bought a CAD program

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Nova SS
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bought a CAD program

Post by Nova SS »

Well I bought a low priced 2d CAD program for the computer. I'm thinking I will take the Tornado plans and use the CAD program to make the changes I want to the Tornado and see if they will work as I want. I want to lengthen the boat the 10%, increase the height of the cowl, add a trim piece around the perimeter of the deck and possibly lengthen the main deck to regain the proper proportions after the boat has been lengthened 10% from the rear of the stem aft. I sort of want the Tornado to look like the one below in the middle except that I think the main deck should be longer as it sort of looks short in that boat.

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Picture of built up area around deck I want to emulate
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Anyway so I'm in the midst of trying to learn CAD. Hopefully I can accomplish what I want. The reason I want to lengthen the Tornado is because I want to lower the shaft angle to 8 degrees. doing this will force the Vdrive forward in the boat. In the original plans the Vdrive is located under the mid deck. That is where I want it. But I suspect with the lower shaft angle it will want to be somewhere between the front seats so I'm hoping the extra length will allow the vdrive to remain under the mid deck.

I also want to recess the cav plates under the rear of the boat instead of mounting them on a hinge on the transom. To recess them you should build up the hull in front of the transom so you don't lose any strength in the hull when you route it out for the cav plate.

Reinforced area for recessed cav plate
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Glassed hull with recessed area visible
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upspirate

Post by upspirate »

Good luck on the mods.Who's shop is in the pics?

Nova SS
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Post by Nova SS »

upspirate wrote:Good luck on the mods.Who's shop is in the pics?
Which pics? There are two different shops. The pic of the shop with the three boats in it belongs to Harlan Orrin. The pic right below that is of a 1959 all wood Mandella that coincidentally was also built by Harlan Orrin. finally the last pics that show the bottom of a boat are taken in a shop owned by John Miller. Wish I had seen any of this stuff in person but its all from the Internet.

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Dave Grason
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Post by Dave Grason »

Wow! This sounds ambitious and yet, on the other hand, it sounds pretty straight forward and doable. So now I'm curious though. What advantage will lowering the shaft angle to 8 degrees do for you? Quicker hole shot, maybe?

I've had a set of Dragster plans for some time and I was noticing in the description of the Tornado, it says "NO" to respacing the frames for extra length. But the Dragster is the exact same length, 18'6" and it's supposed to be able to stretch. Now I'm sure wondering what the diff is? I hope I'm not muddying the waters there.
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

Nova SS
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Location: Stirling, ON

Post by Nova SS »

Dave Grason wrote:Wow! This sounds ambitious and yet, on the other hand, it sounds pretty straight forward and doable. So now I'm curious though. What advantage will lowering the shaft angle to 8 degrees do for you? Quicker hole shot, maybe?

I've had a set of Dragster plans for some time and I was noticing in the description of the Tornado, it says "NO" to respacing the frames for extra length. But the Dragster is the exact same length, 18'6" and it's supposed to be able to stretch. Now I'm sure wondering what the diff is? I hope I'm not muddying the waters there.
Ya the plans for the tornado say no you cannot stretch but I asked about that in the design mod section and got an answer from Glen through Barry that yes the Tornado could be lengthened. It was really just a HP thing and all I would have to do is beef up the battens to 5/4 stock and then add 1 extra batten on each side of the keel and it would be cool to lengthen it.

http://glen-l.com/phpBB2/viewtopic.php?t=2182


Lowering the shaft angle makes the boat a little safer with high HP levels. With the higher shaft angles (10-12 degrees as in the plans) the prop tends to generate a fair bit of lift in the rear of the boat. This can cause issues with large amounts of HP. With the lower shaft angle the boat has way less lift in the rear being generated and more forward thrust.

