Sailing canoe with Hobie Mirage drive - layout

Discussion in 'Boat Design' started by Eciton, May 9, 2017.

  1. Eciton
    Joined: May 2017
    Posts: 16
    Likes: 0, Points: 1
    Location: Virginia

    Eciton Junior Member

    Hello!

    I'm going to be building a 16' sailing canoe and want to put in a Mirage drive for additional non paddle propulsion. I have some questions as to where to place the mast step and the ideal location of the Mirage drive.

    I'm starting this summer by modifying an old canoe we have, a Sunrise 16' from Indian River

    specs on the sunrise: 16' canoe, 36'' beam

    Normally I would be taking it out with my 2 sons (about 80lbs between the two of them) and myself (170lbs) The would be sitting in front of me and the mirage drive.

    Questions:

    1.) where is the best place along the length to put the mirage drive for best propulsion? dead center? farther back? farther back would be easier for me to use the stock seating locations on the canoe - although they need to be lowered.
    2.) the mast step/thwart i had planned on putting about 3.5-4' back from the from the bow (just aft of the front seat). is there any reason to modify that?
    3.) is there an easy way to figure draft (so I can make sure the trunk for the mirage drive is above it) or should I just load it up and sit it in the water and measure from there?
    4.) can the mirage fins be used as a daggerboard or should i plan for the additional daggerboard or leeboard

    thanks!!!
     
  2. Tiny Turnip
    Joined: Mar 2008
    Posts: 683
    Likes: 141, Points: 43, Legacy Rep: 743
    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Hello and Welcome!
    The most critical relationship for successful sailing is probably the position of the centre of effort of the sail relative to the centre of lateral resistance provided mostly by the combination of the leeboard (yes you will need one) and the rudder. You also need to consider trim (load distribution fore and aft) and yes, I'd just load it up and measure tbh. You might want to consider outriggers. Have a look at the Solway Dory website, and the Open Canoe Sailing Group, They also have a very active facebook.
    Best wishes
    Adrian
     
  3. Eciton
    Joined: May 2017
    Posts: 16
    Likes: 0, Points: 1
    Location: Virginia

    Eciton Junior Member

    I've drafted up a sketch about what I am envisioning. I only drew one outrigger but I would like two symmetrical 14' long ones from 8'' PVC (I have 15 sticks of 15' long PVC from a project we just finished) End caps would be foam and glass shaped like the bow of a canoe.

    I have not marked the leeboard as im not entirely sure where the best place is. thought I might make one that could be moved around until I could find the best spot. Sail type will likely be a bermuda rig, about 40sqft.

    Currently my biggest concerns are having so much weight in the back and ability to control the sail from the back overtop of my kids.

    Any thoughts?

    sailingcanoedraft.jpg
     
  4. JosephT
    Joined: Jun 2009
    Posts: 856
    Likes: 106, Points: 43, Legacy Rep: 218
    Location: Roaring Forties

    JosephT Senior Member

  5. Eciton
    Joined: May 2017
    Posts: 16
    Likes: 0, Points: 1
    Location: Virginia

    Eciton Junior Member

    tandem-island-studio-top-golden-papaya-150109_png_5000x5000_rotate90_generated.png

    Looking at this picture I'm not far off of hobies layout. I wonder how they handle with just one adult in the back seat though.

    To truly flatter them i guess the seat/mirage could be moved forward a foot and the outriggers shortened.
     
  6. upchurchmr
    Joined: Feb 2011
    Posts: 3,051
    Likes: 149, Points: 63, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Pvc is heavy, not very stiff for the weight, but strong.
    Something else would work better.
    Length of the outriggers (amas) depends upon how much sail area you want to use. Hobies have a relatively small area.
    Size or submerged volume will depend upon how strong your mast and rigging is.
    Small amas can submerge early, keeping you from breaking the mast or rigging.
    Larger ones submerge in higher wind, putting more force on the mast and rigging, so they have to be stronger. But you go faster - more fun - IMHO.

    You need to figure out where the center of effort is for the sails. Generally you would just use the center of the combined area. So you need to know the size and shape of the sails you will use.
    Plot that point on the boat hull, then place the center of the leeboard a little aft of that.
    With a typical leeboard you can swing it forward or aft to get the position fine tuned until it works best.

