Gino Morrelli Explains: The Velocity Prediction Program MULTIHULLS REPORTING ON CATAMARANS AND TRIMARANS WORLDWIDE SINCE 1975 May/June 2015 www.multihullsmag.com The New Neel 65 World s Largest Production Cruising Trimaran Also in this issue: www.multihullsmag.com MULTIHULLS Magazine Insurance: Sailing to Cuba Building in China Pt. 5 An Education of a Lifetime Proa Evolution
Talk with an Expert by Gino Morrelli Gino@Morrellimelvin.com What the Heck is a VPP?! One of our new clients was hanging out at our design office the other day, while we were enthusiastically debating the minutiae of one VPP versus another. In a brief break, he quietly asked me What the heck is a VPP? It was then I came to realize that not everyone, even experienced owners, may completely understand just what a VPP is and why it s so useful for designers and sailors. VPP stands for Velocity Prediction Program. It s typically a computer program that most yacht designers covet and protect to help figure out how fast a boat will go. Normally, for multihull sailboats, we enter in the basic parameters of a given boat, like length, displacement, hull beam, wetted area, rig parameters, individual sail areas, etc... and it spits out a matrix of boat speeds for each combination of True Wind Speed (TWS) and True Wind Angle (TWA). In the case of the latest high performance America s Cup VPPs, we upload the actual 3D hull models with boards and rudders. We started building our first primitive computerized VPPs during the 1988 America s Cup with Clay Oliver and SAIC for Dennis Conners successful defender, the first 60-foot wing sailed cat Stars and Stripes. We were just trying to accurately predict hull flying wind speeds and apparent wind angles. As time went by, we kept Clay busy upgrading our version of his commercially available VPP with customizable inputs and outputs. During the last two Cup campaigns (BMW/Oracle Trimaran in 2010, ETNZ AC72 cat in 2013), we were involved with developing even more sophisticated versions that helped us develop the fully flying AC72s that we saw blasting around in San Francisco fully flying on hydrofoils! Polar Diagrams: The output from a VPP is typically presented in what s called a Polar Diagram. (See the diagram on page 24, 24 which is from our new Morrelli & Melvin-designed Rapido 60 trimaran www.rapidotrimarans.com). Magazines typically print these crazy intimidating circular rings without explanation! They are basically displaying the vessels boat speed at different True Wind Speeds (TWS) (2-25 knots) over a range of True Wind Angles (TWA) (0-180 degrees). Each squiggly line on the diagram represents a particular sail combination, like Full Main Sail and Jib or Full Main Sail and Reacher, etc. Multiple sail configurations/lines can be overlaid on the same Polar Diagram and you can see where the lines Crossover. Crossovers: For an owner, these Crossovers help predict when you should change sails as you go from upwind to reaching or downwind, in different wind speeds. We can tell the VPP program maximum Apparent Wind Speeds (AWS), any sail can operate in, helping you not break a sail or push it past its recommended limits. So, if you re rounding a point or a mark you can look at the Polar Diagram and predict with better confidence what sail you ll want to set next, saving energy or possibly damage by setting the wrong sail for the combination of True Wind Angle/Speed. Holes in Your Sail Wardrobe: The VPP output, when given to a sailmaker, can assist him in building sails that work best within the apparent wind angles predicted, so the sail is not built too full or too flat. There is a bit of give and take between the owner and sailmakers in deciding on the Apparent Wind Speed (AWS) limits of any given sail, especially reachers and spinnakers. Sailmakers want to divide this into small ranges and sell you more sails to improve performance for every wind angle and speed! A good VPP provides guidance in finding MULTIHULLS Magazine May/June 2015
a good compromise on the number of sails, their respective Apparent Wind speed/wind angle limits easier so as to avoid Holes in your sail wardrobe. Steering/Trimming Performance: On many modern boats with wind instruments, you can upload your VPP output into the onboard computer. Then while sailing you can select % of Polar on your instruments and compare how you are doing versus theoretical. It s a good way to gauge how you are sailing, day-to-day or especially at night when it s very tough at times to gauge if your trim is off. This gives you an objective benchmark to compare against. On race boats, as each helmsman comes off the wheel, he can go to the navigator and receive a Report Card, telling him that for his period of driving, he sailed XX% of Polar helping to assess the actual level of his