Luhrs 320 Convertible
By Jack Hornor
Revised by BoatUS editors in October 2012
For boaters who enjoy both fishing and cruising the Luhrs 320 Convertible offers style, solid construction, and a sensibly laid out design. Add to that an extensive list of features intended to satisfy cruisers and fishermen alike, affordable price and it adds up to one of the company's most successful designs.
For nearly 60 years, the Luhrs Corporation has been designing and building boats. Their reputation has long been strong among coastal fisherman who were looking for vessels of solid value without the costly fancy finish and custom crafted joinerwork of more expensive fishing machines. In an attempt to lure (no pun intended) customers who enjoyed fishing as well as the amenities of cruising boats, Luhrs introduced their Tournament series of flybridge convertibles in 1986. The 320 Convertible was added to the line in 1988 and, with a length of 31'-6", was the smallest model in the series.
The 320 Convertible was a break from Luhrs' tradition of bare-bones fishing boats and offered an extensive list of standard equipment. Items such as a custom aluminum tower, transom door, rod holders, fresh and seawater washdown pumps appealed to the fishermen while a fully equipped galley, a main saloon and an honest stateroom with comfortable double berth appealed to those with cruising interest. The 320 Convertible remained in production until 1999 and used models are in demand on the used market.
Photo by Fritz Grell – United Yacht Sales
Cored composite construction is boatbuilding technology that has been around for more than 30 years and is well understood by the boating industry. In recent years this method of construction has become increasingly popular with powerboat manufacturers due to the significant advantages of lighter weight structures. When properly engineered and constructed, composite hulls are very strong and long lasting. However, no matter how well constructed, cored composites are always more subject to puncture failure than solid laminates. Considerable care must be taken when mounting fittings and hardware to ensure water is not allowed to enter the balsa wood core.
From its introduction in 1988 through the 1990 model year, 320 Convertibles were built using end-grain balsa wood composite construction both above and below the waterline. After 1990, only the hull sides and decks were cored and the bottom was solid fiberglass which significantly reduces the potential for core related problems. In either case, used models must be thoroughly inspected for signs of elevated moisture, cracks or delamination of the composite. Although this type of damage is not typical, once it becomes apparent to the eye, it may be too late to avoid a costly repair. Repair costs depend on the extent of damage but even a small area, of two or four sq. ft, could cost several thousand dollars to fix. Luhrs used isopthalic gelcoat surface finishes to help prevent osmotic blistering and, to date, 320 Convertibles have not been know to have significant blister problems.
Reinforcement of the hull is accomplished with fiberglass-encapsulated plywood stringers and frames attached to the hull by secondary bonds of fiberglass. Limber holes, drilled through frames and stringers to allow drainage, are sealed with gelcoat. To Luhrs credit, this method of finishing exposed plywood edges is better than some that leave the wood grain exposed but it is prone to cracking and should be checked periodically to ensure the seal is intact.
Like nearly all production boat manufacturers, Luhrs makes extensive use of one-piece molded fiberglass liners for interior and cockpit components. The benefits of molded liners are ease of maintenance and reduced cost of construction while drawbacks include lack of accessibility for maintenance, inspection and installation of after-market equipment.
The deck-to-hull joint is fastened with adhesive sealant and stainless steel screws on 12-inch centers. A high-density plastic rub rail is added at the deck edge with stainless steel insert to help prevent damage from docking. Deck fittings and hardware are securely fastened with stainless steel nuts bolts and washers. An aluminum plate is molded into the cockpit deck for extra support if an owner wishes to install a fighting chair.
Typical of Carolina-styled sportfisherman, the maximum beam of 320 Convertible is carried forward of amidships resulting in a very large foredeck area. The foredeck is flush and unobstructed by anything other than a single deck hatch. There is a pulpit that extends past the bow a little more than three feet and provides convenient and secure anchor storage. A welded aluminum rail that extends to just past the cabin surrounds the deck and pulpit. The decks along the cabin house narrow to less than one foot in width and moving fore and aft can be a bit tricky. Luhrs has provided conveniently placed handrails along the cabin for added safety.
As with all boats of this style, there are necessary compromises in order to accommodate fisherman as well as cruisers. For the serious fisherman those compromises will be most noticeable in the size of the cockpit, which is only about 70 sq. ft in area. Cockpit space is further restricted by an insulated icebox along the port side and tackle locker and sink to starboard. There is a removable fish box below the cockpit deck and a walk-through transom door to port.
While the flybridge of any 32-footer is bound to have restricted space, the 320 Convertible can accommodate four without serious crowding. There is a helm seat and mate's seat behind the helm console and a bench seat forward. There is plenty of space below the console and bench seat for storage of gear.
Standard equipment included a custom welded aluminum tower with canvas top over the flybridge.
The 320 Convertible is one of only a few boats of this style and size to offer a true owner's stateroom. The forward stateroom is fully enclosed and features a center island berth large enough for two adults. There is six feet of standing headroom and sufficient room, with the door closed, to change clothes without feeling like a contortionist. There are two good-sized hanging lockers on each side of the cabin and storage drawers below the berth. And, so you won't forget you're in a fishing boat, there are rod storage racks overhead.
Aft of the owner's stateroom is a head and shower to starboard and galley to port. The head is larger than most I have seen on boats of this size and the shower is integral. The galley is small but efficient with a two-burner countertop stove, sink and 110/12v front-loading refrigerator.
There were two layouts of the main saloon offered one, which featured a convertible couch to port and settee to starboard and a second that substituted a small two-person dinette to port in place of the settee.
The standard power package for the 320 Convertible was two, 454-cubic-inch displacement, fresh-water-cooled gasoline engines supplied by either Crusader Marine or Marine Power Corporation. Both Yanmar and Johnson & Tower diesel engines were offered as options at considerable extra cost. Due to the substantial cost, these were not popular choices and it is unusual to find a diesel-powered 320 on the used market.
With standard gasoline engines, cruising speed is right around 20 knots (23 mph) and top speed is about 28 knots (32 mph). There is a single, 270-gallon, welded aluminum fuel tank. Assuming an average fuel consumption of about 30 gallons per hour and a 10 percent fuel reserve, the 320 Convertible has an effective cruising range of about 180 miles between fuel stops.
The hull form is a modified "V" with a deadrise angle (the angle of the bottom to the water plane) of 18 degrees which is fairly typical of this type of vessel. It results in a smooth comfortable ride under all but extreme conditions. There is considerable flare to the 320's hull sides at the bow and the ride is very dry even in choppy water.
Standard equipment includes hydraulic steering and the 320 responds quickly and is easily controlled. Hydraulically operated trim tabs control the trim angle for changes in speed, sea condition and load.
Designing a successful powerboat of this dual-purpose type is a delicate balance of compromises and it's impossible please everyone with just 32' of length to work with. Serious fishermen are likely to find the size of the cockpit and the range of the 320 Convertible a little less than they would like. The dedicated cruiser may find the tackle locker a waste of space and rod racks overhead of their berth just a bit too salty for their taste. The fact the 320 Convertible remained in production for 12 years and remains a popular choice among used boat buyers would seem to confirm that Luhrs made just the right compromises with this design.
Naval architect Jack Hornor was the principal surveyor and designer for Marine Survey & Design, Co., based in Annapolis, MD. He was on the boards of the American Boat and Yacht Council, the National Association of Marine Surveyors, and the Society of Boat and Yacht Designers. He and his wife sailed their Catalina 42, Legacy, based on Maryland's Eastern Shore.