Predicting Bad Behavior

The 30-knot, V-bottomed, 30' surf rescue boat (SRB) pictured here was plagued by a dangerous, unstable condition at high speed: She would suddenly depress her bow, heel to port, then broach to starboard. Such dynamic instabilities are more common in planing craft than many designers might care to admit.

Consider the following cases:

• A 28′ (8.5m) lobsterboat, repowered for a race, turned turtle at high speed.
• A 23′ (7m) tournament-style bassboat would chine-walk violently at high speed.
• A 30′ (9.1m) U.S. Coast Guard surf rescue boat would roll, pitch, and yaw at high speed.
• And a 36′ (11m) U.S. Navy SEAL-team delivery craft exhibited chronic pitch-instability—the boat would stuff its bow—at high speed.

What these four powerboats had in common is one or more potentially dangerous dynamic instabilities at the high end of their respective speed ranges—all of them in excess of 25 knots. Did the instabilities occur due to design, or operation? If design, then is such behavior predictable?

A Rush on Skimmers

Kvichak (all)

Kvichak Marine in Seattle, Washington, started building 30 units of its 30′ (9.2m) Rapid Response Oil Skimmer early this summer to help clean up the Gulf oil spill, and more orders are on the way.

Kvichak Marine, a builder of aluminum workboats in Seattle, Washington, this summer received multiple orders for its 30′3″ x 8′ (9.2m x 2.4m) Rapid Response Oil Skimmers fitted with the MARCO Pollution Control CL-1 Filterbelt oil-recovery module. Kvichak’s eager buyers are among those working the Gulf oil spill along the Louisiana, Mississippi, Alabama, and Florida coasts.

Offshore Passage Prep: Hydraulics

Steve D'Antonio (all)

The author made port in the Faroe Islands having avoided a potential hydraulic failure by replacing a broken raw-water pump on the passage from Scotland. Carrying the correct spare parts is essential when voyaging to such remote destinations.

Since my first bluewater passage aboard the 120′ (36.5m) steel schooner R/V Westward nearly 25 years ago as a student, I’ve developed a strong appreciation for what’s involved in maintaining a boat on any voyage where support and resources are limited. On that well-found boat, from Cape Cod to the Grenadines and the British Virgin Islands, we performed routine maintenance and numerous repairs. Westward was a relatively unsophisticated boat: saltwater showers, no air-conditioning, and lots of original equipment, including the pneumatic-start diesel, dating to her 1961 construction by Abeking and Rasmussen. Navigation was primarily by compass, paper charts, and sextant with LORAN when in range. But even those simple systems demanded regular attention and racks of spare parts to assure operation offshore.

Design Challenge II Winners

Professional BoatBuilder and WoodenBoat magazines’ second design challenge drew 58 excellent submissions from professional and amateur designers in 17 countries. Our panel of judges had the pleasure of studying all of them, and the unenviable task of choosing those that best fit the design brief of Design Challenge II: More Pleasure at 2 Gallons per Hour. Intended to inspire designs for cheaper, more fuel-efficient, and seaworthy vessels capable of carrying a family on overnight excursions, the parameters were as follows:

• Must be trailerable for affordable launching, over-the-road transportation, and storage.
• Max beam 8′ ; max length 40′
• Minimum length 24′, stem to transom
• Trailerable weight (with engine) should not exceed 3,500 pounds
• Must burn less than 2 gallons per hour (7.6 l/hr), maintaining a 10-knot cruising speed in a 2′ (0.6m) chop and 15-knot breeze while carrying 800 lbs/362 kg (family of four). Favorable consideration will be given for continued efficient fuel consumption and good seakeeping abilities at speeds in excess of 10 knots
• Must include at least spartan overnight accommodations (berths, head, galley) for two adults and two children
• Must be a new design
• Submissions should be the designer’s original, previously unpublished work, and include lines, profiles, sections, table of offsets, accurate weight study, cost calculations, and performance predictions.

Now we have the winners in all three categories: wood, metal, and composites. In-depth stories about the winning designs as well as a roundup of innovations, good ideas, and details from other submissions will appear in upcoming issues of Professional BoatBuilder and WoodenBoat magazines.