Patent Application
20190351976
Retractable bowsprit for sailboat—U.S. Pat. No. 7,367,276
Sailboat spinnaker bowsprit—U.S. Pat. No. 6,857,380
Bow Sprit Arrangement—U.S. Pat. No. 5,765,498
Retractable bowsprit for Sailing Vessel—U.S. Pat. No. 7,762,204 82
U.S. Pat. No. 7,367,276 This bowsprit connects at the forestay and the mast. As an aftermarket addition it would require a major modification to the foresail point of attachment. It would not be very strong as it does not utilize a bobstay to resist upward force and has limited ability to handle lateral side forces. It encumbers a large amount of deck space and would make traversing this area hazardous.
U.S. Pat. No. 6,857,380 This spar is mounted below deck and protrudes through the forward sections of the deck creating interference with both areas. The opening caused by the protrusion creates a breach in the watertight integrity of the forward section. This as well as the lack of support for the articulating spar limits its application to only the smallest of sailing vessels know as dinghies.
U.S. Pat. No. 5,765,498 This complex hinging mechanism creates many moving parts and potential points of weakness for failure. Adjustment and stowage of this design can not be accomplished from the cockpit. The complex geometry of the retracting mechanism would eliminate its installation on many boats due to interference with deck geometry and fitting layout, it would be difficult to remove and stow, and when removed there would still be a lot of deck hardware cluttering the foredeck.
U.S. Pat. No. 7,762,204 82 This design comprises of two hinged spars controlled by a complex arrangement of line and blocks to affect the extension length in front of the boat. In a retracted position the spars splay out to the side of the boat to a considerable degree. Making a very awkward configuration for seaworthiness or even docking the boat in confined quarters. It is unlikely that this design possesses any practical application.
Bowsprits are spar appendages to the bow of sailing vessels to extend and increase the sail area on a given size boat. Modern sailboats are re-inventing themselves in the never ending quest to become faster, safer and easier to handle. One common trend in sailboat design borrows a concept from yesteryear by utilizing a spar mounted on the front (bow) of a boat to extend the rack point forward for the attachment of sails, this spar is known as a bowsprit. This phenomenon is partly driven by contemporary designs that have more vertical or plumb bows, than the sweeping lines of long overhangs typical in sailing vessels designed in the first half of the 20th century. Modern designs tend to extend the waterline length to the extremities of the bow and the stern, thus maximizing speed potential for a certain sized length over all (LOA). The market demands the fastest boat possible for a certain length as this dimension drives the overall cost of ownership, as monthly storage charges are based on LOA and various other ownership costs tend to be proportional to the LOA cubed.
With the evolution of plumb bows, sailors have forfeited the ability to deploy sails well forward of the mast thereby compromising the area of these foresails. A reduction in forward sail-area also impacts the steering balance of the vessel. The further the tack point is in front of the mast the larger is the sail-area possible. Furthermore boat steering is enhanced and overall performance improved when the center of effort (which approximates to be the center of sail area) is well in front of the center of resistance (which approximates to be the center of displacement). This stabilizing concept is analogous to the vessel being pulled through the water rather than pushed and requires less corrective steering which is detrimental to speed.
Modern boats are capitalizing on aforementioned beneficial characteristic by re-discovering this once forgotten spar, the bowsprit. The challenge therefore becomes how can modern boats capitalize on benefits of this forward protruding spar without permanently being effected by its encumbrances that escalate storage costs and general awkwardness.
Designing an aftermarket bowsprit that is capable of being mounted to a wide variety of sailing boats poses an interesting challenge, as each boat has its own specific geometry and existing fittings and hardware. A major consideration for such a sprit is to have maximum adaptability in placement positioning to overcome existing geometry or hardware constraints.
Currently there are three concepts active in the marketplace attempting to solve this issue:
Pros & Cons of aforementioned bowsprit concepts:
Concept 1 simply extends the tack of the sail forward but does nothing to decrease the overall LOA when the boat is in a storage configuration; therefore storage is awkward and expensive. Remaining in a permanently protruded configuration is also detrimental to maneuvering the vessel in tight quarters, and can be difficult or dangerous to service or adjust when the vessel is underway.
