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PostPosted: Thu Sep 09, 2010 4:25 pm 
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Will it be possible to fit the new two piece mast to the AI? Having a bigger sail would be great in lighter wind and going downwind....and fun! The rest of the time it could be partially furled....


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PostPosted: Thu Sep 09, 2010 5:11 pm 
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Not possible. The drum is at a different height on the mast. Plus the larger sail would extend well aft of the transom on a AI.

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PostPosted: Fri Sep 24, 2010 3:40 pm 
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I would be interested in using the TI mast in an AI as well, but not with a TI sail, which has way too much area for an AI and as you noted, is not a workable shape for the AI. My intent would be either having a custom sail fabricated or possibly use a Bravo sail. The TI and AI share the same mast receiver (part numbers match), but the TI's crossbar is taller, so the bearing plate welded to the front of the bar is presumably higher, forcing the drum up the same amount. However, since the 2011 AI apparently will have the same aka hinges as a TI, it seems likely that the 2011 AI crossbars will be the same height as on the TI, and the crossbars might even be interchangeable, although that seems unlikely since the TI is a wider boat and Hobie probably wants to avoid a TI mast fitting in 2011 AI's. But this drum position problem can be rectified by removing the drum from a TI mast, and installing a new one at the correct height. The part numbers for the two drums are different, which would make sense if collecting a longer furling line, but both are stated to be 12'. In any case, for those of us who had to re-install their AI drum with G-Flex when it came loose, removing and installing a new furling drum seems possible. Obviously only people who love improving their AI would pursue such a venture, but given the number of people already pursuing their own jibs and spray guards, I can see them wanting a taller sail with only an incremental increase in area if they already have a reason to be buying a new mast or sail. After all, the inquiries about aka conversions are already being presented! Personally I would like to see Hobie redesign the AI ama, extending it proportionally to that of the TI. This might reduce diving and perhaps even result in a higher buoyancy rating. Since Hobie amas are symmetrical, only one relatively simple new mold would be needed, far less expensive than a mold for a new hull dedicated to AI service. I would move up to a Weta, but that means giving up the Mirage drive, imposing the risk of being stranded in light winds. It is an expensive boat as well since it is fiberglass.


Last edited by mjvoet on Fri Oct 01, 2010 5:19 pm, edited 1 time in total.

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PostPosted: Sat Sep 25, 2010 7:48 pm 
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Yep....I think that the bigger mast with a tailored sail would look better...and handle breezes better.....probably a bit less roach. The think that attracts me to the larger sail is the ease of furling....in the stronger breezes or when really tioght on the woind you could furl it in....letting it out when going downhill or on a reach. It is all a bit like the turbo fins....proably not necessary, but a bit of fun and possibly useful in some situations.

Given that Hobie look as if this is not something that they will want to play with, I am going to look at fiddling (as you have mentioned) and seeing how I can get the mast into my AI...and wander down to the sail loft to see if they could cut me a cool sail....it will look cool and add a bit of edge to my AI!


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PostPosted: Wed Sep 29, 2010 3:49 am 
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Hi Mark

There may be another way.

In windsurfing we changing the rig size to suite wind conditions and if we rig a larger size sail and the luff is longer than the mast we use a mast extension at the base to gain required luff length, but there are also extensions to fit on top of the mast. So it may be possible to extend the top of the std AI mast and have a sail custom made sail to gain the extra sail power required.Don't know if the AI mast is up to it (my windsurf masts are 100%carbon)

This just another possible way of gaining more power.

Nerdycross


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PostPosted: Wed Sep 29, 2010 4:21 am 
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MarkFreeman wrote:
Yep....I think that the bigger mast with a tailored sail would look better...and handle breezes better.....probably a bit less roach. The think that attracts me to the larger sail is the ease of furling....in the stronger breezes or when really tioght on the woind you could furl it in....letting it out when going downhill or on a reach. It is all a bit like the turbo fins....proably not necessary, but a bit of fun and possibly useful in some situations. !

Mark,

Why do you think a bigger sail will be easier to furl? Do you think sacrificing sail shape and upwind performance is worth a little more downwind speed?

