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Trireme Rowing Geometry, 6th Century B.C. (Time-Life Books: The Ancient Mariners, Page 71)

Sunday, June 5, 2016

Want a Downwind Sail?


In an oar cruiser, there are times when a downwind sail could provide a rest from rowing or a safety 'valve' in an emergency.

In this post, we include plans, examples of homemade sails and commercial downwind sails.


WindPaddle's Downwind Sail on a Kayak


WindPaddle sells kayak sails that clip to available cleats, can be deployed in seconds, rotated to provide for varying wind directions, instantaneously eased to de-power in a gust, and folded in a couple of seconds to an approximately 19” diameter flat package. Three different diameters; 42”, 47” and 52”.

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AirKayak's Downwind Sail

AirKayaks Corp. sell a kayak sail that could be used (downwind only) on oar cruisers. Five attachment points are needed on the fore-deck. The sail is stored in an 18” diameter bag. After clipped to the deck, it can be doused with a ‘dousing’ line. There is no ability to rotate the sail to control direction.

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Balogh Sail Designs Downwind Sail


Balogh Sail Desings sells three different sizes of this sail, 20, 30 or 40 square feet. The sail can be doused instantaneously and can be used to sail “almost to a beam reach”.

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Overview of Michael Storer's Plans for an Integrated Sail and Leeboard


Michael Storer sells plans for a drop-in sail unit with an integrated leeboard that could be used as a downwind sail for an oar cruiser.

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“Blutack”, on Song of the Paddle posted this photo of a homebuilt downwind sail he made.

The Sail Described Below in Use

I believe this sail could be easily adapted to an oar cruiser. Based on what I read, the base must be curved in order to keep the two ‘masts’ spread. The bungees leading forward are what ‘launches’ the sail. The two ‘sheets’ leading aft control the sail, and also are used to bring the sail aft and flat when not used.

Instructions below for the sail came from a set of plans by Rebecca Heap that were posted on the New Zealand Kayak Building site, which is no longer active. I saved those plans and they are reproduced in full below.

The "Heaps of Fun" Kayak Sail

“The following was generously contributed by Rebecca Heap. She has offered the plans and concept as "Public Domain" so anybody can make one, but retains the copyright on any commercial production. Please respect this and manufacture for your personal use only.

"Paddling in the City of Sails has the major advantage that on virtually every trip there will be some wind. In 1995 I decided to make the most of that wind and designed the following sail. It has proven to be very popular and successful as it is safe as well as cheap and easy to make. Guaranteed to make your kayak go like a rocket downwind up to 40 degrees either side!


Plans for the Sail

"Shopping List

  • Ripstop Nylon - 1.5m x 150cm wide 
  • Thin nylon cord - approx 5m
  • Velcro - 20cm or 25mm wide 
  • Bungee 6 or 8 mm - approx 0.6m
  • Bungee 5mm - approx 2.5m
  • 15mm Class E PVC pipe x 2 
  • Tee peices for 15mm pipe x 2 
  • Bamboo Canes 1.2m long x 2 
  • End caps to fit over pipe x 2 
  • Tiny Stainless shackles x 2
  • Brass dog clips 2 x 12mm, 
  • 1 x 20mm Saddles and bolts (see note below)

"Making the Sail

"There are two techniques - either sewing as given below or use seamstick which is a 3M product used by sail makers. It is like double sided sticky tape and you won't need to do any sewing at all.

1. Draw the sail pattern into the ripstop nylon using the dimensions shown and cut it out. Using the off cuts make up two strips 12cm wide and about 1.7m long for the mast pockets. 
2. Fold over a 1cm hem on top and bottom of sail, pin and sew. 
3. Hem the ends of the mast pockets then fold mast pockets in half lengthwise and pin down each side of sail. Sew allowing a 1cm seam. Reinforce the tops of the pockets if desired to reduce wear. Sew across tops. 
4. Half way down mast pockets, cut a hole 8cm long and 4cm wide to allow guy lines to be tied to the mast. 
5. To make velcro sail tie, overlap 2cm of the fuzzy side with 2cm of the hooky side to make a long strip. Place a 20cm length of cord across the join between the two pieces and sew together. The cord is used to hold the tie to a convenient saddle.