    Id be concerned with your weight in the far aft also, you might have most of the bow waving about in the wind - not good for good control.
     
  7. Tiny Turnip
    Joined: Mar 2008
    Posts: 683
    Likes: 141, Points: 43, Legacy Rep: 743
    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    I concur with all that upchurchmr has said.
    I have used amas made from pipe with end caps, and found them to be draggy.
    Also, I'd be concerned that long, straight amas may hinder ability to turn readily. A bit of rocker would help. Its not too hard to make successful ply amas from scratch.
    For comparison on size of amas, my 16ft canoe tri carries 88 sq ft of unstayed ketch rig, and the amas offer 200litres of buoyancy each. If I'm close hauled in a F5, I can start to drive them under, but its time to back off then.
    You might get on better with you and the mirage drive in the middle between the thwarts, and one child forward and one aft.
     
  8. JosephT
    Joined: Jun 2009
    Posts: 856
    Likes: 106, Points: 43, Legacy Rep: 218
    Location: Roaring Forties

    JosephT Senior Member

    The solo model has the seat centered. Remember with smaller boats center of gravity is very important. If you're going solo I would advise centering the seat. I paddle solo canoes & kayaks all the time. Unless you want to stuff dead weight up front to balance it out your bow will rise and stern will squat...not good for performance. It will be less sea worthy as well if you're out of balance.

    [​IMG]
     
  9. upchurchmr
    Joined: Feb 2011
    Posts: 3,051
    Likes: 149, Points: 63, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

  10. Eciton
    Joined: May 2017
    Posts: 16
    Likes: 0, Points: 1
    Location: Virginia

    Eciton Junior Member

    thanks for the help guys. ive read a lot of the threads over there, i think the biggest difference is mine is trying to squeeze in both the sail, the akas, and a mirage drive while retaining enough room for my kids to be there reasonably comfortably.

    This is my latest design to make the weight distribution better and after a couple people told me about PVC making poor outriggers. There is a local supplier of 3 ply 1/4'' birch that I hope coated in epoxy will be sufficient. In this design the kids will sit forward of the mirage trunk on a little bench. (not shown) I think the weight distribution is way better. the amas are 8' long and 14'' wide at the widest. I am unsure as to whether having them this far forward is an issue, i have read differing things.

    Can you mount a leeboard on a rail between the akas or does it have to be right up against the canoe?

    Any input welcome. I hope to get started tomorrow as I have a free weekend, and that doenst happen often.


    sailingcanoedraft2.jpg
     
  11. upchurchmr
    Joined: Feb 2011
    Posts: 3,051
    Likes: 149, Points: 63, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    You can put it on the side of the canoe or on a rail. Either will work the same.
    However you need to layout the sail you expect, so you can locate it.
    For a reasonable size sail (in my mind) the leeboard might need to be where the aft aka (cross arm) is.
    But who knows until you draw it out.

    I was thinking about putting a Laser sail on a kayak I have.
    When I finally laid out all the parts, the board would have had to be exactly in the middle of the cockpit.
    Wouldn't work for what I was planning.

    I hope you are planning on a rudder (I only mention it since there is none on the sketch.
     
  12. philSweet
    Joined: May 2008
    Posts: 2,327
    Likes: 190, Points: 63, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    I don't know if this is even feasible with the Mirage drive, but in an ordinary 16' canoe, to operate solo, you sit in the front seat and paddle it backwards. Is the Mirage drive installation readily reversible?
     

  13. Eciton
    Joined: May 2017
    Posts: 16
    Likes: 0, Points: 1
    Location: Virginia

    Eciton Junior Member

    reversible like you can take the mirage out and turn it around to go backwards... yes
    reversible like I can get rid of the mirage trunk and hole in the canoe... not easily

    i was considering this earlier today as when i have solo'd a canoe i have paddled it stern forward from the front seat as you are describing. i think the problem is the seating is much more elaborate in the mirage system (think recumbent bike seat) so i'm not sure how well reversing it will work. Would make it hard to reverse the mast thwart and step as well unless I glassed in two

    plan to have a rudder but figured there was only one place to put it so I didn't illustrate it.
     
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.