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PostPosted: Wed Aug 15, 2012 7:01 am 
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That dude can SAIL!!

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PostPosted: Wed Aug 15, 2012 7:24 am 
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But how is he going to get back upwind in those conditions? I guess that is why the camera boat was there :lol:

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www.scenefromabove.com.au


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PostPosted: Wed Aug 15, 2012 7:45 am 
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tonystott wrote:
But how is he going to get back upwind in those conditions?

That will be his next video! :wink:

It will be much longer... much.... much longer!

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PostPosted: Sun Sep 30, 2012 1:40 pm 
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older topic but interesting to me as I sail Sunfish. When comparing speed you have to decide if it speed through the water or time to a destination that is the measure. On most points of sail an AI or TI be able to hang with a Sunfish very well. One others the AI or TI may be faster but just to throw fuel on the fire...... A TI or AI will top out somewhere as they are displacement hulls, they don't plane. However the Sunfish will plane, like the Laser in the vid (used to sail those too). So if you could keep the boat upright a planing hull has almost no top end. My H17 tops out in the 22 mph range, my Wave around 17 mph, but I have had my Sunfish at 15 and could have gone faster still. Meaning I was still able to control the boat and felt if a few more mph were added to the wind I could have handled it. Given the correct amount of righting moment the Sunfish should top out a bit higher, the foils really being the limiting factor. However point to point, especially over great distances the AI or TI will be faster as there is less fatigue on the crew. Interestingly there was a Sunfish in last years Watertribe Ultra Marathon (EC first leg as separate race). He didn't finish but I wonder how he did to weather in 20-25 against the TI's and AI's.


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PostPosted: Sun Sep 30, 2012 3:18 pm 
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VTwave:
If you put enough sail on a brick ( TI displacement hull) you can even get that to go. With my spinnaker and jib flying I have 265 sq ft of sail on my TI. I have been been 18 to19 mph and held it for quite a distance on several occasion now. Very wet ride though, as sometimes the bow is completely submerged.
I used to sail sunfish when younger, would go over quite often, have not tipped my TI in way over 2000 miles of sailing sometimes in pretty bad condition.
This is just my opinion but I feel the TI is much more versatile.
Bob


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PostPosted: Sun Sep 30, 2012 5:55 pm 
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We own a Sunfish and AI. My son and I race each other informally. As reported, the Sunfish goes to weather better(sans drive), and under 15 kts the AI is faster off the wind. Over 15kts the AI has problems with steering unless significantly reefed which slows it down relative to Sunfish which doesn't have to be reefed for those over 175 #. Just let it luff a little. For comfort during an afternoon sail the AI wins hands down. For a difficult passage upwind in a narrow channel prepare to use the pedals a lot on the AI. I find the AI sails better with the pedals removed so it's back and forth for me. BTW, I have an early version rudder system.


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PostPosted: Sun Sep 30, 2012 8:06 pm 
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perflem wrote:
BTW, I have an early version rudder system.

Yeah, the new rudder completely changes the balance of the AI. It's not just better at controlling weather helm - it actually eliminates the weather helm, even with the rudder neutral. My take on it is that the much bigger area of the rudder blade moves the centre of lateral resistance aft.

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PostPosted: Mon Oct 01, 2012 10:23 am 
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Location: Sollentuna, Sweden, Europe
NOHUHU wrote:
Before anyone gets cocky and decides to challenge a lazer (at least this guy) you might want to check out this video first.

[youtube]http://www.youtube.com/watch?v=50nJ8UkOGwg&feature=player_detailpage[/youtube]
You'll thank me later,.. :lol:


Yes this guy can sail!
How much wind is it?
How high are the waves?
Can anyone make a intelligent guess?

