Thursday, February 5, 2015

Sail plan - what to do?

The biggest question I've been wrestling with is what to do for the sail plan. The 16' plans call for a 90 ft2 stayed gaff rig. I'd much rather use a simple sprit rig, and the 13' plans use a 72 ft2 sprit rig. So I'm considering scaling it up to near 90 ft2 on roughly the same footprint as the 16' gaff rig. This allows me to accomplish several objectives: (1) Use a simple unstayed sprit rig instead of a more complicated stayed gaff rig (2) Use 12' spars all around, which I *think* will stow inside the boat (3) Add reef points to optimize sail area depending on weather.

In theory I'm not opposed to a more complicated rig. I've built two Penobscot 14' boats as Gunter-rigged sloops (stayed rigging). But for a Melonseed it just seems to me that I should choose more simple over more complicated.

Here's a quick sketch of my idea. If you see an obvious flaw in this idea please let me know! Just remember I'm interested in quick set, unstayed rigging, and ease of operation over top performance. I figure I have some extra wiggle-room since the lightweight hollow spars will keep down the weight aloft.

I'm leaning toward Douglas fir over Sitka spruce for the hollow spars. Where I live, clear d-fir and s-spruce are the same price, so there is no cost savings one over the other. But I'm thinking d-fir is so much stronger than s-spruce that for hollow spars it makes more sense to use d-fir. I welcome your comments.

The red lines show the approximate footprint of the 16' sail plan as stayed gaff rig. The blue lines show my idea of scaling to 88 ft2/68 ft2 reefed unstayed sprit rig. The smaller rig gets the clew & foot of the sail (and the boom) further up and out of the way of the crew.

Spar layouts

I also spent some time working out the details for the spars. I'll make them using the birds mouth technique. The birds mouth router bit from Lee Valley makes short work of this. I've made other spars this way and they turn out great. To simplify construction I'll not taper them.

Rudder & centerboard drawings

Barto's plans include scaled drawings of the rudder & centerboard on a 3-inch grid. So I transferred those grids to an AutoCAD layout and printed them full-size on a plotter. It will be easy to transfer these full-size plots to the glued-up rudder and the PVC sheet for the centerboard. After reading Roger Crawford's web site, I thought about how much sense it makes to construct the centerboard from 1/2" PVC instead of plywood with a lead weight, so that's the plan.

Sunday, February 1, 2015

Building forms cut out

The building forms are cut out and ready to be installed on the strongback.

John's transom glued up

John's transom is glued up and sanded. It's 7/8" solid mahogany, from 3 pieces just over 6" wide each. This will look beautiful on his boat.

My transom glued up

My transom is glued up and waiting to be sanded. I will cover it with a piece of marine plywood after the cedar strips have been installed, and before the hull is sheathed in fiberglass. I've used this technique on two other boats, the Penobscot 14 (designed by Arch Davis) and a takeoff of the Rangely Lakes guideboat that John and I built from the offsets in John Gardner's "Building Small Craft" book.

My inner & outer stem completed

The inner and outer stem have been glued up on the jig. This is my stem. My friend is still getting out the strips of ash for his stem.