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PostPosted: Thu Feb 04, 2010 11:22 am 
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On our recent AI extended camping trip
http://www.hobiecat.com/community/viewtopic.php?f=70&t=7276&start=90
(scroll down until you see the title “Flamingo to Chokoloskee, Jan 13-18, 2010”)
we had a couple days of strong tailwinds. During those days, each of us experienced numerous instances where our AI bow dove below a wave and stayed submerged for several seconds. This was not a new observation.

In my write-up of our trip, I pointed out that the AI hull had a typical “diver” design. The picture and my comments explain.
Image

Aloha Dan pointed out that the AI hull is designed similar to the Epic touring kayak. I’ve owned an Epic and agree. My Epic reminded me of my original white sea kayak above.

My Epic Endurance
Image

My surf ski
Image

My Adventure
Image

Yes, the Adventure hull looks middle aged and pot-bellied, but it bears some resemblance to an Epic.

What these 3 boats do have in common is little rocker. “Rocker” is the tendency to turn upward at both ends of the kayak. Boats with little rocker tend to run a straight course and be less maneuverable. Little rocker also increases a boat’s waterline, which is a feature related to increasing the inherent speed of a boat. Now, the Adventure hull is never going to be a kayak speed demon, but perhaps this is the impression that the Hobie designers hoped to convey.

Here is a heavily rockered British sea kayak.
Image

Kayaks with little or no rocker also have a tendency to cut through waves and dive below waves. To discourage this tendency, most surf skis build a large volume into the bow. Some designers even build a “wave deflector” into their boat's bow to prevent diving.
Image

Matcoburn was able to retro-fit his boat with an add-on wave-deflector in an effort to reduce diving by the Adventure Island. Shufoy posted a video of his add-on wave-deflector.
Image

Outrigger canoes (OC1s) solve this problem by having an extremely rockered outrigger.
Image

Kayaking Bob’s spray shields have also been suggested to reduce the diving tendency of the AI.

With all these options, surprisingly, Hobie, through this forum, has made no comment on any actions they are taking to reduce or eliminate the diving tendency of the Adventure Island.

Matt, could you give AI users any insight into Hobie’s ideas/intentions regarding this problem?

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PostPosted: Thu Feb 04, 2010 11:40 am 
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This is not what I would call a "problem". It is simply a sailing characteristic. Not something requiring a design change. Most are not sailing in such conditions as you describe. Reduce sail and slow down / change course to cross the wave to limit the bow down the back of the next wave. Not every product will perform in all types of conditions to everyone's liking.

Would a taller bow help in these conditions... yes. Will we change the Adventure hull to make this happen? Probably not. This is a sailing version of a standard Mirage kayak hull. Will we come out with other versions of the single seat AI someday? Maybe, but nothing is in the works on this.

More rocker = slower

More bow = more weight

Example of a similar issue: The Hobie 16 is the number one selling cat in the World. It is known for small bows and the potential for a pitch pole (bow stuff and capsize). Is it a defect? No... You learn to sail within the design and conditions... its the most popular catamaran in the world still. You can pitchpole any size cat with any size hulls and bows by pushing hard enough.

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PostPosted: Thu Feb 04, 2010 7:00 pm 
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Thanks for your quick reply, Matt.

I am surprised that Hobie is not considering some of the modifications I (and others) suggested. To compare the AI to a Hobie 16 is a stretch. Hobie itself classifies the AI as a sailing kayak--not a catamaran like the Hobie 16. Even the 16 has considerable rocker in it's hulls:
Image

The design of the AI encourages wave-diving at modest speeds. Maybe Hobie should bring out an Adventure-sailing hull.

I think the following items would not significantly impact the Hobie bottom line:
(1) an add-on wave-deflector for the Adventure hull (Hobie could make money on these,)
(2) outriggers with significantly upturned bows,
(3) a hull with a factory built-in wave-deflector bow--this would be a small modification of the Adventure hull.

I owned a Hobie 16 back in the early 70s, and, yes, I did a few pitch-poles. Didn't like them one bit.