Now the big question!
Is this weather too much for an Adventure Island?

br
thomas


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PostPosted: Mon Oct 01, 2012 6:08 pm 
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fusioneng wrote:
VTwave:
If you put enough sail on a brick ( TI displacement hull) you can even get that to go. With my spinnaker and jib flying I have 265 sq ft of sail on my TI. I have been been 18 to19 mph and held it for quite a distance on several occasion now. Very wet ride though, as sometimes the bow is completely submerged.
I used to sail sunfish when younger, would go over quite often, have not tipped my TI in way over 2000 miles of sailing sometimes in pretty bad condition.
This is just my opinion but I feel the TI is much more versatile.
Bob

I'll admit, I threw out a hook there and you took the bait. I agree the TI is a more versatile platform, but that wasn't exactly the question. The TI is fast, no question. But as a displacement hull it has a top end. Past that no matter how hard it blows or how much sail, all it will do is dig a bigger hole. My H17 is the same, so is my Wave. Extremely efficient displacement hulls. The H17 will do about 22-25 but then no more. However a Sunfish will plane and if the sailor is good enough to keep it under him the top end is theoretically much higher. In that vid I bet the Laser hits close to 18-20 on a few of those waves. If the wave was taller and steeper it would have been faster still. Another area where the Sunfish will do great is deep down wind. You can sail a Sunfish very fast almost dead down, where a TI would like to be heated up a little. Over the course of a run in high wind the Sunfish will likely win. I have seen Impulse 21's beat 1-14's on a run despite being over 600 lbs. heavier and going slower. But here VMG was better. I did the CT River race 2 years ago in a Sunfish and while there were no TI's there was an H17 and 14. For the first 6 miles it was light and shifty. The Lasers and I were horizon jobbing the cats, till the river opened and the wind hit 12-15. Then the cats gained back and took over. However the lead laser finished within 20 minutes of the H17, on a 12 mile windward course.


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PostPosted: Sun Sep 01, 2013 8:11 pm 
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These results surprise me . I've sailed sunfish and a tri hull sailing katak and found the kayak faster particularly in light air.

Pete


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PostPosted: Mon Sep 02, 2013 11:04 am 
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vtwave wrote:
fusioneng wrote:
VTwave:
If you put enough sail on a brick ( TI displacement hull) you can even get that to go. With my spinnaker and jib flying I have 265 sq ft of sail on my TI. I have been been 18 to19 mph and held it for quite a distance on several occasion now. Very wet ride though, as sometimes the bow is completely submerged.
I used to sail sunfish when younger, would go over quite often, have not tipped my TI in way over 2000 miles of sailing sometimes in pretty bad condition.
This is just my opinion but I feel the TI is much more versatile.
Bob

I'll admit, I threw out a hook there and you took the bait. I agree the TI is a more versatile platform, but that wasn't exactly the question. The TI is fast, no question. But as a displacement hull it has a top end. Past that no matter how hard it blows or how much sail, all it will do is dig a bigger hole.


Agreed, but in a displacement hull there is still speeds greater than the hull speed rating. Despite stern squat and such it would seem if the sail area is high enough and the wind blowing - it'll triple your hull speed or at least double it. Its not efficient as a planing hull, but as posted before I think the low wind efficiency on displacement hulls can be surprisingly good.

I'd be interested to hear what reinforcements and such were needed to fly 265 sq ft at 19mph.
I'm contemplating 100sq ft and that has all my structural concerns a light.

Interesting thread - hope you guys don't mind me reengaging it.

Pete


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PostPosted: Mon Sep 02, 2013 11:29 am 
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There really isn't a limit as to how fast a displacement hull can travel. But once beyond a certain point it takes a disproportionate amount of additional power for just for a small increase in speed.

Planing hulls actually require less force or power to go faster once they get up on plane.


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PostPosted: Mon Sep 02, 2013 11:52 am 
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I've often thought it'd be great to have the f14 tomcat version of a kayak sailing hull. In lighter air its pure displacement - as the speed increases the hull retracts and changes form. Of course the mechanics of such a thing wouldn't be anywhere near as elegant as a Tomcats, to say nothing of the leaks ! But its a notion Ive wondered about. Maybe the proper use of foils for and aft could approximate a displacement hull and then change pitch or config one way or another to a planing hull.

Saw the ultimate planing hull this summer - if you can call it a hull...

I'm sitting at Ft Adams beach in Newport and this guy cones shooting through with one of those Moths. You'd think the last place u want to be is in a congested marina Fourth of July week. Didn't hit anything though and the sight of it is just wild. The learning curve for that thing has to make windsurfing seem easy!

