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 Post subject: Unbalanced AI
PostPosted: Thu Oct 07, 2010 5:09 am 
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Joined: Tue Aug 18, 2009 2:07 pm
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Location: Saint Johns, Florida
I'm not sure if unbalanced is the correct term but my AI seems to be much heavier in the bow than other AI's.

My wife and I started off with 2 AI's a little over a year ago. My bow always seemed to dive under the surface more than her's. I thought it was because I weighed more. Then we bought a TI and sold her boat because mine had the transducer mounted in it. She immediately noticed that her bow was now diving more than it did with her original boat.

Yesterday I went out in the AI with two other guys in AI's and I noticed when running down wind the front of my boat would be under water up to the mast when a wave would hit and lift us from behind and the guy next to me wouldn't even be getting the nose under the water. We are both about the same size.

Can anyone tell me a way to check and see if there is some wierd weight problem with my boat? If I empty it out and put a level in it should the hull show level?

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Jerry D.
St. Johns, Florida
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 Post subject: Re: Unbalanced AI
PostPosted: Thu Oct 07, 2010 2:42 pm 
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Joined: Fri Jan 05, 2007 9:21 pm
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Location: Maui, Hawaii
If you and a friend lift the AI from the center handles, how balanced is it?

Also, which holes do you have your seat pegs in, the front set or the rear? (I find using the rear seat holes much better for trim in waves, even though the front position is more comfortable to me.)

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 Post subject: Re: Unbalanced AI
PostPosted: Thu Oct 07, 2010 3:02 pm 
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Location: Saint Johns, Florida
I always have my seat in the rear holes because I'm 6'3".

Do you think I should I try lifting it with the amas on or off?

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Jerry D.
St. Johns, Florida
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 Post subject: Re: Unbalanced AI
PostPosted: Thu Oct 07, 2010 3:04 pm 
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Location: Maui, Hawaii
Just the hull to start with.


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 Post subject: Re: Unbalanced AI
PostPosted: Thu Oct 07, 2010 3:51 pm 
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Location: Kailua 96734
Interesting idea. We know that Amas are not all balanced equally.

Putting your wife's observations aside for the moment, lots of other factors would influence the tendency to dive (and trump any possible imbalance in the hull).

Your sail trim/state of furl has a huge influence downwind
Your direction relative to the trailing waves (small degrees = big difference)
The distribution of weight in the hull (both you and the cargo)
Water in the hull, at any given time
Possibly your "drive" and dagger positions (I know, I know,.. )
And, no offense meant, but your buds may just be better surfers.

So you will never really have exactly the same factors on any 2 AI's, at any given time.

Next time you sail, if you adjust some of the physical factors you may see an improvement right away. More than anything, just laying back as far as you can while cresting the waves will rebalance the boat immediately and give you a better ride, as will steering off a little and spilling some air.

You are not going to be able to do anything about the hull anyway, so I would explore repositioning your weight load (low and to the rear) to find a better tipping point. Since you are the "movable ballast", maybe it's time to experiment with a rear seat or tramp position, you might really enjoy the drier ride and the new view as well. I sure do.

If anything, your hull just may be a little faster than others for some reason, such as color (I know, I know,..) :wink:

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 Post subject: Re: Unbalanced AI
PostPosted: Thu Oct 07, 2010 4:02 pm 
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I would focus on differences in the bow shape rather than weight. A small difference in hull volume up front would be more dramatic. Hulls do vary and if the bow area was sunken-in... less volume could seem like it dives more. If it were a catamaran, I would look at mast rake, but the masts should not vary... but hey, who knows. If your mast leans more forward, that could do it. More full shape in the sail up high can also cause the bow to be pushed down harder.

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 Post subject: Re: Unbalanced AI
PostPosted: Fri Oct 08, 2010 3:56 am 
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Location: Saint Johns, Florida
Nohuhu,

All good ideas but I have tried most of them.

When running down wind I was leaning back and even brought my knees up to get my feet back as far as I could (after all size 13's are heavy). When my wife and I used to sail together in AI's I noticed the problem sailing to weather but just thought it was the difference in our body weight. Then she started sailing my hull and immediately noticed her bow was down further than her original boat.

By the way, while sailing on Wednesday, we both had our drives in because the wind was strong enough to require the sail to be reefed and I still have not figured out how to get through a tack with a reefed sail without some outside help in the AI. (I'm not too proud to use training wheels when I need them.)

Is the rake of the mast adjustable? That could cause something like this and also give me lee helm in my TI.

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Jerry D.
St. Johns, Florida
2010 TI
2008 AI


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 Post subject: Re: Unbalanced AI
PostPosted: Fri Oct 08, 2010 8:27 am 
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Rake is not adjustable, but since shrink rates of the plastic varies... and I suppose relative positions of the hardware on the deck vs hull bottom "could" vary... I would not be too surprised to see some slight variance in rake from boat to boat.

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 Post subject: Re: Unbalanced AI
PostPosted: Fri Oct 08, 2010 4:10 pm 
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Joined: Tue May 18, 2010 2:31 pm
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Location: Kailua 96734
I figured you had Jerry. You own a TI and know the benefits of sailing in the front vs rear cockpit. Most of those techniques are obvious to experienced sailors, but since they can quickly mitigate a diving bow, they are worth noting in the discussion, for others to try.

