Design and Origins
The hull form traces back to a Herreshoff 18-foot tender, which the designers lengthened to produce the current 21-foot LOA and 19-foot waterline.
The Sea Pearl monohull uses leeboards rather than the centerboard fitted to many shallow-draft sailboats. Its kick-up rudder allows the stern to ride over mud and sand without damage. This choice wasn’t cosmetic: eliminating the centerboard trunk freed the forward part of the cockpit for seating or overnight use, a layout consequence unique to this boat.
The Tri and Tri-Sport trimaran variants have a 14-foot beam, a recorded displacement of 950 pounds, and a centerboard rather than leeboards. Their trailering weight rises to roughly 1000–1500 pounds, compared with 600 pounds for the monohull.
Construction and Ballast
The hull is hand-laid fiberglass cloth over Corecell foam, with no structural wood to rot. Construction includes an integral deck and liner.
Easily filled and emptied tanks beneath the deck provide ballast. This system lets the owner adjust righting moment for sailing or empty the tanks for trailering, without carrying permanent lead. The capsize screening ratio of 5.7 and comfort ratio of 2.23 place the boat firmly in the small, trailerable expedition category rather than the offshore-cruiser class.
Rig and Handling
The Sea Pearl carries twin masts in an unstayed cat-ketch rig, with spars short enough to lie on deck without overhanging the bow or stern. The sails furl directly around the masts, and the masts are easily stepped. A short-handed crew can therefore rig or stow the boat without a crane.
The trimaran’s recorded sail plan carries 166 square feet, and hull speed is near 5.84 knots. The design is light enough to be driven at a useful pace by a small outboard or even rowed if the wind fails. The Tri draws only 0.67 feet with its boards up and 2.67 feet with the centerboard down, preserving the original shallow-water brief.
Cockpit and Accommodations
Without a centerboard trunk intruding into the forward cockpit, that area provides family seating or a place to sleep. An optional cabin top or bimini adds weather protection for overnight stops.
In the single-hull version, the central cockpit is ten feet long and the aft cockpit measures six feet six. Those dimensions reflect the boat’s emphasis on open space rather than an enclosed cabin. Its simple design and low maintenance help make it a credible small expedition boat. Owners have taken Sea Pearls around Patagonia, across the Caribbean, and up the Danube.
Models and Ownership
Marine Concepts offered custom configurations in mono, Tri, and Tri-Sport form. The builder claimed that a custom order could be completed and delivered in six weeks.
The manufacturer also claimed that well over 500 monohull Sea Pearls were on the water. That figure is higher than the 415 hulls recorded in the database for the broader model line.
The Verdict
The Tri Sea Pearl 21 is a specialist’s boat: brilliant where the water is thin and the launch ramp is home, but less compelling as a conventional coastal cruiser. Its shallow draft, centerboard, unstayed twin-mast rig, and open cockpit make the trimaran a genuine shallow-water tool with a proven expedition pedigree. On the monohull, leeboards and a kick-up rudder preserve the same basic purpose while leaving the forward cockpit free of a centerboard trunk.
Pros
- Six-inch draft with boards up opens waters closed to most sailboats
- Trunkless forward cockpit provides unusually open seating or sleeping space
- Unstayed cat-ketch rig and mast-furling sails simplify short-handed handling
- Corecell-and-fiberglass hull contains no structural wood to rot, easing upkeep
Cons
- Light 950-pound displacement and a 5.7 capsize ratio limit offshore ambition
- Ballast tanks require more active management than fixed ballast
- Trimaran trailering weight of 1000–1500 pounds calls for a larger vehicle
