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PostPosted: Sun Mar 22, 2015 7:40 pm 
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I enjoy using the Hobie sail kit (including furler) on my 2013 Sport but I can’t help thinking that adding a boom to the kit would enhance the sailing experience.

The existing sail kit performs quite nicely close hauled but sail efficiency drops off markedly the further off the wind you sail. The loss of efficiency means that heeling forces are increased at the expense of forward motion, making for a more ‘tippy’ kayak. The sail seemingly folds in half when running before the wind in light breezes. I laugh.

A boom, with a boom vang and outhaul, enables a more aerodynamic sail shape to be maintained throughout all points of sail. In light winds, the sail is given full shape by easing the vang, outhaul and downhaul. In strong winds, the sail is flattened (depowered) by putting as much tension as possible on the vang, outhaul and downhaul. When I raced a Laser dinghy, there was strong demand for the services of the club gorilla when rigging on windy days…

Can it be done? There are at least a couple of examples of boomed kayak sail systems, including Kayaksailor (https://kayaksailor.com/) and Falcon Sails (http://www.falconsails.com/). The latter system uses carbon fibre masts and booms; weighs less than four pounds; and can be raised, lowered and stowed in response to changing wind conditions (an important safety requirement). The two cited examples seem to be designed for paddle kayaks so they are located to enable paddle clearance. I think this requirement limits the size of the sail compared to our pedal kayaks. There are videos on both the above mentioned websites seeming to show their sail-equipped sea kayaks handling 15 knot wind conditions very comfortably.

Does a boomed sail unnecessarily complicate a sailing kayak? I don’t think so, based on the examples above. IMO, a properly designed and robust boomed-sail system would simply increase the seaworthiness and joy of sailing my kayak in stronger winds through reducing ‘tippiness’.

I am really interested to hear others’ opinions and experiences before I take any next step. Given Hobie's experience with its glorious sailing catamarans, has any thought been given to adding a lightweight boom to its kayak sail kit?


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PostPosted: Sun Mar 22, 2015 8:52 pm 
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I used to have a sunfish, there is one big difference between kayak sailing and sailing a laser or sunfish, thats your ability to use your body to counter weight, on a kayak this is much more difficult. I suspect this is the reason for the boomless furlable sq top sails. We have kayak sailed for a long time, its kind our favorite thing to do. Actually I don't recall ever taking our Hobies out without a kayak sail strapped to the side of the boat. One really cool feature of all Hobie kayaks is they are designed from the ground up to be a sailing machine. By using both the sail and the mirage pedal drive together the boat actually performs pretty well, including upwind. Nearly all of the aftermarket kayak sails I have seen are downwind only. By pedaling and sailing you can sail suprisingly close hauled. When not pedaling pointing your pedals down acts like a daggerboard. I have tried putting larger sails on my hobies, they get pretty tipsy even in light winds with big sails without a keel weight. If you can find wing sails they seem to work the best for kayak sailing because the have almost no heeling moment.
Hope this helps
FE


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PostPosted: Mon Mar 23, 2015 12:02 am 
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Lead Belly wrote:
The existing sail kit performs quite nicely close hauled but sail efficiency drops off markedly the further off the wind you sail. The loss of efficiency means that heeling forces are increased at the expense of forward motion, making for a more ‘tippy’ kayak. The sail seemingly folds in half when running before the wind in light breezes.

I got a similar impression from 2 trips using the Hobie sailkit for inflatable kayaks (includes fore and side stays). Perfect sail shape for upwind, but a taco shape in light side or following winds. I ended up sailing upwind but using a faster pedal for most of the return. I would first look at an extra batten about one third up, rather the drastic step of a boom .

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PostPosted: Mon Mar 23, 2015 12:30 am 
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There are posts on this. Search for 'boom batten", "boom batt" etc.
viewtopic.php?f=11&t=50246
It is possible to slip a fibreglass batten into the pocket along the foot of the sail.
Works well down wind.


