i bought a Reynolds 21

Hahaha I hope so hell yes! Ok then that will not be done then with weighing her I am just trying to figure out how much ONE hull weighs... I have to get it in my garage and flip it over so i can do the bottom!

I really think your numbers are all wrong, but who cares. Sail it and have fun.

I've always felt that the advertised weight for the 21 was low, mine was near 1000 lbs all up. When I pulled a hull off the trailer we were 4 guys, and that was managable. Have your cradles built and in place. When the hull comes off the trailer you can set it on the keel, and gently lay it over on its side. With the nacelle secured in the closed position and some blankets on the ground, begin to roll it onto the nacelle, and lift the hull up in the inverted position, and walk it to the cradles.

So obviously weight of the hulls and displacement would not be related.

They certainly are related. The displaced water has exactly the same mass as the object that displaced it, Archimedes Principle.
You must remember that it is not just the hull, but the entire mass of what you threw into the water.
Example: 2 hulls have a total mass of exactly 200 kilograms (440lbs, I'm using metric because the math is so much simpler than that archaic system you continue to use, in fact so simple a caveman...) If you throw them in the lake, they will displace exactly 200 litres of water,(1 litre weighs 1 kg). You are correct in saying they don't sit on top of the water. Archimedes Principle says they sink, & displace water. They contnue to sink, & displace water,until the amount of water displaced exactly equals the mass of the boat.
In the example above, we have displaced 200 litres, which has a mass of 200kg. Now, a rather rotund friend, with a mass of 150kg comes down, & jumps onto the boat. What happens? The boat sinks further, & displaces more water. How much more? Another 150 litres, which again has a mass of 150kg.
So, when you launch your Cat, it is not just the hulls mass that counts. It is the entire mass of the boat,ie, hulls, beer, mast ,sails,people etc. The boat sinks until the mass of water displaced exactly equals the mass of the loaded boat.
This is not Grade Nine, this principle was used by Archimedes & demonstrated when i was in Grade 5 science.
You take a container & place a toy boat hull in it.Set this apparatus inside a larger container. Completely fill the container containg the toy boat, right to the brim. Gently drop an object into the toy boat. The boat will sink & diplace water, that will run over the edge into the second container. Take this container, with the displaced water, & pour the displaced water into a graduated cylinder. Lets say the cylinder shows 454 milli litres of water. Again the metric system makes it simple. An ml of water has a mass of 1 gram, so 454ml has a mass of 454 grams. We know that 454 grams = 1 lb, so the object you dropped into the toy boat weighs exactly 1 lb.
The only cause for confusion will be in how the manufacturer defined displacement. Did they mean the max displacement legally allowed, that is with a max load of people/gear?
Or did they mean the displacement of the boat rigged for sailing? If the boat rigged for sailing displaces 200 litres, then it weighs 200kg.
And you guys thought physics was boring, or useless?

Edited by Edchris177 on Dec 21, 2011 - 03:21 AM.

Another route is to completely set up the boat, put it on 4 scales and sum the 4 weights (must be no wind)

You don't even need 4 scales, two, or even one will be pretty close. When hiway stations weigh big trucks they rarely are able to place the entire truck on the scale. They drive up & weigh part of the truck, then pull forward & weigh the next axle & so on.
You can do the same. You need your boat on a level surface. Lift the stern & place scale under both stern points, sum the two readings. Do it again for the bow points, add that sum to the stern sum & you will be very close. You can even do it with one scale, & take a reading at each corner.
Try it with a 16' 4x4. Place a scale under one end, then the other end. The sum of the two readings will be the same as if you stood the beam on end on the scale. On a cheap scale they won't agree exactly, because of scale error & your inabilty to exactly read each measurement, but it will be close.

Edited by Edchris177 on Dec 21, 2011 - 03:23 AM.

the z-21 is basically an r21 afaik

so 300-400lbs per hull?, say 350...

specs

LOA: 21' 0"

LWL: 20' 2"

Beam: 11' 0"

Beam (On Trailer): 8' 6"

Deck (Trampoline) Area: 120 s.f.

Displacement: 925 lbs. +/-

Draft (Boards Down): 3' 0"

Draft (Boards Up): 0' 8"

Mast Height: 29' 0"

Mainsail: 190 s.f.

Jib: 66 s.f.

Screacher: 178 s.f.

Berths: 4

Auxiliary: 5 h.p. Outboard

Estimated PHRF Rating: Low 80's

WOW thats some nice math there, well i was just wanting a estimate to go on and if they weighed my intire load i subtract the number of my truck from my door! You know they have the weight of the vehicle there?

