Auxillary Sails Added to Ocean 55

55' steel fuel-efficient sail-assisted ocean-going motor yacht. Fuel tankage of 1700 usg will allow a cruising range approaching 5000 miles at 7 knots. The 2006 commission was updated recently with a 833 sq ft ketch sailing rig to provide added fuel savings, increased range, and roll stabilization without the underwater drag of fins or paravanes. The sails are individually small and easily handled, and the vertical clearance is still less than 50’ for Intracoastal Waterway travel.

Stabilizer Systems and Auxillary Sails

  • Stabilizer Systems

    • Active Fin Keels, Booms, Paravanes

      Seagoing powerboats can be made far more livable with the installation of some form of stabilizer system. One option is powered active fins and I’ve done a number of retrofits of these, including to a plank-on-frame wooden motoryacht. Booms and towed paravanes are another popular option, I‘ve created a number of these systems for both new and existing vessels. Other options are flume tanks, gyroscopes, moving weights, dagger boards, bilge keels, and steadying sails.

    • Roll Reduction for Offshore Cruising

      Stability and roll reduction is a major concern for many people contemplating offshore cruising in a powerboat. Decent roll reduction is what makes offshore cruising (and in many cases coastwise cruising) in powerboats possible and pleasurable. Which system or combination of systems chosen for a particular boat will depend on a number of factors. However, the major factor will be area and length of planned voyages, along with the desired comfort range expected. The three most popular systems, as mentioned above, will provide varying amounts of roll attenuation. Each system also adds some resistance when the vessel is underway. Active fins and bilge keels add drag all the time, paravanes only add drag when they are deployed.

      Retrofit of powered active fins to a plank-on-frame wooden motoryacht
      Retrofit of powered active fins to a plank-on-frame wooden motoryacht

      A General rule of thumb states that active (powered) fin stabilizers will eliminate about 90% of rolling, which is very good. The down side is that they are vulnerable and a complex electro/mechanical system that can break down. Many think that passive towed paravanes eliminate about 70-80% of rolling, which is great for a non-powered system. And bilge keels have a varied reputation as there are so many variations of size/style/position. Generally they should eliminate 50 % or less of rolling. The gyroscope is the newest system gaining popularity, but due to the addition of weight and huge power draw it makes little sense ultimately.

    • Roll Reduction for Coastwise Cruising

      If I were contemplating for example a trip to Alaska up the inside passage, I would fit small fixed bilge keels. These provide some stabilization underway, but very little when the vessel is anchored. This is okay as the inside passage includes endless protected anchorages. But if you are heading for Panama or South America, I would consider a combination of all three systems. The active fins work very well underway, but need the protection of the bilge keels. The paravanes are a great backup to the active fins, and they work while the boat is anchored.

      Which system or combination of systems is chosen for a particular boat will depend on a number of factors. However, the major factor will be area and length of planned voyages, along with the desired comfort range expected.

    • Mast and Stabilizer Redesign: Two masts, boom and paravane stabilizer system
      Mast and Stabilizer Redesign: Two masts, boom and paravane stabilizer system for Island Eagle

    • Construction drawing of a stabilizer base
      Construction drawing of a stabilizer pole base

    • Construction drawing of a fin stabilizer
      CAD construction drawing for an active fin stabilizer

  • Steadying and Auxillary Sails

    • Auxillary Sails as Stabilizers and Get Home Propulsion

      This also includes adding sails or stabilizer poles to power vessels.

      The addition of sails as stabilizers and get home propulsion is a concept which I believe is under-utilized. Most powerboats have opted for very complex rigs (derived from racing rigs) with expense and maintenance all out of proportion to their use. This is an area that needs more work.

      Auxillary, Steadying Sails on the Timbercoast Troller 22
      Auxillary, steadying sails on the Timbercoast Troller 22

    • New Sail-assisted Passagemaker Lite 6002

      A new ketch-rigged 60' aluminum Passagemaker Lite in the 02 series is in development. It will be the largest of our current sail-assisted power designs, the Timbercoast Troller 22, Northcoast 34, and Ocean 55.


    • Northcoast 34: Sail-assisted power cruiser

Tad Roberts