Keith

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I sail: Biscayne Bay, Everglades to Cape Romano, Ft Desoto, Cedar Key

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein


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PostPosted: Thu Feb 04, 2010 8:48 pm 
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Keith

Really some wonderful pics and thoughtful insights.

The AI nose diving has not been too much of a problem for most of my sailing, but I do notice it.

That's not to say I wouldn't appreciate future Hobie innovation to tweak the performance.

One possible cure is to allow one to adjust the height and position of the outrigger/ama. Consider the lowly but effective Hobie sidekick with its adjustable height.

Better still, add some kind of hydrofoil to raise the nose up out of the water - especially if it added to your speed.

I wonder if the AI tandem sailed solo would dig into the waves :?:


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PostPosted: Thu Feb 04, 2010 9:39 pm 
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MATT, MATT, MATT, I'M VERY DISAPPOINTED IN YOU AND HOBIE IF THAT'S THE WAY YOU'RE GOING TO BLOW OFF OUR CONCERNS AND RECOMMENDATIONS....... and, if I were your boss "you" would be severely reprimanded.

Yes, Chekika is a friend of mine, and he's a nice guy. Beyond that he's an intelligent, and very experienced outdoorsman that anyone who knows him looks up to. And more directly to the point, he's a professional, and unlike you, would never dismiss a well thought out, illustrated, and presented recommendation that could resolve "a problem" many of us have experienced all too many times. And, THIS IS NOT A PROBLEM THAT IS ONLY EXPERIENCED WHEN THE AI IS LOADED DOWN FOR MULTI-DAY EXPEDITIONS. THIS "DOES" ADDRESS A PROBLEM THAT COULD IMPROVE PERFORMANCE FOR EVERYONE. DON'T YOU READ THE POSTINGS ON RECONLON'S SPRAY-SHIELD AND HOW IT HELPS TO REDUCE DIVING. CHEKIKA WANTED HOBIE'S RESPONSE TO THAT. YOUR RESPONSE WAS NOT WHAT WE WERE LOOKING FOR...OR DESERVED.

Our continued loyalty and faith in Hobie depends on how you address our concerns. I strongly suggest that Chekika's ideas get the consideration that "we the owners" believe we deserve.

Very, very sincerely,

W. A. Waller

P.S. - Don't apologize, just do what you should have done in the first place.


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PostPosted: Fri Feb 05, 2010 12:27 am 
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Matt, could you give AI users any insight into Hobie’s ideas/intentions regarding this problem?

Would a taller bow help in these conditions... yes. Will we change the Adventure hull to make this happen? Probably not. This is a sailing version of a standard Mirage kayak hull. Will we come out with other versions of the single seat AI someday? Maybe, but nothing is in the works on this.


Very salient reply. Didnt think it was 'dismissive' at all, maybe I'm missing something.


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PostPosted: Fri Feb 05, 2010 12:33 am 
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Hey, Polecat, don't shoot the messenger (Matt)!

Matt is just one of many employees at Hobie, and pushes for us and our causes often. Remember, our great little Adventure Island was not designed for what many of us use it for or the conditions we use it in. It was designed as a day sailor for up to maybe 8mph speed in mostly flat waters. What you and I and Keith and many others of us get it to do, just proves how well the Hobie team designed and built them.

I like you wish for many improvements to our wonderful boat, but am still very happy we have Hobie as the company designing, producing and standing behind them, even when not all of our wishes come through. Like Keith and others, keep GENTLY prodding Matt and Hobie for changes, but please don't beat him over the head! :)

Now back to your regularly scheduled programming...

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PostPosted: Fri Feb 05, 2010 1:07 am 
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Chekika wrote:
Now, the Adventure hull is never going to be a kayak speed demon, but perhaps this is the impression that the Hobie designers hoped to convey.
Very interesting discussion. In comparing boats, I would make the distinction between the Adventure (kayak) hull design vs. other kayaks, as opposed to the AI sailing trimaran. I spend a lot of time in the Adventure as a kayak. For its length and stability I haven't seen a faster boat yet. As you know, I race this thing occasionally. IMO, the design on this boat is about as good as it gets.