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PostPosted: Mon Mar 23, 2015 3:16 am 
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daft wrote:
Perfect sail shape for upwind, but a taco shape in light side or following winds.


Laugh of recognition - yep, "taco" is the perfect description of the sail shape.

Thanks, will certainly look at the boom batten option. (Did a search of the forum but the term "batten" did not occur to me).


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PostPosted: Mon Mar 23, 2015 5:20 am 
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Location: Naples, Italy
It's easy to improvise a cheap boom for a Hobie kayak or Island sail. Here's how:

1. Buy some collapsing fibreglass fishing rod blanks of the diameter/stiffness you want (I used a 5 m and a 6 m rod for my Adventure Island boom) 2. Assemble your chosen sections, twisting and pulling or pushing hard to stop the sections from collapsing in use
3. Wrap a 1m length of padded self-adhesive bandage around the mast end of the boom to stop it chafing on the mast when the boom is on the windward side. I used extra adhsive bandage on top of that and at the other end of the boom too.
4. Attach the boom to the mast with a prusik loop (I use 3 turns and a fairly tight loop, but not so tight that the mast can't rotate freely) 5. Attach the clew eye of the sail to the other end of the boom with another prusick loop, then the mainsheet pulley hook to the boom with a third prusick loop on the INSIDE of the prussic loop for the clew eye - I used 2 turns for both these loops

The advantage of such a boom over a boombat or no boom at all is that you can control/adjust the sail draft for any sail angle by heading into the wind to take the tension off the sail, then reaching up and back to slide the clew and mainsheet pulley prussic loops along the boom. Prusik loops are wonderful in that they slide easily unless under tension, when they lock up completely - this means you can still furl the sail by sliding the aftmost loops along the boom as you furl the sail.

One disadvantage of such a boom compared to a boombat is that the boom, being straight, is lower, so that you need to lean back more to go under it when tacking or jibing.
Image
My boom works well downwind in less than 10 knot winds as it stops the sail from collapsing, but becuase there'd no vang the boom does lift in stronger gusts, making it harder to control the sail than when I use my (smaller) aftermarket sail with boom and vang.
Image
It's hard to fit an effective vang (from the mast base to the boom) because the Hobie sails go down to almost deck level, meaning that the angle between the vang and the boom is very small, resulting in poor mechanical advantage (although there is someone on this forum who has done this)

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PostPosted: Tue Mar 24, 2015 11:13 pm 
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My thanks to Fusioneng, Daft, Stringy and Siravingmon for helpful suggestions – much appreciated.

Fusioneng’s fixed wing idea is beyond my modest capabilities, but the various suggestions for battens and poles have possibilities. I also like the idea of adding two reinforced patches sown on around the middle of the foot of the sail to which the mainsheet is attached, along the lines of the Flat Earth Sails’ approach shown here http://www.flatearthkayaksails.com/. (I think Flat Earth Sails are Australian-based). The sail can then be sheeted directly to the middle of the kayak, rather than via a point at the stern. This approach probably requires the use of a pole, rather than a batten, to prevent the sail going ‘reverse taco’ in stronger winds. The cost is largely whatever a sailmaker charges for adding the reinforced patch, unless I decide to go for a pricey carbon fibre pole.

But I also think I will go ahead with purchasing a carbon fibre mast and boom system that the US vendor says will fit my kayak. The cost is about US$600, delivered to Australia from the United States, including a 1.3 square metre. This sail system can be easily lowered to the deck when on the water. The cost is acceptable to me (and my wife?) because I get as much fun out of sailing my Sport as pedalling it; I am a tragically hopeless fisherman.


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PostPosted: Tue Mar 24, 2015 11:57 pm 
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I'm afraid I think you'll be disappointed with such a small (1.3 m2) sail. The standard Hobie kayak sail at around 1.9 m2 is wimpy enough as it is, in my opinion.

