Main mast rebuild

[NPen]

Hi all!

I told Bob months ago that I would post the details of my main mast rebuild as I go, and am finally carrying through on that promise. I just posted several photos of the process, but also have a ton of close ups of the mast before I pulled it apart. They might be good for anyone looking to do a similar project who doesn't want to get to the rebuild process having forgotten where each hardware fixture goes.

 

This project started because, like my mizzen, water had gotten underneath the fiberglass and started to get into the wood. Or at least so I had assumed, based on the blistering I was seeing under the paint. When I started pulling the fiberglass off to see the damage, however, I saw that the water had actually caused the glue to release. Or maybe the glue had just gotten old and released, I'm not sure. Either way, as the fiberglass came off, the wood pieces separated, often with a resounding and disconcerting "pop" as if the fiberglass had been holding them in place.

 

After taking the fiberglass off and dismantling the individual pieces (about 12 of them), I put them in the paint booth of the marina shed, and kept it under heat and fan for about two months, until a moisture meter showed them to be dried out. They were pegged on the meter when I put them there, so I was concerned about how much damage the moisture had done. Amazingly, when they dried out not a single piece showed any rot or other damage, and I was able to use all the the pieces. This is amazing because I can't imagine how difficult and expensive it would've been to try to buy and cut douglas fir to fit the exact dimensions of those pieces. Not on my budget.

 

So the pieces inside have plywood strips on the inside that serve as alignment pieces. It gives you two inches on either side of the side pieces that the narrow side pieces fit into. Those little strips were pretty rotted out, and I broke half of them getting the mast apart, but it was pretty easy for the carpenter here to cut me a whole set of new ones on the cheap. They ended up fitting perfectly. There were four pieces on the top of the mast as it tapers that would've been hard to remake, but luckily they were in good condition, so I kept those.

 

As you can see in the photos, once the wood was dry the really only challenge in the project was the set up--getting the pieces exactly flat on a level would be crucial to getting them aligned and making sure the mast was straight when I glued it together. The poured concrete floor of the warehouse shed was nowhere near flat. For the building table I took plywood boards on end, supported with 2x6's. I ran carpenter string from the end to end, then put in the plywood as frames. I shimmed each one with wedges until they just barely hit the carpenter's string. It worked out really well, and when the mast pieces were laid out it gave me a flat base to build off of.

 

The rest went pretty quickly. I used system 3 epoxy with wood flour and colloidal silica to make the glue, and built the mast up in sections--base, then top, then middle. The middle was tricky. Since the base and top had end pieces, it was very easy to line them up. All of the middle joints, however, join in different places to give the mast extra strength. I had drawn alignment lines where the middle pieces met the base and top joints, but not where all the middle pieces joined together. What I had to do was build up the top and base, then basically glue the middle pieces together at the same time I glued them to the top and base. Yes, I got epoxy everywhere. But it worked, and after heat gunning off all the excess glue, it looks great and, more importantly, straight and strong.

 

I thought fiberglassing would take forever, but it was way easier than expected. The boatyard had a roll of fiberglass two or three feet wide, so I just put that at the base of the mast and, after wetting down three sides of the mast, rolled out fifty feet of fiberglass onto the wetted wood. Then I wetted out the fiberglass, so that those three sides were done. When it kicked, I trimmed off the excess, flipped it, and did the same on the other side. The result is that the mast has two overlapping layers of fiberglass, with so much epoxy wetted into the wood and gluing it together that it must be significantly stronger than when it was first built.

 

After the fiberglass I sanded off the rough parts, primed it, faired it, and have sanded it. It's ready for paint in the next few days, then I'll put the hardware back on. Who knows, I might have a boat with masts on it in the next few months. After three years of fretting and saving up for this project, it's a real dream coming true as I watch.

 

Anyway, sorry, Bob, for taking so long to post, but I hope this is informative and answers any questions people out there might have about what all goes into rebuilding one of our masts. It wasn't easy, but it sure wasn't the nightmare project I had envisioned it might be.

 

Neil

[Hans Petrie]

I would second Clyde's comment on a really nicely painted boat hiding a multitude of sins.  When I bought hull #24 it was the object of perfection looking with an awesome paint job.  I had it surveyed and then the reality sunk in (no pun - it didn't sink).  The boat was riddled with rot.  The port chainplates, the toe-rail, one entire pilothouse wall (2 layers of 3/4" think ply) you could jam a screw driver through the side and it would just ooze water.  The fiberglass hides it all on a nice smooth thin layer of moisture trapping illusion of solidity.  The mizzen was cracked and rotten with wholes in it at the top.  I knew what I was getting, lowered my offering price and decided to have fun in the boatyard.  Fortunately there is really very little on the boat that cannot be fixed though, and relatively easily.  Tap out the hull, mark all the rot locations.  Set the depth on your skill saw to 3/4".  Zip out the rotten hull.  Put in some re-inforcing frames next to existing frames where needed.  Put in some backing plates where needed.  Put in some new plywood skin.  Epoxy fill the gaps.  Smooth it out.  Put on new fiberglass skin.  Paint.  Is the boat weaker or stronger?  I don't really know.  I have not had any problems with the oak frames or anything structural although I re-inforced the chain plate area I fixed with extra steel just to overdo things.  But yeah, it is a lot of work.  You have to get into the idea that working on a boat is a fun thing to do on your vacation.  But once done - I have had nearly a decade of enjoyment and living aboard a nice platform that can sail the seas, live on the hook and survive storms, and pilot up rivers and estuaries.  Well worth it.  But fiberglass hides everything.

