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Possibilty of the AI nose diving?
http://www.hobie.com/au/en/forums/viewtopic.php?f=71&t=13173		 Page 1 of 2
Author:  Fly'n C Lion [ Wed Jul 22, 2009 11:35 am ]
Post subject:  Possibilty of the AI nose diving?
Is it be possible for the AI to nose dive?

This summer's wind has been so different in the bay than last summer's. It's stonger, with longer and heavier gusts. These wilder sails are causing me not only to learn how to sail the different winds, but also to have longer and more interesting (funner) rides. The winds have often allowed me to sail straight N and so on my way back, I will loosened up my sail so it's out to the front side of my boat. The waves, aprox. 1 1/2' come up from behind and crest right about in the middle of my AI, which makes a sweet, musical sound. I've noticed after the waves crest in front of me, the front of my AI seems to very gently point downward and will often cut into a wave in front of me. The bow of my AI is under water and the tips of my amas are also. My AI is going quite fast and I've caught myself instictively (and later feeling a bit silly :oops:) pulling back on the black sail line and leaning back in my seat thinking I'll somehow lift the front end up. The bow often stays under for sometime, quite a few seconds until the next wave comes up from behind and seems to lift the boat up again. This has made me feel a bit uncomfortable thinking my AI might at some time, possibly with a larger, or wider wave, nose dive. I've been reading this forum since Dec., and I don't recall anyone addressing this issue. A few weeks ago there was a line in the forum on the bow of the AI and the amas cutting into incoming waves, but I'm worried cutting into the back of waves may react differently?
The greatest fun though, when you have the wind to your back, is when you actually sail faster than the waves. You skim right over the tops of those cresting waves and you feel like you are flying!!!

I would like to add, this forum literally warmed me last winter. I was able to live vicariously through all of your warm water, warm weather adventures. Seeing pictures of the sun shining on the water, and you sailors actually wearing sunglasses! I would actully have to squint at the computer screen when these photos came up. It was so cold and wet here in the Pacific Northwest this last winter and your stories and pictures helped me escape that. Thank you.
Fly'n C Lion
Author:  Aledal [ Wed Jul 22, 2009 12:16 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
A bow shield extending upwards and out would do the trick but difficult to make and attach to the boat. It`s definately possible to do though.
Or a floatation bag attached to the bow? :idea:
Author:  KayakingBob [ Wed Jul 22, 2009 12:23 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
The AI does like to go through waves instead of over them, sometimes leaving me with water up to my armpits!

But it always has come back!

When it starts to do that, just turn the boat just a little bit either way and it usually will pop the nose up.

To not have it do it, change direction a bit and cut across the waves down wind. It's actually faster, and quite a ride surfing the waves at maybe a 45 degree angle instead of straight downwind, when you are going faster than the waves are.

Kayaking Bob
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Author:  chrisj [ Wed Jul 22, 2009 2:04 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
Bob, is it modesty preventing you mentioning that your sprayshield design helps a lot with preventing the bow from getting submerged?
Author:  Aledal [ Wed Jul 22, 2009 2:27 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
He`s modest Chrisj. :)
Author:  KayakingBob [ Wed Jul 22, 2009 3:01 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
And yes, a sprayskirt can help with some of the problem. :)

Kayaking Bob
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Author:  Aledal [ Wed Jul 22, 2009 3:11 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
Yes it can.
and thanks Bob.
Author:  TIDALWAVE [ Thu Jul 23, 2009 7:02 am ]
Post subject:  Re: Possibilty of the AI nose diving?
My spray shield was constructed as a 'one-piece' so that the material extends
across the bow. Normally, I don't need access to the front hatch.
I found that leaving the material lie flat caused the sprayshield to act
as a scoop if the bow cut into a wave, so I installed a fibreglas rod
which extends from one side to the other of the shield. A simple buckled strap
allows me to slightly bend and hold the rod upward. There are a couple
of older threads which gave me the idea. The shield then has a slight spoon
shape to it. Now when it cuts into a wave the shield generates a slight amount
of lift and helps pull the bow upward.
Because of the upward pull on the sprayshield, the middle of the fabric wanted
to pull upward off the bow deck. I ran a bungy cord from the port hatch
bungee deck attachment up through a grommet in the shield, across the deck,
back through a second grommet and clipped down on the starboard hatch
attachment. This keeps the sprayshield fabric from lifting up from the hatch
when I hit a good sized crest.
I used 'shade cloth 85%' for the fabric...but after installing the Hobie tramps...
I am going to replace the 'shade cloth' with tramp material if I can find some.
The 85% shade cloth drains water easily but breaks an oncoming wave into
a spray of small droplets. The Hobie tramp material drains well and the weave is
so tight that little if any water sprays through it.
So if you plan to cut and sew your own spray shield I would recommend using
tramp material rather than shade cloth. (I didn't use tent nylon because I was worried
that the shield would then conduct water down the bow into my lap)
Author:  KayakingBob [ Thu Jul 23, 2009 10:59 am ]
Post subject:  Re: Possibilty of the AI nose diving?
My first Sprayskirt I made was with waterproof material, and it held two puddles because of it. I ended up adding a grommet on each side as a drain.

