JetChopper30 mono deep v hull FRP

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Leo Ho

Well-Known Member
Joined
Oct 29, 2009
Messages
72
JetChopper30 mono deep v hull FRP

Coming soon.

Design not yet finished.00002719.jpg00002721.jpg00002722.jpg00002723.jpg
 
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Ref.: ADVANCED R/C BOAT MODELING P.8 BY JOHN FINCH

http://www.amazon.co...g/dp/0911295216

Mono hull runs on one continuous wetted surface. Strakes must be ended smoothly. With a RIDE PAD, it is still one continuous wetted surface.

Likely legal mono class.

Leo
 
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It is not a NAMBA legal mono hull because of the flat keel. Must come to a point.

Mike
 
Oh, wonderful. I aware that SD3 and DF33 have similar ride pad. It was ported from 1974 YAMAHA fishing boat.
 
DF33, won the Naviga mono class World Champion for many years, has similar ride pad. Naviga rules might not apply to NAMBA. In the design, I prefer to adopt Naviga rules.

best regards,

Leo
 
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A mind suddenly come up. Although www.boatdesign.net suggest that strake should have a small negative angle. The -1 degree angled strakes make tunnels between the strakes and bottom. The boat would be put into the hydro class. Need to change the angle to 0 degree.

Leo
 
Flat pad is legal in IMPBA. Strakes with -1 degree angle also legal, but strakes cannot be lower than keel. A mono will not ride on multiple wetted surfaces if the strake is only -1 degree. Strakes cannot have a squared off rear, they must be faired in if they end before the transom.
 
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Flat pad is legal in IMPBA. Strakes with -1 degree angle also legal, but strakes cannot be lower than keel. A mono will not ride on multiple wetted surfaces if the strake is only -1 degree. Strakes cannot have a squared off rear, they must be faired in if they end before the transom.
Hello Jon,

http://www.boatdesign.net/ suggest that strake should have a small negative angle. They obey law of physics. RC boat not only obey law of physics but also the NAVIGA rules.

Never ever thought that a design would be so controversy. Attached file show how the -1 degree strake angle make tunnels at intermediate depth. Not sure if this satisfy the NAVIGA mono class rules. Need more consideration on the strake length and angle.

Best regards,

Leo

 
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I understand what the CAD section will show, but in reality, -1 degree is not enough to make multiple planing surfaces. IMPBA does not state that the strakes have to be parallel to the base, only that the hull does not have multiple wetted surfaces at running attitude, the strake are a maximum of 3/4" wide, and 5/16" deep, and that the strakes are not even with the keel.. You can see the IMPBA rule book at IMPBA.net

I don't know the NAVIGA rules.
 
That flat keel is NAMBA legal. There's even a picture of a flat in the book. As long as it's not more than 15 degrees per side of the keel. What am I missing here?

We've been running the No Step boats with flat keels like that for a dogs age in FE.
 
Thanks to those who participated in this discussion.

Things becoming more clearer. IMPBA rule book shows a padded v hull.

The design might not meet the requirement of all boating organizations but hope to meet most of the requirements and are reasonable. Will soon proceed to CNC the prototype. Will post update here.

Best regards,

Leo
 
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It is not a NAMBA legal mono hull because of the flat keel. Must come to a point.

Mike
I understand what the CAD section will show, but in reality, -1 degree is not enough to make multiple planing surfaces. IMPBA does not state that the strakes have to be parallel to the base, only that the hull does not have multiple wetted surfaces at running attitude, the strake are a maximum of 3/4" wide, and 5/16" deep, and that the strakes are not even with the keel.. You can see the IMPBA rule book at IMPBA.net

I don't know the NAVIGA rules.
That flat keel is NAMBA legal. There's even a picture of a flat in the book. As long as it's not more than 15 degrees per side of the keel. What am I missing here?

