Wednesday, July 14, 2010

Flat Earth Kayak Sails fitting instructions

Flat Earth Kayak Sails add an exciting new dimension to sea kayaking. A major UK sea kayaking manufacturer/retailer is currently negotiating to distribute these Australian made rigs in Europe. Currently there are five rigs in Scotland and all who have tried them have been impressed. A large consignment is on its way to Scotland in time for the International Paddle Sport Trade Show in Germany in October. As it is likely that many others will be keen to try these sails, I have recorded my experience of fitting them to a Valley Nordkapp LV and a P&H Quest LV.

Valley Nordkapp LV

Mick MacRobb of Flat Earth Kayak Sails has some excellent video guides on his website and suggests you try and fit the mast about 175cm in front of the lowest part of your seat (where the bones in your bottom sit). The good news is that this is just a guide and it does not really matter where you fit the sail as long as it is somewhere near the front! On my Nordkapp LV 175cm in front of the seat low point lies between the compass and the front hatch which is not practical. I chose 190 cm in front of the seat which is just in front of the compass. For reference, this is 100cm behind the tip of the bow.

The sail is controlled by only two lines. The uphaul/forestay runs from the front of the mast below the sail to a pulley tied onto the front deck line fitting then back to a cleat at the right side of the cockpit. The sheet runs from the middle of the sail bottom down to a pulley on the deck then back to a cleat mounted at the left side of the cockpit.

Before you do any drilling check that you can reach the top of the mast and ideally the (shorter) end of the boom batten from the cockpit, this is important to allow you to furl the sail. Obviously the overlap with the edge of the cockpit will be greater in a longer keyhole cockpit like this than in a shorter ocean cockpit.

This close up shows the flexible polymer joint of the mast foot, which is permanently screwed into the base of the mast. It is attached to the upper of two plates, which twist together. the lower plate is permanently screwed to the deck of your kayak with two bolts.

I checked the mid line of the kayak with a thread tied between the bow and stern. Stick some tape on to protect the gel coat. The bolts need large penny washers inside the hull to spread the load, so you need to check they will fit inside next to any deck recesses.

Before you drill, have a little think, are you in the right place?

I use a light pressure and a high speed which does little damage to the gel coat at the edge of the hole. Screw the first bolt in and start the second hole by drilling through the deck plate hole.

Move the deck plate to the side then finish off drilling the hole. It will be in exactly the right place!

Remove the tape revealing two perfect, neat holes. Clean the area with acetone (available from a pharmacy store).

For sealant I never use silicone. I use a waterproof adhesive such as "No more nails" which is just as good as Sikaflex but a lot cheaper.

Then bolt the deck plate in place.

I cut the bolts to the right length before hand, remember to screw a nut on before you cut so it reforms the thread when you unscrew it. You should make sure you use nyloc nuts rather than plain nuts and spread the load with penny washers. You might get away with not cutting the bolts. We have found that M4 bolts with 12mm long threaded sections (and appropriate nyloc nuts and penny washers) are the ideal length for 3 British composite sea kayaks' decks. This saves having to cut a stainless screw with a hacksaw which is never easy.

On the Nordkapp LV I was lucky that there were already deck fittings (RDF) on either side of the mast foot to attach the side stays (shrouds). On narrow bowed British style kayaks it is best to have the side stays at right angles (or just behind) to the mast and use a back stay. On a broad bowed kayak or sit on top you may get away with mounting the side stays well behind the mast foot and do away with the back stay. I fix the side stays to spectra cord loops through the RDF with 32mm snap shackles. The stays need to be "twang tight when the mast is vertical and it is best to adjust the stays by making a loop with a bowline. By trial and error, a bowline is easy to readjust to get the right length. I have not cut the line off at the knot but have looped some spare secured by a cable clip as I am using these rigs on a number of different kayaks.

On the Nordkapp LV I originally tied the back stay to the front RDF of the deck elastics but I moved first it and then the sheet pulley...

