All of us on Team Möbius had last week off as it was the big holiday for the 5 day Hajj pilgrimage to Mecca for the Muslim world so Christine and I seized the opportunity to go eXplore more of the many sites surrounding us here in Antalya Turkey. I put together THIS separate post with pictures of our week’s adventures in this post if you’d like to see more of the awemazing sites we saw.
This week it was back to the shipyard at Naval Yachts and back to work for all of us and more time to get to know our way around Möbius now that she is right way up at last. I have some pictures of the week’s progress but I shot a series of videos to take you on a bit of a guided tour through all the spaces on Möbius now that she’s right side up and hope it will give you a better sense of the layout and scale of our soon to be new home.
The last remaining area of the hull needing to be assembled is the prop tunnel and skeg and this rendering shows what it will look like when finished.
Enver is standing on what will be the aft section of the prop tunnel as he and Umit complete the welding and preparation of the 25mm/1” thick frames where this 15mm/ 5/8” tunnel plate will be inserted. The large hole by Enver’s foot is where the 225mm/ 8” diameter aluminium rudder tube will be welded.
The aft most tunnel plate is lifted in place and mechanical jacks are used to carefully move this complex plate into just the right position on all axis. With everything lined up the tunnel plate is tacked in place to the 25mm thick frames on the inside.
Then the outer edges of the tunnel plate are lifted up tight against the edges of the curved cut out in the hull plates until they are flush and tacked to hold them there.
Rather than creating a full width Engine Room by running a bulkhead across the whole beam/width of the hull as is common, we have decided to create a smaller Engine Room Enclosure that wraps around the Gardner and Nogva CPP servo box to create a smaller dedicated Engine Room.
Can you guess what this equipment is for??
This black and silver cylindrical part looked to me like it had been brought over from some 1950’s science fiction movie set.
The partially welded Day Tank was put onto a rolling table cart to help position that cylinder the right distance from the hull.
On the inside Master Welder Sezgin and this visiting expert were carefully positioning these rectangles of black plastic film and taping them over welds along the whole length of the hull in about 20 places.
Then similar sized plastic rectangles were taped in the same spots on the outside of the hull plates.
A beam of light from the cylinder was used to aim it at the center of these outer plastic rectangles and little wooden wedges were used to hold the steering wheel like ends of the mystery cylinder in that position.
Solved this mystery yet?
Would it help if I told you that this plastic divider box is full of small lead numbers and letters of the alphabet which the mystery guest carefully taped to the outer plastic rectangles?
Or does the acronym NDT ring any bells for you?
CORRECT!! It was time for the first set of Non Destructive Testing aka NDT of the welds! This is the X-Ray machine you’ve been seeing and hence the safety issues of keeping everyone clear while X-Rays are momentarily present. Remember how your dentist used to step out of the room when they were X-Raying your teeth? Same thing here.
Those lead letters and numbers were taped to each plate with the plate #, Möbius and other identifying information that appears on each developed film plate. Other forms of NDT are being used as well to check for things like porosity and we will have the results back in the next few days.
OK, let’s climb up on top and explore the various compartments of Möbius now that she is right side up. I’ll start wtih some very rough renderings of just the interior cabinetry to give you an initial orientation of where things are and how the living spaces fit together and then I will let you watch the videos at the end for a tour through these spaces as they exist in very rough form right now.
Zooming in a bit on the inside of the SuperSalon and moving counter clockwise from the bottom corner is the Galley with the Dining area forward and adjacent, stairs down to Master Cabin, Main Helm chair in blue front and center, Lounge Chairs upper corner and along Port side, cabinet of drawers at the base of the stairs coming down from the aft deck WT entrance and the stairs going down to Christine’s Office and the Engine Room/Workshop access.
We have changed the layout of the Galley cabinets to have a cabinet and countertop running along the back of the adjoining Dining table seat back but not had time to update this model yet.
It is difficult to capture from any one angle but this is looking from the Stbd/right side into Christine’s Office and the Guest Cabin. You are seeing the inside of a large full height wardrobe in the bottom left corner of this shot with a pull out Queen bed to the right along the hull which will also have a fold out Pullman bund above. Christine’s Office desk and chair can just be seen to the left of the wardrobe running along the Engine Room wall and the doorway on the right side of her desk leads to the shower on the left and head/toilet on the right. This also leads into the short hallway that connects the stairs down from the SuperSalon on the right to the Engine Room/Workshop WT door on the left.
These plan views of the two floor levels show the scale and layout of the interior spaces. As in the rendering above the Galley counter against the Dining table seat back has not been added to this drawing yet.
Philip and I serendipitously met back in 2009 when we were both single handing our sailboats around the world and were waiting to check into Ecuador. We had lunch together and have become best of friends in the years that followed as our wakes continued to cross and we shared many anchorages throughout the entire South Pacific.
Thanks for a GREAT visit Philip hope you can make it back before or for the launch around the end of next year.
