Boatworks

DIY Bowsprit

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Solace’s new bowsprit in action, with a carabiner holding the inboard end in place

I’d always dreamed of using a spinnaker to propel our Tartan 31, Solace, along on a light-air summer’s day, but the thought of wrestling with an unruly kite (prior to running it over, of course!) was never appealing. Then one day I read about the benefits of rope-luff sails and their ease of handling in the January 2012 issue of SAIL magazine and decided, “I can do this!”

The anchor roller before its new bowspritBecause Solace’s large roller-furling drum prevented me from attaching a small continuous-line furler for a light-air gennaker, I decided I would also need to add a bowsprit to keep the sail forward of the jib and in clear air. Because the bowsprit kits I found on the market were all either too beefy, too expensive or just plain ugly, I decided to fabricate one on my own.

Since I’m an engineer, I started out the project (as would any good engineer) by making a list of project requirements.

The list for this particular project was:

Do no harm! (minimize the need to drill holes)

Use the existing anchor roller

Ensure sturdy construction to handle moderate winds

Achieve a lower cost than commercial bowsprit products

Ensure the final product is attractive (no “DIY” look)

Make it easy to install and remove

The bowsprit deployedI also took a close look at Solace’s anchor roller, which protrudes about 9 inches from the headstay and consists of a thin stainless steel plate screwed down with four small ¼-20 screws. It was obvious that these little screws would be no match for the loads a sail would impose on them if the bowsprit were used in winds up to 20 knots—the top end of my desired range. A 495ft2 sail in those conditions can generate sheet loads of over 850lb. These then would be magnified by the unsupported bowsprit acting as a big lever and could result in a potential upward load on the roller of 1,600lb or more. This was sobering: all the more so since there was insufficient room belowdecks to install larger screws. 

Fortunately, the anchor-roller plate was attached to a sturdy bow plate, which was secured with five 3/8in through-bolts to carry the high loads of the headstay. I removed the lowest bolt and replaced it with a 3/8in eye bolt, and I then connected a 5/16in turnbuckle and tang to the existing anchor roller pin to make a mini bobstay. Sweet success and no new holes drilled! It was also easily removable, meeting yet another one of my requirements. 

The next step was to come up with a suitable sprit tube, one that would be thick enough to prevent it from buckling around the bail at the top of the anchor roller. To create a safety margin, I made it from a 3ft 6061 aluminum alloy tube with a 2.5in outer diameter and a ¼in wall thickness. Tubes of all sorts of dimensions and in various lengths can be purchased online from McMaster-Carr (mcmaster.com). I drilled holes for 5/16in eyebolts at each end to accept a shackle from the continuous-line furler, and so I could fasten the aft end of the bowsprit to an existing deck-mounted anchor chain stopper with a stainless steel carabiner. The force on the aft end of the bowsprit is mainly downward, so the mount on that end is needed mainly to hold the bowsprit in place.

Finally, to give my bowsprit a professional look, as well as to protect it from the environment, I had a white marine powder-coating applied. Many shops provide coating services for recreational uses. I used Prism Powder Coating (prismpowderusa.com) in Wareham, Massachusetts, which did an excellent job in less than two days at a very reasonable price.  

My finished bowsprit is easily deployed, rests on top of the anchor and is held in place by the anchor-roller bail. On Solace, it allows my gennaker to clear the bow pulpit and jib roller to prevent friction when furling.

A bobstay was necessary to ensure the anchor roller could handle the loads of the new sail

The bowsprit is also easily removed. I simply detach the carabiner to stow the unit. The total cost (not including the sail, furler and sheets) was approximately $370—about half the cost of a commercially made bowsprit kit. Last two requirements met! The end result looks beautiful, allows my gennaker to fly in undisturbed air and, thanks to the mini bobstay, won’t pull the anchor roller off the deck when the breeze picks up! 

Budget for bowsprit

Aluminum tube  

McMaster Carr

$76.54

Power coating 

Prism Powder

$150.00

5/16in turnbuckle

West Marine

$59.99

 2 hole 3in tang 

West Marine

   $13.49

Carabiner    

West Marine

 $22.99

3/8in eyebolt       

West Marine

$25.98

   

  Total: $348.99

 


 

Sprit Kits

Seldén’s aluminum or carbon fiber Gennaker Bowsprit So you want a retracting sprit but don’t have the desire or know-how to make one? Three companies make retrofit sprit kits: Seldén, Sparcraft and Forte. The poles supplied are either thick-walled aluminum, with inside diameters ranging from 2.9in to 5in, or carbon fiber. The rule of thumb when installing an aluminum pole is that two thirds of the length of the pole must be supported; hence, the further forward you want your sprit to protrude, the longer a section you will need. The kits all come with various mounting options and DIY installation should be straightforward enough, depending on your boat’s construction.

Seldén’s aluminum or carbon fiber Gennaker Bowsprit comes in seven sizes to fit boats from 20 to 60 feet and up. It slides through a circular stainless steel collar with a low-friction liner that an be affixed to the foredeck or to the side of an anchor roller. Two padeyes are bolted to the deck in line with the bracket, and the aft end of the pole is secured to one of these, depending on whether it is extended or retracted. A separate tackline runs through the bowsprit, or a tack block can be fitted at the forward end. From $360

seldenmast.com

Sparcraft’s removable aluminum bowsprit kits are spec’d for boats from 25 feet to 57 feet. They include end fittings, a collar and deck fixing blocks. A fitting that allows the collar to be bolted to the anchor roller is optional. The deck blocks are nearly flush-fitting, and the collar can be removed from its deck block to leave a totally uncluttered foredeck. The built-in stopper for the tack line is a nice touch. From $899

sparcraft-us.com

Forte Carbon Fiber Products has a range of sprit kits to fit boats from 15 to 60 feet and up. The carbon fiber poles are built to suit individual boats and the diameters and wall thicknesses of the carbon tubes therefore vary according to a boat’s displacement and/or sail area. The poles are clear-coated and, because 50 percent of their length can be unsupported, do not need to be as long as their aluminum equivalents. From $1,675

fortecarbon.com/marine

 

Contacts

If you don’t want to make your own retracting bowsprit, try:

Facnor, facnor.com

FORTE CARBON PRODUCTS, fortecarbon.com

Seldén Mast, selden.us

 

Photos by Jim Vernon

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