Ok digression over.

Thanks Tom!


Pete


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PostPosted: Mon Sep 02, 2013 4:28 pm 
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Petewp61 :
Old thread, but still fun, I used to have a sunfish and loved it (brings back memories).

If you thinking about adding sail area to a TI there are only a couple areas that you need to pay attention to.
First off, the mast itself is very strong and shouldn't give you any problems adding more sail (within reason of course, and be wise about using it). The V brace system for the mast on the TI (and AI) is very strong from side to side and you shouldn't have any difficulty with that either as long as you check it often and make sure everything stays tight.
The problem when adding sails is in specifically 2 areas:
The bow on the TI is fairly weak and if hanging a sail on the front you need something to attach the sail to. I'm not sure I would trust the lifting padeye for too long (an accident waiting to happen). And with a sail on the bow the bow moves around quite a bit and your hatch will leak much more. To fix these problems I made a V brace for my bow out of aluminum that is clamped to the ends of the front AKA crossbar (strongest point on the boat), then form a V in the front and attached to the padeye. The sail is mounted to the V brace, this fixes two potential problems with one piece.

The other issue is if you look at the design of the mast holder, you will see it is braced very well side to side (you shouldn't have any problems there), and the front AKA cross bar (with the white bearings) on newer boats is double welded, so that will never give way. The problem lies on the bottom of the hull, there is a 1/4 in stud that holds the bottom of the mast cup to the bottom of the hull. Of course the mast cup sits on a beveled riser molded into the bottom of the hull, but honestly there is very little preventing the mast from pushing forward or backward given the 17 to 1 leverage of the mast on that joint. Basically if you took an 18 ft pole (length of mast) and placed a brick 1 ft from the end, you can lift your car with the short end. This analogy outlines the stress on that tiny 1/4 inch stud. On my hull I cut a small piece of aluminum about 1/8 x 2" x 8" and placed it behind the mast holder and up against the mirage drive pocket. I then built a clay dam around it and buried it in epoxy (inside the hull). Didn't take more than an hour, but now I know the hull bottom and mast bucket are strong enough for heavy duty sailing, and able to withstand extra sail area. (which I do often).
If adding just a jib you probably don't need a rear stay line, but if you are planning to add a huge spinnaker (like mine) then I highly recommend adding a rear stay line. The forward force from the big spinnaker is huge, and can damage your boat without a rear stay ( I snapped a rear stay line once, and that 3/16 line was at least 300 lb test) I now use heavier line that is stretchy (nylon).
All my mods are well described in the thread The ultimate Tandem Island ( viewtopic.php?f=69&t=33720) in there you will find designs for mast toppers, re-enforcements for this and that, and all the crazy kinds of things I've done to my TI's (tinkering is part of my hobby), hopefully you can find something in there you can use.
Bob


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PostPosted: Mon Sep 02, 2013 5:23 pm 
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"There really isn't a limit as to how fast a displacement hull can travel. But once beyond a certain point it takes a disproportionate amount of additional power for just for a small increase in speed"
A "displacement" hull generates a 'displacement' wave which has its speed governed by its wavelength. If you have enough power...once the hull has exceeded the wave speed...the hull is actually planing. But it takes quite a bit of power to break the 'speed' limit. I once had a speedboat that was a displacement hull at low speeds but was excellent at planing at higher speeds. At about 10 knots the hull would 'bow up' and push about 2-3 feet of water out of the way. Increase power (250hp) and the hull would literally jump out of the water and plane. I could then cut engine power by nearly 50% without loosing any speed.
I believe that a forum member calculated the TI hull speed as being between 5.5-6.5 knots. I have had my TI going significantly faster than that (gps). I could feel the hull planing when I exceeded about 6 knots. Bow splash moved aft about 1-3 feet.
I have had people refuse to believe that the TI was planing! They always state the 'displacement hull speed' barrier. Similar to the old aeronautical engineers whe swore that planes couldn't get past the sound barrier. Which was mostly true for prop-driven planes but not for more powerful jet engines. Tho' a couple of WWII fighters did break the sound barrier in high altitude vertical dives.


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