TRIDENT 42, POWER VERSION
Front View, TRIdent 42P
Side View, TRIdent 42P
TRIdent 42 Power Cruiser
The Cruising Powerboat variant is designed for a 10 knot
cruising speed with a single diesel, up to 250 HP. The hull form is identical to
the sailing version, however the cabin sole on
the powered version has been raised 10" to the level of the cockpit, allowing for
three midship fuel tanks totaling 900 gallons and two forward tanks of 125 gal.
each. Fully loaded displacement is 20,000 pounds. The powerboat has its
fiberglass thickness increased in selected areas and the workshop removed to accommodate a
larger (250 hp) engine. The cabin sole is also raised 10 inches to the level of the
cockpit. This provides space in the middle of the center hull for a molded in place 500
gal. fuel tank. In addition, a raised landing is added under the steps leading down into
the outer hulls. This provides space for another 200 gal. tank, giving a total fuel load
of 900 gal.. Since these tanks are located near the center of gravity, the boat will not
go out of trim as fuel is consumed. Fully loaded, the displacement is 20,000 lbs., and the
draft to increases to 3.8’. On deck, a small raised cabin is added over the engine
room. This cabin is fitted with a removable overhead to allow access to the engine for
major overhauls, and fitted with an 18" square opening hatch for light and
ventilation.
This TRIdent 42 is a Wave Piercing (WP) catamaran design that looks like a normal catamaran when viewed from the rear, but from the front it shows a sharp, slender third hull which drops down from the center of the boat and runs forward to a position slightly ahead of the outer hulls. This center hull is very narrow and short, with fine, sharp sections that are designed to "split" oncoming waves before they reach the outer hulls. This lowers the force on the boat and spreads it out over a longer time. The result is that the boat has more time to respond to the wave action and moves with an easier motion. Since the center hull contributes considerable flotation, the forward sections of the outer hulls can also be finer than normal. The combination of staggered, fine sections on all three bows lets the boat punch through waves with less violent motion, and reduces pounding. In short, a better ride, improved seaworthiness, and reduced crew fatigue. One of the more successful applications of this technology has been in the area of high-speed ferryboats, where several types of WP designs have proven themselves seaworthy under some very stressful conditions.
The most interesting feature of the TRIdent 42 is the center hull. Its primary purpose is to improve seaworthiness, but it also provides quite a bit of storage space, including room for the engine. Starting from the bow, the center hull contains the headstay, anchor, windless, rode, engine room (with 6’ headroom), 250-hp Yanmar engine, 80 gal. water tank, four batteries, two 25# propane tanks, and the rudder. Removing these items from the outer hulls allows more room and flexibility in designing the interior, and needing only a single engine reduces weight, cost, and construction time. If you really have to have twin engine maneuverability, several manufactures sell small electric bow thrusters that can also fit in the center hull.
The TRIdent 42 has a 21’ beam, 36" draft, and an empty displacement of 15083 lbs. The outer hulls are set back 4 1/2’, have a LOA of 37.5’, 36.3’ DWL, a deck beam of 5’, and displace 5666 pounds each. The aft sections of the outer hulls are full, and only slightly vee’d, which increases interior space and promotes high speeds. The forward sections are flared to insure good reserve buoyancy and quick recovery if you do punch into a wave. The center hull is 39’ LOA, has a waterline length of 27.2’’, a waterline beam of 3’, and displaces 3751 pounds. Clearance under the wing starts at 55", drops to 26.7", then rises to 38" at the transom. Cruising speed is 9 - 10 knots, quite respectable performance for a cruising boat, where comfort and safety are the primary design constraints.
The TRIdent 42 is designed to provide every luxury for two people. The master stateroom and head takes up the entire starboard hull. A sleeping stateroom is provided for guests in the port hull, and a pilot berth is located in the cabin. Using the sofa, the boat sleeps six comfortably. The staterooms are large, with lots of drawers and hanging lockers, have full 74" headroom, and pick up additional space from the areas below the cockpit seats. The cabin is optimized for offshore cruising, with an inside steering station and pilot berth. The "L" shaped aft galley has a freezer & refrigerator, double sinks, ample counter space, and a large pass through window between the galley and cockpit. The inside steering station is on the port side, near the steps leading down to the chart room. The dinning area is to starboard, and a large reclining chair (taken from the motor home folks) rounds out the cabin décor.
The forward section of the port hull is fitted with a 36" x 48" chart table, swing away seat, and the usual assortment of electronic gear. When guests are not aboard, the port cabin becomes a place to relax, watch TV, catch up on e-mail, or just kick back and read. The workshop area, which is part of the center hull engine room, has room for a workbench and lots of storage in deep lockers to port and starboard. The engine is aft of the workshop and is completely enclosed in a sound deadening box, reached from the workshop by removing the steps.
The building sequence for the TRIdent 42 is a little unusual. Construction begins by setting 4x4 posts around the contour of the main deck, then cutting them to the height of the shear line and deck camber. 20 foot long 2x6’s are then laid across the posts and shimmed to the plan’s dimensions. The deck panels are lightly glued to the support structure and laminated with epoxy to a thickness of ¾" (three layers of ¼" plywood). After a rough trim, the deck is glassed with one layer of 24 oz. Woven roving, with an additional transverse layer of 12" bias ply tape (the fibers run at +/- 45 degrees rather than 0 and 90) at each of the four permanent bulkhead locations.
