WBH Prema Masts

FREE-STANDING MASTS

**NEW SAILING RIGS FOR WOODEN BOATHOUSE's PREMA DINGHIES**

Fig. 1. The WBH Prema 141, the 14' dinghy with the final rig.

Boatbuilder and cabinet maker Steve Hirsh called me in the summer of 2008 and said, "Everyone I talk to says that you are the one to help me." Steve had recently moved from Pennsylvania to De Leon Springs, Florida, just south of St. Augustine, to begin pursuing his dream of building boats. Backed financially by his long-time friend and client Paul Wagner, Steve bought a house and built a wonderful boatbuilding shop in the backyard. He had designed a series of dinghies in three lengths, 16', 14', and 12', called the Prema 161, 141, 121, all with the same basic shape and differing just in length. He wanted a sailing version for each one, and that meant designing a rig, daggerboard, and rudder that would fit each boat. Steve and his wife Christine came up to my office for a visit to show me the 16' boat, and to work out a plan for designing the new parts.

The daggerboard and rudder were going to be quite easy--one size fits all, each made out of solid mahogany with a bullnose leading edge and tapered trailing edge. The tiller was left to Steve to design since the tiller can be an artistic expression that reflects the builder's tastes. The more difficult part of the project was the rig which would have to accommodate the three different boat sizes corresponding with differences in overall boat weight. The mast and boom had to fit into the boat the same way; the head clearance had to be the same; and all the bronze hardware had to be the same. The boats were built with Cypress, and so it would be best to build the masts and booms with Cypress. Cypress looks and feels a lot like Spruce, and it is similarly lightweight and strong. Cypress has been used in Florida and Gulf Coast boatbuilding for centuries.

We decided that a free-standing mast with half wishbone boom would be the best rig overall because it was necessary to set-up and breakdown the rig very quickly and easily. Steve did not want his customers to work all day just to set up and take down rigging. What could be easier and quicker than no rigging wires at all!? So I did some engineering and design and came up with what I thought was a pretty good first pass for the rigs as shown in the sailplan below. The mast had a 3-1/4" diameter laminated round section where it fit through the bow deck, but it tapered to an elliptical section with a constant chord, same diameter, from the boom gooseneck to the masthead. The boom was a 2-1/4" square laminated section. Laminating glue is epoxy from the Gougeon Brothers.

Fig. 2. The WBH original sailplan. Note particularly the differences in sail area and the angle of the boom to the mast.

We found on our first sail, however, that the spars were overly heavy. It was not easy enough to set them up, although the boat performed more or less as intended. The wind was very light that day, as shown in the photos below with the 12'er.

Figs. 3 and 4. Steve Hirsh and I in the Prema 121 on the first sail. There wasn't much wind, just enough to move around the harbor and determine that both the spars and the sails needed improvement.

I went back to the drawing board and Steve worked on getting a new sailmaker as the business with the first one had not worked out to his liking. I recommended Scott Loomis at Doyle Sailmakers in Stuart, FL, who had done some very good work for me on a previous project. Scott had a very quick understanding of the bending characteristics of the rig, and built a set of tanbark sails for the Premas. The tanbark color, as shown in Figure 1 above, I think adds quite a bit of character to the design. The Doyle sails worked nearly perfectly.

In the new sailplan, I reduced the section of the boom considerably, from 2-1/4" square to 1-1/2" round. Steve recommended that, based on further sailing, lowering the gooseneck might give a better set to the sails, as well as make the gooseneck easier to reach when setting up the rig--that was obvious from the get-go. I also tapered the mast in the fore/aft direction to get a nicer bend when sailing. All these changes proved out quite favorably, as seen in the final sail plan drawing and the next photos.

Fig. 5. The WBH revised sailplan with the smaller spars, booms in new positions, and a reshaped 12'er leach to more closely reflect the shape of the two larger sails.

Figs. 6 and 7. This is the Prema 141 with the new sail and the redesigned boom, but the mast had not been tapered yet. The Premas are a dream to sail; they balance very nicely.

Steve Hirsh has a number of boats under construction now and is trying to line up outlets where he can sell them. Advertising and promotion are whole different jobs that require thought and money to be the most effective. One of the venues where the Premas are shown is the Sunnyland Boat Festival in Tavares, FL, in March every year.

Fig. 8. Paul Wagner, me, and Steve Hirsh at the 2009 Sunnyland Boat Show.

To learn more about Steve Hirsh and the Wooden Boathouse Prema boats, you can visit his website by clicking here. If you would like to discuss this project or a similar project, please feel free to use the Contact Us link below.