In that CNC offers superior capability, I think that the only problem would be
with people altering the CNC file to hug the edges of the tolerances in areas
that might prove beneficial. CNC is quite capable of this. For this reason
there may be some merit for the CNC builders to be held to a tighter tolerance.
What are the tolerances placed on Ovington, Vanguard and other professional
builders of the 49er?
In any event everyone should be able to hold the boat to +/- 1/2" at the
stations regardless of the technology they employ. The major benefit of the
CNC is time savings. Time is the killer for production outfits that are
looking to offer the boat to people who are not able or don't want to build.
Anything that can be done to reduce cycle time without sacrificing quality will
improve their ability to produce a boat that will be profitable for them and
reasonably priced for those who are looking to buy.
On a personal note I have to say that I'm disappointed with the negative energy
that's swelled in the last handful of days. Clearly Bram is handling an
enormous task and is doing everything he can to make this a rewarding project
for everyone. Hopefully issues like "5 mm is not 1/4 (25%) of an inch. 5mm
(5/25.4 = .19969) is 19.7% of an inch--13.5% less than the 1/4" tolerance Bram
claims exists. Even 6 mm is not 1/4" (25%) of an inch. 6 mm (6/25.4 = .2362)
is 23.6% of an inch" aren't a foreshadowing of unbearable regattas. Hopefully
the spirit of the Swift Solo will be more like the 505 and less like the
49er...
Greg Strickland
505 - Bb - 4768
49er Crew and Swift Solo hopeful, waiting for a builder... hopefully the VMG
report isn't being delayed too badly by the email exchanges.
> -----Original Message-----
> From: Harveynestor@xxxxxxxxxxxxx [SMTP:Harveynestor@xxxxxxxxxxxxx]
> Sent: Wednesday, November 26, 2003 7:11 AM
> To: swiftsolo@xxxxxxxxxxxx
> Subject: Reasons For Proposed Amendment to Class Rules
>
> Fellow Swift Solo Sailors:
>
> As many of you know, I have proposed that our class rules should be written
> such that either:
> (a) boats built with the use of CNC technology should be prohibited or
> (b) alternatively, some different measurement rules should be used for
> boats built without the use of CNC machinery.
>
> These are the reasons why I have made this proposal:
>
> 1. Bram has not provided us with plans to build our Swift Solos.
>
> Plans are lines drawings that show a hull in three views--profile
> view, plan view, and body plan view. They are typically provided on mylar
> that does not change shape with temperature and humidity or else as CAD
> files. These drawings enable a builder to check his measurements as he
> progresses with the construction of his boat. Without plans we cannot check
> our measurements as we build our boats.
>
> 2. In lieu of plans, Bram has provided us with station templates printed on
> paper.
>
> Station templates are typically made by either (a) drawing plans out
> full size and taking measurements from them or (b) a computer process if a
> CAD file is used.
>
> The paper templates provided by Bram are subject to changes in both
> size and shape as a result of humidity and temperature changes. The paper
> templates are also subjected to some moisture when they are glued down to cut
> out the mold stations and will ultimately produce construction problems such
> as:
>
> (a) the mold stations are not the precise size and shape that
> they should be
> (b) the mold stations are not perfectly aligned,
> (c) the jig is not fair
>
>
>
> 3. Any errors resulting from the use of paper templates will produce a jig
> that is not fair.
>
> The only ways to fair a hull built on an unfair jig: >
> (a) fair the hull before glassing,
> (b) fair the hull after glassing by building up low spots with
> fairing compound,
> (c) some combination of (a) and (b).
>
>
> (a) Fairing the hull before glassing reduces the core thickness and
> weakens the hull.
>
> Western Red Cedar is a very high density core material, and its weight
> and the class rules prohibit using a core thickness greater than 1/4".
> Sanding an already thin core material reduces stiffness that is obtained
> through panel thickness.
>
> (b) Fairing the hull after glassing by building up low spots with
> fairing compound adds otherwise useless weight to the boat.
>
> Large amounts of fairing compound increase the weight of the hull
> needlessly. This weight could be better used to strengthen the hull.
>
> 4. A boat built from a jig constructed from paper moistened with glue and
> then cut by hand with a jig-saw pales in comparison with a boat built from a
> jig cut with CNC machinery.
>
> A blind man with a CAD file and CNC machinery could produce a jig far
> superior to one produced by a skilled craftsman with 20/20 vision using
> moistened paper as his pattern and cutting the wood with a hand-held jig-saw.
>
> www.fabricam.com has a very good picture of a CNC router table. Can
> your glued paper mold stations and jig-saw compete with this equipment
> available to Patrick Owen and John Vinkemuhler of VMG Skiffs?
>
> 5. Bram claims that the use of CNC machinery to produce bulkheads, mold
> stations, transoms, and misc. would be a service to the class, and to deny
> the use of CNC machinery would be a disservice to the class.
>
> Would it not be a better service to the class to level the playing
> field by either (a) allowing ALL builders to use CNC machinery, provide them
> with the mylar templates, CAD files, etc. or else (b) not allow the use of
> CNC machinery by any individual or certified builder.
>
> 6. The use of CNC machinery by certified builders only starts the class
> down the slippery slope of a class dominated by certified builders.
>
> This would move the building process one step at a time out of the
> hands of class members and pave the way to allowing design and construction
> changes that could obsolete hand crafted boats.
>
>
> 7. Bram touts his concern with fairness and foiling "cheaters" who might
> try to gain an unfair advantage by altering his design.
>
> Bram apparently fears that there are some or many among those
> approximately 50 constituting the Swift Solo class building their own boats
> who would use "builder error" as a cover for redesigning his Swift Solo and
> thus build a more competitive boat.
> Fairness dictates that the approximately 50 people who have
> purchased plans at the cost of $575.00 should be allowed to build competitive
> boats that are equal to those built by his certified builders.
>
>
> 8. The unfair advantage definitely goes to the certified builders who are
> allowed to use CNC machinery.
>
> We, as individual builders who are denied plans and/or measurement
> templates with which to check our hand crafted boats cannot hope to achieve
> the precision and accuracy of computer driven machinery. Bram's subjective
> test of allowable "builder error" might force sailors who would otherwise
> build their own boats to purchase boats from his certified builders at
> several times the cost of building their own boats, thus destroying an aspect
> of the class that first attracted us to it; otherwise, why else would we have
> paid $575.00 for a set of plans (which we have not yet received)?
>
>
> Alternatively,
>
> #1. If the class feels that CNC capabilities should be allowed,
> then CAD files of the plans should be provided to ALL builders who have paid
> for plans, not just to Bram's certified builders, >
>
>
>
> OR ELSE
>
>
>
> #2. > Differen> t rules should be used to measure the dimensions
> of non-CNC boats so they can be as well built as their CNC counterparts
> through fairing of the jigs upon which they are constructed before they are
> built.
>
>
>
>
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