At this point, we need to stop and think ahead a little. Is transporting a 21 foot wide catamaran going to be a major problem? If it is, now is the time to build some simple joints into the primary bulkheads and deck structure along the starboard side (to miss the steering system) of the boat. This will allow the boat to be cut into two parts, one 7’ wide and one 14’ foot wide for conventional trucking. Once this minor detail is settled, hull construction continues with the fabrication of four full beam primary bulkheads and two partials, using ¾" plywood. These bulkheads are positioned on the deck, aligned, and glassed in place permanently using 12" bias ply tape. The remaining temporary forms, on 3’ centers, are lined up and tabbed lightly to the deck.
DuraCore balsa strips and sheets are the ideal material for stripping the hulls and building the interior structure. It is expensive, however, and strips cut from any clear 2x8 stock like redwood or western red cedar will work just fine. The type of wood is not critical since it will be completely incased with fiberglass. Even plywood, ripped from full length scarfed ½" panels, can be used. In any case, a simple butt joint with a backing block is used to get the lengths required. Milling cove and bead features into the strips is unnecessary.
The strips are placed along the shear first, using a heavy layer of thickened epoxy to insure a good bond between the first strip and the deck. Position the strips with the backing blocks on the outside, where they can be easily removed later. The strips are epoxied to the permanent bulkheads and each other, and held in place with sheet rock screws and staples. 1" wide strips may be necessary where the curvature is high, and several layers of thin vertical strips will be required to form the flare at the bow(s). When the strips have reached a point several feet above the deck, the inside of the hull to deck joint should be cleaned up and glassed with two layers of 12" wide bias ply tape. Glassing this area would be a nasty job if the boat were upright. Longitudinal stiffeners (3/4" plywood or DuraCore) are fiberglassed to the deck at the 30" and 60" butt lines and trimmed for a close fit with the strips. When the three hulls and the connecting structure is complete all screws and staples are removed, the surfaces faired, and everything covered with one layer of 24 oz. Woven roving. The roving should be cut to overlap by 12" along the stem and keel area, and 24" at each of the four wing fillets. An additional layer of bias ply cloth is applied along the keels and the fillets just to make sure their "bullet proof". Traditional fill and fair techniques are then used to finish the surfaces in preparation for painting. Be sure to use enough surface filler to prevent sanding into the woven roving.
Inside the structure, the permanent bulkheads are glassed to the hull skins (more bias ply tape) up to the point where hull curvature makes the job to messy. Check the entire boat for any missed places on the permanent bulkheads, cockpit seats, and longitudinal stiffeners that can be glassed easily inverted, since this is the last time the boat will be upside down (hopefully). Before turning the boat over, add temporary wood supports from one side of the boat to the other, across the cabin and cockpit area. These should be screwed to the temporary forms.
Turning the boat over is a tricky operation, requiring a pair of cranes and some careful preparation. Four 20’ slings are placed around each end of the outer hulls then led in pairs to a crane on each side of the boat. The boat is lifted slightly and broken loose from the support structure. The support structure is then removed and the boat lifted about ten feet off the ground. The tricky part starts as one crane lowers while the other takes up, until the boat is hanging completely support by one crane. The other crane now resets its slings over the top of of the boat and begins to pull. Slowly the boat will turn right side up and you can breath again. It sounds worse than it really is, and there is little danger of the boat falling or breaking apart. Some builders have turned boats over using hay bails, tires, pickup trucks, and an old forklift, but I would not’t recommend it or even want to watch.
With the boat turned over, the advantages of this construction method begin to pay off, as the deck and hulls are almost finished. All that’s left on the outside is to trim and radius the hull to deck joint and glass the deck. Again, bias ply tape is used at the hull to deck joint. The cockpit sole can be installed next and glassed along with the seats. Inside the boat, the temporary interior forms are removed and the insides of all three hulls and the connecting wing structure are cleaned up and glassed with one layer of 24 oz. woven roving. As before, a 12" overlap is formed along the keel of each hull. An extra layer of full width (39") woven roving is then added over the fillets between the hull and wing. Two by six beams on 12" centers are glassed across the wing structure (out to butt line 60) to support the cabin sole, and the sole (two layers of ½" plywood) is then screwed and epoxied to the stiffeners. The sole is then glassed into the hulls and bulkheads with bias ply tape, and covered with one layer of 24 oz. Woven roving.
The cabin is built separately from the boat with wood strips over forms and glassed on both sides like the hulls. The preferred sequence is to build the cabin after the deck has been fiberglassed, position it under the deck structure, and bond it in place. If you decide to attach the cabin after the hulls are built, it’s a good idea to mold a 4" high "lip" in the deck to the dimensions of the cabin. When turned over, this lip will align the cabin and provide structure for bolting it to the deck. In either case, the cabin is positioned on the deck, bonded with epoxy, and glassed with bias ply tape, inside and out. With the primary structure now complete, the interior features can be mocked up, propulsion details sorted out, and thoughts given to the electrical, fuel, sanitary, water, rigging, sails, deck hardware, etc.
Many custom features are possible for a project like the TRIdent 42 depending on the individual needs of the owner. The complexity of these features, the amount of design work needed, labor expense, and hardware quality will largely determine the overall cost of the project. As a minimum (work full time on the boat, use lots of used stuff, and nothing fancy), I would estimate $50k and 2-3 years. $100k and 6 years is probably more realistic, especially if you need to work a regular job at the same time.
Prototype TRIdent 12 Now Under Construction
Current status: The building forms have been cut out using a high precision water jet cutter and assembled. The hull is now being stripped. A 1/6 scale model was first cut out using the water jet to avoid any "surprises". The model faired perfectly, and was used as a plug for laying up a hull mold (a finished part is shown above). Several model hulls have been built for flotation verification and deck design studies. The model is similar enough to the larger designs to allow for mockup interiors, deck, and cabin variations. It also clearly shows the volume and benefits associated with the center hull. The model is priced at $40, plus shipping. Click here for pictures of the prototype TRIdent 12.