...forward to a deck clip I mounted just behind the front hatch. Flat Earth sails have no kicking strap to hold the boom down. It is important that the sheet (black) comes down to the pulley as steeply as possible so that the sail does not twist too much. In the photo above this one, you can see that the sheet is angled too far back and not holding the boom down enough. On the Nordkapp LV both the back stay (green) and the sheet pulley are attached to the same deck clip. On the Quest LV there is a central deck clip much more further forward to which the back stay can be attached. It is too far forward to mount the sheet pulley. To avoid drilling holes you could mount the sheet pulley to a rope strop tied between the deck lines. The sheet pulley ...

...and the uphaul/forestay pulley are both tied to the appropriate fitting with a small loop of spectra cord.

When folded and stowed on deck, the rig is secured by a short length of shock cord tied to the rear of the deck lines and secured by a plastic olive cleat... this.

I like to keep a deck bag with a camera in the middle of the deck so I have chosen to mount the two clam cleats to the side of the deck just behind the front deck elastics. The cleats are mirror images of each other and I have mounted the open end towards the mid line so that a quick tug will release the line in a hurry. Before you mount the cleats here, make sure they clear your J bars for transporting the kayak on the roof rack.

The free ends of the uphaul/forestay and the sheet can be secured next to the cleat by a simple figure of eight knot round the adjacent deck elastic. Any loose line can be kept out of the way under the deck elastic.

If you have an uncluttered deck you might consider mounting the cleats in the mid line. In this case mount them with the open ends facing outward, again so a quick tug will release the line quickly.

As supplied you might think the sheet is too long. Don't rush to cut it off. An important safety feature of the Flat Earth Rig is that the lack of kicking strap and sidestays mounted below the sail mean that if you are overpowered when running down wind, you can let the sheet go and the sail will weathercock round in front of the mast and depower, if the sheet is long enough!

Because I mounted the uphaul/forestay cleat on the side of the cockpit, a straight line between the bow pulley and the cleat caused the line to sit in the groove on the outside of the Valley hatch cover. When I pulled the uphaul, it very neatly flipped the cover off! To get round this, I have routed the uphaul/forestay line through a mid line fairlead made by a heavy duty cable tie
looped round the deck elastics just behind the mid line RDF. You can see how this diverts the line over the middle of the hatch.

P&H Quest LV.

On the Quest LV, Mick's ideal position of 175cm in front of the low point of the seat is the RDF in front of the compass. I found that if I mounted the mast base there, the stowed mast did not lie nicely along the deck like in the Nordkapp LV. It touched the deck in front of the cockpit then stuck up into the air behind the cockpit, where it would have hit my hand while paddling. I therefore fitted it at 208 cm in front of the seat low point ( 90 cm behind the bow). There were no lateral RDF fittings to mount the side stays to so I had to bolt two deck clips to the side of the deck. Mick recommends fitting them at right angles to the edge of the deck but because the bow was narrow I mounted them parallel so that the stays were as far apart as possible.

In this mast foot position the Quest LV sails perfectly and is very easy to steer to the wind using very small adjustments of the skeg. However I am only 5'8" and I find reaching the sail to furl it a bit more awkward than in the Nordkap LV. In retrospect I might mount a Quest LV mast foot 198cm in front of the seat low point. The end of the stowed mast would stick up a little but not too much to impede paddling.

Whatever, the thing to remember about choosing a mast foot position is that there is a wide latitude of variation in which your kayak will sail well and the most important thing is to choose a position that keeps the folded rig out of the way, is easy to reach for folding away and uses as many existing RDFs as possible.

Finally, if you don't have a suitable central RDF to mount the sheet pulley, you could make up a strop from cord (in this case stiffened with a plastic tube) tied to the deck lines on either side. Personally I preferred sailing with a pulley mounted close to the deck and I think I would prefer just to drill holes for another deck fitting and tie the sheet pulley to that.

On the Quest LV, I had used one of the existing RDFs (at the front of the deck elastics) to mount the boom pulley. I found this allowed too much twist in the sail and decided to move the pulley mount forward so that it was more beneath the sheet attachment on the sail. One thing that has been a sight worry about fitting a sail is the potential the stainless steel deck fittings have for damage in a T rescue situation if sliding an upturned hull over a rescuer's deck.