performance. Comparing Boats... Maybe: VPPs are a bit of a house of cards. As with any computer program, VPPs suffer from Garbage in Garbage out. For example if a boats displacement is modeled as unrealistically light, then the VPP will give too fast a prediction. In addition, each element: sail coefficients, wave drag theory, efficiency of dagger boards/rudders all affect speed. So getting all of these formulas to balance and accurately reflect reality is easier said than done and is what determines the quality of the proprietary VPP tools that a boat designer develops, through experience, over time. Accurate data, fed into a mature, well-tested VPP program, does produce predictions that quite accurately reflect expected performance. So, VPP programs can be very useful to all concerned. As designers we use proprietary VPPs that we have developed over the years to test our design decisions. We experiment with different combinations of hulls, rigs, beam, dagger board styles (curved Cs vs. straight) vs. mini keels, etc., to optimize our designs, over the widest range of conditions. As buyers if you are out shopping and comparing boats, you might want to use published VPP results as an essential part of your decision criteria, but take it with a grain of salt. As owners VPPs are not something you need to own, but their information can improve your sailing performance, and reduce some of the guess work in choosing which sails to use in any given conditions. www.multihullsmag.com MULTIHULLS Magazine 25
VELOCITY PREDICTION PROGRAM POLAR DIAGRAM RAPIDO 60 TRIMARAN WWW.RAPIDOTRIMARANS.COM WIND DIRECTION 10 20 30 40 50 60 BOAT SPEED (KNOTS) 6 10 14 4 6 8 10 12 14 16 18 20 22 24 26 28 6 6 10 10 14 20 B 70 80 100 TRUE WIND ANGLE (DEGREES) 14 20 A 110 20 120 170 160 150 140 130 LEGEND 10 TRUE WIND SPEED (KNOTS) JIB + MAIN REACHER + MAIN SPINNAKER + MAIN POINT OF OPTIMUM VMG A B POINT SHOWING BOAT SPEED OF 26.5 KNOTS @ 110 TWA, 20 KNOTS TWS WITH REACHER + MAIN CROSSOVER POINT 26 MULTIHULLS Magazine May/June 2015
Company Spotlight by Paul Hakes sales@hhcatamarans.com Boat Building in China Part 5 Assembly & The Production Line We continue to witness the fruition and payback of well-detailed design, good planning and clever tooling. This month we can see assembly advancing well on boat HH66-01, which we will look at in more detail. We will also now take a look at our production line as we see HH66-02 emerge from the molds and undergo stage 1 assembly, and HH66-03 start the lamination process. With three boats on the go, production planning and coordinating with sales and design is critical. We look at the special care taken to identify design and production issues encountered with HH66-01 and how we feed this information back into the design and production planning departments to eliminate any errors being repeated. In looking at our production, I will talk about a word that has been treated as Royal Taboo amongst boat builders for many years PROFIT; it seems this word is not used regularly by boat builders as they worry about the idea of owners seeking further discount or a better deal elsewhere if they are seen to make a profit from yacht construction, an obvious mistake when we all know a company must make money to survive. For sure, we are blinded at times by our passion to build wonderful sailing or power boats, and the romance of building such The giant carbon fiber port topside and sidedeck molding is moved into position. 28 MULTIHULLS Magazine May/June 2015
The production line emerges with Hull 01 in the background Hull 02 in front and hull 03 in the lamianting clean room behind them both. epically beautiful man-made creations often clouds our clarity that the necessity of the business is that we must be profitable. HH66-01 has undergone a remarkable transition that is set to continue for the next month; the topsides, which include the side decks, have been fitted and bonded. At last we get to appreciate the true size of this beast and the spaces contained within. In the first hull, the client has opted for the port hull to be a dedicated owners hull (no guest rooms), and so it is grand and palatial in its size. Still the spaces within the starboard hull are equally impressive with two staterooms, each with separate large showers and bathrooms. The topsides being bonded were held off from being attached until we felt all systems were as far advanced as possible, this means all systems under the soles are fitted out; wiring looms are complete, air conditioning conduits complete, black/grey fresh and saltwater systems all in, tanks all connected, diesel transfer pumps and bilge pumps all in place. Rather a lot to preplan and install at this early stage and only possible with well executed systems design. Small problems encountered were High strength epoxy adhesive is applied on all glue surfaces prior to the big bonding. getting our workers to think about the small details that were to occur, like: how a hose clamp should be orientated is the hose clamp orientated correctly to be able to access at a later date? Are there spare wires pulled into the wire looms for the small pieces of equipment requested at the last minute? www.multihullsmag.com MULTIHULLS Magazine 29