"Making the Masts

1. Cut a 5mm ring off the end of each mast and cut across to make a split ring. Glue these with pipe cement or Uhu to the masts about 2cm up from where the bottom of the hole in the mast pocket is positioned. They will stop the guy lines sliding down. 
2. Find some bamboo canes about 1.2m long that are a tight fit inside the pipe (the split rings are a good thing to take to the garden center to use to test the diameter!). These reduce the amount of flex in the pipe - dowel or other ridged material will also work. 
3. Glue or tape end caps on. 
4. Insert masts into pockets on sail.

"Fixing the Footing

1. Fibreglass and Kevlar boats will require the addition of two saddles 25cm apart just forward of the front hatch. Puffins have these saddles already, and plastics like the Penquin and Squall can have the footing tied around the mouldings where the deck lines go. 
2. Make the foot as shown in the diagram. It is essential that the hose betweeen the tee pieces forms a tight fit so that the foot is not sloppy. Wrap with high density foam to avoid scratching the deck. You may need to build up the foam if you have a flat decked boat like a Spectrum or one with a steep pitch like the Squall so that the sail opens nicely - try first and see. 
3. Using the 6 or 8mm bungee loop it either round a saddle or deck moulding (or shackles) then through the hose and tie off round the other saddle or deck mounting. You will need to pull it up very tight. The footing is usually left permanently on the deck and the masts inserted when needed.

"Rigging the Sail

1. Place the masts into the footings and get a friend to hold the sail perpendicular to the deck. Tie a length of bungee onto one side above the split ring, add the 20mm brass dog clip and clip it on to the carry handle. Tie the other end of the bungee to the mast on the other side. The bungee should be firm but not stretched. 
2. Do similar with the nylon cord looping it twice through each of the 12mm brass dog clips as this acts like a locking knot so the angle of the sail can be adjusted.

"Stowing the Sail

"Pull the nylon guy lines towards you to lower the sail and secure using the Velcro tie which should be attached to a saddle near the cockpit. To release the sail, undo the Velcro and the bungee will automatically pull the sail up into position. Adjust the lines to catch maximum wind.

"Important Note

"Although this is a very safe sail in that the bungee footing gives way in a strong side gust before you get tossed out, I recommend carrying a good paddlers knife just in case you need to cut the guy lines for any reason. However, the good news is that there are about 60 of these sails in use in Auckland and there have never been any near misses or nasty accidents.

Happy Sailing!

Rebecca Heap March 2002”



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Marc Dufour on the Can-AmDinghyCruisingAssociation@yahoogroups.com and I had an email conversation about a downwind sail he make for his canoe.  Following is a description of the sail and its set-up:

The sail is 5’ (1.5m) by 8’ (2.4m). The mast is approximately 8’ long, depending upon how much bury there is from the mast partner (he ties the mast to a thwart) to the base. The yard is 10’ (3m).

At the top of the mast is a short rope double loop. The halyard is tied to the middle of the yard, runs through the loops and down to be tied off. Marc ties it off to the thwart with a quick release knot (such as one round turn on the thwart and then a slipped half-hitch so that he can douse the sail quickly if required. As Marc noted, “That only happened once and it worked perfectly! Sail dropped, swim averted”).

He ties the forestay to the bow (Marc uses the bow lift-loop in his canoe). He ties two backstays to a thwart using ‘trucker’s hitches to tighten them.

The two sheets, one to each bottom corner of the sail, lead back to the slots between the inwale and the gunnel with the two sheets tied together. He says the friction of going through the slot is sufficient to hold the sail at the angle he wants. Only when on a reach does he have to actually tie the windward sheet.

In his canoe, he ties one paddle vertically to the side of the canoe at the thwart with a line running from the paddle (at waterline level), under the canoe and up to the thwart on the opposite side. A short line holds the top of the paddle to the same thwart on the other side. He steers using the second paddle.

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Rick Thompson's Downwind Sail

Control for the Sail

Rick Thompson made this downwind sail for his custom Walkabout. He told me that he used the sail only once, when these photos were taken.

Rowing downwind, he said I can go almost as fast as sailing and I just don’t use the sail anymore.

Let us know your experience using downwind sails.


2 comments:

  1. Tom - The sail on my Walkabout was copied directly from the Balogh "Twins" you show above. It was recommended by Todd Bradshaw (author of Canoe Rig) as one of the best downwind rigs. There's a video of the test: https://www.youtube.com/watch?v=VIlRBvcXjMg
    It works well to about 45 degrees of downwind. At any other angle to the wind you have to row, and any part of the rig left up is just harmful windage. As I said before, rowing downwind is easy in any case so carrying all the gear on a row cruise is just not worth it to me.

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  2. Rick... thanks for the additional link on your test of the your own downwind sail...

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