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anybody weighed their boat with bathroom scales? #259738
05/20/13 11:59 PM
05/20/13 11:59 PM
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
Team_Cat_Fever Offline OP
Carpal Tunnel
Team_Cat_Fever  Offline OP
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Joined: Sep 2002
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Roanoke Island ,N.C.
Has anybody weighed their boat on bathroom scales? How would you do it? One under each hull and add them together?


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
-- Have You Seen This? --
Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #259739
05/21/13 12:40 AM
05/21/13 12:40 AM
Joined: Jun 2001
Posts: 3,293
Long Beach, California
John Williams Offline
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John Williams  Offline
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Long Beach, California
Yep - the front two can go just forward of the front beam, and the back two go just forward of the rear beam. That'll keep your hulls off the ground. Easiest way, track it into position, lift the bows to pull the trax, and set it on the front scales. Then lift the stern, pull the chocks, and set it on the back scales. You might need some help with the math. whistle

Rub it down, flip it and reverse it to take it off. If you have scales that can be zeroed and show one decimal place, they can be used to get an official weight. Most can show Kgs as well as pounds. 180kgs is the official weight for an F18 - check the rules for what can be included (compass, righting line) and what can't (wrench, sponge, empty beer cans). Weigh it dry and mast down to emulate weigh-in at a regional or NA Championship.


John Williams

- The harder you practice, the luckier you get -
Gary Player, pro golfer

After watching Lionel Messi play, I realize I need to sail harder.
Re: anybody weighed their boat with bathroom scales? [Re: John Williams] #259742
05/21/13 07:02 AM
05/21/13 07:02 AM
Joined: Jan 2004
Posts: 1,884
Detroit, MI
mbounds Offline
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Detroit, MI
More accurate (but more difficult) is to use two scales. Balance the boat on two scales set on a hard surface. Mast down.

The scales' error is additive. If each scale's accuracy is +/- 1 lb, that means 4 scales = +/- 4 lbs; 2 scales = +/- 2 lbs. Just because the display reads to the 0.1 lb doesn't mean it's accurate to that amount. Calibrate the scales with a known weight that's close to the expected weight of the thing you're weighing. (For an F-18, 2 scales = 200 lbs each).

Load cells are still the best (most accurate) way to weigh boats.

Re: anybody weighed their boat with bathroom scales? [Re: John Williams] #259745
05/21/13 09:01 AM
05/21/13 09:01 AM

M
MN3
Unregistered
MN3
Unregistered
M



Originally Posted by John Williams
Rub it down, flip it and reverse it

thought he said "how to weigh it" ... not "how to make love to it"

Re: anybody weighed their boat with bathroom scales? [Re: ] #259746
05/21/13 09:43 AM
05/21/13 09:43 AM
Joined: Jun 2001
Posts: 3,293
Long Beach, California
John Williams Offline
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John Williams  Offline
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Long Beach, California
Originally Posted by MN3
Originally Posted by John Williams
Rub it down, flip it and reverse it

thought he said "how to weigh it" ... not "how to make love to it"


Have you seen him sail?


John Williams

- The harder you practice, the luckier you get -
Gary Player, pro golfer

After watching Lionel Messi play, I realize I need to sail harder.
Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #259747
05/21/13 11:42 AM
05/21/13 11:42 AM
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
Team_Cat_Fever Offline OP
Carpal Tunnel
Team_Cat_Fever  Offline OP
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Roanoke Island ,N.C.
Thanks folks. 2 scales was my goal as I'm just looking for a rough weight, nothing official. Don't want to go out and buy a bunch of scales just for one go.
Jdub, I'm not sure what to say to the "rub it" thing. Kinda makes me glad I didn't buy that boat from you after all.


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #259748
05/21/13 11:44 AM
05/21/13 11:44 AM
Joined: Jun 2009
Posts: 522
Petten Netherlands
N
northsea junkie Offline
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northsea junkie  Offline
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Posts: 522
Petten Netherlands
Huh ??? Why so difficult with 2 or 4 scales?

Just place the cat on the trailer and lift one hull up somewhere in the middle. then you shift a box or something else with the weighting scale on it under the hull.
Do the same on the other side (on the same place of the other hull!

