Old people can answer this question! : )

As speed increases, asymmetry matters more, but forces don't increase at lower speeds except with planing boats.
At very low speeds, water is nearly frictionless. A child can lean on the stern of large boat in still water and move it after a while.
My own boat, I found out after two seasons of uneventful sailing, was wider on one side from the centerline by a half inch at a point only four feet back from the bow--- and it's a 15 footer.
You can't see it without stretching a string from the bow to the mid-point of the stern and measure the two sides.
Yet, there is nothing in the performance to indicate asymmetry.

 

wow
I built custom homes for years and if I found a quarter inch I was not happy
half inch and someone was going to hear about it
and fix it
I always use a laser level and transit device to shoot in my grades and dimensions
and only used a tape to lay out floors and walls
seems only logical that the same system will work nicely setting up my molds for my coaster
yielding hopefully similar results
that 1/4 inch is great but measuring with a tape is always going to yield inconsistent results
( 1 inch 25' metal tape and every one using the same brand and size is the only way to go )
I set up a laser bench and rope it off first thing at each project
the bench is steal set on concrete and its temp is taken at each set up with an emphasis being made to take all measurements at the same temp
thus yielding the most accurate results
I also set up a bench mark to calibrate from also steel set in concrete and also well away from the path of any large trucks or excavations
the laser level is self adjusting so I only need one bench mark
also its automated so once set in place there needs be no reason to touch it
its operation being handled by remote control

not sure if I will be humbled by my first project in a long time
but I can only imagine what my grandfather would have said if I built something an inch off let alone four inches
hell Im not sure I would be alive to tell the tail if I had
he was serious about his strong or light calls
as are most good finish men

having hired and fired a lot of carpenters in my time Im always hardest on myself
Im leaning toward a Ted Brewer design called the Sofia Christina
but may end up having to settle for the big friendship sloop
ones forty feet
the other forty six
either way
Ill be aiming for that 1/4 inch I always held myself to
wish me luck
sounds like Im going to need it
best
B

ps
accuracy starts with a decent slab of concrete

 

Boston i whole heartedly agree with this

and then VERY VERY important to work CLEAN
you cannot imagine how much time it saves when you are highly organized and everything is either in a pigeon hole or a dedicated shelf

however extreme accuracy on a boat wastes time
believe me i have just gone thru it on a very small dinghy
1/8 inch = 3mm which is not bad
be carefull not to waste too much time like i just did on fancy woodwork and delay getting to the water

now that i am 90% thru my "shiny woodwork" i am asking myself why the hell did i do it - just one of those things i suppose - had to get it out of my system !!

i will be posting pics of my tiny dinghy soon when completely finished

but be carefull - over the top accuracy is not always necessary

 

Wow, a quarter inch is as good as some can do?

Obviously you have never built boats to a racing rating rule. A quarter inch tolerance on an IOR build would have been unacceptable and scrapped. If your freeboards were off by a quarter inch at measurement points the rating could be off by FEET.

Last month one of the Volvo 70s was docked points because her LOA was off by 2mm. That's +2mm in 70 feet. If the builder holds that tolerance, think how close he was in freeboards of 4 to 5 feet?

 

Nothing like laying out your string lines and then checking the square and finding you have created a diamond.

 

I have built many a boat in my backyard, garage, driveway etc... Never a level floor. So I had to be careful, used cross string to make sure things where square. Never perfect though, went with feel of shape and wood.
That said, if you can't build a big straight work table or jig, then you shouldn't be building a boat. I guess people get lazy if the know no one can tell the difference.

By the way Boston, I was taught in "School" that many times rooms are purposely built not perfectly square to avoid echoes... Or concrete was slanted to avoid water collecting in the middle. I think these are just typical on the job site margin of error adjustment.

On boat building. My biggest problem has always been the weather. Too Cold, too Hot, rain, etc... Hard to keep anything straight or dry. I am building a 300' concrete wall now, the wood bracing moves every day. I goes from straight to crooked everyday. Will have to make straight before I pour concrete. So little things make big differences.

 

And nothing like spinning a model around in AutoCAD or deadweight and just knowing - even just for yourself - that it is perfection : )

 

in ya dreams, netjaws, reality is in the build, sure nice lines on an LCD screen impress customers, building is another game mate.

 

Ditto that Lubber. There's nothing like rolling it into the sun light for the first time and having a real look at the curves and shapes that were too poorly lit or housed in too close a space to see properly, to prove (or disprove) your building abilities.

I just experienced this (for the umpteenth time) recently. Bright Florida sun doesn't let a single flaw hide.

 

I make big goofy fish tanks from time to time
thing is to cut and bevel the glass at this size at the plant would have cost about 1.25 a foot
the tank is 100 inches and there are eight panels with two beveled edges each
thats 1600 inches of beveling at 1.25 pr inch

I did it myself with a special saw I built and a few gallons of polishing compound
were it more than a few mils off this tank would leak

also the stand
three main bearing points and two keelsons all needing to be dead perfectly straight

also the support beams needed to be dead straight as well as the supporting structure

the tank weighs about 3000 lbs and the glass was 3/4 inch thick

no room for error at all or my customer would end up wet and angry

my theory is Ill spend whatever amount of time necessary to ensure the level of accuracy necessary for the job

when it comes to my boat that Ill be staking my life on
Im going to be dam accurate

oh I might screw something up
but Ill be fixing it whatever or however painful that fix may be

cheers
B

 

Boston, well aint you a clever little ****, very nice work mate, always nice to see someone doing what they can do......I wonder what we would all make if we had the time to do so insread of just working for a living.....

 

glad you liked the octagon

am working on a rhomboid next



sorry about the bad rendering
but I got the stand done for it and am waiting for more glass



did I mention there are no metal fasteners in any of my stuff







just finished this one



kinda helps me keep the skills alive till I can afford the pile of lumber Im going to need to build the coaster



the deck houses are going to be taller, out of cherry and have lots more glass as well as more extensive skylights
basically if Im going to be spending any significant time in this thing
I want light and air
and lots of it
would also love to find a way to get a pilot house onto it without wrecking the look of the toy schooner
but Im not sure it can be done
Ive talked to the designer and he believes it possible
but Ive done a little pencil work of my own and it just looks funny however I try it
any ideas kids
I was thinking if I make a pilot station in the aft cabin and make that cabin a little taller than the fore
then I could have some windows in front and a dam tall chair or something to make the hole thing work
who knows
but if I get into weather Im not interested in riding out the storm with my as tied to the wheel in an open cockpit
been there
done that
not interested
I want hot cocoa and a nice cushy dry seat
dancing girls if possible

 

And what side was the sun shining? How warm was the weather? Was it wind? Those things give you more inaccuracy within 70' than 2mm
Anyone can use a grinder to set LOA perfectly in 0.2 mm in the morning.. but measure it ion the evening and you are a way off..

 

Im all for you Teddy

also it pays to all be useing the same brand of tape round the shop

ps
you double posted brother
thought for a minute there I needed to stop drinking

 

No need.. and I might pour one for myself too Just my connection made some mystery moves along the way..
Sun warms up surfaces even if the air temp remains the same. Warm deck and cold(er) hull makes the difference etc.. These are just those things why people with mm's in their scale have to standardize their workshops to certain tolerances of warmth, humidity and about everything..
Nice boat