Wednesday, May 19, 2021

KCS KY-Pro Sail System test and review.

Photo by Donald Wilcox

Since lock down lifted I have been testing various prototypes of the KCS KY-PRO Sail System. The system is available in three versions:

1. Sail only to fit other rigs such as Flat Earth Kayak Sails.

2. Sail, carbon fibre mast and boom, universal joint and deck fittings which require the deck to be drilled.

3. Sail, carbon fibre mast and boom, custom front hatch with mast foot and stay fittings, cleats that can be attached to the RDF fittings near the cockpit by using longer bolts. This option is for those that do not want to drill their deck or want to attach a sail to a borrowed, hired or demo boat.

Background to the test
I have been a long time user of a variety of kayak sailing systems. I have owned and used Pacific Action V sail, the KayakSailor rig and various Flat Earth kayak sails. I have also borrowed and used the Baloghsailsystems Batwing and Falcon Sails rig. They all are excellent in their own way and each has their strengths and weaknesses.

For the type of paddle sailing I do in the west of Scotland I prefer the Flat Earth sails in 0.8sqm size. They suit the open exposed waters and the sometimes gusty winds off the mountains. They are not as large and powerful as the KayakSailor, Baloghsailsystems and Falcon Kayak Sails rigs so you always need to paddle while you sail but in chilly Scotland this keeps you warm, especially in winter. The Flat Earth Kayak Sails in addition to being smaller also have a looser leach and this gives them a much wider wind range than the other designs.

I was therefore delighted when Ronnie Weir of KCS produced his prototype sails to find they are a similar size to Flat Earth designs and, though of different design and materials, have a similar range of intended use, i.e. for most users they are intended to be used on flat or rough open water from F2 up to F4/5. The KCS sails are made in Scotland by Owen Sails, a long established yacht sail maker based in Oban. Owen Sails started out in the mid 1980s making windsurfing sails and I still have one of their 6sqm, six batten slalom sails. So they know about smaller sails too.

This test was carried out on the Solway Firth, Firth of Clyde, Firth of
Lorn, Sound of Sleat and Loch Hourn on the west coast of Scotland. Conditions varied from F2 to F5.

Sail construction.

This sail is constructed from heavier cloth than the equivalent Flat Earth sails. The 0.75sqm KCS is also a good bit smaller than the FE 0.8sqm. The upper/luff panel is made of Dacron which is flexible enough to give warning when the sail is about to backwind if you point too high into the wind. The leech/lower panel is made of a heavier trilaminate cloth than that used in Flat Earth. The sail is loose footed unlike the Flat Earth TradeWind sail, where the boom is sewn into the sail like a batten. The KCS also has a longer boom and sets fuller with a deeper draught than the equivalent size FE. Like the FE TradeWind sail, the KCS sail is a spritsail with a single diagonal batten, which rises from the tack (the corner of the sail where the boom meets the mast). The KCS sail has a stiffer batten than the FE and the batten is sewn into the pocket with more tension than in the FE. This means it puts more 3D shape into the sail making it more powerful for its size. However, in very light winds, the batten might flip its curve to the wrong side of the sail. The stiffer batten also holds onto the sail's power longer in a gust before twisting off and releasing wind pressure from the roach of the sail (the part near the upper end of the batten).

The 0.75sqm KCS KY-PRO sail overlaid on a 0.8sqm Flat Earth TradeWind sail. Note similar head and upper roach but reduced area, shorter luff and longer foot of the KCS. 

1. The KCS KY-PRO 0.75sqm sail tested on a Flat Earth aluminium mast and boom with the mast foot bolted to the foredeck forward of the compass recess.

The KCS sail was paddled alongside a Flat Earth TradeWind 1.0sqm and...

...a Flat Earth TradeWind 0.8sqm in a variety of wind strengths from F2 to F5.  The KCS sail performed excellently overall but especially in the higher winds. In lighter winds both sizes of the FE TradeWind sail have the edge on a reach/broad reach.

However, at bottom of  F4 the KCS produces more power and in  mid F4 and above feels significantly more powerful than the 0.8sqm TradeWind. In gusty F4 conditions the TradeWind remains very controllable due to the leech twisting off more easily but in doing so it looses power. The tighter leeched KCS is more powerful but, as it is significantly smaller, remains a lot of fun in these conditions. It does require a bit more experience to handle than the TradeWind in these upper end conditions. In this respect, it is similar to the double battened, loose footed, Flat Earth Footloose sail. Overall, I think the KCS sail is a good compromise between size, leech tension and fullness of cut/power. Upwind when paddling in F3/F4 there is little performance difference between the KCS and the Tradewind except, when well worn, the loose Tradewind leech motors (flaps) in the breeze. So far the KCS sail is not showing signs of this.