We've been running the No Step boats with flat keels like that for a dogs age in FE.
Hello fellow members,

These links answer my questions:

IMPBA OFFICIAL RULE BOOK, March 2006, Page K-5, Technical Standards, Mono Hull Definitions and Restrictions, by IMPBA

IMPBA OFFICIAL RULE BOOK, March 2006, Page K-6, Technical Standards, Appendix 1 Mono Hulls, by IMPBA

http://mail.impba.net/images/stories/Rulebook/sec-k.pdf

NAMBA OFFICIAL RULE BOOK, Section 11, Page 2, Revised 3/15/06, Strake specification by NAMBA

http://www.namba.com/content/library/rules/namba_rulebook.pdf

IMPBA RULE BOOK has a picture shown a padded V hull.

I believe JetChopper30 is legal mono.

I actually could not found the NAVIGA rule book.

Things are becoming clearer. Design almost done. Will soon proceed to CNC the prototype.

Best regards,

Leo
 
Thanks to the following individuals, groups, organizations who lead me to many ideas on designing JetChopper30.

Discussion on lifting strake, angle, width, number, position, spray rail, lifting pad, chine walk by members of http://www.boatdesign.net/

http://www.boatdesig...akes-23218.html

GETTING STARTED IN POWERBOATING by Bob Armstrong, Robert J. Armstrong

http://books.google....0design&f=false

Chine Walking-Why it happens and how to fix it by Jim Russell

http://www.aeromarin...HB_Jan2008.html

Why Does a "Pad" Make a V-Hull Faster? by Jim Russell

http://www.aeromarin...B_Sept2005.html

Discussion on hull design by members of OFFSHOREonly

http://www.offshoreo...ull-design.html

Strake, Advanced R/C Boat Modeling by John Finch

http://www.amazon.co...g/dp/0911295216

Ride Pad, Hull Technology in HydroStream Boats by Virus at HydroStream Boats

http://www.hydrostre...es/HullTech.htm

Ride Pad, original YAMAHA design 1974, by Allmand Boats

http://pangacraft.co.../structure.html

Ride Pad by CornelP at http://www.rcgroups.com/

http://static.rcgrou...15-DSCF4625.jpg

Ride Pad by Ron Frank

http://www.modelpowe...nt.php?116-hull

IMPBA OFFICIAL RULE BOOK, March 2006, Page K-5, Technical Standards, Mono Hull Definitions and Restrictions, by IMPBA

IMPBA OFFICIAL RULE BOOK, March 2006, Page K-6, Technical Standards, Appendix 1 Mono Hulls, by IMPBA

http://mail.impba.ne...ebook/sec-k.pdf

NAMBA OFFICIAL RULE BOOK, Section 11, Page 2, Revised 3/15/06, Strake requirement by NAMBA

NAMBA OFFICIAL RULE BOOK, Section 23, Page 1, Revised 3/15/06, C. 4. Logitudinal bottom strake requirement by NAMBA

http://www.namba.com...ba_rulebook.pdf

Best regards,

Leo
 
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I am not sure if the ride pad on the keel is legal for racing.

David
Hello David,

These links answered your question:

IMPBA OFFICIAL RULE BOOK, March 2006, Page K-5, Technical Standards, Mono Hull Definitions and Restrictions, by IMPBA

IMPBA OFFICIAL RULE BOOK, March 2006, Page K-6, Technical Standards, Appendix 1 Mono Hulls, by IMPBA

http://mail.impba.net/images/stories/Rulebook/sec-k.pdf

NAMBA OFFICIAL RULE BOOK, Section 11, Page 2, Revised 3/15/06, B. 5. Strake requirement by NAMBA

NAMBA OFFICIAL RULE BOOK, Section 23, Page 1, Revised 3/15/06, C. 4. Logitudinal bottom strake requirement by NAMBA

http://www.namba.com/content/library/rules/namba_rulebook.pdf

Best regards,

Leo
 
It was designed to have a big motor compartment to install geared drive, e.g. CMB .21 VAC GEARED DRIVE.

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