No sailboat is very efficient going dead down wind. One part of the problem is that you sail using apparent wind not the actual wind. When you are going to weather the movement of the boat increases the apparent wind speed when going downwind it decreases it. This causes the actual speed of the boat to drop a little but even more important it makes you feel like you're going really slow. If the wind is blowing 10 miles an hour and your close hauled at 5 mph you probably feel a 12 to 15 mph wind in your face. When you turn the boat downwind if you’re still going 5 mph you only feel a 5 mph wind at your back and it feels like you're barely moving.

I don't know why you want to reduce the roach of your sail. I was watching some America's Cup mega sailboats about a week ago and they have all gone to the large roach like the Hobies.

Hobie chose the mast height for a reason and North Sails is a very good sail loft so I don't think you can do much to improve the performance of your boat unless you add a second sail and then you chance damaging your boat by putting forces on it that it wasn't designed to handle.

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PostPosted: Wed Sep 29, 2010 8:35 am 
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IMHO, if you want to increase the performance of your Island (TI or AI), add a head stay. Don't use spectra line, but a line with a bit of stretch in it (nylon based?). Lead it through a block at the bow to a cleat aft, so it can be released for furling. And add tramps so you can get out to windward.

Consider: Hobie designed the bendy mast for the safety of the majority. A good gust, the mast bends, spilling wind from the top of the sail. Safety feature. A head stay will limit that bending moment, keeping the top of the existing sail working in stronger winds.

Also consider a downhaul on the mainsheet for close-hauled sailing. This also helps keep the top of the sail at a closer angle of attack.

Although I've only had my TI for ~2 months, my planned speed improvements, in order, are:

1. Get a crew(person) out on the windward tramp.
Speed Increase: Substantial, I think, by a long shot.
Cost: Nothing: requires NO mods to your Island (assuming you already have tramps).
Complexity: Minimal. Just need an agile supermodel. :D

2. Add a head stay. May be more effective in the TI, as it has an attachment strap at ~4/5 mast height for the 'future jib'. On the AI, I'm not sure how the mast will bend in between. Might even be unfavourable for the AI.
Speed Increase: Noticeable, I think.
Cost: low: just a pulley, cleat and line.
Complexity: Low. Even a supermodel can yank a line... :lol:

3. Add a downhaul. When close-hauled, the mainsheet also works as an outhaul. However, sail shape (especially at the top) could be improved using a downhaul. Given the relatively narrow width of the main hull, it cannot be placed in an optimal position, and also has to be able to be swapped from one side to the other.
Speed Increase: Noticeable, I think.
Cost: low-medium: fairleads and cleats on both port and starboard sides, S hooks, and line.
Complexity: medium-high. Whilst two extra lines in the cockpit rate a medium, having to manually swap them between tacks rates a high. The supermodel just quit. :(

4. Add a furling jib. This is a subject in it's own right, so I'll start another thread for that one. :wink:

The supermodel is following to the next thread, coz it sounds vaguely cool :roll:

Disclaimer: I'm just an aero-hydrodynamics theory enthusiast, who by now has had a few Scotches. :? And for the ladies on this forum, my wonderful wife Sandy just gave me a smack on the head for being chauvinistic. My apologies to the supermodel.

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PostPosted: Wed Sep 29, 2010 9:39 am 
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Max,

Maybe I don't speak Australian but to me your TI already has one downhaul. It's the line that pulls the sail down at the bottom of the mast. The more wind you have the tighter you want the line to be but it's not very adjustable on our boats. You could add a cunningham but I'm not sure the sail could is designed for one. Adding an addition downhaul for sailing close hauled wouldn't buy you anything because when the main sheet is pulled in tight it pulls the sail both down and back (out).

Boom vangs and additional downhauls are normally used for sailing off the wind to prevent the bottom of the sail from lifting up which causes the sail shape to change. Not having a boom makes it very difficult to add a downhaul to prevent sail lift when running.

Outhauls are the lines that control the tension on the foot of the sail. It is attached to the boom and since we don't have one of those it would be hard to install one.

You said the mast bending is a safety feature. Then why would you want to try to prevent it from bending? If you really want to improve performance install a stiffer mast. Of course the boat isn't really a designed for one so I wouldn't try to predict how much wind it would take to make a disaster.