And yes they weighed my truck and trailer at the same time! it was a huge SCALE! it was like 2 min. form home. ALL is good well this boat must be less then the Z21 becasue i was left with 1500 bls with boat and trailer so you subtract 1500 from what ever number u want that is a Light boat ! for 21 ft. if u ask me!
Just to dam heavy for 1 or 2 people!

I'm using metric because the math is so much simpler than that archaic system you continue to use,

Why is it that whenever you post you want to help but sound so condescending. That archaic system by the way developed the most powerful country on Earth.

That archaic system by the way developed the most powerful country on Earth.

........up to their eyeballs in debt to the Chinese?????......... :cry2:

That archaic system by the way developed the most powerful country on Earth.

Sorry Golf, no offence was intended.
I do stand by the old British system as being archaic. Had the British not won the war when America was still a colony,you too would be using metric (SI), as does nearly the entire world.
The US exports lots of stuff, all of which has to be converted for international trade. If people knew the true cost of using the Imperial system, they would bite the bullet & make the change. Short term pain for long term gain. England used to be the de facto world power, boasting an Empire on which the sun never set. They continue to cling to remnants of the old system, 'nuff said.
Think back to how much time was wasted in grade school memorizing things like 12"=1ft, 5280'=1 mile,(how many yards was that).
16.5' equals a rod, I think 3 rods,(maybe 4) equals a chain, & 1 chain pulled over 1/2 a mile,(can't remember offhand how many feet are in 1/2 mile) will give you an acre.
2 pints to a quart, I can't remember how many of those equals a peck, but I think 4 pecks = a bushel. Now a few teaspoons equal an ounce, but depending if you use the Imperial or US gallon, the number of ounces varies, & just how much mass is in a cup, pint,gallon or cubic yard of water?
You need to cut some threads for a Nacra mast ball. The DS is 9/16", so you need to drill a hole of 33/64ths,(WTF I don't have that bit in my toolbox) then cut national fine threads,which are how many to an inch?
When I go to do up those fittings, through experience i know that if 1/2" is to small it might be 9/16, but what if that is to big? What are the 32nds or 64ths wrenches in between...much easier to grab a 10 mm,too small, get the 11m or 12mm, there is never any mental gymnastics involved.
Just how tall is a horse that stands 17 hands? My hands, yours, Jethroes?
The system is so complex that most people constantly get it wrong. How many times do you hear folks referring to "weight" as lbs? As in my boat weights 375 lbs. when lbs is actually a unit of force. The measure of mass in that system is "stone".
The system was developed when all people had to measure with were their feet, hands, field rocks, & other implements of the bronze age. We don't build roads the way the Romans did. There is no reason not to progress, otherwise we would all be pulling our Hobie 14s to the lake with ox carts.
Many might argue that it doesn't matter, but it does, big time. The mixing/confusion of improper units is akin to mixing concrete. Mixing improper ingredients, or the wrong values of ingredients does not yield concrete, it yields disaster.
You already use the metric system for money, 10 pennies gives you another unit,(dime). Ten of those gives the next unit,($), & 10 A. Hamiltons gets you a Franklin.
The entire metric system is that easy, kids learn it in 10 minutes, & never forget as there are no multitudes of archane values to memorize. The proof is in the pudding, I showed a method to get a very accurate value for the mass of an object that requires no pencils, calculators, or math. The project could be easily & cheaply scaled to weigh large objects with a simple dunk tank.

This is like History class 1790s wow i wasn't born yet! 🙂 this conversation was started yet either! ***GRIN**

back in the day i remember working on the tail fin of a 747 and finding out that my 3/8 spanner was a size too big

so what's 1 size down?

2/8 is a 1/4, that was too small

but 3/8 is also 6/16 so maybe it was 5/16

but that was small too

so it was back down in the cherry picker for that very rare aircraft spanner

1 size up from the 5/16, which is also 10/32

11/32!

when you are tired it just much easier to think 5,6,7,8mm...