[Clyde A. Phillips]

I cannot argue against not fiberglassing the masts.  Before fiberglassing, which only has a 50 or 60 year history, there are many years of history without it.  But probably most of those years were with solid masts on boats with short lives.  But hollow, built-up wood masts have a solid history and they have worked well.  Just keep the paint in good shape.  The problem with fiberglass is that it has a reputation of making things maintenance free when there is no such thing.  That’s one of the reasons so many Newporters are running around with so much rot that they are unsafe.  The old expression is “a little paint hides a multitude of sorrows.”  Every time I see a good looking, well painted, Newporter I wonder about its soundness.

 

I agree with you on the halyard sheave slots as a point of entry for water.  I urge any of you considering redoing your masts (hired out or DIY) to take them as far apart as you can and survey the interior.  Make sure the tops of the solid blocks are angled down to a drain to the next down hollow, all the way down through the bottom of the mast to the bilge.  Also, consider an annual check of the halyard sheave slots.  Some may have been glassed, some had a layer of silicon seal smeared on bare wood to waterproof them.  The sheaves can easily wear through to the wood.  Do everything you can to keep that area tight.  Just remove the throughbolt holding the sheave to remove the sheave.

 

I do not agree with the enclosed halyard sheaves having a weakening influence on the mast head.  The metal masthead fitting, with a throughbolt above and below the sheave (with a third one holding the sheave while applying holding power to the head) and with a bolt or eyebolt through the wood and metal, has a good history of standing up the stresses of its work.

 

Keep up your good work.  It is good to see owners doing their own repairs.  It’s not only a good way to learn about your boat, it will teach you how well your boat is built and that will give you confidence in her.

 

Peace.

[Hans Petrie]

So I got my mast rebuild done several weeks ago in Napa but I ended up not fiberglassing them.  They are just painted wooden boxes.  I replaced an 8 foot section of the mizzen and built new 13:1 scarf joints and hand fitted everything.  I was in a boat yard and didn't bother leveling anything very much.  I did the best I could do by "eyeballing it".  They ended up coming out straight.  The main only needed one side re-glued as the glue joint was failing and beginning to pop off.  So I had three sides to work with and the only rot was in the very top.  The wad was in reasonable shape and the rot was really weak - so I used Smith's penetrating epoxy to kill the rot and harden the wood.  It soaked up a lot but I was confident it would hold.  The outer boards were in good shape.  Moisture had gotten in in the hollow part where the pulley is built in to the top of the mast.  In retrospect I'm thinking the internal pulley was a bad idea since I think it would make it weaker up there and the spinning action would wear on the wood and potentially cause moisture to get in.

 

Anyway - they are all back on the boat now and very solid.  I am confident that it is a great repair.  I had thought I would fiberglass them originally.  It is interesting to think about doing that but I don't think I will.  They served me for eight years fine without fiberglassing and I'm sure they will last another 20 with only painting at this point.  I was sure to properly bed all the screws and bolt holes so if I can keep moisture from running away on them I think it will work out.

[Clyde A. Phillips]

Neil,

 

Good job.  And though I will add below some of my thoughts, realize that my present thinking is that anyone working on his own boat, who must do the best he can with what he has, who in the end has what he wants has done a beautiful job!  So, here's my thoughts

 

Quoting paragraph 4: “So the pieces inside have plywood strips on the inside that serve as alignment pieces. It gives you two inches on either side of the side pieces that the narrow side pieces fit into.”

The “two inches on either side” has me guessing.  When I built the masts we used for the main mast four long “staves” of 1-1/8 inch by 5-1/2 inch Sitka Spruce (earlier boats used Douglas Fir).  We glued and nailed (1” brads to provide gluing pressure) 8’ long strips of ¼” plywood on the front and back pieces to provide a ¼” rabbit to hold the side pieces apart.  The width of the plywood was 5-1/2” minus 2 times 1-1/8”, or 3-1/4”.  Being somewhat chicken I sawed these plywood strips at 3-1/8” to allow the edges of the front and back pieces to stand full of the side pieces (which allowed a 16^th of an inch to sand off; much less sanding if the side pieces stood full of the front and back pieces).  You called the plywood “little strips” which caused me to think of smaller pieces than the 3-1/4 inch wide pieces I used. 

 

Then in paragraph 6 is, and I quote: “The middle was tricky. Since the base and top had end pieces, it was very easy to line them up. All of the middle joints, however, join in different places to give the mast extra strength. I had drawn alignment lines where the middle pieces met the base and top joints, but not where all the middle pieces joined together.”  Then you spoke of the difficulty of putting the mid section together as compared with the top of the mast and the bottom section, each of which are “ends” of the mast and the ends gave good alignment marks.  It seems to me that you rebuilt these sections as a whole (box section).  I would suggest others first put each individual stave together (from top end to bottom end) before assembling the “box.”  This was the standard method in building the masts.  Of course I had the advantage of building new.  Alignment of the ends was simple because I joined the tops in alignment and after the masts were glued up and cured just cut the bottom to the measured length (having made the staves a few inches long to allow for this).  But, if the mast came completely apart then re-gluing the scarph joints should be reasonably simple.  Just lay them side by side so that the tops and bottoms are in line, then just “fill in” with the other stave parts and glue the joints.  Then build the “box.”  Do this by first laying out the back stave and glue all the solid blocking in place.  Using this as the base, apply glue for the side pieces and put those in place, then glue the front piece in place.  Sounds simple but other things must first be considered.  See my Newporter Shipyard website and its Mast Construction page for other details that may help you in your project.  Try http://mysite.verizon.net/vzer3v5t/id12.html to see my write up (which is still under construction, but should give what you need.  I’ll check it out and add what may be missing).  If this link doesn’t get you there, somewhere on this site you should be able to find a link that works.