I decided to experiment with a softer solution which consists of simply a loop of 2.5mm spectra cord threaded through holes drilled in the deck.

This is a 3mm hole and it was quite easy to get the 2.5mm spectra cord through. A 2.5mm hole is a fiddle and I do not think it would be possible from inside, at arm's length through a hatch! Spectra cord tends to unravel, I found cutting it at an angle with a very hot scalpel blade left a fine tapered but sealed end which could be fiddled through a 2.5mm hole.

On the inside, I used a small stainless washer, tied a not in the cord then...

...cut off a slice of two part epoxy putty and kneaded it till it was mixed then plastered it over the knot and washer to seal and strengthen the loop of cord and the hole.

It may or not work. I will see how the boom fitting stands up to use before replacing the two side stay deck fittings. I might thread both ends through from inside and tie a knot in the external loose ends to make a loop.

P&H Quest.

This time we have mounted the mast foot 10 cm further back than on the Quest LV above due to the way the mast lies on the higher deck on the Quest. The centre of the mast foot is 100 cm behind the bow and 198cm in front of the low point of the seat. We experimented with a tri-stay set up, with the two side stays behind the mast and doing away with the back stay. This worked fine when the wind was behind but one of the beauties of Mick's rig is it allows beam and even close reaching. We found that when the sail was sheeted in, in the reaching position, it pulled the mast slightly back against the tension in the uphaul/fore stay elastic. This slackened off the rear set side stays and allowed the rig to lean over to leeward. For this reason we prefer to mount the two side stays at 90 degrees to the mast and to use a back stay.

We used an extra deck fitting, just behind the front hatch to fasten the block for the sheet. David decided to mount his cleats a little more inboard than I have on the two kayaks above. Note the angle of the cleat with respect to the sheet.

Another completed rig! Note the steep angle of the sheet compared to the bottom of the sail. If we saved drilling another set of holes and had mounted the sheet pulley further back, on the existing RDF, it would have pulled the sail back more and not down enough.

The little snap shackles we use are rather expensive at nearly £12 each or £36 for three. A cheap alternative has been suggested by my friend Geoff, which still allows quick assembly but uses a knot called a truckers hitch.

Tie a small loop about 2/3 down the stay. take the free end of the stay and thread it through the attachment point in the deck, now put the free end through the loop and pull it tight while you hold the mast upright. Now tie a couple of half hitches round the stay below the loop to secure.

Happy kayak sailing to David!

P&H Cetus

We have now fitted a Flat Earth sail to a P&H Cetus.

We fitted the centre of the mast foot 88cm from the tip of the bow.

On the Cetus this required fitting some deck fittings for the shrouds but an existing RDF was used for the back stay.

It works!

P&H Cetus MV

On the P&H Cetus MV the Flat Earth Kayak Sail mast base is ideally situated just forward of the compass recess and just behind the central recessed deck fitting (RDF) for the deck elastics. The deck here is stiff and strong because of the proximity of these mouldings. Unfortunately the lateral RDF's for the deck lines are just too far aft of the mast base to provide optimum lateral support for the side stays. I have put a loop of 3mm Dynaema through two holes in the deck. Inside they go through stainless steel washers and are knotted. I have covered the lot with a splodge of two part, kneadable epoxy putty to form an internal seal.

The uphaul/forestay, back stay, and sheet are mounted on existing RDFs. Low profile Clamcleat CL213/CL214 cleats are mounted forward of the cockpit to secure the uphaul and the sheet.

P&H Delphin.
When I first tried the P&H Delphin I was impressed by all the usual things: its comfortable ergonomics, its stability in rough water, its manoeuvrability, its surfing, its rolling, its behaviour in winds... but I really couldn't wait to put a sail on it. Those hard chines at the bow are just asking for a sail to provide the drive to push through the waves in front!