Well you were certainly over my head but it was interesting reading. "The kids learn it in 10 minutes and never forget" however I can speak as an authority "balderdash "( to use an archaic English term) You obviously are not a high school math teacher.
I did tell my students once that we were going on metric time 10 sec to a min, 10 min to 1 hour, 10 hours to a day, 10 weeks to a month, 10 months to a year. Thy bought it. Parents called and wanted to know when the switch.
With an ox cart I wouldn't need beach wheels so I guess we haven't progressed. 😆

All I know is that my Nacra 5.2 was faster than my buddy's Hobie 16 so there must be something better about the metric system. I am stuck with the old system but I have to admit that tools are a lot easier to figure out when you are working in metric units.
What I think is funny is that I have pretty much forgotten all the conversion formulas. I know that 10 Km is equal to 6.2 miles and do the math that way. I know that 5.0 meters is about 16 feet and some change. That's about as far as my math goes for converting.

we used to have a "fathom" club

if you could stand in a fathom of water and the top of your head was dry, you were a "fathom"

if you couldn't do that, you were a "blot"

What r you talkin about now ""erice"" ???? explain

Fathom is 6 feet right? I find it pretty easy to use either system

The metric system is easier in almost all respects, and I no longer hang my patriotism on the English system.
The Brits gave us "hands" and "feet" and then bailed on the entire thing for the millimeter.
The US officially adopted the metric system as legal measurement in 1866, the year after the Civil War ended.
We're just a little slow on the uptake.

looking around the house i noticed pretty much everything has standard and metric units on them, it's here to stay for sure...they use the metric where it really counts like the hospitals(they don't measure drugs by the teaspoon anymore)...now you can measure soccer players by centimeters and kilos but in america we like to hear our football and basketball players in good old fashion terms...take damon, for example, he's like 6'29" or so...it sound cooler when you hear your team has 2 seven footers!!! hell, you need both sets of sockets to do a job because one or more of each is missing and the others will work anyway. the good thing about standard measurements in construction is it keeps your fraction skills sharp for important things like estimating how much beer is left in the keg...1/3?, 2/3?,...and so on. hope this clears things up! oh, and music is on the fraction scale too...very important...

In forestry and surveying we measure in chains. There are 80 chains in a mile. Also, a chain is 66 feet.
Stew on that a while.

Isn't a standard road allowance 1 chain? We used to timber cruise in board feet, & though you still buy hardwood that way, I think our guys now measure standing timber in cubic meters.
Way back when I was doing engineering work for water projects, Canada converted its surveys to metric. That was about a 4 year delay after implementation of the system. From that date all surveys/blueprints had to be submitted in metric. The long stick that the field guys ran around with taking "shots" was called a rod, hence they were rodmen. I think it was 16 1/2', hence 4 of them equaled a chain. When conducting precision surveys, usually for the design of spillways in dams, the "chaining" had to be accurate. We hooked a scale to one end of the "chain",(which was not actually a chain, but a steel tape resembling a sewer snake. It was then stretched to 40lbs tension, & the temperature taken to account for thermal expansion. Measurements were taken from a tack driven into a 2x2 hub. The tack had a pinhole in the center, from which the measurement was initiated.
No one had a "metric rod" for shooting stadia at the time so myself & two colleagues were tasked with designing one. After several days the eureka moment struck, we didn't have to invent anything, just have the stadia side of the rod painted in 1/10 of a meter increments, alternating black/red for visibility. The transit X hairs & declination angles would work exactly the same as before, only the results would be meters instead of yards. The front side would have a centimeter tape for precision shots.
In practice it turned out to be much better than the old system. Because everything was based on multiples of 10, you could convert the shot into meters in your head, as you recorded it. The old way you had to count inches & feet, then run it through a formula.
That was in the old days, instrument men today just click a button on their Theodolites, & the numbers get crunched. Gone are the days of yelling out readings to note takers, & having them plot on a plane table as the rodmen walked the grids. Even though I did that work for 4 years, I still have to think about an acre, it's 43 thousand some odd square feet, so how many gallons or cubic yards of water do you store with a 1500 acre feet system?
The metric system is just so much easier, even 30 odd years later I can crunch those numbers in my head. Unless you have suffered a stroke it is hard to forget how to manipulate 10's, 100's or 1000's. I still wonder what the guy was smoking when he came up with water freezing at 32F & boiling at 212F. Tell a kid 0 & 100, they never forget it.
Probably one of the most common tasks is premix gas/oil for two strokes. If you need 50:1 how many ounces do you add to a 5 gal can? What about the odd engine that wants 32:1? With metric you do the math in your head, to borrow a line from Philip, so easy a caveman...

Probably one of the most common tasks is premix gas/oil for two strokes. If you need 50:1 how many ounces do you add to a 5 gal can? What about the odd engine that wants 32:1? With metric you do the math in your head, to borrow a line from Philip, so easy a caveman...

You are making things way too hard, You buy 5 of those little bottles.

coastrat wrote: the good thing about standard measurements in construction is it keeps your fraction skills sharp for important things like estimating how much beer is left in the keg...1/3?, 2/3?,...and so on.

I feel your pain, brother!
I prefer optimism, so the keg is always half full!
😀
Sheet In, or out!?!!

so the keg is always half full!