BTW there is nothing wrong with the 10-12 degree angle the plans specify and for a family type ski boat with say a max speed of 60mph or so it is perfectly fine along with bronze underwater hardware like the strut, rudder, and fins. BUT if you want to go a lot faster then that, and I hope it will, then you should lower the shaft angle, change the underwater hardware to steel, likely reposition the motor forward from the spot the plans show, and install a whirl-away. These changes are all in the name of safety and if you want to go fast then you should make it as safe as you can. Remember it wont just be you in the boat but your loved ones as well. Safety should be paramount.
Last edited by Nova SS on Sat Nov 24, 2007 9:22 am, edited 4 times in total.

Nova SS
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Post by Nova SS »

One thing I forgot to mention in my first post is I'm still kicking around the idea of adding anti-trip chines to the Tornado. IF they really make high speed turns in a flat bottom safer then to me it would be a no brainer to add them. I'm still trying to get a difinative answer on that one and have a few feelers out. I'll let ya know what I find out.

Nova SS
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Post by Nova SS »

well I got the answer I was looking for about the anti-trip chines. Not needed on the Tornado. But the person did mention adding lift strakes. I'm not sure why but I didnt think they were used on flat bottoms. I'll inquire some more about this.

J Patroni
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Post by J Patroni »

Which Cad program did you purchase?

Is it a mechanical or architectural base?
If you don't build it now, You will regret it later! Already regreting it

Crackerbox Build
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Nova SS
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Post by Nova SS »

J Patroni wrote:Which Cad program did you purchase?

Is it a mechanical or architectural base?
Mechanical...Its Called DesignCad17

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Caber-Feidh
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Post by Caber-Feidh »

novass wrote:well I got the answer I was looking for about the anti-trip chines. Not needed on the Tornado. But the person did mention adding lift strakes. I'm not sure why but I didnt think they were used on flat bottoms. I'll inquire some more about this.
They add a load of drag, and are useless on a flattie. All they would be doing is adding square footage to the wetted area. The lifting strakes provide a riding surface that is parallel with the water's surface, (or at least reasonably close to). In the case of a near-flat bottom there is already a parallel surface... the whole wetted area (at speed) in most cases.

I am not that familiar with DC, How do you like it? I am a long time AutoCad victim... er, I mean user. But modeling is easy, and somewhat fun with the protus/rhino suite. (not really for a small boat, but still...)

Eric
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Post by Eric »

Duane

Design Cad 18 has been our for over a month, you should contact them and ask for a free upgrade if you just bought it.

Eric

Eric
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Post by Eric »

Correction, I bought my Design Cad 18 August 20, 2007. They are pretty good there I bet they will give you the upgrade.

Nova SS
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Post by Nova SS »

Caber-Feidh wrote:
novass wrote:well I got the answer I was looking for about the anti-trip chines. Not needed on the Tornado. But the person did mention adding lift strakes. I'm not sure why but I didnt think they were used on flat bottoms. I'll inquire some more about this.
They add a load of drag, and are useless on a flattie. All they would be doing is adding square footage to the wetted area. The lifting strakes provide a riding surface that is parallel with the water's surface, (or at least reasonably close to). In the case of a near-flat bottom there is already a parallel surface... the whole wetted area (at speed) in most cases.

I am not that familiar with DC, How do you like it? I am a long time AutoCad victim... er, I mean user. But modeling is easy, and somewhat fun with the protus/rhino suite. (not really for a small boat, but still...)
YA the lifting strakes part has me a little confused...but then again if you were to ask any of my ex's they was say its not to hard to confuse me...lol

I'm still trying to figure DC out. I think it will be a good program but I still have to learn it. BUT the price was awesome at only 30 bucks ;)

Nova SS
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Location: Stirling, ON

Post by Nova SS »

Eric wrote:Correction, I bought my Design Cad 18 August 20, 2007. They are pretty good there I bet they will give you the upgrade.
I will see if I can get the upgrade. Thanks for the heads up :)

Nova SS
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Post by Nova SS »

lift strakes on a flat bottom...this is a Bisemeyer bottom (sp?)

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