A head sail would definitely help the performance of the boat but my understanding is that Hobie is having second thoughts about whether the bow of the boat is strong enough to take the load.

The best idea I have heard yet is to add the trampolines and a supermodel.

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PostPosted: Wed Sep 29, 2010 9:45 pm 
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dosjers wrote:
Outhauls are the lines that control the tension on the foot of the sail. It is attached to the boom and since we don't have one of those it would be hard to install one.

How about modifying a Hobie Bravo boom for use on the AI/TI?

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PostPosted: Thu Sep 30, 2010 3:28 am 
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dosjers wrote:
You said the mast bending is a safety feature. Then why would you want to try to prevent it from bending? If you really want to improve performance install a stiffer mast.

When I get that forestay rigged, I'll let you know. Don't want a permanently stiff mast... adjustable is my ideal.
dosjers wrote:
The best idea I have heard yet is to add the trampolines and a supermodel.

Here, here! :lol:

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PostPosted: Thu Sep 30, 2010 4:31 am 
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Max,

I can tell you an easy free way to get your TI or an AI to sail faster. Pull your mirage drive and stick the plug in the hole.

Can't see why everyone wants to do all these expensive modifications to their boats when they're dragging those fins through the water.

Sailing with the mirage drives installed is like riding a bicycle with training wheels. They keep you from falling over but you really don't learn to ride untill you take them off.

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PostPosted: Thu Sep 30, 2010 3:54 pm 
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Agree with the drag from the drives. I've tended to leave them in for river sailing, as there are some rather narrow channels in places between sand banks, and they are a great help with quick tacking. Also, getting them back in is a bit fiddly, as I find I have to have them at exactly the right angle... not good to be fumbling as I'm rapidly approaching a rocky breakwall. :roll:


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PostPosted: Thu Sep 30, 2010 4:21 pm 
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I leave 'em in and just bungee it with the supplied bungee so that the flippers lie flat against the hull. Doing so I'm able to achieve dizzying speeds (well, up to 8 or 9 mph so far anyway). I guess I could take it out, but then I'd have to secure it... then I'd have to climb over the wife and do the same for her drive.

That sounds like a lot of work, and would deprive me of the pleasure of barking "lock the drive and release the furling line!" and watch my wife *actually* execute the commands.

It's a uniquely rare but distinctly beautiful thing!!!!

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PostPosted: Thu Sep 30, 2010 4:53 pm 
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tspbrady wrote:
I leave 'em in and just bungee it with the supplied bungee so that the flippers lie flat against the hull. Doing so I'm able to achieve dizzying speeds (well, up to 8 or 9 mph so far anyway). I guess I could take it out, but then I'd have to secure it... then I'd have to climb over the wife and do the same for her drive.

Yes but how fast would you have gone without the flippers dragging in the water? Even tight against the hull they cause a lot of resistance.

I just came back from taking a friend sailing who has never sailed before. I didn't have to take the drives out because I never put them in. We just paddled about 50 yards, unfurled the sail, and took off.

I do agree with Max that there are times when using the drives make sense just like motor sailing in a larger boat. I just think that those times are few and far between. It will make you a better sailor if you learn to control your boat under sail and take out the training wheels.

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PostPosted: Thu Sep 30, 2010 5:00 pm 
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I can only speak from the perspective of an AI, but there are two types of speed to take into account, water speed and point to point speed.

The first mode is "speed mode", pulling the drive, getting on a beam reach and blasting away, preferably out on the tramps.

The second is expedition mode, where you are trying to reach a destination. On the average, you are going to be travelling upwind more than half the time and using the Mirage drive is going to get you there significantly faster. Of course, when the wind is favourable, you can always pull the drive and drop into speed mode as well.

A third mode, much loved by the Hawaiians, is out to sea in high winds and rough conditions. In those circumstances, you want all the control possible over the boat, so it's good to have the drive in.

They are all fun ways of using these boats, though personally, if I really feel like some "pure" sailing - no particular destination, at high speed, I go out in a Cat.

There's definitely no point leaving the Mirage drive in if you aren't going to use it.

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