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Installing a New Bowsprit

Murre, Mariner 31

Hull 150, 1972


October 2009



Let me confess immediately that this was all Bruce’s idea. 


Bruce Allen keeps his lovely Mariner 31, Gitana Vela, in a Sausalito marina just up the street from Murre.  After a particularly gusty afternoon off McNear’s Point last fall, a fateful afternoon that laid his boat on her ear and brought her back up minus her rig, he found himself in need of a new main mast and bowsprit.  And knowing Murre as he does, he recommended I have one made at the same time.  He got around to the installation before I did, and so recommended all of the procedures chronicled below*.  On this one, I’m just the scribe.


Much of this article may be appropriate only to owners who have the same pulpit and/or anchor roller set-up as Murre and Gitana Vela.  I thought long and hard about customizing both, but in the end stayed with the original equipment.


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The new bowsprit was fashioned and sealed and delivered in the spring of this year, and then it sat in my garage all summer while I awaited the approach of the muse.  When the sun shines and the wind blows, the sailor thinks not of sanding or varnishing or the half finished rewiring job or the leaky stern gland.  Any jury rig that will keep his boat sailing till fall, till the first good storm introduces another season, is employed.  Because riding the great, wet wings of that first storm is the muse—the boat project muse.


In October the remnants of typhoon Melor fell upon the California coast with 60 knot winds and three inches of rain in one day, so out came the new bowsprit.



Preliminary to installation was getting the varnish on.


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I hung the spar in the garage and applied ten coats of Bristol finish, one in the morning and one in the evening, over a five day work week.  This two-part finish was new to me, but I found its ease of use and beauty made up for its expense—$95 a can.  It required no sanding between coats, and it flowed on like liquid glass.  The sprit took the better part of a quart.



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Next came dry fitting at the boat.  It would have been smart to fit first and then varnish because accurate as the carpentry was, the sprit could not be squeezed between the Samson posts nor would it allow the cranse iron to seat properly.  Both ends needed shaping and eventual refinishing. 


Only after fitting the butt into the Samson posts could I mark for the various fastener locations.  I found that the pulpit did not have to be removed in order to remove or fit the sprit.  Its deck bases and life line support meant it was plenty stable, though awkward looking, hanging out there on its own.



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After I removed the old sprit, it was easy to see that much of its decay was at the fasteners, so I followed Bruce’s suit and slugged all the fastener holes on the new sprit with epoxy.  The slug holes were bored with a one inch spade and a drill press.  Note blocking at the far end to keep the sprit perpendicular to the drill bit.  (I also chose not to replace the large eye bolt for the storm jib that, on Murre, was located a few inches forward of the Samson post.  The rot was worst there, and so I will locate this fixture someplace else.)



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Unfortunately, because the drill press only had a three inch drop, I had to go at the bore from both sides.  In order to ensure precision, I bored as far as I could from the top, and then knocked a pilot hole through to the other side with a hand drill.  I used a guide for the hand drill, here a piece of plywood cut at a 90 degree angle.



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The result looked clean and professional if intimidatingly large.



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Next I reshaped the nose of the sprit so it would comfortably allow the cranse iron with some room to spare for varnish.  This was mostly done with a hand sander and a chisel for the corner.  Be careful as the difference between taking off just enough and taking off too much is very small, and neither the sander nor the cranse iron will give any warning as one crosses the line.


The spoke shave was pictured for nautical effect.



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And then came epoxy slugging.  The bottom of the bore was double taped and a run of wax paper was laid over the plywood work bench to avoid fusing the sprit to the bench if the tape failed, which in one case it did. 



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This out-of-sequence photo helps demonstrate a special step necessary for the third pulpit fastener hole.


The underside of the new sprit was not rounded as was the old, but instead a flute was laid into both bottom corners.  This meant that the third pulpit bore from the nose went exactly through the flute and necessitated that the base for the nut and washer be countersunk.  I bored this hole from the top, stopping the press some ways above the flute’s top edge, and then I drilled a pilot hole the rest of the way so as to have a guide later.  This hole was slugged with the others, and after it had set I bored to the slug from the underside.



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Six coats of varnish over the shaved ends and one more for good measure over the entire spar had me singing sea shanties.  I’m not sure if the urge to sing came from an artistic reverie or if it was induced by the exotic fumes of Bristol finish, but I knew I should call it a night when my neighbors threatened a gag order.



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Back at the boat, more fitting and drilling out the slugged holes for the fasteners. 


I drilled for the anchor roller first—the easiest to mark—before setting the sprit in place and marking for the Samson post bolt.  This fitting exercise was the most difficult of the lot because of the lack of space in the bows for a hand drill and what I think turned out to be a mismatch of fastener location in each post.  It didn’t help that the bolt, a bronze rod, was bent with age.


After the sprit was “permanently” in place, I marked for the pulpit fasteners, whose installation was a breeze.



I wouldn’t have guessed at the outset that the addition of this one spar would add so materially to Murre’s beauty, at least as such is gauged by Murre’s owner.


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Mostly because of the drying time required between coats of varnish, this installation had kept us at dock the better part of two weekends.  So the moment the rig was solid on the second Saturday, I was impatient to get away to our favorite hidey-hole.


