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Reinforcing the Mast Step
This page was last updated on 17 January 2004.

During the summer of 2003, I became somewhat concerned about the condition of the mast beam and/or mast step.  During the initial restoration of the boat, I did not recore the coachroof, nor did I replace the mast beam as is common.  The mast beam looked to be in good condition, and with so many other projects to complete I did not see a reason to do the mast beam at that time.  There were no obvious signs of damage to the deck, and there was no need to core the area at the time, as sounding and other standard tests revealed no evidence of compromised core.

The factors leading to my concern were twofold:  first, I had had a leak through the nearby wire chase for the mast wires, which I corrected early in the season after I noticed it, but I was unsure how long it had been going on.  Second, the main upper shrouds' turnbuckles, were cranked up nearly all the way, which was definitely more than they had been three years earlier when the mast was stepped for the first time since the restoration.  Part of this was because the wire was an inch or so longer than it should have been, as the turnbuckles were always cranked up more than I would have wanted ideally, but I felt that it was worse than it had been.

IM009347.JPG (149609 bytes)Also, I noticed water pooling around the mast step during the season, and there was a definite depression in the area.

With the boat at home in the shop after the season ended, one of the first things I did was remove the mast step from the deck to determine what, if anything, was going on beneath.  I also removed the wire chase fitting, which exposed some rotted core (which was new since I installed the fitting three years earlier--bummer).

I sounded the deck beneath the mast step, which revealed evidence of moisture saturation in the core beneath.  So, if nothing else, it looked like I was going to be faced with removing the core in that immediate area and filling the area with solid fiberglass reinforcement


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A few days later, I bit the bullet and cut a hole in the deck.  Taking a saw to a nice deck is always somewhat traumatic, though with my previous experience recoring the boat several years ago it was less of an issue for me--even though the boat now was nicely finished, when before it was a near derelict.  Perception and experience changes all.  However, there was no reason to mess around here:  the deck needed reinforcement, so I marked off an area about 12" wide and 24" athwartships  to remove the top skin (after measuring the location of the mast step and taking photos of the whole area to ensure proper placement later).  Then, with my small circular saw set to about 1/4" depth, I cut out the top skin.  It took no time at all, but cutting fiberglass in this manner creates copious amounts of dust and debris.  What a mess!

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IM009386.JPG (168471 bytes)The core was still fairly well adhered to the underside of the top skin, so to make it easier to remove the fiberglass I made several more cuts across and lengthwise.  The smaller pieces were easier to get started.  I used a large chisel to pry off the top skins, then used the same tool to remove all the core from the area.  The core was in better condition than I had expected, but was obviously badly compressed in the area directly beneath the mast step, and there were definitely signs of rot and water damage--though not even close to the extent of my decks back in 1999 when I bought the boat and embarked on a major recore.  Once all the core was removed, I swept it up and vacuumed the entire area to keep things clean; with the boat finished, I didn't want to grind the abrasive fiberglass dust into any shiny painted or varnished surfaces.  

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With the core removed, I could see that the inner skin was cracked on each side of the mast beam, where the deck had flexed around the more solid beam over the years.  I was happy to see that the core all the way around my cutout was clean and dry, though.

Before continuing with the fiberglass repair, I moved inside the boat to remove the existing mast beam.

Click here to read that portion of the job now.  Or, just keep reading, and you'll find another link to the mast beam at the bottom of this page.

My next step was to laminate solid fiberglass in the area on deck where I had removed the core beneath the mast step.  First, though, I sanded the inner skin in the uncored area to remove old resin and core bits, and then, after cleaning the area thoroughly, mixed a small batch of thickened epoxy and applied it to the edges of the opening, to seal the surrounding core and to fill the small voids that had been created when I removed the inner portion.  Then, I began the laminating process.  Earlier, I had cut a number of pieces of fiberglass cloth to the correct size for the opening.  Because I had a large supply of 10 oz. cloth on hand, and I was anxious to get the project completed, I used the materials on hand.  Heavier material would have filled the area with fewer layers, of course, but my local supplier didn't have any of the biaxial cloth I wanted, so I pressed on with the lighter material. 

wettingout.JPG (161672 bytes)Because I was unsure how hot the resin I was using would cure (MAS low-viscosity resin with medium hardener), I began with around 4 layers of cloth.  To make my life easier, I wet the material out on a piece of cardboard on my bench, then carried the whole cardboard up to the boat, where I transferred the glass to the opening and rolled it out.

 


firstlayers.JPG (172166 bytes)Over the next several days, I repeated this process twice per day--in the morning and late in the afternoon, which allowed the previous layers to cure sufficiently while retaining the green stage that allowed the new layers to chemically bond.  Since there had been no signs of heat from the 4 layers I used the first time, I increased the number as I went, sometimes installing up to 8 layers at once.  Any thicker than that and it becomes hard to roll out the air, so I left it at that.  The cloth is so thin that 8 layers doesn't add up to that much, thicknesswise.


maststepglassed.JPG (174740 bytes)Finally, after several days of this, the material was built up thick enough to approach the surface of the deck.  I lost count of how many layers it took to fill the 1/2" thick void.  To avoid building up fiberglass thicker than the surrounding deck surface, I erred on the side of caution and left it a bit low, allowing the final layers to cure before sanding off the edges and determining exactly how much more material, or fairing compound, was to be necessary.


