The story of my boat building life can be summed up as “I always have more time than money.”  While building a boat on limited funds is not the way to go, I still think the majority of homebuilders are stuck with it.

This duly noted “mind set” or attitude prevailed throughout my building my classic Ariki “PUMA” from 1976 to 1996.  When it came time to buy or build a mast, I considered my options.  First there was the choice of making PUMA either ketch or cutter rigged.  I decided for the cutter rig as only one mast and boom are needed to be built or bought (a big consideration), and increased performance of a single stick over the ketch rig (before the Tiki two masted rigs).

Someone said to me during my research, “why not build a mast out of fiberglass?  It’s strong, the weight is not to great, it will never rot, and as long as you keep it painted, the sun cannot hurt it.”  This sounded interesting, but I have never found any books on fiberglass mast building.  I remembered reading articles about homebuilders making them, but I had a lot of research to do.  This was the age of composite spar building, using carbon fiber, epoxy resin, ovens to bake/cure the things in etc.  I new that all this high tech stuff would be expensive even for a homebuilder.  I remembered a book I had on ferro-cement boat building and in the outfitting section; I found a short article on fiberglass mast building.

  This article recommended using some sort of mandrel, such as foam core to lay up the fiberglass on.  Wood would be used where spreaders and attachment points would be needed, and also to have something to screw the sail track into.  This article spoke of fiberglass masts loosing a stay or shroud and bending like a noodle, but not breaking, giving the crew time to bring the boat about or lower sail so a jury rig could be made.  Well, that sounds great, a flexible mast going on a very flexible catamaran. But I was concerned as to how much weight this type of construction would result in.  I didn’t want some huge beast thrashing around up there.

The article mentioned that some builders destroyed the foam core after the mast was laid up to lighten the spar.  So, if you don’t really need a mandrel, then why built one at all?

A crazy idea popped into my head.  Why not build a hollow fiberglass mast, using an oval shape to give it strength.  Being hollow, it most likely would not weigh more than an aluminum mast.

Fine, now how do I engineer this spar so it will not fall down?  I looked at my boat building books, and looked at overall dimensions of wood and aluminum spars.  I knew that the right oval shape was what I wanted.  I decided on a fore/aft dimension of 12”, and about 7” wide.  Using manufactures data on fiberglass laminates; I thought three layers of 24oz woven roving would provide the beef, while a final two layers of 6oz cloth would make for a nice finish.  I priced out the materials using polyester resin, and figured that I could build the mast, minus hardware for about $1,500.00 US (1990 prices).  This is something I can do, as I have the knowledge to build in this medium, and the cost is within my budget.

The mast length for Ariki (cutter rigged) is 44 feet.  Too big and too much work to make a mold.  How about dividing the mast into quarters, 11 feet would be easy to make.  So the plan is to make a mold 11 feet long, half of the mast section (split across the small or athwartship axis).  The eight sections required would be made in the mold.  One section would be cut in half.  This would give staggered joints.  The eight sections produced would end up being the inside of the mast when finished.  My idea is to make these sections as thin as possible, just strong enough to keep their shape while laying up the fiberglass.  So this light shape of the mast would be my mandrel on which to lay up the layers of woven roving/mat/ and cloth.

To cover the mold shapes, I made a “sheet of fiberglass”.  I needed a strip of material at least one foot wide, and eleven feet long.  I laid a sheet of plywood (anything smooth will do) on the ground.  I laid waxed paper on the ply where the fiberglass would go.  I cut two layers of 6oz fiberglass cloth 2 feet wide and eight feet long.  I mixed up some resin and applied it to the cloth.  Saturate the cloth enough that the top will have a smooth surface also.

I used a lay-up of cloth/mat/cloth.  I made eight half sections.  To fasten them together, I made a heavy lay-up of a sheet of fiberglass.  When this sheet cured, I took my saw and cut two-inch wide strips.  I needed eighty-eight feet.

I positioned four sections (inside up) on the bench, and fiber glassed them together using two layers of 6oz cloth tape.  On the inside of both edges I fastened the heavy fiberglass strips, using thickened resin, and self-tapping sheet metal screws.  The screws go from the outside in, as they will be removed later.  When this cured, I put the top on.

I started six and one half feet from one end, to stagger the joints.  Using the thickened resin and sheet metal screws, I fastened one top onto the other.  When I got to the end, I had an overhang, which I cut off and placed at the end where I started.  When this cured, I had a shape of the oval mast I wanted.  It was to flimsy to move, but it was just fine on the bench I built.  I could roll it around carefully, as the top of the bench was about two feet wide.

I started with the final fiber glassing by laying the mast on one of its sides, and cut mat and roving woving in a width that would allow it to go exactly half way around the mast.  The first layer was mat.  I carefully removed the screws, then applied the mat dry and saturated with resin last.  When cured, roll over and do the other side.  Now there is one layer of mat holding everything together.  Now with its long dimension up, I applied woven roving, overlapping the joints of the mat.  When I had three layers of mat/roving, I finished up with a final layer of mat and then cloth to smooth things out for finishing. 

I fastened a 1X2 inch wood batten to the aft face of the mast.  This would be used to fasten the 7/8-inch stainless steel mast track.  I make fillets and rounded the top edges, then sealed the whole thing with two layers of 6 oz. cloth. 

Mast tangs were made from 3/16-inch mild steel, hot dipped galvanized.  All tangs were doubled, with the hand spliced rigging eye held captive by a ½ inch pin.  The one set of spreaders had a compression tube.  It was heavy walled steel tubing, about ½ inch inside diameter.  Then a ½ inch bolt went through, holding tangs on both sides.

If I was to do it over, I would use epoxy resin only, any maybe eliminate one layer of woven roving and put in some layers of carbon fiber.  But that would double the cost.  I really don’t know if I would do it again, not with the success of the “Tiki” rigs.

I offer this article as information as to how I did it; I do not recommend that anyone do it this way.  I would encourage anyone building a Wharram design to utilize the plans and really explore using the “Tiki” rig, even retro-fitting the older, classic designs.  Having the Wharram design team figure out the details for a reasonable fee would free up one to get on with the building, and save the irritation of designing one!