Rocker has its advantages, but speed is not one of them. IMO, rocker increases draft which increases the wave trap at higher speeds. I spent some time on the water with a designer and his customized pedaling 16' Heritage Nomad (similar dimensions to the Adventure but with rocker -- known for its "speed" and "glide").
Image
It was kicking up a discernible bow wave above 5 1/2 MPH and losing stability at the same time. We also did some glide tests. After switching boats it became obvious to both of us that the Nomad is no match for the Adventure, despite its reputation and smooth fiberglass construction.

As you say, the Adventure slices through chop. Oddly, because of its longer bow, it's actually drier (in this regard) than the shorter Hobies despite their added rocker and bow volume.
Image

The AI though is a different boat all together. I agree that it's definitely bow heavy in certain conditions. But then, it's running at weights and speeds beyond the kayak realm, so it carries a lot more inertia into the swells. As long as the AI shares the same hull as the Adventure, I would be aghast if Hobie were to modify or redesign it (and ruin an outstanding kayak in the process) -- there appear to be alternate solutions as you've pointed out.


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PostPosted: Fri Feb 05, 2010 2:22 am 
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What Roadrunner said!
It seems a hull that is going to please every one is not possible.
I like the idea of adding a wave deflector to the bow as a good compromise.
Hobie's solution for the cats was this:
Image
I wonder if something similar could be designed for the AI?
BTW- Great post Keith to start this discussion! 8)


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PostPosted: Fri Feb 05, 2010 3:02 am 
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The hyrofoil is very similar to the wave deflector i think hobie does need to address this because even at very modest speeds going down wind i regularly get the bow up to the mast base. I plan on making Bob's spray shield, but it should not be up to the consumer to create solution for a design flaw. While the hull design is that of a kayak, we the consumers spend a premium price on what Hobie sells as a Sailing Trimaran, not a kayak and thus it should have the ability to be sailed in reasonable conditions.

I personally think the hull is a decent design however i do believe that it would be significantly improved with a raised bow/wave deflector and lets get real the additional 1/2 Kg would not be a problem.However I don't think the hull should have a raised stern Rocker. I also think Hobie would be stupid not to design an add on Wave deflector and a Wave skirt like bob has designed. Both items would cost little to produce and would sell like hotcakes. As for the outriggers, they should have been designed differently from the beginning.

If Hobie brings out a wave deflector at a reasonable price i will buy it... wouldn't you?

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PostPosted: Fri Feb 05, 2010 3:14 am 
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if Spirt can offer these for $20 aud i'm sure Hobie a far larger company could come up with something similar.

Quote:
Wave Deflector

Designed specifically for ocean paddling to deflect waves preventing craft from nose diving. Fits securely to nose of single CTR Ski.

Exact Fit to single CTR Ski nose
Manufactured utilising High Grade UV treated PE Plastic
Colour matched to craft
Aesthetically appealing design
Simple to remove when not required.



Image

http://www.spiritpaddle.com.au/content.asp?cId=3&pId=34

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PostPosted: Fri Feb 05, 2010 5:43 am 
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Great comments! Thanks. Polecat is an ex-Navy man--his bark is worse than his bite, and he is a good man to have along on an extended AI-camping trip.

Kayaking Bob, I do want to take issue with your statement that the AI is designed as a day-sailer. I don't see any mention of that in their literature. I think as early as 2006 there were 2 AIs in the WaterTribe's Everglades Challenge--a 300-mile race along Florida's SW coast including the everglades. Then, last year, Hobie had 2 fiberglass prototype AI tandems in the race. So, Hobie is previewing their AI tandem in anything but a day-sailing environment. The AI's carrying capacity and storage volume just beg an owner to go on a camping trip.

I absolutely agree the AI is a tough little boat--much tougher than any spectator would ever guess.

From the comments, it seems we all pretty much agree that Hobie could do some significant things to make the AI less prone to plow through chop and dive under waves. Hopefully, Matt will let the people in charge know our feelings.