You are lucky. We bring those 10 & 20 litre kegs of good German beer back from Munich or Frankfurt...they always seem to be empty! Accentuating the positive, they are much more convenient on a Cat, the only way to cool the 60L models is in a cut off 50 gal drum.

You are making things way too hard, You buy 5 of those little bottles.

Those are hard to find here, & you could buy a 2nd Cat with what they cost, compared to jugs. One must also remember that there are at least two sizes of gallons, the Imperial being 20% larger than the US gal.
I think the only place that stocks them is the Stihl chainsaw dealer. I still have a large 2 stroke in the fleet, we buy oil in 5 litre jugs.
Jerry cans only hold 23 litres, or 30 for the large ones, makes for awkward numbers in gallons, & awkward mixing. Small tools such as weed eaters & chainsaws don't use much fuel. In order to prevent problems resulting from stale fuel we generally only mix 4 or 5 litres (1 of your gallons, 1 of our gallons respectively) for a season, using something like Shell V-Power, as it contains no ethanol. If I ever forgot that 100ml in 5000ml (5L) equals 50:1 then I must have died! No matter what size batches you are mixing, 20ml to each litre can be done in your head. Years ago I had a Bingo chart, listing ounces on one axis & gallons/quarts on another, but the damned thing always seemed to be missing when you needed it.
Some day Uncle Sam will find the political balls to implement what the rest of the world uses, & you will wonder why such a good idea was so long coming.

Edited by Edchris177 on Dec 23, 2011 - 05:12 PM.

Ok, this thread is entirely hijacked! Unless maybe that Reynolds 21 was built with the metric system. 😆

To continue with the hijack.

Here's the thing, all my life the question I get from strangers is "How tall are you?" The answer, since I was 16 years old, has been 6 ft 7 inches.

If I had been born in one of those ferrin countries who don't understand good ole amerkin feet and inches, what would be the answer?

2006.6 millimeteres
200.66 centimeters
20.066 decimeters
2.0066 meters
0.0020066 kilometers perhaps?

Basketball is pretty popular in some parts of Europe, in the USA it gets mentioned if a team has a "7 footer" in the middle. What's the standard for a really tall player with the metric system?

Hey Hans, did you see that team Europa just signed a 2.1336 meters'r?

Just don't seem right.

Merry Christmas everyone.

The answer, since I was 16 years old, has been 6 ft 7 inches.

You should say "2 metres,& I weigh 16 stone" look them in the eye, or down in the eye I guess:-D and say nothing more. It might be fun to watch the mental gymnastics as they try to figure out what the hell 'yo be takin 'bout boy? I bet they go easy on the "boy".
Merry Christmas to all, wish I could be sailing, the wind at my place was 15kts, but the water was 5C,.. er make that 41F:lol:

Edited by Edchris177 on Dec 23, 2011 - 06:16 PM.

soulofasailor wrote: Yeap Thanks man! It was alot of work to set it up my head was spinning when the guy was showing us how to set it up! But i did video tape it! I want to take it up to Lake Erie in the COLD! But i am still pondering that thought a little! 🙂 Cant wait for spring! I am now hunting down any OWNERS i know there is not a lot of them!

I've got a 1984 Reynolds 21, and it is a blast!!! I am new to sailing and I have learned (the hard way) that it is a pain in the butt right these boats once you flip them.....

Any chance you could send some detailed pics of your trailer. Mine is in terrible shape and I am having it rebuilt. I'd like to show my trailer guy what it should look like!

It's getting close to spring, do you have yours set to sail?

Paul

So where do u launch urs at on lake Erie. I can take a pic for u .. and did u rig a stereo on yours

Unfortunately, I am not up in your area. I live down in Pensacola, Florida. I have not rigged a stereo on mine because I am not convinced that I have the ability to keep the boat upright when I take it out. I take it out on light wind days and my girl loves it. When the winds pick up a bit, I'll grab a few buddies and we tend to push it past our sailing abilities. So, I keep it fairly barebones to minimize the amount of things that can be damaged. Not to mention, I like the peace and quiet out on the water- no music, no motors....

Edited by takeiteasy on Mar 08, 2012 - 08:31 AM.

Oh i thought you were in my area, OK but how do you flip this BOAT it is heavy and i do like to go out in 20knts of wind what is the wind conditions your in to flip it! this will be my first sailing season with it! I refuse to get into the water so i will not flip it! But i guess you are getting the hull out of the water? what point does this happen ? How fast is this boat also? thanks! i cant wait to use it on Lake Erie!