I mounted the pulley for the uphaul/fore stay on the front deck line recessed deck fitting (RDF). The pulley for the sheet and the back stay went on the front deck elastic RDF. The existing side deck line RDFs were just too far behind the mast to provide support when reaching or beating so I mounted two stainless steel saddles on either side of the mast and attached the side stays to them. If you were only interested in downwind sailing you could use the RDFs and do away with the back stay.

I mounted the sheet and uphaul cleats in front of the cockpit and to either side of the 4th hatch.

The ideal position for the mast base was just forward of the compass mount but the foredeck on the Delphin is peaked. Purists will be horrified but I just fitted the mast base to the right of the mid line on the flat part of the deck secured with two penny washers to spread the load below deck.

I use the same mast on my Nordkapp LV, which does not have a peaked deck. The side stays were therefore too short, so using bowlines, I adjusted loops of 2mm Dyneema cord through the saddles and clipped the snap shackles into them. If you only use the sail on one kayak you could clip the snap shackles directly through the saddles.

The beauty of the Flat Earth flexible tendon universal joint is that the mast is still vertical despite the mount and...

...the wind couldn't tell the difference!

  Rockpool Alaw Bach
Not all Rockpool Alaw Bachs have a skeg fitted but mine already had one. I find  a skeg is a great help to ease of sailing a variety of courses, without having to apply a lot of corrective strokes or edging.

I chose to mount the deck plate for the mast foot right on top of the forward mid line deck elastic mount. Mouldings in the deck increase the stiffness and make an ideal place to mount the mast foot. By chance the deck line RDF mounts are ideally situated at right angles to the mast base to secure the side stays.

I like to use snap shackles for the side and back stays to make rigging quicker. Up until now I have only been using the sail on two kayaks but I now have sail mounts on 4 kayaks. To accommodate two kayaks with the same stays, I have just made the loops through the deck fittings different lengths on each kayak. However, with 4 different kayaks I needed a wider adjustment, especially with the back stay,  so I have used  Clamcleat Line-Loks CL266. These are rated for 1 to 3mm line.

These little cleats seem quite strong, as evidenced by this publicity photo on the Clamcleat web site. They are much quicker and easier to adjust the side stays to twang tight than tying bowlines. If you only fit your sail to one kayak, it would be better to just spend time with bowlines.

NB. In practice, these cleats have been a disappointment on 1mm line. Although they have good grip on dry line and in winds up to F4, they slip when the cord is wet in F4 and above conditions. I have found they work well with 3mm line.

I mounted the cleats just outboard of the cockpit rim. Note that the Clamcleat CL213 starboard and CL 214 port cleats do not have fairleads  so in an extreme gust just yank the sheet (pink) towards you and its away. This also works if you are underwater setting up for a roll! Note also, I have fitted the starboard version of the cleat to port and vice versa!

Necky Chatham 16 Polymer.
The Necky Chatham 16 is a manoeuvrable kayak that should suit a Flat Earth Kayak sail very well.

Unlike the P&H Delphin, which has a rigid foredeck, the Chatham deck is soft and would not be stiff enough to support a mast foot without some modification. The stiffest area was between the compass recess and a central deck elastic fitting. This was also in line with the deck line fittings, which saved drilling extra holes for the side stays. To make the stays easily adjustable I used Clamcleat white CL266W/R Mini Line-Lok cleats.

To stiffen the deck, I cut a piece of 3" thick black closed mini cell foam and pushed it into place so that it was under moderate compression.

The black sheet and the red uphaul were led aft to a pair of Clamcleat CL 213 and CL214 low profile line cleats. note how the red uphaul is threaded behind the rear deck elastic then forward...

...where it is tied off to the loop formed where the yellow back stay goes through the snap shackle. To lower the sail if there is a strong wind from behind (on a run), uncleat the red uphaul, then pull on the end. This pulls the back stay towards you collapsing the mast. If you rig the Karitek way (with two rear set stays and no back stay) you can't do this and in a strong wind you need to turn the bow of the kayak from down wind round into the wind to drop the sail.