Keith

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I sail: Biscayne Bay, Everglades to Cape Romano, Ft Desoto, Cedar Key

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein


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PostPosted: Fri Feb 05, 2010 9:13 am 
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:D Hey guys your comments here are very much appreciated. When I logged-in this AM I was expecting my post to be deleted, but your quick and thoughtful comments should make it clear to HOBIE that "THIS IS" AN ISSUE WITH SOME WEIGHT TO IT...AND SHOULD BE ADDRESSED SOON!

There are a lot of good people here like Roadrunner, Reconlon, Aloha Dan, Chekika, et.al, who make substantial contributions to the substance of these forums. Most preface their comments with "IMHO" (in my humble opinion) and try to express themselves as professionally and tactfully as they can--it's the right thing to do. It's not easy, or comfortable, to say what I did, BUT FELT IT WOULD BE MORE INAPPROPRIATE (and lame) TO NOT RESPOND THE WAY I DID.

Again, thanks for your part in helping give this "DIVING ISSUE" the EMPHASIS IT DESERVES.

Very Respectfully, :roll:

W. A. Waller

P.S. - And Keith, my BITE IS worse than my BARK, thank you! :mrgreen:


Last edited by Polecat on Fri Feb 05, 2010 10:07 am, edited 1 time in total.

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PostPosted: Fri Feb 05, 2010 9:43 am 
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Polecat wrote:
MATT, MATT, MATT, I'M VERY DISAPPOINTED IN YOU AND HOBIE IF THAT'S THE WAY YOU'RE GOING TO BLOW OFF OUR CONCERNS AND RECOMMENDATIONS....... and, if I were your boss "you" would be severely reprimanded.

Yes, Chekika is a friend of mine, and he's a nice guy. Beyond that he's an intelligent, and very experienced outdoorsman that anyone who knows him looks up to. And more directly to the point, he's a professional, and unlike you, would never dismiss a well thought out, illustrated, and presented recommendation that could resolve "a problem" many of us have experienced all too many times. And, THIS IS NOT A PROBLEM THAT IS ONLY EXPERIENCED WHEN THE AI IS LOADED DOWN FOR MULTI-DAY EXPEDITIONS. THIS "DOES" ADDRESS A PROBLEM THAT COULD IMPROVE PERFORMANCE FOR EVERYONE. DON'T YOU READ THE POSTINGS ON RECONLON'S SPRAY-SHIELD AND HOW IT HELPS TO REDUCE DIVING. CHEKIKA WANTED HOBIE'S RESPONSE TO THAT. YOUR RESPONSE WAS NOT WHAT WE WERE LOOKING FOR...OR DESERVED.

Our continued loyalty and faith in Hobie depends on how you address our concerns. I strongly suggest that Chekika's ideas get the consideration that "we the owners" believe we deserve.

Very, very sincerely,

W. A. Waller

P.S. - Don't apologize, just do what you should have done in the first place.



If you want to contribute to these forums and make suggestions... please do, but DO NOT come off as accusatory towards Hobie Cat and state that this is a "Problem" that Hobie must solve for you. Especially in this case where the product is so well received and enjoyed by so many, that is not going to be well received by me at all.

I responded in a very professional way and quite clearly stated the facts and suggested the obvious solutions to the way you are using the product. No need to get pissy because I don't agree with you.

As I stated: I fully understand the issue. I am not blowing it off, but it is not a "problem"... it is what it is for this model kayak.

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PostPosted: Fri Feb 05, 2010 10:53 am 
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:) Good Morning Matt! My posts normally end with the words "I love my AI". It is a great boat, and I really appreciate how Hobie stands behind its boats, and provides a forum to stay aware of customer comments and concerns about their products. That's why I was so stung by the tone and attitude expressed in your terse, dismissive response to a happy, loyal, customer like Keith Wellman. I believe Hobie will be shocked by the way you handled this. That's why I'm taking this issue up the food chain until "we the "owners" get the response we deserve.

:mrgreen: Havva nice day Matt!

W. A. Waller

P.S. -- No Response Necessary from you Matt. I've heard quite enough!!!


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