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PostPosted: Mon Dec 17, 2007 12:52 am 
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Location: Central Coast NSW Australia
When I borrowed the extra sail for my twin sail project I needed to make it furl without drilling holes or pressing a bearing onto the mast in case I had to return it. The simplified system works well and is easy to fit. In an earlier system I made I had a bearing at the base of the mast which added complexity. This is not needed.
Here are the parts required:
Image
The main parts are the 7/8" Canopy Bow Knuckle readily available from a boat supply shop and the thrust bearing balls and retainer which I ordered from an online bearing supply shop. It has the following specs and fits the Hobie mast perfectly:
Nominal ID (mm) : 22.225
Nominal OD (mm) : 34.925
Nominal Thickness (mm) : 2.362
Material (Retainer / Balls) : Nylon / 440C Stainless
Ball Size : 3.962
The other parts are readily available from a good hardware store.
Here's how it looks assembled on the mast and fitted to the boat:
Image
The system relies on the weight of the mast bearing on the thrust race. To get clearance from the end of the mast in the mast tube assemble the bearing and knuckle on the mast, fit to boat, tighten knuckle with screwdriver, remove mast and then fit the washers. This will allow the mast end to sit above the tube base and spin freely.

The knuckle needs to be notched for the sail downhaul bungee. I drilled it out but it doesn't need to be this deep. :oops: A round file may be better to use to get a knotch just deep enough so the bungee doesn't slip.
Image

The plastic tubing fits over the knuckle bolt to protect the line from the sharp threads. A tube clamp can be used to retain the bearing when not in the mast tube
Image

or the furling line can be tied around the mast end:
Image


The sail is fitted to the boat furled around the mast. The small furling line is wrapped clockwise around the mast a couple of times higher up and then threaded through a small jam cleat located just in front of the hatch.
Image
A small eyebolt allows smooth operation of the furling line:
Image
The mainsheet can now be locked down.

To unfurl the sail undo the furling line from the cleat and pull on the mainsheet. The mast will turn as the sail unrolls and the furling line will wrap around the mast. With a little practise the sail will unwrap easily from around the mast. I find it helps to unfurl the sail a bit, release tension allowing mast to straighten and then pull on the mainsheet again.
To furl loosen the mainsheet and pull on the furling line. The sail wraps easier than it unwraps.
Great for landing or when the wind picks up!
PS- If you cannot get the thrust bearing retainer I think you could try the Hobie teflon disk they sell for their cat mast. Drill a 7/8" hole in the disk for the mast to fit through and fit it between the washers. It should work but I got the bearing for about half the cost of the teflon disk. If you use a hole saw you may even be able to drop the cutout into the mast tube for easier spinning!
It may even work just with the washers -though not as smoothly :)


Last edited by stringy on Sun Dec 23, 2007 4:14 am, edited 1 time in total.

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PostPosted: Tue Dec 18, 2007 9:02 pm 
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Joined: Mon Jan 29, 2007 11:06 am
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Location: Montana
Thanks for the ideas. What type of retainer keeps the mast in place?


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PostPosted: Wed Dec 19, 2007 12:00 am 
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G'Day Geezer,
The cleated furling line stops any uplift of the mast although I have found that the mast doesn't really need any locking down. Gravity does a pretty good job. :)


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PostPosted: Wed Dec 19, 2007 8:07 am 
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Location: sacramento california
G'day Stringy
Nice bit of work there on that furler as per usual :lol:
Hows the sailing going ? Have you had any good wind lately ?
Post up some more digi-pickies when you can.
Kepnutz


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PostPosted: Thu Dec 20, 2007 2:11 am 
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Location: Central Coast NSW Australia
Thanks for the kind comments Kep :)
Hoping to get out in the next couple of days - had a hectic week but managed to finish end of year jobs . I'll try to get a friend to take some better pics. I'd like to see for myself how the twin sails shape up. The forums have been a bit quiet. RR is conspicuous by his absence :wink:
I guess your season is ending as the main thread seems to be cold weather gear! Ours is just beginning and I've got some trips planned for our summer break. Will keep you posted.
Any trips planned down (up??) your way? Always enjoy reading your travelogues 8)


