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Pro's & Con's between full tunnels and tunnels with center pods

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Old 11-19-2003, 11:51 AM
  #61
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Quote:
Originally posted by BROWNIE
Not surprised to see the CF registration # on that weird boat, T2x.
Many years ago the earth tilted..and all the center pods and trimarans....slipped to Cal-ee-forn-ia....and many of them barrel rolled with excitement.

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Old 11-19-2003, 12:04 PM
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Originally posted by TopSpin80
In my opinion it becomes a trimaran when the center 'pod' becomes the longer and bigger of the three pods. However I am sure there are many other opinions out there.... so let's hear them.

T2x in today's powerboat market there aren't many 'symetrical' catamarans offered. Most planing hulls do better without sponson symetry. Most catamaran sailboats however are dislacement hulls and therefore do better as a catamaran and not a tunnel.. plus they are going too slow to have any advantage in packing the air to create lift.

Ernie

what do you think?
Assymetricals turn better because of the abrupt edges at the forward entry...and throughout the sponson length. I doubt that there is any inherent straightaway speed advantage between symetrical or assymetrical cats. I think that the Deepvee cat's "advantages" could be duplicated with steeper deadrise in an assymetrical design..... I believe the "deep vee" is more prone to stuff due to the lack of overall sponson lift forward and throughout..... Lift being a function of overall lateral surface...rather than symmetry.

The ground effects discussion is interesting..in that we always put a small vee in our tunnels to provide a break in the air flow, while at the same time allowing for a slight cushioning/cutting effect in the event of direct water contact....... we also added graduated steps on the tunnel walls to provide increased lift as the tunnel submerged in rougher conditions..........best of both worlds methinks.

T2x.......
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Last edited by T2x; 11-19-2003 at 12:07 PM.
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Old 11-19-2003, 12:09 PM
  #63
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P.S....... to answer your next question.... NO, .... Catamaran design has not progressed beyond that design point...to date.

Deck lift..airfoil changes, rear overhang, horsepower, drives and propellers have been the primary focal points since then.


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Old 11-19-2003, 12:20 PM
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Originally posted by T2x
P.S....... to answer your next question.... NO, .... Catamaran design has not progressed beyond that design point...to date.

Deck lift..airfoil changes, rear overhang, horsepower, drives and propellers have been the primary focal points since then.


T2x
Sounds like someone has been thinking a lot about ways to improve today's catamaran designs...I wonder who that is or what he or she may do about it?
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Old 11-19-2003, 02:14 PM
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Ok, T2's post reminded me of another difference on my boat. I highlited the corner of the hull (if the chine is on the outside, what do you call the inside corner?) to show where the change was made. On this hull the corner is square and sharp. My boat has a 45 degree bevel. This bevel changes from zero to 2" in width. It starts at zero, goes to 2" and then back to zero. It's widest point is around the point where the bottom flattens out. This was done to aid in turning. Many people have said that cats don't turn. Although this boat doens't turn nearly as well as my old v-bottom with a massive reverse chine, it doesn't do too bad either.
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Old 11-19-2003, 02:17 PM
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Here is a pic of a mod-vp. Sure wish I could find a pic really showing the tunnel.
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Old 11-19-2003, 02:20 PM
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Quote:
Originally posted by Cord
Ok, T2's post reminded me of another difference on my boat. I highlited the corner of the hull (if the chine is on the outside, what do you call the inside corner?) to show where the change was made. On this hull the corner is square and sharp. My boat has a 45 degree bevel. This bevel changes from zero to 2" in width. It starts at zero, goes to 2" and then back to zero. It's widest point is around the point where the bottom flattens out. This was done to aid in turning. Many people have said that cats don't turn. Although this boat doens't turn nearly as well as my old v-bottom with a massive reverse chine, it doesn't do too bad either.
I'd call that line the keel.......

As to cats not turning.....The only fools still spouting this crap are Vee bottom manufacturers.

It is common knowledge that the fastest...highest g force........ tightest radius..... racing machines on the planet are......


Tunnel boats....

or should I say ...Asymetrical outboard ram wing catamarans.

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Old 11-19-2003, 02:34 PM
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Has anyone made a large ModVP? Kind of like a V in the front and Cat in the rear.
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Old 11-19-2003, 02:52 PM
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?Why is Bacardi silver sitting on a Budweiser trailer? in post 51
Anheuser Busch isn't Affiliated with Bacardi.
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Old 11-19-2003, 02:53 PM
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Quote:
Originally posted by cobra marty
Has anyone made a large ModVP? Kind of like a V in the front and Cat in the rear.
Yes...it was called a Triton..based on an English design.... it had a mediocre career in offshore racing in the 80's...it ran okay with outboards (2 boats I remember)..and the first attempt with stern drives barrel rolled.......(we have the tape).

The English predecesser hull set a record on Lake Wyndemere at some inflated speed with the Countess of Cantalope (or some such) behind the wheel.

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