When the material was cured, I determined that the glass was built up close enough (within 1/8") to the existing deck level--therefore, no additional fiberglass was to be needed to fill the void, as I could make up the small difference with structural fairing compound.  First, though, I sanded the rough edges of the patch, grinding off any material that had spilled up over the edge during lamination.  Then, with the patch cleaned, I troweled in a coat of epoxy fairing compound (low density filler and cabosil).  To form a crown that would match closely the surrounding, existing coachroof, I cut a straight board to a bit wider than the patch, and used it as a screed to smooth the putty and ensure that it was at the same level as the surrounding deck, and at the same curvature.


IM009454.JPG (175995 bytes)Later, after the latest coat kicked, I washed the epoxy with water, sanded off any high or rough spots, and troweled in a smooth coat to fill the waves and voids caused by the screed.  This made the patch smooth and level with the surrounding deck, and when it cured the area was ready for the final layers of fiberglass reinforcement, which would strengthen and tie the area in with the surrounding deck.


IM009457.JPG (160414 bytes)The next morning, I washed and sanded the patch, and ground the deck a few inches on each side of the patch to prepare for laying in the final layers of material.    I used 17 oz. biaxial tape to glass the area, with two layers in the area directly under the step, laid up in epoxy resin.  I left the patch to cure fully before continuing.

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IM009478.JPG (168216 bytes)With the new fiberglass fully cured, I prepared it for the final fairing steps by first washing it with water (not being sure if System Three resin blushes appreciably or not and deciding to play it safe) and then sanding it to eliminate high and rough spots, and to widen the sanded area of the surrounding deck a bit so that the fairing compound could fair naturally and smoothly into those areas.   The new patch sits slightly higher than the surrounding area, which is just what I wanted.  I intended to create a sort of "power bulge" in the deck around the mast step, which bulge would be neatly faired into the coachroof and thus barely noticeable.  I also removed the protective plastic that had been covering the surrounding deck, since with the messy fiberglassing complete it was no longer necessary and was becoming a hindrance.


IM009482.JPG (166122 bytes)I mixed up way too much (as usual) of a thick epoxy fairing compound using low-density filler and cabosil, and troweled it over the edges of the patch and through the middle, leaving just enough in place to fill the weave of the cloth and to fair the edges down to the deck around.  I left it to cure overnight before continuing.

I hand sanded the hardened fairing compound the next morning, as it was smooth enough that I saw no need to get out a machine.  It was also easier to maintain the pleasing curve and contours of the patch with hand sandpaper on a rubber sanding block.

IM009483.JPG (165023 bytes)After cleaning off the dust, I prepared to apply what I hoped would be the final coat of fairing compound.  I used a new product for me:  System Three Quick-Fair putty, a two-part epoxy material that already contained thickening agents and therefore only required mixing the two parts in the proper ratio.  The material was extremely smooth and creamy in texture, unlike the coarser texture of epoxy putties made with the traditional fillers.  It's designed to cure to a sandable stage in 3-4 hours, unlike the 24 or so hours requires for epoxy.


IM009485.JPG (159859 bytes)I applied the Quick-Fair using standard methodology, and was pleased with the texture.  After curing overnight, the material was hard and sanded very easily and smoothly, leaving an excellent surface.  However, there were few pinholes in some of the exposed cloth (exposed after the putty was sanded), so I mixed a small batch of the Quick-Fair and applied it one final time, sticking only to those areas with pinholes or other minor surface interruptions.  


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To complete the patch, I coated the fairing material with unmodified epoxy resin, using a foam roller, and, after the material kicked, I sanded it one final time.  Then, I applied a coat of white primer as a final preparatory step before the nonskid paint application.

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maststepgooped.jpg (28561 bytes)Later, after repainting the nonskid and taking care of myriad other projects, I reinstalled the mast step in a heavy bed of 3M 101 polysulfide.  As before, the step is simply screwed through the deck into the forward portion of the mast beam.  After drilling pilotholes and my usual countersink at the top, I filled each screwhole with 101, pressing the tip of the caulking gun into the hole, and heavily caulked the entire base area of the step, the screwholes through eh step, and then, after installing the screws, filled the remaining countersinks at the top (weather) side of the step with more 101.   While the deck is now solid fiberglass in this area, I certainly wished to avoid any possibility of water ingress into the wooden mast beam.  When the caulk had cured overnight, I cut away the excess.

Along with the deck repairs, I also built a new  laminated mast beam to support the area from beneath.

Please click here to continue with the mast beam.


Glissando, Pearson  Triton #381
www.triton381.com 

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