Freedom Series Boats

[SeaHusky]

I have been watching Jim Browns you tube videos of the sea runner 31 and it is a very intriguing design. It was a few years since I drew junk rig sail plans from Arnes instructions but what you have looks good! I see your sail area is 46,5 square meters. Is that correct? If I recall correctly Arne thought that  28 was the largest sail area one could comfortably manage on one mast. Larger then that he recommended two masts?

[Frank]

Friends Brad and Brenda base out of the Florida Keys but have crossed to winter in the Abacos for years now with their tri. Great folks, fast boat!
With the right conditions....their speed is in the teens!
Just confirmed with Brenda that it is a Sea Runner.

[Owly055]

I have been watching Jim Browns you tube videos of the sea runner 31 and it is a very intriguing design. It was a few years since I drew junk rig sail plans from Arnes instructions but what you have looks good! I see your sail area is 46,5 square meters. Is that correct? If I recall correctly Arne thought that  28 was the largest sail area one could comfortably manage on one mast. Larger then that he recommended two masts?

     That is correct.    Arne drew this sailplan for me, so he must have changed his mind on the limits.    The only real limitation is the weight on the halyard, which is typically run through a multipart block so the sail may be easily hoisted by hand, but there is no reason why a winch can't be used.  Sheet loads are never heavy with the balance area forward of the mast transfering a very significant percentage of load to the mast itself that would ordinarily be on the sheets.
     Since Arne drew up this sail plan, I've determined that due to structural and space considerations, the mast has to go about 20" further aft, and be offset about 8" to one side, which as unusual as it sounds, has been done before for the same reason, and works fine.  The location and area of the sail would remain more or less the same, but due to the increased balance area, only a split junk rig would work properly.
     Thankfully "talk is cheap", and I can work out this stuff far in advance of actually doing the conversion or even buying the boat, which somebody else is paying slip or storage fees, insurance, etc for right now.    I will be constructing a full size simple wood and cardboard mock up of the interior spaces to determine to what degree access will be compromised by the mast.   The forward part of the boat is not a heavily used area.  The two sea berths extend from the first forward compartment under the cockpit seating, in the portion of the boat with the least motion, the best sleeping area.   Forward of this is a dressing room, which has full standing height.  The sleeping area does not due to the centerboard trunk, leaving only about 4.5 feet.  The dressing room provides a place where you can stand and dress, and has the wash basin for the head which is another step downward.   Aft of the cockpit is the most important area.  The galley, which is full height, and the dining and lounging area aft of the dining area, which is a step up and not full height, and has windows all around.    My original mast location was dead center in the dressing room, which is a small area.   The location was selected because of the need to keep the mast from blocking doorways, and seemed the only viable location.  This of course compromises the small space making it inconvenient.   It also places the mast forward of the primary structural elements of the boat which are the centerboard trunk and the massive bulkhead forward of it to which the struts are attached.   This intersection is the ideal location in terms of structure, but placing the mast in the middle of it leaves only about a foot on either side of the mast, and I can't weasel through a space that small.  Shifting the mast to one side 8" makes this opening useable if a tad snug, takes advantage of the structure here, and leaves the dressing room a useable space.    The only other alternative is a strutted tabernacle right on top of the heavy bulkhead with about 6 struts going to strong points.   This would NOT be pretty, but would have some distinct advantages.  The tabernacle in this case would have to extend to the height where the boom crosses the mast, and be quite strong.   The struts would then angle downward to the 6 hard points where the coach roof meets the 3 bulkheads involved.    An ugly contraption at best.   
     Aside from the mast relocation, there is the issue of center of effort and center of lateral resistance.  The center of effort is going to move aft which will give weather helm which will have to be counteracted by some strategy to move the CLR aft.   I have several ideas on how to do this.
     What it all boils down to is that this is NOT going to be a simple conversion, but I'm not someone to go into a project like this with my eyes wide shut.   I'm very very good at visualizing and running through mental simulations of what the issues will be, and devising solutions to them before other people even know they exist.    It's what has made me successful and sought after in my business.   I see the problems before they happen, and know just what to do weather it's something I'm designing and building or someone else's project.  I'm just wired that way.

                                                                                H.W.

[SeaHusky]

Have you tried sketching a two-mast rig to see if you get better options for mast placement?

[Owly055]

Have you tried sketching a two-mast rig to see if you get better options for mast placement?

     I have not for several reasons, though the thought has crossed my mind several times.   The main reason is simplicity, and the other structural.  First of all, the mast pretty much must go just forward or aft of the main forward structural bulkhead, for structural reasons.  That's where the strength is in the boat.   A foremast would be in an area with little structure, and would of necessity be small.  It would not have the "bury" because the coach roof ends well aft of the possible location.  Logically a head stay as is used on the Freedom series yachts, carrying jib with a furling device would make more sense for balance.  It would accomplish the same thing with less structure.   My goal is simplicity, I would like to have one sail, period.   The junk rig sail is a low stress sail that reefs instantly, and has very light sheeting loads.  The jib is a reasonable compromise, but a foremast would seem not to be practical in this boat.   The whole project involves some serious challenges due to the very small interior.    Plunking the mast down directly through the dressing room still makes sense to me, but it would make the dressing room as it exists pretty useless except for stowage.  However if the mast is offset to one side at the aft end of the dressing room by 8-10 inches so it allows access, it would have minimal impact on sailing due to the rig being 33% balanced (33% forward of the mast), and the very wide stance of the trimaran.    My thinking at the moment is to do this, and to build an oversize balanced transom mounted rudder with a trim tab that can either be set so as to create a neutral helm, or driven from a windvane.    Some of these boats have a transom mounted rudder, others have the rudder forward.  The ideal boat would have a forward rudder on a skeg, and a transom rudder would be added.  This forward skeg mounted rudder could then be used as lateral resistance as if it were more keel, or even set up to be deflected to one side or the other as needed for trim, while the transom mounted rudder would be the steering control.   I don't believe the forces would be very high.    An additional trimming tool on a sailboat is not a bad thing.

                                                                                                               H.W.

[Frank]

Just looking at boats for sale on a rain day. Always entertaining.
Thought of Owly when I saw this one.
28ft
Cat ketch
Free standing carbon fibre spars
Diesel
Only 2.5ft draft board up!! (I love shallow draft!)
Etc etc
Note...price is Canadian!
About $6850 USA$$

http://www.kijiji.ca/v-sailboat/barrie/1981-freedom-cat-ketch-diesel-drop-keel:-2-5-draft-easy-project/1261371487?enableSearchNavigationFlag=true