Is there some gross deformity in the hull? I expect you would see it and could try a remedy. Some folks get this from storage and transport in hot climates. I saw one recently, but the owner had no complaints. If you can't see one, that seems like a stretch to me.

Wall thickness might do it. It's not as detectable, unless you compare a couple different boats with lights in the hull. Hard to imagine that much material shifted to the bow though. It would take 40 lbs or more to make a big difference. That's a LOT of plastic.

A few gallons of water in the hull and Amas will create this diving effect rather quickly though. Have you noticed if your boat takes on more water than the others?

A battery, an anchor and some diving gear up front would have the same impact. Or something (other than the hull) causing drag. (When the mirage is not installed, where is it stowed?)

Just things to keep in mind...

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 Post subject: Re: Unbalanced AI
PostPosted: Fri Oct 08, 2010 9:52 pm 
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Location: Calga NSW, Australia
It's amazing the difference a small bit of weight makes to the boat's characteristics. I had virtually never experienced significant submerging of the bow until I packed a camping hammock and a sleeping bag in the front of the hull - that was enough to make the bow dive markedly when travelling downwind.

BTW., I must agree with Nohuhu that sitting on or behind the rear crossbar is an effective way to solve the problem, as well as being a lot of fun.

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 Post subject: Re: Unbalanced AI
PostPosted: Sat Oct 09, 2010 9:05 pm 
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Location: Saint Johns, Florida
I haven't touched the boat since my posting but I can tell you I have never seen any gross deformities on the hull. Weight wise it had the same stuff in it as my wife's old boat that didn't tend to "dive".

The interesting thing is the hull seems to be fairly fast compared to other AI's. Next time we're out with other AI's I'll try to take a close look at their hulls compared to ours.

By the way, the main reason I sail my TI from the rear seat is that you can see the sail much easier from there. (Have you ever seen a sailboat with the wheel up front?) My wife sailed from the front seat for about 45 minutes one day and had a sore neck from a week trying to keep an eye on the sail.

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St. Johns, Florida
2010 TI
2008 AI


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 Post subject: Re: Unbalanced AI
PostPosted: Sat Oct 09, 2010 11:02 pm 
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Location: Kailua 96734
Jerry, how would you rate the downwind, downswell performance of the TI?

Sailed from the rear, it usually exhibits a tendency to lift the bow and porpoise a bit - probably a desirable trait when the wind and waves are at your back.

This is the rebalancing act we go for with our AI rear deck seating setups.

Here's a perfect example of them in action, shot by my pal Ty.
http://vimeo.com/7805377

Check out the first minute or so and again at 4.00. Turn on HD.

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 Post subject: Re: Unbalanced AI
PostPosted: Sun Oct 10, 2010 6:34 am 
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Location: Saint Johns, Florida
NOHUHU wrote:
Jerry, how would you rate the downwind, downswell performance of the TI?

The TI does not perform very well downwind but then no sailboat performs that good downwind.

If you watch sailboats racing as in the America's Cup you will see that they almost never head dead down wind (ddw) and they carry all kinds of different down wind sails. If you want to get somewhere faster you should sail on a broad reach and jybe when needed to get to where you want to go if it is ddw from you.

If you wanted to catch waves and surf with the TI I would think the best place to sit is in the front seat. I used to have a 17 foot touring kayak and I had to lean as far forward as I could while paddling like crazy to catch a wave. It was difficult but what a rush when you did it.

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 Post subject: Re: Unbalanced AI
PostPosted: Sun Oct 10, 2010 6:44 pm 
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Location: Port Macquarie, Australia
Nice vid that you linked to there Nohuhu! Great music... I'm searching for "M83" now... :)

My observations of the TI is that it's never ideally balanced when solo - which comes as no surprise of course.

On a broad reach, one ought to be mid-way between the seats, and close-hauled, slightly more forward than mid-way. For surfing swells downwind, forward seat to catch it - then aft seat for better control... just as on surfboard.

I'm waiting for the day when one of our inventive members builds a sliding seat for solo TI sailing! :lol:

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Last edited by captain-max on Mon Oct 11, 2010 3:56 am, edited 1 time in total.

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 Post subject: Re: Unbalanced AI
PostPosted: Sun Oct 10, 2010 8:13 pm 
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Joined: Sat Nov 12, 2005 10:46 pm
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Location: Escondido
dosjers wrote:
The interesting thing is the hull seems to be fairly fast compared to other AI's. Next time we're out with other AI's I'll try to take a close look at their hulls compared to ours.
I use a 5 lb dumbbell in the nose of the Adventure to keep the bow from lifting at faster speeds (and shortening the LWL). This also reduces squatting slightly (and attendant stern wave formation). It appears to add a small amount of speed -- about the same as shifting the cockpit forward about 3". You can try the opposite to see if 5 lbs in the stern counters the increased diving tenancies from your heavy bow (equivalent to moving the cockpit back about 2"). 8)


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