Great Moments In V Bottom History
11-12-2001, 11:26 PM
#251
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C-Spray, man I love reading your posts. Every comment either sings the praises of Volvo or the bat-boat. I hope to sell you something someday (and I'm not in sales), anything really just because you'll promote the hell out of it for me! 
Now, as for the stepped-hull question; below is Harry Schoell's (marine engineer) description of the hydrodynamics involved in the signle-step hull he designed for Active Thunder. I just want to see what some more engineering minded members' opinions are.
"The forward Delta Conic hull has an eloped conical entry with constant delta planning, and incorporating a wide lipped chine system.
The aft hull develops a constant planning surface that displaces a delta pattern when running. The forward hull creates a bow wave under the hull, allowing the aft "to ride the wave". As speed increases, the wave moves aft thereby lifting the stern. The boat will then plane with a level attitude without climbing over the "traditional hump".
SLOW or FAST, the trim attitude is nearly the same. The DDC has a high degree of lateral stability as a result of the forward chine notch. As planning speed is achieved, air is vectored under the planning section thereby reducing suction loads, as illustrated in the picture above. The forward and aft hull planes at minimum and optimum angles, allowing the aft to "surf" on the bow wave at high speeds. This performance characteristic eliminates the need for trim tabs or wedges. Thus the DDC achieves higher speeds, greater efficiencies and stability, softer ride and effortless control."
Just felt like re-invigorating this discussion a bit.
Now, as for the stepped-hull question; below is Harry Schoell's (marine engineer) description of the hydrodynamics involved in the signle-step hull he designed for Active Thunder. I just want to see what some more engineering minded members' opinions are.
"The forward Delta Conic hull has an eloped conical entry with constant delta planning, and incorporating a wide lipped chine system.
The aft hull develops a constant planning surface that displaces a delta pattern when running. The forward hull creates a bow wave under the hull, allowing the aft "to ride the wave". As speed increases, the wave moves aft thereby lifting the stern. The boat will then plane with a level attitude without climbing over the "traditional hump".
SLOW or FAST, the trim attitude is nearly the same. The DDC has a high degree of lateral stability as a result of the forward chine notch. As planning speed is achieved, air is vectored under the planning section thereby reducing suction loads, as illustrated in the picture above. The forward and aft hull planes at minimum and optimum angles, allowing the aft to "surf" on the bow wave at high speeds. This performance characteristic eliminates the need for trim tabs or wedges. Thus the DDC achieves higher speeds, greater efficiencies and stability, softer ride and effortless control."
Just felt like re-invigorating this discussion a bit.
11-13-2001, 02:29 AM
#252
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Miller - I buy what I believe in, therefore I believe in what I own. You (and GL) have had a first-hand demonstration. 'nuff said.
T2x - You're pretty good yourself. I didn't use the "V" or "BB" words in my last post, yet you managed to assail my beliefs in those products while neatly sidestepping any direct response to my technical assertions/questions. You must be a graduate of the Fred Astaire school of speaking: "Don't address the issue, just dance around it".
Don't know much about all the Ocke stuff you brought up - The last I heard, Peter Hledin was in the process of saving humanity. Too bad he's doomed to failure - every Skater I've ever seen has multiple steps. The horror....the horror.... 
T2x - You're pretty good yourself. I didn't use the "V" or "BB" words in my last post, yet you managed to assail my beliefs in those products while neatly sidestepping any direct response to my technical assertions/questions. You must be a graduate of the Fred Astaire school of speaking: "Don't address the issue, just dance around it".
Don't know much about all the Ocke stuff you brought up - The last I heard, Peter Hledin was in the process of saving humanity.
Too bad he's doomed to failure - every Skater I've ever seen has multiple steps. The horror....the horror....
11-13-2001, 07:45 AM
#253
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I have a question:
A couple of years ago a good friend of mine was planing on buying a 27 Fountain (I'm making no opinions on this type of boat,just stating the fact that this is the type of boat my friend wanted) but did not know if he should buy the stepped version or not. He planned on putting big power and running the boat 80+.
He asked the opinion of a very reputable (will not be named)person with thousands of hours of R & D with this particular brand of boat. He was told to buy the non-stepped version of the boat. Espesially (sp) if he plans on running that fast. Now if the steps are so "revolutionary " why not go the stepped route and gain the "standard" 10 mph?
A couple of years ago a good friend of mine was planing on buying a 27 Fountain (I'm making no opinions on this type of boat,just stating the fact that this is the type of boat my friend wanted) but did not know if he should buy the stepped version or not. He planned on putting big power and running the boat 80+.
He asked the opinion of a very reputable (will not be named)person with thousands of hours of R & D with this particular brand of boat. He was told to buy the non-stepped version of the boat. Espesially (sp) if he plans on running that fast. Now if the steps are so "revolutionary " why not go the stepped route and gain the "standard" 10 mph?
