Sail Fail - Sort of

Introduction

This week project involved the addition of a sail to the Aquamarán. The idea behind the sail is to provide additional means of propulsion when kayaking out at sea. Now that the kayak has been stabilized with the pontoons the only other thing that I think is missing is a way to improve the propulsion when doing long kayaking trips out at sea.

After seen a fair amount of videos on the internet about what people do to kayaks I discarded the gas motors because it is a noisy and messy addition to the kayak. Another option is an electric trolling motor, but it seems to me limited in terms of battery life. I finally decided that a sail could provide adequate propulsion specially on open waters which is my target medium. It is completely clean, doesn't add significant weight to the kayak, and has potentially unlimited energy resources available.

Design

I watched as many ideas as possible on the Internet on how to build the appropriate sail for the kayak.  I decided that the new windpaddle type of sail weren't good enough since it works only when "running" i.e. going in the same direction as the wind. So I decided to build a more typical type of sail. I wanted the sail to be on the same frame I built for the pontoons.

I selected "ballistic nylon" which I found on a local fabrics warehouse because of its strength and impermeability. To provide the internal rigging of the sail I used remaining carbon rods I had from a camping tent, (these are the ones with a bungee elastic inside). I wanted the look and feel of the sail to be that of a fish dorsal fin, so I used two reinforcing rods. The mast was built using PVC tube schedule 40 of 1" diameter. The horizontal support was built using 1/2" PVC tube. For the base of the mast I used a concoction made out of plumbing PVC parts. The base is essentially a toilet flange of 3" with a reductor to 1-1/2". Inside the reductor there is another reductor to 1-1/4" and a 6 inches long piece of 1-1/4" PVC schedule 40 tube. All this makes a sturdy base for the mast which easily rotates when inserted because the 1" tube fits snuggly in the 1-1/4" tube.

The mast has a cross tee union that provides two lateral sockets. These were intended to provide some sort of handles to be able to change the position of the sail while sitting in front of it. The end result looked good and is easy to assemble.

Performance

Unfortunately the performance test wasn't good.  I struggled to find the best orientation of the sail mainly because being behind me I couldn't see how the wind was affecting it. The sail did picked up the wind but only when running in favor of the wind. Even then I found it hard to control the direction of the kayak using the rudder. I think that being on the back of the kayak the force exerted by the wind on the sail worked like pushing a pencil on the tip. The front of the kayak "anchored" to the water rendering the rudder ineffective for steering. 

On the good side the overall size of the sail did not affect the stability of the kayak. Maybe this is part of the reason the performance was so poor, but it seems it is one of the good aspects of the design. 

In conclusion, I am planning of relocating the sail on the front of the kayak were ironically visibility of the sail is important to its control. I will also consider using a different material and sail design, something more lightweight than the ballistic nylon. We'll see.