Another week goes whizzing by faster than a MIG welding flash and with lots more progress on the building of the hull for our new boat and soon to be full time home, the mv (motor vessel) Möbius, our all aluminiuum 24m / 78’ eXtreme eXpedition Passage Maker or XPM here at GreeNaval Yachts in the Antalya Free Zone. Thanks for your interest and welcome aboard.
I will continue with the usual style of a series of annotated photos taken throughout the week and end with a similar video version that compiles the videos I shot during the week. Hope you enjoy and please be sure to leave your comments, thumbs up/down and questions in the comments section at the end.
As per the title of this week’s post there is a lot of “baffling” work going on as Team Möbius begins assembling the fuel and water tanks which will soon form the entire below waterline portion of the hull, as well as assembling the framework for the bow section of the hull and continuing to finish the welding all the stringers and bulkhead frames to the deck plates which were put in place last week. Lots to cover so let’s jump right in starting with the baffling part first.
With the eXtreme amounts of liquids we want to carry on Möbius for ocean crossing passage making, the hull has been designed such that pretty much everything below the WL (water line) is filled with either water or diesel fuel. I’ve done a quick colouring of the profile view to the left to help you see how this is all positioned.
In total we will be able to carry about 14,000 litres/ 3700 USgals of diesel and up to 5700 L / 1500 USG of water. The water will all be potable, as we only fill them with the close to pure H2O generated by our high volume watermaker which makes about 220 L/hr 60 USG/hr. However the for such a large tankage of water onboard is primarily to serve as movable ballast. This enables us to trim the boat for different sea conditions as well as balance weight as the fuel is used up. All tanks are divided up into multiple independent compartments with plumbing and valves which enable us to move both water and fuel from any tank to any other tank as needed.
The magenta surfaces are the tank tops and all the green squares are tank access hatches. The access hatch holes were not CNC cut because we will wait until we finalise the interior arrangements to decide exactly where they will go in order to provide full access to every area within all the baffled compartments for future inspection and maintenance.
As you can see, this integral grid like structure makes the underwater portion of the hull eXtremely stiff and strong. Furthermore, with all of the hull below the WL being tanks we have a significant built in safety factor in the very unlikely event that something should puncture the thick hull plates. A feature we definately hope not to test out!
Here is one of the many piles of baffle wannabes …………..
If you were wondering, the tanks need to be so fully baffled to reduce what is known as the free surface effect which is the technical marine term for what we might more commonly know as “sloshing”. The more detailed definition is:
Free surface effect is the change in stability of a vessel caused by liquids moving about freely in a tank or hold. As a vessel rolls, liquids in tanks or breached compartments accentuate the roll by moving freely from side to side of the tank accumulating first on one side and then the other, and may adversely affect the stability of the ship. The free service effect can be reduced by having baffles in a tank to reduce the free movement or by either emptying the tank or filling it completely.
Given the enormous quantities of diesel and water we will be carrying on Möbius you can understand why we treat this with extreme care and seriousness as it can cause serious instability as noted in the definition above when we are at sea. Fortunately the solution is relatively simple, divide the tankage into multiple independent tanks and put lots of baffles in every tank to reduce the free surface effect.
The top edge of each baffle plate has a 10mm flat bar welded on to provide a surface for welding the tank tops onto after the hull is completed. Our head welder Sezgin was kept busy welding these flat bars as well as continuing to weld all the stringers that were installed last week onto the deck plates so it was a very busy week for Sezgin and he is very fast and very good.
Other Team Möbius welders were busy cranking out more baffles for Sezgin by tacking the flat bar onto the top edges of baffles. You can see how they tack diagonal braces to hold the bar and plate perpendicular when they are being fully welded in place.
For scale, my thumb is on a piece of 12mm flat bar and the stiffeners are 10mm.
Here are some of the bottoms of these frames with their temporary flat bars tacked in place to keep them flat while being worked on and welded. You can see all the slots cut into their outer edges the stringers which will be slide in there once these frames have been positioned along the length of the keel.
On the left of this shot closer to the center of this frame bottom, you can see one of the tank side plates mentioned above with its stiffeners welded in.
That cavity in the middle is one of two which form the battery box for our mammoth 24v house bank of batteries giving us total capacity of 54kWh. These batteries have a mass of 1320 kg / 2910 lbs BUT it is “good weight” in that it sits as low down as you can possibly get and does double duty as ballast which helps with the ride and comfort at sea and perhaps most importantly part of what makes this hull self righting. This was one of several attributes of our sail boats, all monohull sailboats, which we were not willing to give up.
You can now see how these grids of closely spaced baffles very effectively deals with the free surface effect I mentioned earlier.
Here is a closer look at one of these large radius flat bars welded into one of the many frames.
Which provides a good segue to go check out what’s been happening up at the bow where you will see more examples of these frames.
Looking at the other side of this Frame/WTB #4 we follow Uğur and Mehmet forward as they start assembling the particularly puzzle like assembly of different shapes and sizes of plates that make up the deck at the bow.
Note too how the deck drops down and slopes down toward the bow so that all the water and anchor muck drains off easily.
Note Frame #2 on its side against the wall behind Mehmet waiting to be inserted in the appropriate slots in the decking.
The forepeak storage area runs from Frames 1 to 4 so 3m / 10 feet long and will provide a huge amount of full headroom storage for lines, fenders, anchor gear, pumps, tanks, etc.
This area is made of thicker 12mm plate compared to the 8mm on the rest of the bow deck to provide an even stronger base for the ground (anchor) tackle and the critically important windlass that brings in the chain and anchor.
Whew! Another busy and productive week for Team Möbius and your summary video below as promised.
Hope you enjoyed this week’s update and please add your questions and suggestions in the comments section below. Thanks again for joining us, wouldn’t be the same without you!
– Wayne
Mind boggling number of parts!!
I quite like the anchoring setup, it has a lot of advantages including much easier – and safer – access in bad weather compared to having it all the way in the bow. But have you considered adding identical assembly to the other side? Even if left initially unoccupied, would be so simple to build at the same time compared to job of adding it later.
Yes, Dennis did a fabulous job and we put a LOT of work into coming up with this end result for the anchor arrangement and think it is going to work our really well. Much safer and easier to manage as you noted, kept our overall length down by more than a meter and avoided the potential of an up front anchor being a battering ram in any run in with other poor boats. We also really like how the whole bow design then evolved over time with that beautiful, to our eyes, rounded nose as the robust rub rails wrap around and that big thick “doughnut” as I’ve been calling it for the snubber lines exits below. This also serves as a built in drain for the well sloped anchor deck so that all the anchor gunk will quickly and easily drain right off the front.
No need for a second roller assembly on the Stbd side as we believe strongly in the “one and only” BIG anchor method. Learned this on Learnativity as well when I was upgrading her anchor gear and putting on a whole new SS bow roller assembly I had designed while I was in Whangarei NZ waiting out the 2009/10 cyclone season. I had ordered a 50kg Rocna but this was when Rocna was moving manufacturing over to China and they made me an offer I ended up not being able to refuse for a 75kg monster. Thought it would be too big and look like I had an anchor with a boat attached but they agreed to let me try a trial fit and she looked very good so I kept it. Worked fabulously, never dragged or moved once and trust me we were in many situations where Mother Nature tried her best but that big old anchor just stayed put or rotated and reset immediately.
We have designed the new setup on Mobius for a 125kg/275lb Rocna/Manson anchor so I think we will have even better holding and add to our SWAN factor. The anchor setup and bow is being built as I type so no changes possible in any case but as per above we wouldn’t consider a second anchor anyway.