Tratrix
A 25' 3" V-Bottom Raised-Deck Cruiser
By William Atkin
A Vee-Bottom Cruiser
A twenty-five foot cruising boat of any type is an excellent choice; not too big for one person to handle, nor too little for comfort, safety and ability. Tratrix was designed for the accommodation of two and if the little craft is built exactly as shown in the plans will become one of those cherished material things that does not drift in on every flood tide. If she is not built like the plans, that, of course, is again another matter�and that, I can add with much feeling, is a pity, if not a heartache.

A look shows that Tratrix is of raised deck type with a wholesome sheer line protected by a real guard rail, a necessity on any motor boat that must come to floats for refueling, water, etc. In a sense the bull is not streamlined but she has symmetry and with the conservatively designed modern pilot house looks and is shipshape and refreshing. And in addition to all this she is a boat that can be built with ordinary tools and common materials.

Below she is laid out for the comfort of two. The cockpit is 7 feet 8 inches in length and 6 feet 6 inches wide. The cockpit floor is not self-draining and is kept low so as keep the pilot house top within reasonable and safe height. A seat across after end houses the gasoline tank. There is a galley 3 feet 5 inches long with stove, sink and ice box on the port side; companion step and locker on the starboard side. Two full length berths have lockers under. And then comes a toilet room outfitted in current style with hooks for clothes and a locker forward of the low bulkhead shown. The headroom under the cabin house beams is 5 feet. Please, now, don't increase this; just sit down the while you are below. Under the pilot house top beams the headroom is 6 feet, therefore, excepting for giants, ample to stand under.

Tratrix has an overall length of 25 feet 3 inches, a breadth of 8 feet, with a draft of 2 feet 1 inch. The freeboard at the bow is 3 feet 6 1/2 inches; at the stern, 2 feet 8 3/4 inches; and the least freeboard, which is at station 9, is 2 feet 7 inches. She is a V bottom; the bottom sections are straight from rabbet to chine; the topside sections are moulded, those forward have flare and flam, those aft have tumblehome. The keel extends in a straight line from station 3 to station 9, thence sweeps upward to the lower end of the stuffing box flange. This gives excellent rudder and propeller protection, eliminates the necessity of shoe or strut, and gives a clear way for the water flowing into the propeller. Boats that have a long keel or deadwood handle better running down the wind in rough water, and so far as I can determine have excellent ability to turn sharply providing the rudder is of correct area for the area of the lateral plane and its shape. Hulls like Tratrix always heel in when making sharp turns, in fact unless some glaring defect is made in the design it is difficult to make them do otherwise.
Tratrix is designed for speeds up to 15 miles an hour with modest power. For this particular design I would suggest a motor of four cylinders having a capacity of 186 cubic inches. This will mean cylinders 3 5/8 inches diameter, stroke 4 1/2 inches, or equivalent. Not too many revolutions and, of course, without reduction gears. At 1700 r.p.m. the speed of Tratrix will be a good reliable 15 miles an hour. Not brilliant; but good for the power and the accommodations.
 
PHOTOS OF TRATRIX
Plans for Tratrix are $65
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