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PostPosted: Thu Dec 20, 2007 7:55 am 
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Location: sacramento california
G'day Stringy
No kayaks trips up this way for awhile :(
The weather is a bit rooted now plus the days are real short and cold like they been saying.
Roadie is probably out getting chrisse-prezzies for all his rello's and such or off on chrissie hol's like most of us.
We can only sit here on our fat dates in front of our pooters now like bloody buggery whingers with our underdaks in a bunch and watch while you have a go till our weather improves.
Im just about to go troppo with a few kangaroos loose in my top paddock from all this mucking about indoors. So give it heaps when you can for all us northern hemi blokes and post some more digi's !!
Cheers
Kepnutz


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PostPosted: Sat Dec 22, 2007 7:01 pm 
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Location: Montana
Stringy,

Is the grub screw holding the "knuckle" to the mast sufficiently strong to hold the sail furled partially in a blow? Also, I am installing this on a "Sport", and there is not enough room around the mast tube for the knuckle to sit atop a bearing on the mast tube. I plan to tighten the knuckle just high enough for it to turn freely and force a small piece of teflon into the mast tube for the mast to turn on. Sure hope the mast stays put in a blow without a retainer. The water is a little hard now here in Montana for much Kayaking/sailing for me to give this a try.

I spent a year in Cairns in the early 90's and sure wish the AI or a sailing kayak had been available then.


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PostPosted: Sun Dec 23, 2007 1:43 am 
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G'Day Geezer,
I'm not familiar with the Sport. Next time I visit my Hobie dealer I'll have a look.
The bearing is about the same size as the mast tube and the washers are only only slightly larger. What is causing the obstruction? Could you use a spacer between the knuckle and the mast tube to bear down on the bearing/teflon disc?
This is my newest sail and I have had it out only a few times but I have had no problems yet. Today the wind was a steady 25 km/h with gusts at about 35km/h. At times I furled to the tell tales and even past them. Everything still tight and certainly no lifting of the mast. If you're concerned about the knuckle screw not holding you could always screw a selftapper directly into the mast through the knuckle.
Hope you can get it working OK. I couldn't do without furling now! :)


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PostPosted: Sun Dec 23, 2007 4:12 am 
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Oops! Just realised my mistake about the furling line. It goes in a CLOCKWISE direction around the mast :oops: I edited the original post.
Or is it different in the Northern Hemisphere? :wink:


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PostPosted: Sun Dec 23, 2007 8:39 am 
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Location: Montana
Thanks for the update. I will build up a spacer to work with the bearing and will try with and without in the spring, I am running the furling line to the left side of the Kayak, through a cheek block to a cam cleat just in front of the rudder control. A little variation to your idea.


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PostPosted: Mon Dec 24, 2007 12:01 am 
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Sounds great Geezer. :)
Any pics?


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 Post subject: Trouble finding bearing
PostPosted: Fri Dec 28, 2007 12:15 pm 
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Location: Orlando, Fl
Stringy would you mind supplying the link to the web site that you found that bearing at?


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PostPosted: Sat Dec 29, 2007 12:52 am 
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Location: Central Coast NSW Australia
G'Day Frank,
I got the bearings from a supplier here in Australia:
http://www.smallparts.com.au/cgi-bin/st ... hes=0=post
Looks like they will post overseas although I don't know how long it would take especially now being the Christmas break. It took about 4 weeks for them to arrive during normal business times . :(
I'd be surprised if you couldn't source them locally. I've always been envious of what you can get in the US that we can't get here and how much cheaper things are :?
You could try this site in the US that I came across:
http://www.torquetrans.com/ball_thrust_ ... /index.htm


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PostPosted: Mon Jan 07, 2008 12:30 pm 
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Thanks for the info Stringy!

Torquetrans.com sent the bearing today and it looks great. I machined a part to look like your knuckle out of billet aluminum and plan on anodizing it to match my sail. I will post a photo when I get the project completed. Thanks again for the awesome idea.


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PostPosted: Mon Jan 14, 2008 4:36 pm 
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Glad I could help Frank- I hope it works out OK. :)
We have just returned from a week away where we sailed every day so I was able to give the system a good workout.
A problem I have found with this newer system is that the furling line being attached low at the knuckle can become tangled in the bearing if you are not careful when unfurling with the main. Holding the furling line up while pulling on the mainsheet prevents this. Remember this design eliminated holes drilled into the mast but I think now I am going to drill a hole further up the mast and run the furling line inside the mast then exit through the hole. I am also thinking about some type of cup with a small hole for the furling line to exit from located above the knuckle and mounted so that it spins freely. This should prevent line tangles.


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