Add and done!

accuracy = 2 x scale accuracy + 2 x reading accuracy (only with analog scale)


ronald
RAIDER-15 (homebuilt)

hey boy, what did you do over there, alone far out at sea?..
"huh....., that's the only place where I'm happy, sir.
Re: anybody weighed their boat with bathroom scales? [Re: northsea junkie] #259749
05/21/13 11:47 AM
05/21/13 11:47 AM
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
Team_Cat_Fever Offline OP
Carpal Tunnel
Team_Cat_Fever  Offline OP
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Originally Posted by northsea junkie
Huh ??? Why so difficult with 2 or 4 scales?

Just place the cat on the trailer and lift one hull up somewhere in the middle. then you shift a box or something else with the weighting scale on it under the hull.
Do the same on the other side (on the same place of the other hull!

Add and done!

accuracy = 2 x scale accuracy + 2 x reading accuracy (only with analog scale)


That sounds nice and easy.I like it. Have you tried it that way?


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #259750
05/21/13 11:54 AM
05/21/13 11:54 AM
Joined: Jun 2009
Posts: 522
Petten Netherlands
N
northsea junkie Offline
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northsea junkie  Offline
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Posts: 522
Petten Netherlands
Yes, I've done this numerous times.
Only problem with being single-handed, you have to shift the scale+box with your belly under the cat.

(for me, having no belly at all, only muscles, tht's difficult)

Last edited by northsea junkie; 05/21/13 11:59 AM.

ronald
RAIDER-15 (homebuilt)

hey boy, what did you do over there, alone far out at sea?..
"huh....., that's the only place where I'm happy, sir.
Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #259751
05/21/13 12:03 PM
05/21/13 12:03 PM
Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
Team_Cat_Fever Offline OP
Carpal Tunnel
Team_Cat_Fever  Offline OP
Carpal Tunnel

Joined: Sep 2002
Posts: 3,224
Roanoke Island ,N.C.
I've got plenty of belly, no problem. If you need some let me know.


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: anybody weighed their boat with bathroom scales? [Re: northsea junkie] #259752
05/21/13 01:23 PM
05/21/13 01:23 PM
Joined: Apr 2008
Posts: 921
Alachua, FL
Mugrace72 Offline
old hand
Mugrace72  Offline
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Joined: Apr 2008
Posts: 921
Alachua, FL
Originally Posted by northsea junkie
Huh ??? Why so difficult with 2 or 4 scales?

Just place the cat on the trailer and lift one hull up somewhere in the middle. then you shift a box or something else with the weighting scale on it under the hull.
Do the same on the other side (on the same place of the other hull!

Add and done!

accuracy = 2 x scale accuracy + 2 x reading accuracy (only with analog scale)


This method is likely to produce errors. It is essentially a three point lift with one point on the scale. Then doing a mirror image on the other side.

Theoretically, it could work if everything is absolutely level and there are no torquing forces between the beams and hulls.

Fat chance of getting all those variables out.



Like Matt says, two scales will do it. All of the weight on one or the other scale at the same time. Calibrate beforehand with a known weight close to what you will be weighing.

Mast up is OK if there is no windage. Even then, if you read both scales at the same instant you will be fine.





Jack Woehrle
Hobie Wave #100, Tiger Shark III
HCA-NA 5022-1
USSailing 654799E
Alachua FL/Put-In-Bay
Re: anybody weighed their boat with bathroom scales? [Re: Mugrace72] #259754
05/21/13 02:34 PM
05/21/13 02:34 PM
Joined: Jun 2009
Posts: 522
Petten Netherlands
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northsea junkie Offline
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northsea junkie  Offline
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Joined: Jun 2009
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Petten Netherlands
Originally Posted by Mugrace72
Originally Posted by northsea junkie
Huh ??? Why so difficult with 2 or 4 scales?

Just place the cat on the trailer and lift one hull up somewhere in the middle. then you shift a box or something else with the weighting scale on it under the hull.
Do the same on the other side (on the same place of the other hull!

Add and done!

accuracy = 2 x scale accuracy + 2 x reading accuracy (only with analog scale)


This method is likely to produce errors. It is essentially a three point lift with one point on the scale. Then doing a mirror image on the other side.





If your trailer is symmetric and you place the scale under exactly the same point of the hulls, I don't see any inaccuracy.
Even if you miss some centimeters or having it not exactly balanced on the same level, the theoretical fault you make, is neglectable and falls problably within the inaccuracy of the scales

If you question the accuracy of a measurement, it's very easy to test this:
roll the trailer 1 meter further and start the measurement again starting with the last hull.