This week’s video below is much longer than usual as they are running in real time rather than the usual 4-8X speed I’ve used on the previous videos but I hope my guided tour will bring the interior spaces more to life for you as it is doing for us. Use the fast forward button as needed to get through them quicker if you get bored.
Enjoy!
Congratulations on reaching the righting milestone. I am impressed with the speed and quality of work from your team.
I have been wanting to ask for a while about the large propellor. I have held off as I think this question is linked to your choice of engine and transmission and could inconvenience you with preparing a long reply!
It’s just when I see the prop tunnel, I realise this choice has had a significant impact on hull shape.
I know you will want the power to hold of a lee shore in a super gale. But for 99% of cruising time, I would imagine you would want maximum efficiency at what would be considered hull speed. Getting the boat to cruise efficiently at 10 (?) knots without climbing her bow wave all day. Does a large prop / tunnel help or hinder here?
If a subsequent builder of a second boat chose a modern type diesel turning a smaller prop on a hull without a tunnel, what do you think would be the performance differences?
Thanks
Thanks Nigel. Flip Day was a very big milestone for all of us here and we are definitely enjoying working on her right side up now and being able to see her form emerge more and more every day.
A long reply from me?? Lucky for you I am a bit short on time so this response will be shorter than my usual ramblings.
As you appreciate the entire propulsion system of such boats are a set of complex and entangled relationships between a lot of different factors which you hit upon such as the shape of the hull itself, prop size and type, engine torque and power, hull and fuel efficiency, motor selection and so on. Changes to any one of these aspects affect at least some of the others and so it is that typical and constant balancing act to find the just right combination for each unique boat and owners.
The prop tunnel was certainly deeply entangled within our myriad of propulsion design decisions and we did a lot of work with Dennis both with and without a tunnel. As you’ve seen quite vividly in the recent posts we decided to go with a prop tunnel and our prime drivers for that were what we believe will be improved overall efficiency of the hull itself as well as the propulsion system and the reduction in draft that will allow us to go places other boats cannot and be true to this being an eXtreme eXploration Passage Maker.
Based on a lot of research and talking with others my limited understanding is that in general propeller efficiency goes up with bigger and slower props. I’ve had some explain and push the point that in purely theoretical terms a one bladed prop turning at less than 100 RPM would be the most efficient! To that end though we used this to drive our decisions towards a larger and slower prop and then worked with the experts to design the ideal for Möbius. We have ended up with a prop OD of just a hair over one meter and with a reduction ratio in the CPP gearbox of 2.95:1 so with the Gardner likely ticking over at about 1200-1500 RPM max this prop will be spinning about 400-500 RPM. There was an option to go with the higher/slower 4.15:1 ratio as well as a 3 blade and 4 blade CPP prop and after months of work with our engineers, especially so the ones at Nogva who make our CPP system, it was decided that the 2.95 ratio driving a 4 bladed prop was the just right combination.
Your observation matches ours that we definitely want to be confident that our propulsion system is fully up to the challenge of lee shores in strong gales and other demanding situations but at the same time these are very rare and day to day cruising wants to have maximum efficiency of hull speed and fuel burn. More good examples of that balancing act. However in our case we don’t think these two scenarios are at all mutually exclusive. While it will remain theoretical until we launch and start getting real world data, all our calculations and computer testing say that that we should be able to have both the tremendous “grunt power” from the huge torque from the mighty Gardner slowly spinning the large CPP prop and that those same characteristics will give us maximum efficiency at hull speed. To your astute question as to whether the large prop and tunnel helps or hinders, our estimation is that it helps with both the rare lee shore type scenarios and highly efficient 10+ knots cruising.
It would be most likely that the second XPM78 boat would use a modern type diesel that would have higher HP and RPM but less torque and so the prop size would likely be less as well. Indeed Artnautica and Naval Yachts are already having that discussion and research now. And the question of twin screw vs single comes up again for sure. However in my opinion the largest decision difference would be between fixed and CPP props. My estimate is that that a modern diesel with a fixed prop would work just fine and I don’t think there would be much difference in the cruising speed. It would have higher acceleration and get up to that cruising speed sooner, but it would be affected more by large wave action and be significantly less fuel efficient. I will say that I have come to believe that in terms of overall performance and efficiency a CPP prop system provides significantly better propulsion system in these type of ocean crossing passage makers.
In the end I think it must always be remembered that there is no singular “best” design or decisions for any of these things however there is a just right set of choices for a given boat and owner. The choices you are seeing coming to life in Möbius are the ones which Christine and myself, along with LOTS of expert assistance, believe to be the just right combinations for us and that Möbius will be our Goldilocks boat for hundreds of thousands more nautical smiles for us. Along with you I’m sure, we all anxiously look forward to putting all the theory and engineering that has gone into Möbius to the test out on the high seas and will provide those results as they come in.
In the meantime I’d be very keen to hear you and others here think the performance differences would be between these different choices of engines, props and hull designs and look forward to continuing this always intriguing and educational discussion.
-Wayne