Flow & Membrain Runs On the SeaCart 26
The team behind the SeaCart 26 has not saved any energy or expense in our aim to provide the market with the best sports multihull package possible. To make sure the mast and sail shapes are optimized an extensive flow and membrain program have been run using input from test sailing sessions and racing the first SeaCart 26. The findings have been implemented on boat No 2 which is now out sailing.
This sounds like a lot of mumbo jumbo but it is in fact extremely valuable if you are serious about your intentions. For those who would like to read further into the matter we have posted North Sails notes on the subject below. When you read on you get the picture that this is not an task done quickly in a few minutes, to the contrary, it’s seriously time consuming and highly scientific. Pictures in the article show a SeaCart 26 under OD Gennaker.
DESMAN [TM] … rig and sail modeling. Desman creates a complete rig/sail model in a three-dimensional environment. In Desman, North designers can specify mast size, rigging position, rigging attachment points at the deck and trimming locations. The modeled sail/rig system incorporates the mechanical properties of the spars, standing rigging, running rigging and sails in terms of moments of inertia, sail and spar surface area, materials stiffness and resistance to stretch. Later in the process, Membrain (described later) uses the Desman model to determine deformation under load for the sail and every piece of standing and running rigging, right down to stretch in the sheets and halyards. Link to North Sails Desman.
3D LAYOUT [TM] … define the structure of sail. 3D Layout is used to define the structure of a sail in terms of yarn layouts, panel layouts, tape layouts, yarn density, and/or film types. Output from 3D Layout is used to shape 3DL molds or provide seam curves for paneled sails. All yarns are plotted in the same 3-dimensional space they will assume when sailing. 3D shapes are translated into panel layouts for downwind sails. 3D Layout also has powerful analytical tools which can be used independently or in conjunction with Membrain. Link to North Sails 3D Layout.
FLOW [TM] … applies wind pressure to 3-dimensional sail mold. Using Flow, wind pressure is introduced over the sail’s three-dimensional “mold” to produce a pressure field on the sail’s surface. The pressure varies over the surfaces based on the size and shape of the sail and the strength and direction of the air flow. The resulting pressure field is then linked directly to Membrain for finite element analysis. Flow also reports the drive and moments developed by sails, which can later be used by either the North Sails VPP or other VPPs for sail performance analysis. Link to North Sails Flow.
MEMBRAIN [TM] … balances wind pressure, sail shape and rig. Membrain takes the sail/rig model from Desman and applies pressure fields from Flow, deforming the mast and sail as a single unified structure. As the sail/rig structure is deformed, the shape of the sail changes, so Membrain then links back to Flow to acquire new pressure fields for the deformed surface. This changes the sail shape in Membrain yet again, so the process is repeated until there is stable balance between pressure and rig/sail deformation. Membrain can be used to test sail shapes, optimize mast design and rig tune, create sail shapes to test in North VPP, check loads for designers, and more. Membrain applies pressure to the integrated rig/sail system and then iterates the results back to Flow until pressure and sail deformation achieves a stable balance. Link to North Sails Membrain.