a ultimate MotorSailer idea, Dynarig motorsailer

I do not believe, a single masted Dyna Rig motor sailor will work very well. For course triming and stability this type of rig is asking for at least two masts if a Dyny Rig is really wanted.

As my present wife does not like to sail on my monohull cruiser-racer, because she hates sloping floors, when cruising with inclination under sails, I am looking presently for a 165 ft custom made catamaran with a Dyna Rig. Below a 165 ft Catamaran design, Kajan Yacht Design did for me. A very balanced and beautiful sailboat. We are presently in contact with several Naval Architects and Internal designers and most of all, a qualified yard, capable of building it. Not many yards in Europe can and are willing to accept such an order, mostly for its beam and because of the large carbon structures.



This pretty fast boat with backup diesel electric propulsion (generators driven by the VP props under sail) will have a rather low carbon footprint when underway.

Mike Kajan is a great designer. I am sure, we will hear from him more in the future.

HTMO9

Interesting vessel Mr. HTMO9:
What would the draft be? Retractable keels?
Maybe I will see you in the Bahamas, this one should be easy to spot
on the horizon with it's unique profile.

The draft will be around 3,4 meters with fixed keels. Draft is not the problem with such a big boat but the beam of 23 meters will exclude most of the well known sailboat yards, building that boat in carbon or Alustar. It just does not fit in their sheds. Means, we are talking about a yard capable of building much larger vessels. And my favorite yards have pretty long waiting lists.

I will post the progress of the project.

Wow, Beamy with a Big B, 75 feet..
You will need a Port and a Starboard crew.

The last of my fathers 1.200 ft bulkers, I was the Captain on, had a beam of 36 meters and the wheelhouse with its wing stations had a beam of 45 meters. If You wanted to talk to the watch on the other wing, You almost had to make a phone call in order to get a command through. That was beamy!

23 Meters of beam for a 50 meter boat may seems to be large but according to the naval architect, it makes a very stable, manouverable and fast boat and most of all, generates a lot of space. But I agree, mooring fees will be heavy. You have to pay for two slots, when med mooring.

I have a favorable Dutch yard for that project. They are capable to built it completly in carbon. Their shed would be wide enough. It only can't get through their door. The three yards at the Weser River could built it easily in Alustar but the carbon Dyna Rig would have to be build at Green Marine in the UK anyhow. But when building at the Weser River, I would be 80 years old, by the time the boat would be ready. Not due to the building time but the waiting list is so long.

Wide Body boat for sure. I can see a lot of twisting forces being generated from different wave pattens on the 2 very far apart hulls, so it will probably be designed to move around a bit instead of resisting the forces?

I know, carbon fibre is strong, but how does it react to salt water over time?
What kind of coating will stick to carbon? Epoxy?
Then use epoxy based bottom paint?

I know, a fool can ask more questions than 10 wise men can answer.

Good luck on the catamaran project, most people downsize as they age, but it looks like you are full speed ahead. Bon Voyage.

The final beam is presently calculated by the naval architects. It can and may go down to 20 Meters of beam but not less. The foundation of the mast will for sure have to be strong, as this is no monohull, where the mast can go down to the keel. Here we can only go down to the bottom of the connecting bridge deck. But the naval architect is confident to solve that problem. Standing rigging and Dynarig do not work together.

Well..
In all fairness: I wasn't suggesting the builders install hinges between the hulls with a bunch of
shock-absorbers to dampen the motion..

My thoughts was rather flexibility in the structure, like the wings on modern airplanes:
Build it to bend without breaking: B-787, a metal and carbon fiber combo super plane: Here is the wing testing video:

...food for thought, 23 meter beam...

Attached a comparison between the 23 meters of beam and 20 meters of beam. The naval architect and I believe, the 23 meter version looks more and better proportioned.



The final hull shapes, especially in the bow area, will be determined in the towing tank with thoughts towards buoyancy (and its distribution) resistance and optimum flow between the hulls (to avoid slamming under the bridge deck). The hulls may end up being asymmetrical in the bow area. But one thing is sure already, that beast will be fast.

If the specialists will come to the conclusion with their advanced CAD/CAM and fluid dynamic software, that the load of the Dyna Rig masts cannot be supported in hull structure with the shorter distances between the upper and lower mast bearings (in our case, a bit over 6 meters), compared to a monohull, we have a plan B.



A performance ketch rig with standing rigging, running aft stays and foresails. More complicated to sail, needs more hands to handle but still sailing upright because of the large beam of that Cat.

A lot of R&D in progress at the moment. Standby for more results.

HTMO9

Update

On strong advice of the Naval Architect, we have given up the idea of a twin mast Dynarig design for the large sailing Catamaran. Too much hassle with the mast foundations and far too expensive for it's advantages. We go for a sloop cat rig with standing rigging, a square top main sail and three forestays. With a 55 to 60 meter carbon mast, carbon park avenue boom and carbon sails a pretty fast and mean looking biest.



We have the choice of two European yards now. One would build with a carbon hull and the other would built the hull in Alustar.

HTMO9

Agreed on all counts. You're also going to discover that a 55-60m single mast isn't feasible either. The amount of structure required to keep it in the boat will be too expensive and heavy, in addition to the effects on your GA. Even with beam 'reduced' to 20m.

Split rigs like ketch/schooner as shown above will align better with primary crossdeck structure, although biplane configuration would likely be the only viable option. At which point Dynarig may be back on the table.

The Naval architect had calculated the supporting structure and the upper and lower bearings for the twin mast Dyna Rig. In contrast to a monohull, where the lower bearing may be located as low as on the keel and the upper bearing in the roof of the highest deck, the construction of the supporting structure on a catamaran is much more complex, as the possible distance between the two bearings is much lower. All of this structure in carbon fibre is rocket science and bloody expensive.

My present 165 feet monohull cruise-racer sloop has a 60 meter carbon mast. Combined with the carbon standing rigging, the sailing gear is not adding very much top weight on the boat with its lifting keel. On the large sailing catamaran Hemisphere with its similar mast height, the construction was rather simple and financially not over the top. We have the complete plans and calculations of this boat. Compared with a similar size Cat with a Twin Mast Dyna Rig, our 165 ft sailing Cat will only have half of the final sales price of the same boat with Dyna Rig. And the increase in performance, both for top speed and maneuverability, is not worse the uge amount of money and the time involved with the NA and the construction. We have no intention for racing anymore. Our intention is push button sailing with minimum sailing crew and upright fast sailing. The sloop rig will be very close to the Dyna Rig design as far as speed is concerned. And sailing around in circles is not our intention either. And beam counts on this design.

Below a picture of Hemisphere with its large single mast.


HTMO9

Attached the newest version of the 50 meter cat project, Mikael just send me. We are coming very close to the final external design. According to the naval architect, this rig is much easier to calculate and far less expensive on the carbon structure of the hull. The boat will be constructed and built in France. It is a fact that the best naval architects, designers and yards for cats are located in France. I was very lucky to get in contact with Mikael Kajan, who was able to convert my ideas and my taste into this beautiful design.


Now the proportions are perfect and the beam will be 20 meters. Not as easy to operate as a DynaRig but with modern electric captive winches still true push button sailing and last but not least for my wife, always upright sailing.

I wish all members and mods of YF and of course JF a happy new Year !!!!

HTMO9

Happy Birthday