2. The KCS KY-PRO 0.75sqm sail tested on the KCS carbon fibre mast and boom with the mast foot bolted to the foredeck, forward of the compass recess.
The KCS carbon fibre mast is one piece but a two piece may be available in the future. The compression collar round the mast retains the stays and the uphaul. It is simple and avoids the need to drill the mast, which could weaken it. The collar will be slimmer in production versions. A longer thinner collar at the bottom of the mast slides over the mast base universal joint stub. The UJ is made by Ronstan and the fixing holes are the same distance apart as the red UJs which are part of the Flat Earth fittings. The boom has a very neat hinged joint and slimline outhaul.  The boom will be shorter in production versions as this one has been used to test a variety of prototype sails of varying dimensions. There is no kicking strap on this type of sail and as the shrouds are below the boom, the boom can swivel forward  in front of the mast. This is an important safety feature as it allows you to depower very quickly if you get hit from behind by a sudden overpowering squall. In these conditions it can be very difficult to either pull the sail down towards you against the wind or to turn the bow into the wind to allow the sail to be blown back towards you.

Everything worked well, the sail set nicely on the carbon fibre spars.  These look great, but I could not honestly detect any difference in performance over the aluminium spars in the Flat Earth rig.

3. KCS KY-PRO Sail, carbon fibre mast and boom, tested on custom front hatch with mast foot and stay fittings.

This is a really novel and well engineered solution for people who do not like drilling holes in their kayak. It consists of a circular outer plate just bigger than the hatch rim and an oblong inner plate, which is narrower and longer than the hatch diameter. These are secured together by three bolts with captive thumb screws. The red and white rope forms a handle to pull the two plates together in such a way that the three bolts in the lower plate line up with the three holes in the upper plate... pure genius! There is the potential for a little water to get in through the holes the rope comes through, you could put a little Vaseline on the rope, but I have not noticed any leakage. The mastfoot/UJ and side stays attach to the aluminium spreader bar, which is positioned at the forward end of the hatch to maximise up wind sailing performance. Access to the front hatch is restricted compared with the usual hatch cover but I was surprised how easy it was to fit and remove. Indeed in cold weather it was actually easier than some conventional rubber hatch covers!!!

The cleats for the uphaul and the sheet are also fitted without drilling. they are attached to the deckline RDF fittings nearest the cockpit using longer than standard bolts. To stop the cleats swivelling a short piece of cord secures the front of the cleat to the adjacent RDF.

The mast foot is obviously to the rear of where most kayak sails would be mounted in front of the compass recess (how this affects paddle sailing is discussed below).

The rearward mount does mean that the stowed sail has a greater overlap with the cockpit. This may bother some. It did not bother me at all.

This is the view forward when the sail is stowed. I was very pleased by how unobtrusive it was. On the production version, the aluminium spreader bar will be even lower.

With the sail rigged on the KCS hatch mount it sailed just as well when running off the wind as when it was mounted further forward on the foredeck.

I also noticed no difference in performance on a broad reach.

However, once on a beam reach to a beat, I started to clatter the end of the boom with the paddle. I switched from a high angle to a low angle paddling style and that solved the problem. This is a limitation of having the sail mounted closer to the cockpit.

Another limitation of the more rearward hatch mount is when beating upwind. You can only point at 60 degrees off the wind with a tacking angle of 60 degrees. When the sail is mounted forward, you can point closer to the wind, at 45 degrees off the wind, which gives a tacking angle of 90 degrees. The formula for working out the pointing angle (p) from the tacking angle (t) is p = 90 - (t/2)


1. The KCS KY-PRO sail is a very well made small but powerful kayak sail which has superb performance, especially as the wind increases.

2. The KCS carbon mast, boom and stays are well made, light and strong, with great fittings.

3. The KCS hatch mount with mast foot and spreader bar for stays is a brilliantly engineered solution for those that do not want to drill holes in their own boat or want to fit a sail to a borrowed boat. Its downwind paddle sailing performance was unaffected but it does limit pointing angle upwind and cause the paddle to hit the boom if you use a high paddle style going upwind or across the wind. 

Potential paddle sailors now have a choice... to drill or not to drill. What a great addition to the choice of paddle sailing equipment available to kayakers. An innovative and flexible paddle sailing system that both performs and is made in Scotland.

Lastly, the way the hatch mount is constructed, I can see no reason why an existing paddle sailing rig, such as a Flat Earth rig, could not be fitted to the hatch mount.