1st design, It also was too small.:
Image

2nd design, much better, but needed to be a little bit bigger:
Image

Final "production" design: :)
Image

Last years prototype:
Image

The prototype will grab water quicker if the nose dips down, so not recommended. But it DOES LOOK GREAT! :)

Image
I'm still thinking on enhancements to make the "perfect" Sprayskirt.

The pattern for the "production" version I posted at http://www.kayakingbob.com/sprayskirt

Also videos including tests of some Sprayskirts are at http://www.kayakingbob.com/sailing-videos

My wife also makes a few every so often for the sewing challenged. :)
Author:  apr67 [ Sat Jul 25, 2009 11:30 am ]
Post subject:  Re: Possibilty of the AI nose diving?
You can get tramp material from Sailrite.

http://www.sailrite.com/

However I understand it is harder to sew tramp material than sailcloth.
Author:  Roadrunner [ Sat Jul 25, 2009 1:53 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
Reconlon, you've really done a great job of refining this concept! It's neat to see how you have evolved the skirt. Also kudos to Gwiz for his innovative early development. This has gotten to be an excellent product and the fact that your wife is making some available to those who would otherwise never be able to build one is really appreciated. IMO, this is a significant enhancement to the AI. Thanks for all your work! 8)
Author:  TIDALWAVE [ Mon Jul 27, 2009 4:34 pm ]
Post subject:  Matt...bow spray shield hint...
I threw my home-made tramps away as soon as I received
my Hobie Tramps (there was no comparison on design and quality).
I hope that I can also throw away my home-made bow spray shield
as soon as Hobie can design and manufacture a spray shield.
Author:  Aledal [ Mon Jul 27, 2009 5:16 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
ditto Roadrunner. Definately nice design Reconlon/Tidalwave
It looks integral to the boat. I plan on going out this Winter and I have a "Mustang" Survival suit. The spray still gets in your face though- so Im considering a skirt. Hobies` tramps arent exactly "spray skirts" right? So maybe you should keep both of them on the A.I.?

Properly color coded of course :wink:
Author:  Tom Ray [ Wed Jul 29, 2009 12:05 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
Getting back to the original question, YES, it is possible to nose-dive the AI. I did it, and thought for a second it might pitchpole all the way over. I now believe that is not possible - it just doesn't have the speed and power to pitchpole itself. At least not with me aboard. ;)

I was going downwind in very steep, short period waves, with winds from 30 to 40 knots (tropical storm nearby). As long as I didn't go straight down the waves, I was OK, just dipping through them with a mighty splash. Great fun.

Then came a moment when I had to go straight down a wave or risk hitting the fenders of the bridge I was going under. At that moment, the biggest wave of the day appeared under me. Also at that moment, the biggest gust of the day blew up. It was a bit like falling off a cliff for a second, then the nose went into the next wave, and kept on going, and going, and going. It felt like the boat was vertical, but I'm sure it was not quite that extreme. Next thing I knew, the mast and sail hit that next wave, which quickly stopped the boat. It was a weird scene, hanging on in my near-vertical boat, mast and sail in the water. I was surprised when everything just kind of froze for a moment in that attitude, and I wondered what might happen next. I also took a split second to consider the fact that I was really, really stupid for being out there all alone in those conditions with no life jacket and no tether on anything.

The next thing that happened was really boring, but great! The boat just slowly floated back up to a normal attitude and took off! :D
Author:  KayakingBob [ Wed Jul 29, 2009 1:15 pm ]
Post subject:  Re: Possibilty of the AI nose diving?
After that experience, I assume you now ALWAYS where a PFD and leash EVERYTHING. :D

Kayaking Bob
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