Pat's Dock » Membership - What's it about?
Release Date: 6/28/2008
MDI offers unique multihull data perspectives. Take a moment to review the information available in the Membership pages: all the vessels in Cal's Evals and Membership Design Reviews.
Initially the MDI website was going to be strictly about model specifications and objective comparisons; "Just the facts". Once we began publishing formulas and data results we received requests for explanations of vessel terms and the formula selections. We developed three resources to address questions and give the necessary explanations: Cal's Evals; a Technical section; and the Membership Design Reviews. To see the available multihull reviews for "Members Only" please visit Membership Design Reviews.
With over 900 multihulls in our database we developed the Advanced Database Search. Members can search the database using 9 different variables based on specifications, performance and stability to narrow their search. The 9 variables by which you can narrow your search are: Base Speed, Beam Overall, Bruce Number, Length Overall, Length at Waterline, Sail Area, Stabiity Speed and theTexal Rating (read Texel Rating to view how MDI modifies the handicap rating). You can see the Advanced Database Search located on the bottom of the Multihull Comparison page.
MDI Members have unlimited access to Cal's Evals' ; the Membership Design Reviews and the Advanced Database Search.
While the specific boat you are interested in may not be one of those reviewed as part of Membership; for those new to multihulls, the Design Reviews will help you develop a greater understanding of multihull dynamics. Along with this you will develop a point of reference for other multihulls and the design features you favor will become more apparent. For the knowledgeable there is the pure appreciation of design and function even for the arm chair sailor.
When evaluating multihull sailboat performance and stabiliy, it is important to understand that there are several variations of formulas for the "First Order" evaluation. Calvin H. Markwood, Engineering Analyst for MDI, discusses the formulas selected for use on this website and the meaning of their results in selected papers in the Technical section.
Our Database contains over 900 multihulls with performance and stability data for each vessel. There are many more vessels in the database than in the Membership Design Reviews.
For those vessels not listed as part of Membership Design Reviews, their data can be viewed in the Multihull Database or the Multihull Comparison Database for a fee. Membership is not required to purchase data from these Databases.
All our MDI evaluations start with 8 basic specifications of catamaran design and 7 for trimaran design. There is no deck clearance evaluation for trimarans. Then we begin a series of 10 evaluations of performance and stability for each catamaran and 9 evaluations for each trimaran. This renders up to 18 objective variables for catamaran evaluation and 16 variables for trimarans. Sometimes we are unable to gather Bridgedeck clearance for catamarans and we only report 16 of the 18 variables. In this comparison example of the Edel 11M catamaran and the Farrier F-33 trimaran you can see the 18 specifications reported for the catamarans and the 16 reported for trimarans.
We endeavor through designers, builders, owners and published information to collect accurate data. Mr. Calvin Markwood elaborates and clarifies data collection and reporting on this website in his two papers Analysis of Multihull Sailboats and Database Maintenance.
Clearly there are many excellent resources for multihull sailboat information. MDI is about saving time and gaining knowledge with minimal investment; our Membership access fee is less than 3 pennies for one hours use*.
We hope you take us up on our offer and become a Member.
Pat Ross
* Membership calculated for 722 hours of service for one month@$15.00/US = less than 3 cents US/hour