The furniture department is also ready. They have all the furniture built, and waiting for first coats of varnish. Indeed, we had to remember to place some units in the hulls prior to bonding the topsides, as they will not fit down the hatches. Next in a fast sequence will be the aft transom steps and cabin top getting installed to complete the bulk of the primary structure. With such good progress on HH66-01, a close eye on the production line is needed to ensure adequate resources are applied to Hull 02 and now Hull 03. This also means the same resource that has done the job before! Our workers The port side and the palatial volume of the owners hull. love to do the same job again, sadly sometimes on the same boat (this is called rework a profit killer!). Once the workers have mastered a task they look to make it easier, reduce the work load and find the efficiencies. So we see the same laminators installing the tank grounds for all eight tanks into HH66-02, and building the hulls and wing-deck, bulkheads and topsides for HH66-03. In the HH Catamaran furniture department they are now constructing the joinery for HH66-02. So it seems the production line has switched nicely from our previous carbon catamaran to our new flagship yacht. The manufacturing process is happening; jobs are being executed to plan, to the right quality, and in the right order. Correct this is boat building after all, this is meant to be the easy part, as we are boat builders! BUT are we a good manufacturing business, with the ability to make a profit constructing this product? We will not know for sure until the first boat is handed over to its proud owner, but we can track costs using our barcode and ERP systems to know ahead of time if we have problems, and we can maximize our chances of a good financial outcome by minimizing the profit killers. The boat must be designed and built to minimize warranty costs, which means maximizing reliability through quality design and building, this is of course priority from a safety point of view as well as a business one. Then minimize rework; ensuring the clients likes and dislikes, wants, and variations are handled professionally; this is a $3.5m yacht, the owner wants to input his or her own personal styles and unique options, which have to be processed through an efficient channel into the finished product. Any misunderstandings 30 MULTIHULLS Magazine May/June 2015
Hull 02 is out of the mold and well into Stage 1 assembly with tank grounds and piping routes be fitted. with the client, or assumptions made by the sales team can lead to costly rework. Then there are the design and production mishaps, which mean rework and doing the job twice. The first corrective action is ensuring the information of a problem gets back to the design engineers, so that the alterations are made to the drawings and errors are not repeated. The second problem area is human mistakes while building generally attributed to only three things going wrong: equipment, information (including training) or materials. It is management s job to supply these three key ingredients to its manufacturing workforce minimizing rework. These are some of the challenges any and all businesses must face to do well, the objective of any growing business is to maximize ROI and profitability and yacht Success, fitted and glued... Next is secondary bonding inside and out to take the join to full strength manufacturing is no different. As we know the boat building industry as a whole has been through a number of very hard financial years, a successful boat yard will let passion drive its desire to build great yachts, but keep a clear head about the reality of organizing a profitable manufacturing business. Our next article will cover both the passion and the business. We will continue to see HH66-01 grow inside and out, and we will take a look at the appendages and accessories, which are big projects in themselves. The 26m masts and 6m long daggerboards will be design and construction composite masterpieces when finished, so we need a closer look. We will also take a spot check on a business level at the HH Catamaran project, and understand where we are doing well or not, and what should a multinational multicultural large yacht manufacturing business do to ensure it is maximizing longevity and financial success. MM www.multihullsmag.com MULTIHULLS Magazine 31