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PostPosted: Mon Sep 14, 2009 12:19 am 
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Joined: Tue Jul 28, 2009 12:16 am
Posts: 238
Location: HISC Chichester Harbour UK
My first attempt at posting some videos of my A1 sailing down wind at various times using my spinnaker pole mod. On the first Vid (taken yesterday) I have taken a shot of the Velocitek which was showing between 4-5.5 knots in a fairly gentle breeze. I have a rather chunky carabina with everything attached. the pole goes through it. Everything works well and it makes a big difference. The vids were shot using my stills camera and are not very good quality.
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PostPosted: Wed Sep 16, 2009 7:35 pm 
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Do you have a parts list and detail about how you did this? It looks very interesting.

How does your AI-with-boom perform in other wind conditions and other points of sail?

Timo


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PostPosted: Thu Sep 17, 2009 1:01 am 
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Location: HISC Chichester Harbour UK
I sourced all the boom parts from my sailing club chandlery. The boom is a carbon tiller extension. It has a standard Optimist dinghy cleat, a plastic rollock that clips around the mast a small Harken pulley block and stainless mounting loop and a holt hook/pulley that hooks into the eye on the sail.To finish it off I found a rubber bung to push over the end of the boom to make it safer. I made it approx 300mm longer that the sail when held out completely flat. I currently have a stainless steel screw type safety harness carabina that is the right size and shape (pear shaped) but is too heavy. I am still look for a more elegant size. I have a Barber hauler that prevents the boom from lifting and once I have set a nice shape on the sail, and simply adjust the booms position with the mainsheet and BH.

I will try and take some more detailed pictures for you this weekend.

It makes a big difference directly downwind when the sail intends to collapse into a big loop ahead of the mast and less of a difference as you gradually get higher up the wind.
There is the argument that you would simply keep zig zagging downwind to keep the sail efficient, but I believe in a lightwind, you will save a lot of time avoiding having to do that and where I am exploring the harbour in small areas, there simply isn't the room to get going before you are having to tack again.
As you start to come upwind from dead downwind, there is a point on a broad reach where the sail is more efficient left to its own devices and it works well until you are trying to point, where such a loose cut sail and bendy mast is inefficient. I initially felt it helped upwind, but am still not totally convinced. It is certainly useful in very light winds where I can tune the sail and monitor the effects on my Velocitek. I will experiment some more this weekend.

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PostPosted: Sat Jul 03, 2010 10:05 am 
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Joined: Wed Apr 14, 2010 8:35 am
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Location: newquay, cornwall, uk
hey rokraider. cornwalls ai'er here. i have never sailed before and have had some trouble heading downwind too. reaching is fine, tacking too. so i trawled throught the forum and found your post. is there any way you could, using a diagram, id the parts used and how they attach both at the mast and onto the back of the sail. it would be most appreciated. my email address is garyambrose58@hotmail.com
many thanks
gary
ps, do you use it often/always and does it offer both pros and cons?


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PostPosted: Sat Jul 03, 2010 7:25 pm 
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Joined: Wed Mar 17, 2010 5:00 pm
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Location: Port Macquarie, Australia
G'day rokraider, enjoying your experimentation. :D

Zigzagging downwind only helps planing hulls, that are designed to exceed wind speed. For example, the Aussie 18 footer skiffs. These never sail straight downwind. Booming out the sail as you have done is the best downwind option, particularly in lighter winds.

I must admit to having thought about a boom for upwind sailing - only in my mind though, as I don't have my TI yet. However... this would work only if you limit the amount of mast bend with a forestay, and possibly side stays. Preventing the mast bend stops the top of the sail from twisting and depowering - which I might add is a design feature. Once you reduce the mast bend, the boom should be hauled down, to induce a flatter sail profile and shift the CE forward.

Bear in mind that this adds a lot more stress to the rig though. The TI, for example, was apparently designed with the view to adding an optional jib, but Matt has advised that they struck some problems with the strength of the bow fitting - this probably applies to the AI as well. The mast base would also be subject to a lot more compressive force, but Matt didn't make any mention of this being a problem when the jib-equipped TI was trialled.

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PostPosted: Mon Jul 12, 2010 8:18 pm 
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Location: Fort Walton Beach, Florida
I just posted a couple of videos of my similar system using a boathook, check them out. http://youtube.com/mcoop571

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PostPosted: Tue Jul 20, 2010 6:19 pm 
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I like the simplicity of mcoop57's boat hook. I have an old boat hook just sitting in my garage. I'll give it a try.

PS: Good Shooting!

Rez


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PostPosted: Sat Jul 24, 2010 3:40 am 
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Location: Lake Macquarie NSW AUSTRALIA
Thats an impressive mod rokraider. Thanks for that. I was wondering what to do tomorrow and what bits and pieces I have to do something similar.

I havent seen that speedo before. Could you let me know the details ?

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