Rockpool Taran 16.
Geoff at Kari-tek kindly fitted sail mounts to his demo Rockpool Taran 16, prior to lending me it for testing. Note he has fitted two sets of side stay mounts. I like mine rigged at right angles to the mast foot, in which case I need to use a backstay. The standard Karitek fitting uses the side stays mounted further back but with no backstay.

Having sailed this kayak in some good winds I would mount the mast foot 45 cm in front of the centre of the fore hatch. Note that racing kayaks like the Taran have a lighter deck layup than touring kayaks. If I was ordering a Taran 16 to use with a sail, I would ask Rockpool to put a couple of layers of extra mat across the inside of the fore deck in that position, about 15 cm wide. The Taran's peaked foredeck should add longitudinal stiffness, so maybe just a single extra layer of mat, 15 cm wide, in the midline, extending about 25cm in front and behind the mast foot.

P&H Aries 155.
The Aries is the composite version of the rotomoulded polyethylene Delphin so I knew it would be a great sea kayak for paddle sailing with a Flat Earth Kayak Sail.

Like the Delphin, the Aries has a peaked foredeck to shed water. Just forward of the compass mount the deck is very stiff due the moulded channels to take the spare paddle shafts. There was a handy RDF here so I removed the standatd bolt and used a longer M6 stainless steel bolt  to secure the front of the mast foot plate. The rear was proud of the deck so I packed it out with two stainless steel washers and drilled the deck for the rear M5 bolt. I used Aquaseal round the bolt to seal the hole.

 The mast foot in place.

 I used two surface mount fittings for deck lines to mount the two side stays at right angles to the mast, one on each side. I have several kayakst set up for sailing so I have a standard side stay length and each kayak has a small loop of Spectra cord which is adjusted to fit the side stays once then the snap shackles allow the rig to be fitted nd removed quickly to any kayak with no adjustment.

As my sidestays are at right angles to the mast I also use a back stay which is attatched to a Spectra loop through the front deck elastic RDF. Once the mast is erected the sidestays become "twang" tight.

I fit the sheet and uphaul cleats (ClamCleat CL 213 and CL214 low profile line cleats) on either side of the cockpit front. Make sure your thumbs won't bang against them when paddling. Note the pink uphaul line loops under the rear deck elastic and then goses foward where it is tied off onto the back stay. If you are running before a strong wind a tug on this will get the sail down without having to turnt the kayak's bow round into the wind so the mast blows back.

All ready to go....


Adjustable grip hitch for side and back stays.
Following on from my post about fitting a Flat Earth Kayak Sail to a P&H Aries 155, Alec commented:

"You say that your stays are a "fixed length" but you seem to have some sort of slip knot (see pic ) for adjustment. May I ask what knot you are using?"

Yes I do use a locking slip knot for fine adjustment. Previously Geoff has recommended a trucker's hitch (which needs tied every time) and Shawn Armitage has recommended the easier to adjust three-turn tautline, both of  which I have used previously. I have also used the Clamcleat CL266 Mini Line_Loks which are very easy to adjust but these slip in winds at the top of F4.

I currently use the adjustable grip hitch as it is as easy to adjust as the three turn tautline but it is also easier to remember how to tie in the field.

Start by making a loop by bringing the loose end over the stay (which is tied to the mast at its other end).

 Now wrap the free end twice round the stay side of the loop.

Now take the free end once more over the stay side of the loop and bring it back under both sides of the loop and thread it through itself.

Pull the knot tight. If you pull the end of the loop, the knot locks tight. However, if you grip the knot itself you can easily slide it in either direction to make the loop longer or shorter.

The reverse of the knot looks like this.

I normally thread the loop through the closed end of a 32mm snap shackle. This means that I can quickly remove and replace the rig from the kayak without knot tying.

To get the tension in the side stays just right, I bend the mast back then gradually shorten the stays by sliding the grip knots. I test the tension by putting the mast into the vertical position, repeating the process until I get the stays "twang tight".

I you do choose to fit a Flat Earth Kayak Sail I can guarantee you will have a heap of fun, we have literally been blown away by them!

Gnarlydog has also prepared an excellent guide to fitting sails of a variety of types which I read (and you should read) before installation.

Last edited 18/5/2013.