11-13-2001, 08:08 AM
#254
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26-probably because over 80 in a 27 F is a pretty squirrelly ride and the guy thought your buddy would be a little safer in the non step version....the 29s are actually a little faster in alot of cases, There is a thread on this in the Fountain section. 
11-13-2001, 08:31 AM
#255
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There waws a great article in Poker Runs Magazine a few months back about why stepped hulls work. Multiple lifting points was the key. They also said most boats under 28' or so did not need or run faster with steps. Also boats in the 20' range with steps get squrrly when running at high speed. I have owned stepped and nonstepped and in my opinion (for what its worth) steps work well in boats above 30'to provide more speed but there is a different driving technique
11-13-2001, 08:41 AM
#256
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I was going to just sit back and let r2d2 put his foot in his mouth yet again but I felt that I had to throw in my two cents.
1. It is utterly naive and completely unreasonable to make the statement the step hulls are not faster than non-steps in anything short of "very big" water - handling characteristics aside. If someone has useful and demonstrative proof that steps do not increase straight-line velocity when engineered into an offshore boat please present it.
2. It is likewise naive to make the statement that there is no point in learning an alternate driving technique to better control an alternate hull design. You can no more drive (trim, etc.) a step-hull Vee the same way as you would drive a non-step Vee than you can drive a cat the same way as you would drive a Vee. Face the facts - different boats need to be driven differently if you are going to drive them safely. Not to stir the pot, but you could even say that it is possible to safely drive with the props rotating in if you change your technique and consider how the boat will respond.
3. Just because a design did not come over with the Mayflower or receive the NJ stamp of approval does not make it a pointless or benefitless endeavor. Both the cat and the Vee posts started as critical observations of (most) manufacturers who developed current hulls off of old designs. Fact of the matter - boats today are faster and safer than boats built thirty years ago. Power being equal, boats today are faster and safer than boats built three, two, or even one year ago. Innovation in design is resulting in better performance. Sometimes, however, drivers (and throttlemen) need to reevaluate their technique to take advantage of these improvements.
4. The bat boats are cool. They are the pinnacle of innovative design. You either love them or hate them but you have to admit, they are among the fastest single engine Vees built. The manufacturers desire to create a truly equal racing class while making it possible for many people to participate in racing (who may not be able to afford to otherwise run a full season) is likewise refreshing.
5. At the end of the day, safe operation of any boat, any design, and any power combination depends on the operator. Control of your equipment requires the knowledge of how it will respond in different circumstances. Sometimes, people have to evolve with their equipment - those who do or can not are destined to sit on the sidelines and criticize rather than participate.
1. It is utterly naive and completely unreasonable to make the statement the step hulls are not faster than non-steps in anything short of "very big" water - handling characteristics aside. If someone has useful and demonstrative proof that steps do not increase straight-line velocity when engineered into an offshore boat please present it.
2. It is likewise naive to make the statement that there is no point in learning an alternate driving technique to better control an alternate hull design. You can no more drive (trim, etc.) a step-hull Vee the same way as you would drive a non-step Vee than you can drive a cat the same way as you would drive a Vee. Face the facts - different boats need to be driven differently if you are going to drive them safely. Not to stir the pot, but you could even say that it is possible to safely drive with the props rotating in if you change your technique and consider how the boat will respond.
3. Just because a design did not come over with the Mayflower or receive the NJ stamp of approval does not make it a pointless or benefitless endeavor. Both the cat and the Vee posts started as critical observations of (most) manufacturers who developed current hulls off of old designs. Fact of the matter - boats today are faster and safer than boats built thirty years ago. Power being equal, boats today are faster and safer than boats built three, two, or even one year ago. Innovation in design is resulting in better performance. Sometimes, however, drivers (and throttlemen) need to reevaluate their technique to take advantage of these improvements.
4. The bat boats are cool. They are the pinnacle of innovative design. You either love them or hate them but you have to admit, they are among the fastest single engine Vees built. The manufacturers desire to create a truly equal racing class while making it possible for many people to participate in racing (who may not be able to afford to otherwise run a full season) is likewise refreshing.
5. At the end of the day, safe operation of any boat, any design, and any power combination depends on the operator. Control of your equipment requires the knowledge of how it will respond in different circumstances. Sometimes, people have to evolve with their equipment - those who do or can not are destined to sit on the sidelines and criticize rather than participate.
11-13-2001, 09:10 AM
#257
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Adivanman - VERY WELL SAID. FYI - Active Thunder builds their 37 in both conventional v bottom and a Harry Schoell designed step...the step version is 12% faster top end and runs more level and faster in rough water.
[ 11-13-2001: Message edited by: ScreaminDemon ]
[ 11-13-2001: Message edited by: ScreaminDemon ]
11-13-2001, 01:27 PM
#259
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Miller - No problem. I unserstood what you were saying. Besides, your comments at the time were pretty clear...
Adivanman: Point #5 = Bingo! Best statement in this thread. After all, the engines aren't in the front at Indy any more, are they?
Adivanman: Point #5 = Bingo! Best statement in this thread. After all, the engines aren't in the front at Indy any more, are they?
