The Design of Mother of Perl

We ordered preliminary plans for the Spray from Bruce and started adapting our layout to the 45 foot hull. When Bruce released his round bilge version, the Centennial Spray 45, we were convinced this was the perfect hull for us. The hull characteristics were a major for our layout without compromising the sailing characteristics. We sent our deck and cabin layout to Bruce and contracted with him to do a set of drawings using them. We wanted to move the engine closer to midships and slightly move the location of the masts. Bruce so much liked our layout that he has been featuring it in his web pages.

A wonderful thing happened when working with Bruce. We had orginally drawn the deck with with a doghouse over the companionway. He, faithfully, had a doghouse in the drawings that he did for us, but he also made a slightly different version of the cabin which used a pilothouse with a steering station on a platform on the starboard side. He sent this alternate design to us as a gift. We so much like the idea of the open pilothouse creating a bright open space out of the saloon and galley that we adopted it. While Bruce's rough design for the steering station didn't work for us, we were able to take the general concept and implement it in our final design which you can see in these pages.

Design Criteria
This design criteria statement was created to help in making decisions when designing and building. It reads as follows:

Overall Design

Mother of Perl is to be the ocean going home of Gretchen Forbes and Ben Smith and their two children: Thomas Forbes (age 8 in 1999) and Kristen Forbes (age 13 in 1999). From July year 2000 to at least the year 2002, this will be their only home. They expect to be in both the Caribbean and Mediterranean during the years. This will not only be their home, but also their school and work place.

The 53 foot steel ketch Samana (Portland, ME) and the book All In the Same Boat (Tom Neale, publ. International Marine/McGraw Hill, Camden, ME, 1997) have major influences on the design of Mother of Perl. Other books that have been important are: Steel Away (Smith & Moir, publ. Windrose Publications, 1986), From a Bare Hull (Mate), Metal Boats (Ken Scott, publ. Sheridan House, 1994), and of course Spray--The Ultimate Cruising Boat by the boats designer R. Bruce Roberts-Goodson (publ. Sheridan House, 1995).

The Criteria

The vessel needs to fill the following design criteria in descending order of importance:

• Safe
• Comfortable
• Easy to Handle under sail and power
• Sails well
• Inexpensive and easy to maintain
• Economical to build
• Gracious to look at

The Hull and Rig Choices

The hull shall be steel because steel hulls are inexpensive as one-off designs, because they are safer than fiberglass when the hull meets something hard (reef, container, another boat, etc.). Steel hulls are inexpensive to maintain over the long haul since they seldom need more than an annual coat of paint and change of sacrificial zinks.

The (Joshua Slocum) Spray style hull was chosen because of it sea kindliness and applicability to live-aboard cabin design. The center cockpit was chosen because it affords a roomy aft cabin and makes the placement of the engine room convenient both from the point of view of cabin layout and simplicity of propeller drive line. The poop deck provides for a large deck space for family activity and maintenance-at-anchor projects. Bruce Roberts-Goodson was chosen because of his extensive experience designing Spray-style hulls.

The ketch rig was chosen because it makes it easier to balance the sails and reduce the steering load on the rudder. The smaller sails of a ketch mean ease of sail handling. The rigging shall be aluminum, which, while it requires galvanic isolation from the steel hull, makes for a relatively light rig and is easily replaced. The weight of the rigging is important because the Spray has a shallow draft keel. Excessive rigging weight would cause rolling at anchor.

The Cabin Plan

The cabin plan must provide private (to the degree of seclusion) space for each member of the crew/family. If we all need to be alone at the same time, each needs a place to go that is both visually and acoustically separate from the others. Thomas and Kristen shall have their separate and equal cabins. Since Gretchen and Ben share a cabin, their privacy from each other is not so simple.

The forepeak is used for anchor and sail storage accessible only from the deck. This ensures the privacy of the foreward cabins and moves them aft so that they may be completely separate (no V-berth conditions).

There is no berth in the salon. No one wants to sleep in the most public of spaces. The salon should be available to anyone at any time of day or night. The salon dining table is round since a round table will sit the maximum number of people comfortably for the space that it takes.

Each cabin requires its own desk space. Thomas and Kristen will be doing their school work at their desks. Ben and Gretchen will be doing their own study, correspondence, and teaching material preparation. The navigation station shall not be compromised for these purposes. The "pilot's berth" shall be used as laboratory and family workspace for clean projects. The poopdeck and engine room can be used for not-so-clean projects.

Neither the salon nor the galley are designed as show places. Comfort, utility, and efficiency of space rule. Mother of Perl is not intended to be a party boat or luxury charter boat.

• Hull
• Deck
• Interior

A footnote: the above rendering was done on a computer using Fractle Design Painter. The entire set of working drawings (from which the boat was built) were all created using Ashlar Vellum Draft, a CAD program that is much easier to learn and equally sophisticated as AutoCADD. It was designed for draughtsmen, not software engineers. Bruce Roberts uses AutoCADD, and so the lines for the hull were done with that program. Bruce's package includes full size templates for laying out the steel ribs.