Check the difference with the first measurement. If it's too big, then I eat my shoe

Last edited by northsea junkie; 05/22/13 03:58 AM.

ronald
RAIDER-15 (homebuilt)

hey boy, what did you do over there, alone far out at sea?..
"huh....., that's the only place where I'm happy, sir.
Re: anybody weighed their boat with bathroom scales? [Re: northsea junkie] #259755
05/21/13 03:00 PM
05/21/13 03:00 PM
Joined: Apr 2008
Posts: 921
Alachua, FL
Mugrace72 Offline
old hand
Mugrace72  Offline
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Joined: Apr 2008
Posts: 921
Alachua, FL
Originally Posted by northsea junkie

Even if you miss some centimeters or having it not exactly balanced on the same level, the theoretical fault you make, is neglectable and falls problably within the inaccuracy of the scales

If you question the accuracy of a measurement, it's very easy to test this:
roll the trailer 1 meter further and start the measurement again starting with the last hull.

Check the difference with the first measurement. If it's too big, than I eat my shoe


I agree that it is about what your tolerances are.

If you are satisfied with + or - 5 pounds (10#), it is negligible.

More important is to calibrate your scale. Bathroom scales can be off by 10# at 200#. If you calibrate that same scale it can repeat within a pound or two.



Jack Woehrle
Hobie Wave #100, Tiger Shark III
HCA-NA 5022-1
USSailing 654799E
Alachua FL/Put-In-Bay
Re: anybody weighed their boat with bathroom scales? [Re: Mugrace72] #259771
05/22/13 10:18 AM
05/22/13 10:18 AM
Joined: Dec 2001
Posts: 5,590
Naples, FL
waterbug_wpb Offline
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Naples, FL
if your scale can handle the total weight of the boat, "tare" (zero) the scale with the beach wheels on it, and then go roll your boat (balanced on the wheels) on the scale.



Jay

Re: anybody weighed their boat with bathroom scales? [Re: waterbug_wpb] #259772
05/22/13 11:05 AM
05/22/13 11:05 AM
Joined: Jun 2002
Posts: 1,658
Florida Suncoast, Dunedin Caus...
catman Offline
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I wouldn't trust a bathroom scale at all. Have you ever seen a woman use one and believe it was correct or close?


Have Fun
Re: anybody weighed their boat with bathroom scales? [Re: waterbug_wpb] #259774
05/22/13 11:40 AM
05/22/13 11:40 AM
Joined: Jan 2004
Posts: 1,884
Detroit, MI
mbounds Offline
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Detroit, MI
Originally Posted by waterbug_wpb
if your scale can handle the total weight of the boat, "tare" (zero) the scale with the beach wheels on it, and then go roll your boat (balanced on the wheels) on the scale.


This could work with two scales, but I want to see how you balance everything on one. crazy

Also, you'd have to be damn precise about finding the balance point so you could let go of the boat long enough to read the scales (holding on to the boat to help balance it is going to throw off the measurement).

Re: anybody weighed their boat with bathroom scales? [Re: catman] #259776
05/22/13 12:15 PM
05/22/13 12:15 PM
Joined: Aug 2007
Posts: 3,969
B
brucat Offline
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Originally Posted by catman
I wouldn't trust a bathroom scale at all. Have you ever seen a woman use one and believe it was correct or close?


Yes. They always appear in line at regattas, refusing to be weighed in front of others...

Mike

Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #259792
05/23/13 07:02 AM
05/23/13 07:02 AM
Joined: Apr 2002
Posts: 602
Wilmington,NC
Dlennard Offline
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Dlennard  Offline
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Wilmington,NC
The F18 scales are cart scales with four pads that give total weight and list the weight of each pad. I got my wife to stand on one pad while I stood on another telling her it was a combined weight and her not knowing the pads also listed separate weights.

Re: anybody weighed their boat with bathroom scales? [Re: Team_Cat_Fever] #273191
06/13/14 06:07 AM
06/13/14 06:07 AM
Joined: Jun 2014
Posts: 1
W
Willson Offline
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Willson  Offline
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Joined: Jun 2014
Posts: 1
I think use of a hanging scale or crane scale is best to find boat weight. But the weighing capacity must be higher so you can able to find the weight of Boat. I mostly use my truck scales to find boat weight.

Last edited by Willson; 06/14/14 01:35 AM.

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