Picnic Boat - canals and sheltered waters

Discussion in 'Boat Design' started by cameron.d.mm, Feb 7, 2010.

  1. cameron.d.mm
    Joined: Mar 2009
    Posts: 68
    Likes: 1, Points: 8, Legacy Rep: 14
    Location: Ontario, Canada

    cameron.d.mm Junior Member

    I am in the planning (dreaming really) phase of building what I'll call a picnic boat. Last year I built a small wooden boat (~9 feet) for use in the canals and inland lakes near where I live. My wife and I enjoy it, and have found that it goes well under both oar and electric trawling motor power. It has been great for what I wanted: a small car toppable, basement storeable, boat for getting out on the water a few hours at a time. (You can see pictures of the boat here) [edited the link to lead somewhere useful]

    However, I can now see that there will come a time in the (hopefully) near future where we'll want something a little more. Something that is more comfortable for two adults and their gear. Something that you might be willing to sit in for most of the day. I hope to power it electrically, but haven't deiced exactly how yet (trawling motor, dedicated inboard electric motor, etc...).

    I have attached a lines plan generated by FREEship. I would be interested in hearing people's impressions and comments of the hull. I has inspired by the lovely Winsome by Swallowboats from the UK.

    Hull 01_Linesplan_tb.png

    click here for an even bigger size


    Some of the vitals:
    -length 17' (16.6' at wl)
    -beam 3' (2.5' at wl)
    -displacement 0.7' (~550 lbs)
    -KAPER calculations indicate ~3 lbs resistance at 3 kts

    I am of course rather ignorant when it comes to designing a boat's hull. I welcome any comments of suggestions that anyone would like to make. I think there are already things I will change, but I wanted to begin a discussion with people more knowledgeable than myself.

    My questions revolve around things like the flatness of the hull. The winsome is quite flat at the back, but the hull pictured here is more v like. What are your impressions of stability for the hull pictured? Also, would there be a great benefit to raising the last bit of the transom out of the water?

    I'm really dragging this out, but just a few more quick notes. One thing that occurred to me as a possibility was creating a kind of well near the back of the boat, that a trawling motor could fit through (kind of like the box for a dagger board). I don't know if there would be any benefits to something like this, or just drawbacks. Does anyone have an example of a boat that works like this? (Let me know if I haven't explained myself clearly.)

    Currently I am thinking of building the boat cold molded, and do plan on putting some kind of topside decking on it, like the winsome.

    But, enough from me. I'll sign off now.

    Thanks for your time.
     

    Attached Files:

  2. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    The reverse transom is sexy but not appropriate. Rake the top aft about 15 degrees and use a standard electric trolling motor attached to the transom in the conventional way. A boat of this size and propulsion method does not benefit much from the vee bottom that you show. In particular there is no advantage in using concave bottom sections. This is not a Riva. Take the concave out of the bottom and you will have no need for the cold molding method. Yes, get the aft bottom up so that it just clears the water.

    Why not simply buy a good canoe and clamp on the electric and get in the water a lot sooner. If you want to build a boat for your purposes there are a lot of plans that can be had cheaply. A good example is the Cinnamon canoe that has a square back and the motor is enclosed in a well like you mentioned. It is commodiousand, stable and should be quite comfortable for day tripping. Plans are available from Canoe and Kayaking Magazine. This boat is a stripper, the plans have full sized section patterns and the cost for plans is less than ten dollars as I recall. The designer claims that it will go 12 mph with a 2HP Honda. I doubt that it will, but it can be pretty speedy as canoes go.
     
  3. thudpucker
    Joined: Jul 2007
    Posts: 885
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    Location: Al.

    thudpucker Senior Member

    I lived near a lake/swamp.creek that had all the excitment you could imagine for a small sight seeing boat like your idea.

    The Stumps were all at water level. So running up on a stump was pretty common.
    Your slightly V is a lot easier to get off a stump than a flat bottom for two reasons.
    Going forward if you center a stump, the flat bottom boat will be half way along the boat, and stuck high and dry.
    The V bottom tends to slew off to one side or another. If you center it and the slew doesn't happen, you can get so far up on the stump that you tip over before you know whats happening.
    The lesson for me was to do the flat bottom, not the V.

    Going up the creek with the flat bottom was similar. You find fallen trees you have to glide over. Go fast enough and you can 'Glide' over a tree that's plumb half way out of the water.

    That's defiantly a job done better in a flat bottom boat.

    Then the Lilly pads and beaching in the mud.
    The flat bottom might drag going through the Lilly pads, but going up onto the mud is a lot steadier in a flat bottom boat.

    The older (and more top heavy) you get, the more you'll appreciate the flat bottom boat.
    An electric will make a flat bottom go nearly as easily as it will the Canoe or v.
    Just make sure you have something all the wary round the boat to use for handles.
     
  4. cameron.d.mm
    Joined: Mar 2009
    Posts: 68
    Likes: 1, Points: 8, Legacy Rep: 14
    Location: Ontario, Canada

    cameron.d.mm Junior Member

    My thanks to you both for looking over my post.

    All of your advice sounds sage, and it also fits with experiences I've had in the past. I know that I've used flat bottomed aluminum canoes to 'climb' over logs and other river derbies. A good point Thudpucker. I'm not sure how much of that I'll want to do with this boat, but keeping options open is always good.

    I looked up Riva... What'd'ya mean it ain't gonna be a Riva, Messabout?! But, in all seriousness, I don't mind taking my time and the longer road. I enjoy the process of building boats, and other things. After all, there are already several good canoes, a Pygmy Wineglass Wherry, and my other homebuilt boat all available for my use. I want something else. Something that is 100% my own (for good and bad). It's just the way I am.

    I'll think over everything you folks have said, and then post another lines plan in the next day or two.

    Thanks again!
     
  5. cameron.d.mm
    Joined: Mar 2009
    Posts: 68
    Likes: 1, Points: 8, Legacy Rep: 14
    Location: Ontario, Canada

    cameron.d.mm Junior Member

    I promised I'd upload another sketch (I just know you're all dying to see it), so here it is.

    Hull 02_Linesplan.png

    I've flattened out the bottom of the hull considerably, raised the transom, and shortened and widened the hull (closer to 15.5 x 3.5 feet now). These changes also mean that a 0.5 foot draft now gives similar displacement to a 0.7 foot draft with the first hull.

    I haven't removed the raked transom, as I'm not yet ready to see it go. Thanks for the info about the Cinnamon, Messabout. I looked at the way it has a well for the motor. I'm going to think about this some more. [edit: is the canoe you refer to the one located here? If so, I may not have explained myself clearly. I'll try to put up a sketch sometime soon.]

    I'll keep posting my thoughts and sketches here.
     

  6. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    I used to go fishing up in Ontario with a bunch of guys from Kentucky.
    We always took our light aluminum's along because beaching meant Rock-jumping.

    For that reason, I'd say the "Chin" of your boat is too sharp. Angle it back so you don't crash into the rocks, but glide up over the first rocks.

    Wider and softer (less of an angle side to side) would be better when the wind blew the chop up.

    I like your transom lift. If you have to deal with a following sea, you wont suffer with that following sea overtaking you right down the back of your pants.
     
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