

    Nnnnnnnn Junior Member

  14. rwatson
    Joined: Aug 2007
    Posts: 5,839
    Likes: 277, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Thats a shame. Plywood will give you a lot more value for less weight.

    The temptation to see two instant 'hulls' from off the shelf items is a false economy both in cost and time, and eventually, in usefulness. Don't forget, you have a lot of high stress wheel joints, cross beams and assorted fittings to engineer, and still not have anything firm to sit on yet.

    PVC is brittle, not very strong and a lot heavier than most materials for the strength. It will also row like a pig, and not give you much performance joy.

    That link to 'one sheet boats' is a good start, but I would encourage you to think about 1/4" ply and a bit of epoxy and glass.
     

  15. minno
    Joined: Aug 2014
    Posts: 90
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: Canada

    minno Junior Member

    I just wanna get a boat in the water :(

    after discovering that pvc is a bit more expensive than marine plywood I'm back to exterior plywood, probably 1/4"/6mm if I can't find something lighter, with the cat design I don't need as much durability since I won't be walking/dropping things on the pontoons as they'll be protected by the deck.

    not sure how I'll make my pontoons but I'm leaning towards something like the X-cat pontoons, a bit more flotation in the front partly for when I'm on the diving deck forward pulling crab traps, and partly in case I decide to put a sail on her some day. :)

    Minno
     
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.