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PostPosted: Wed Mar 25, 2015 12:28 am 
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Lead Belly,
I agree with Simon. That's a lot of money for such a small sail.
Have you seen this?:
http://www.ebay.com.au/itm/Kayak-Sail-f ... 4192e6034a


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PostPosted: Wed Mar 25, 2015 12:35 am 
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I am getting the 1.3 square metres as a storm sail - that is, for strong wind days. Had thought about an even smaller sail. For light wind days I reckon your poled sail system (pictured above) will work well for me.


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PostPosted: Wed Mar 25, 2015 12:40 am 
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stringy wrote:
Lead Belly,
I agree with Simon. That's a lot of money for such a small sail.
Have you seen this?:
http://www.ebay.com.au/itm/Kayak-Sail-f ... 4192e6034a


No, I have not seen this. Thanks, very interesting! And cheaper....if we don't start a bidding war.


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PostPosted: Wed Mar 25, 2015 12:48 am 
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stringy wrote:
It is possible to slip a fibreglass batten into the pocket along the foot of the sail.
Works well down wind.

Thanks, but is it too weak to make much difference in side winds?

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PostPosted: Wed Mar 25, 2015 7:55 am 
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Lead Belly wrote:
But I also think I will go ahead with purchasing a carbon fibre mast and boom system that the US vendor says will fit my kayak. The cost is about US$600, delivered to Australia from the United States, including a 1.3 square metre. This sail system can be easily lowered to the deck when on the water. The cost is acceptable to me (and my wife?) because I get as much fun out of sailing my Sport as pedalling it; I am a tragically hopeless fisherman.


Would you care to share this vendor information? If I get better at this sailing thing, I will probably want to go with a CF mast as well.


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PostPosted: Wed Mar 25, 2015 8:04 pm 
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Jcanracer wrote:
Lead Belly wrote:
But I also think I will go ahead with purchasing a carbon fibre mast and boom system that the US vendor says will fit my kayak. The cost is about US$600, delivered to Australia from the United States, including a 1.3 square metre. This sail system can be easily lowered to the deck when on the water. The cost is acceptable to me (and my wife?) because I get as much fun out of sailing my Sport as pedalling it; I am a tragically hopeless fisherman.


Would you care to share this vendor information? If I get better at this sailing thing, I will probably want to go with a CF mast as well.


Falcon Sails http://www.falconsails.com.au. They have a very informative website with lengthy responses to many frequently asked questions.

You can design online the colour scheme of your four panel sail. I like fluorescent yellow in the top panel, medium blue in the second and white for the rest (batten holders, trim, insignia etc). Hobie-like?

I should add that I am not in any way connected to Falcon Sails. My Hobie Sport is the 2013 model that has a round hatch up forward, not the square and sloping front hatch of later models. I sent a photograph to Falcon Sails to see if they thought their sail could be fitted - they said: yes, it could be rigged easily. I am certainly not qualified to say how well the Falcon Sail will fit other Hobie kayak models.

As of now, the quoted cost delivered to Australia (carbon fibre rigging, 1.3 m2 sail) is US$560.


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PostPosted: Wed Mar 25, 2015 10:50 pm 
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stringy wrote:
Lead Belly,
I agree with Simon. That's a lot of money for such a small sail.


What surprised me about this whole exercise was how little extra it costs to get a sail system that gives the sort of sail controls (carbon fibre mast and boom; boom vang; outhaul and downhaul) that markedly extends (I think) the range of winds that I can comfortably sail with my kayak.

The boomed sail system that I am looking at is quoted today at US$545 by the US manufacturer, before postage. This compares with US$376 for the standard Hobie kayak sail system at a prominent US kayak dealer and US$436 if you add the Hobie furling kit (an essential addition, I reckon).

To me, this is a price worth paying to get more quality sailing time from my kayak. Maybe I will change my mind if I get hit too often by the new boom...


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