Concept 2 helps solve the storage issue by retracting into the vessel's interior thus reducing the LOA but requires significant structural upgrading to handle the extremely high point loading configuration. This concept has been integrated into the design of many contemporary boats however there is a significant interference with space in the bow interior. Furthermore this configuration requires a large diameter hole facing directly forward into oncoming seas and leakage around this opening is common. No serious ocean going vessel would consider such breach in the water-tightness of the vessel in this area. Retrofitting this configuration is expensive and complex due to the structural upgrade requirements. The loads developed in this cantilevered sprit are intense. From an engineering perspective this cantilevered bending mode is the least efficient means to carry a load as it results in a larger sectional requirement to limit deflection to an acceptable level. Consequently these sprits tend to be larger in diameter and heavier in weight than a comparable sprit supported by a bobstay.
Concept 3 is similar to 2 except it is mounted above the deck and would seem to have the best of all worlds. In practice however the deck mourned telescoping spar develops extremely high point loads and requires significant structural upgrades prior to installation. Without a bobstay the loads are carried by cantilever bending and is subjected to same load issues as outlined for concept 2. Even with a bobstay the lateral loads are carried by cantilevered bending, which means the size and strength need to be massive. This configuration also creates deck clutter as it obstructs the foredeck area of the vessel. Sailing vessel deck space should remain clear and unfettered to permit the crew safe and easy access. Space at the bow is at an absolute premium and any small protrusion of hardware becomes a serious trip hazard when traversing this space in any sea condition. Another unfortunate aspect with this concept is that it is visually unappealing. A sailing boat's beauty is defined by its vessels lines. Aesthetics tend to be compromised whenever appliances are installed at either end of a vessel that break or obstruct these natural lines. Lastly due to rigging configurations the forward stay (head stay) on a sailing vessel is always mounted on centerline. This is exactly the same location desired for a deck mounted retracting bowsprit. The compromise becomes an angled offset which adds to the overall awkwardness of the look, installation and operation of this device.
The main factors for consideration in the design of an aftermarket bowsprit for sailboats are:
The articulating bowsprit addresses each of these criteria. It comprises of two tubular sections connected at the front by a hinged connector and attached to the mountings to the dock or side of the boat. The geometry of the said bowsprit creates a perfect truss configuration which efficiently carries the loads and reduces weight. The spacing of the mountings is variable due to the hinged connector which gives the device much versatility on where it can be mounted on a boat and it fits most boats. Many other types of bowsprits do not have this versatility and consequently do not fit many boats as there are existing hardware conflicts. The said bowsprit connects to the mounting brackets by pins which facilitates easy removal by hand without any tools. The hinged connector is tubular in construction (hollow) that allows for a variety of attachments to the sail.
Articulating Bowsprit Description
The articulating bowsprit 8 comprises two connector tubes 8A having front ends 8B and rear ends 8C, the rear ends 8C of the connector tubes 8A are either deck or side mounted just behind the forestay. The front ends 8B of the connector tubes 8A are connected by a hinge connector 11. Each connector tube 8A is mounted at or near the side of the boat and forms an isosceles triangle, this shape is effective at resisting lateral forces imposed by the sail. Uplift forces are resisted by a bobstay 5 which attaches to the bow 9 just above the waterline level. The bowsprit 8 can be easily detached from its deck or side mounting by removing pins 14 and folded to a closed configuration for compact stowing. The front hinged connector 11 of the tubes 8A is a hinged joint which permits the angle of incidence of the tubes 8A to be altered. This facilitates flexibility in choosing an optimal location to attach the mounting hardware and simplifies the installation process. The connector tubes 8A are connected together by the hinge connector 11 at their front ends 8B and the rear ends 8C feature pinned connections 13A comprising deck mounting brackets 15, end pieces 13 and end piece pins 14 at the deck. (See