We anchored at Paradise Cove that evening, and I spent Sunday morning getting the foil back together, the jib rolled on, and the turnbuckles keyed.  On such a warm morning, shirtless, bare footed, and a screwdriver between my teeth, I felt very sailorly hung out over the pulpit attempting to assemble the roller guard without dropping it (or myself) in the bay. 


From the vantage of Paradise, Sunday seemed a drifter of a day—occasional breeze, short lived, and each waft from a different quarter.  But as I rounded Pt. Blunt heading toward the city front, it came up steady out of the southwest and well over 20 knots (NOAA reported gusts of 29 knots).  That and a powerful ebb quickly cut up a fierce chop.  I was flying a full main and a genoa only one third tucked in, so we were overpowered, but I left Murre that way to see how my installation would handle a blow.  Murre laid well over burying her bow in the larger rollers. After each dunking I peered anxiously over the house to see that the sprit still stood.  It stood.  Back at dock, I noticed that some of the excess varnish at the base of the cranse iron had squeezed out.



*Bruce’s installation included a few more features I have, thus far, left out.  One, Bruce noticed on Gitana Vela that the sprit was rotting from underneath because it sat right on the deck, which trapped water.  His solution was to raise the sprit off the deck by inserting a 3/8ths inch teak pad up at the bow and between the toe rail pieces.  He says this required minor repositioning of the sprit at the Samson post where he raised the sprit by about ¼ inch, and then using the original Samson post holes as a guide, he drilled the pin hole through the new spit.  Two, he replaced the 5/16ths inch bronze rod that pins the sprit to the Samson posts with a larger 3/8ths inch rod of stainless steel.  Three, he sealed the joint where the sprit butts into the Samson post and the open space where the sprit passes through the toe rail with Mahogany 3M 5200.


Bruce’s comments are as follows:


I changed out the Samson post pin to a SS threaded rod.  I went up to a 3/8ths inch stainless steel threaded rod up from the 5/16ths inch bronze rod, which I think was original.  I used the old bronze rod for all of the fit up and fine tuning, and installed the larger threaded rod for the final install and bedding.  I did that because I wanted to thread the bolt tightly in place, and knew it would be difficult to thread and unthread it the multiple times I would need to for the fit up.  The last time I put in the SS rod, I used a cap nut on one end to screw the whole thing together.  Then I bolted the other side up, hack-sawed off the excess, unthreaded the bolt, dressed up the threads with a thread file, then put the fender washer,  lock washer and cap nut on for good. 


I noticed that I had about a 1/16ths inch gap on both sides of the bowsprit, which I filled with mahogany colored 3M 5200.  You can hardly see the bedding compound seams because they blended in with all the wood and varnish.  I varnished over the bedding compound seams and treated them as if they were part of the wood. That worked out well with the Bristol finish, because they are both polyurethane products (Bristol and 5200), and thus compatible.  I thought a long time about which bedding compound to use, and ended up with 5200, first because you can get it in mahogany color, and second because I wanted the combination of supreme adhesion and sealing power that 5200 has.  There aren’t too many places I would even consider 5200 above the water line, but this was one place where it seemed appropriate.  I figured that if I ever need to remove it, I would just hack saw between the posts, cutting only the bedding compound.  I do not anticipate having to remove the sprit ever again.



Bowsprit Details


The following outlines some construction details of Murres new bowsprit.


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Spar Material

Clear Douglas Fir.  The old sprit was made of Sitka Spruce and D. Fir was used in this application simply because it was readily available.  Having both sprits in hand, I took the opportunity of weighing them.  The old S. Spruce spar weighed 15.4 pounds while the new one of D. Fir weighed 22.2, a difference of nearly seven pounds.


Spar Dimensions

Length: 82 ½”.  This is between ¼” and ½” longer than the original.

Height: 3 3/8

Width: 3 ¾”

Depth of nose for cranse iron: 5 ½”

Flute: 1” wide by 35” long, underside only.  The spar is not tapered.

Samson post accommodations: these should be measured to your own post’s requirements.  On Murre, about ¾” of width was removed from the vertical notches that fit between the Samson posts, and these were rotated forward about 5 degrees to compensate for the sheer of the deck.  The bottom of the notch was 4 ½” from the base of the spar, which was also cut at a 5 degree angle.  An additional notch for the Samson post pad was placed 6” in.


Anchor Roller Assembly

The anchor roller included in the above drawing is original to the boat and is comprised of a bronze sheave in a bronze housing attached to a thick teak block.  There is a small (read “flimsy”) anchor keeper at the top of the roller held in place by two small screws that, on Murre, have sheared off and are not pictured.  A new anchor keeper will need to be fashioned later.  This roller is far from ideal but serves to stow the anchor closer toward the bow, which I like, and will be modified to need later.  The main roller bolt is located 34 ½” from the base of the sprit.


Various Fasteners

Samson Post: 5/16” bronze rod approximately 10” in length acorn nut to acorn nut (I failed to measure while the sprit was out).

Anchor Roller:

Primary: ½” bronze rod of 7 ¾” in length fastened with two acorn nuts.

Secondary: 3/8” bronze rod 6 ½” in length fastened with two acorn nuts.

Pulpit: Four 5/16” hex cap bolts of 4 ½” in length.  The bolt in the countersunk hole should be shortened by about an inch. 


Cranse Iron

Sadly, I didn’t take any measurements of the cranse iron before reassembling Murre.