Row boat conversion

Discussion in 'Sailboats' started by interviewer, Jul 20, 2005.

  1. interviewer
    Joined: Jul 2005
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Windermere, Florida

    interviewer New Member

    Does anyone have any suggestions where I can find plans or information to convert a 13' fiberglass rowboat to sail power? Any leads appreciated.
     
  2. Shife
    Joined: Feb 2005
    Posts: 148
    Likes: 1, Points: 0, Legacy Rep: 9
    Location: Michigan

    Shife Anarchist

  3. lewisboats
    Joined: Oct 2002
    Posts: 2,329
    Likes: 129, Points: 0, Legacy Rep: 1603
    Location: Iowa

    lewisboats Obsessed Member

    Well, here is some basic info. To start; ask yourself:
    1: what kind of lateral resistance are you planning? Do you want a daggerboard, centerboard, leeboard or some kind of full keel. For all but the leeboard, you will need to figure out your rig first.
    2: if you go with a leeboard system, this will, of necessity, be at max beam and parallel to the centerline of the boat. This will affect your rigging choices because you will have to work out your center of effort of your sail to balance your CLR rather than the reverse.
    3: If you go with one of the other choices, then the CE (Center of effort) of the rig will help determine the CLR (center of lateral resistance) of your underpinnings, and concequently your placement of fins or foils. Also, you will have to cut holes in the boat for two of the four choices. Both a centerboard and a daggerboard require a case into which they retract, necessitating surgery to the hull. A leeboard and a full keel will not. A full keel will not allow you to run in very shallow water but will protect the hull when you ground. A pivoting leeboard will swivel will shoal water but not protect the hull from crunching.
    4: you will have to incorporate a rudder and this is also a factor in your calculation of CLR, along with any existing skegging (new word, love the english language) that the boat has.
    5: you will also have to build some kind of step and partner for the mast. The step is a socket that the bottom of the mast rests in and the partner is an athwartship (across the hull from one side to the other) piece that helps support the mast at the correct angle of rake, usually a few degrees towards the back of the boat. You will also need to run the appropriate running lines to control the sail, as determined by your choice of rig style.

    Now I know that there are many people here that are more knowledgeable than me here so I hope that the pipe up and correct anything I may have gotten wrong or missed and also give you their opinions

    Steve
     
  4. interviewer
    Joined: Jul 2005
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Windermere, Florida

    interviewer New Member

    rowboat conversion

    Thanks for the help. I'm looking for something simple...daggerboard, rudder, plus sail of about 70 sq. ft. I may even adapt Sunfish parts if I can't find separate plans.
     
  5. sharpii2
    Joined: May 2004
    Posts: 2,246
    Likes: 329, Points: 83, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Dear interveiwer:

    I think the above advice is sound and reasonable. However, there is another alterative. It is possible to use the rudder as lateral area as well as steering. The trick is is to step your mast far enough aft. An old sunfish rig would be perfect for this. This way you only have to worry about two problems; stepping the mast and mounting the rudder. Neither one of these tasks should require either cutting a hole in the boat (for a center board or dagger board) or adding an outside keel.

    Their are three caveates about this plan:

    One, that the rudder blade probably should be long and shallow (particularly if your boat has a shallow or flat dory like bottom),

    Two, the placement of the sails Center of Area (CA) for this setup is unknown. A reasonably accurate model of the boat (Length Beam proportions and rough approximation of bottom type.) and proposed rig may be neccessary to discover just where that is, and

    Three, will the boat be able to stand up to that much sail. Most real rowboats
    (boats designed exclusively for rowing. Not your typical small riveted aluminum outboard skiffs which are really intended to plane) tend to be somewhat tender because having a narrow flat bottom or a relatively deep V bottom makes them row easier.

    The model making I have in mind does not have to be mantle piece quality. It can probably be made out of either a block of Balsa or several layers of blue insulating foam. the important thing is to get the cardinal proportions right. Length to Beam and usual Draft to Beam as well as top veiw shape. The rest you can do by eye so that the model strongly resembles the real thing in bottom shape. The rudder blade area should be about one thirtieth of the sail area.

    The trick here is to get the model to sail both up wind and down wind. When it can do that, you'll have your rudder design and mast placement down. Then all you have to do is scale it up to the real boats size.

    Bob
     
  6. GTS225
    Joined: Jun 2011
    Posts: 42
    Likes: 2, Points: 0, Legacy Rep: 23
    Location: Waterloo, Iowa

    GTS225 Junior Member

    I hope no one minds, but I'd like to resurrect this old thread.
    Keep in mind I am more of an "eyeball engineer" than a technical engineer. I also consider myself as a.....ummmmm....."recycler", (yeah, that's it), rather than a cheapskate scrounger.

    I am about to buy a small rowing/outboard boat of 13' length. It's an aluminum hull, and in need of at least new transom ply. I was thinking that while I was doing the surgery to the transom, it might not be too bad of an idea to perform a sailing rig conversion to it.
    This hull is outfitted with three seats, aft, center, and forward. I'm toying with the idea of a daggerboard trunk tied into the aft side of the bow seat, with the mast step and partner also incorporated into the bow seat, or leading edge of it. I am also wondering about the possibility of a full keel.

    I ran across this; http://freepages.genealogy.rootsweb.ancestry.com/~fassitt/cranks/dinghy/dinghy_rig.html#(T)
    and it looks like it might lend itself well to my idea.
    I do have a question, though, concerning item #3 from Lewisboat's post above. If I were to attempt a full keel, what would be the definition of "full keel"? I have an idea that a full keel, from bow to stern, of, say 6" depth, made of 1/4" aluminum stock, might do what's needed but am concerned it would adversly affect the ability to change heading with the rudder, or outboard motor if I am using it.

    What say the more learned of this group?

    Thanks.....Roger
     

  7. lewisboats
    Joined: Oct 2002
    Posts: 2,329
    Likes: 129, Points: 0, Legacy Rep: 1603
    Location: Iowa

    lewisboats Obsessed Member

    A full keel is a misnomer nowadays... It no longer starts at the bow but more like 3/4 to3/5 the way aft of the bow and tapers down and aft (called "drag") to flatten out at the desired draft and run to the stern or near stern. Often there are cut outs for propellers and also "Bites" to lighten it and reduce the area somewhat when it isn't necessary. Full keels are less than ideal for a boat of the size you are looking at...especially as a retrofit. It should be designed in from the start. Besides...I don't think your boat has the rear rocker to support a full keel. I assume it originally was a motor boat fitted with oarlocks for when the motor crapped out or for short distance pulling in shallow waters? If the boat you are considering is one of these then don't expect stellar sailing performance from it...the hull isn't designed for it. You're transom will be partially immersed all the time which creates a lot of drag and will slow you down. It will be ok to putter around in but you might consider keeping the boat as designed and building a PDRacer...It will take about the same amount of effort as retrofitting a centerboard/daggerboard and mast step/partner and will perform much better.

    Here is a picture of an old timer...the keel really doesn't start until about 1/4 of the way aft...where the lines of the hull start to sweep up (down?) towards the transom.

    [​IMG]
     
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.