A mast tube for Pegasus

Project Pegasus is at the point where interior layout and "furniture" installation must be considered.  When new, Pegasus had a Sitka spruce, keel stepped mast with a three stay rig.  Both the bow stay and the side shrouds could be adjusted while racing.  The rake of the mast was controlled by a block and tackle system which connected with the bow stay and was lead back to the cockpit.  The side shrouds could be slacked off, downwind, via Highfield levers located under the side decks.

Boat end of adjustable bow stay.  The jaw seen here was swagged on a short piece of wire which fed through the tube soldered on the tang.  In turn, the opposite end of the wire connected with a block and tackle system which led back to the cockpit.

Cockpit end of origianl bow stay block and tackle system.

Boat end of the port side adjustable shroud with which Pegasus was originally equipped.  This bit of wire with a marine fork connected to the shroud, via a corresponding jaw, and terminated with a Highfield lever on the under side of the deck.  The starboard side was similarly equipped.

While Pegasus's original wooden spars survive they are not in serviceable condition.  I do have a spare Europe dinghy mast and have decided, since this is not a slavishly accurate restoration, that in principle Pegasus would still have an adjustable bow stay and no downwind interference from shrouds if I adopt the current semi-free standing rig that some of the other Classic Moths have employed. In order to do that I need to make an oval topped mast tube.

Recall that when John Z. built his Mistral he created an oval mast tube.  In order to do that, he first found a PVC pipe with an i.d. large enough to slip over the heel of his mast.  He then laid up enough carbon  fiber around the pipe to make a tube with roughly a 1/16th inch wall thickness.  After that he split the tube, introduced an oval form at the top while retaining the original diameter at the base of the tube and then closed the sides with more carbon fiber.  That was a lot of work.  This time around he and I took a different approach and made a foam plug of the desired shape and laid up multiple layers of 6oz glass around that plug.  I used fiberglass rather than carbon fiber mostly because (a). I already had an abundance of 6oz glass cloth left over from an earlier project , and (b). I'm cheap.  Will a glass lay-up be strong/stiff enough to do the job?  Don't know.  We'll find out. The pix that follow show most of the steps for this alternative approach for making the mast tube.

First John build up a foam blank by gluing together a couple of rectangles of pink insulation foam with five minute epoxy.  This was done to create a block of foam with enough thickness for the finished plug Next we took a hot wire knife and squared off the ends of the block against a pair of carpenter's squares so that we could accurately attach cardboard templates, an oval on one end to provide the ability to rake the mast at the deck partners, and a circle large enough to accommodate the heel of the mast on the other end.  We then took the "hot wire" foam cutter and allowed it to follow the templates.

After cutting out our plug we had some fairing to do since the hot wire was a little slow on my end and created ridges in the foam.  We filled those in with dry wall spackling compound and when dry, sanded the plug fair.

A few days later we got back together to continue.  Here John is checking the size of the plug to make sure it's fat enough for the mast.  It was a little too small in various places so we added duct tape to increase the plug's size until it passed muster.  Once the plug was deemed satisfactory, it was covered with clear packing tape to give a smooth surface.

The next step was to paint the plug with polyvinyl alcohol (a mold release agent) so that the fiberglass cloth and epoxy resin wouldn't stick to the plug.  While the PVA dried we got busy cutting layers of cloth to a paper pattern that fit the plug.

Your old diarist painting one of the early layers with epoxy.

Our lay up is eight layers thick.  We are shooting for a finished tube with a wall thickness of roughly a 1/16th of an inch.

After all layers were added.  A large, burrito-shaped thing covered with peel ply.  John and I will reconvene once the epoxy kicks to take the tube to the next step.