Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 13-03-2013, 20:41   #16
Registered User
 
RainDog's Avatar

Join Date: Jun 2009
Location: Varies
Boat: Pacific Seacraft 34 #142
Posts: 1,183
Re: Displacement???

I think OP is asking how they come up with the displacement listed in the boat specs. From what I have gathered, there is not standardization on how this is done. Many builders list extremely optimistic numbers. They might list "designed" displacement, but that never really seems to be the actual as-built displacement.

So the answer is basically, in a lot of situations, the listed displacement does not really mean much.
__________________

RainDog is offline   Reply With Quote
Old 13-03-2013, 20:56   #17
Moderator Emeritus
 
Coops's Avatar

Cruisers Forum Supporter

Join Date: Jan 2012
Location: Northern NSW.Australia
Boat: Sunmaid 20, John Welsford Navigator
Posts: 9,550
Re: Displacement???

Quote:
Originally Posted by sabray View Post
I think you just broke the be nice rule. Even if your right it still breaks the rule.
Was not aimed at you good sir, but any man asking for a ladies displacement, was a general insult not a specific one.

Coops.
__________________

__________________
When somebody told me that I was delusional, I almost fell off of my unicorn.
Coops is offline   Reply With Quote
Old 13-03-2013, 21:06   #18
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,152
Re: Displacement???

Quote:
Originally Posted by Eumelia View Post
Displacement = weight
Period
Thank gawd someone said it.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 13-03-2013, 21:55   #19
Registered User

Join Date: May 2010
Location: Elsewhere on the Water
Posts: 571
Re: Displacement???

If you want more details . . .

Displacement (ship) - Wikipedia, the free encyclopedia
__________________
St. Elsewhere is offline   Reply With Quote
Old 13-03-2013, 22:04   #20
Registered User

Join Date: Oct 2011
Posts: 2,434
Re: Displacement???

Displacement = weight____except when the Coast Guard is involved, and then it gets much more complicated. Registered tonnage is a measure of volume of the enclosed spaces of a vessel,less the spaces that are considered machinery spaces. This has lead to many ways to cheat on tonnage to get under rules that only apply to larger boats. I was told many years ago(I hope it is no longer true) that the SF bay ferries used to remove the rear doors on the lower decks at measurement time so that they were not considered enclosed spaces, and after the measurement was taken, put the doors back on. This allowed them to have less regulation (less safety) than if they were measured according to the law. As I said, I hope this is no longer true, but I saw some very large vessels being run by 100 ton masters and safety rules that applied to 100 ton and smaller vessels. Your CG tonnage on your documentations has little or nothing to do with the weight of your vessel. __Just something to think about.____Grant.
__________________
gjordan is offline   Reply With Quote
Old 13-03-2013, 22:37   #21
Registered User
 
markpierce's Avatar

Join Date: Aug 2010
Location: Central California
Boat: M/V Carquinez Coot
Posts: 3,416
Re: Displacement???

Quote:
Originally Posted by gjordan View Post
... I was told many years ago(I hope it is no longer true) that the SF bay ferries used to remove the rear doors on the lower decks at measurement time so that they were not considered enclosed spaces, and after the measurement was taken, put the doors back on. This allowed them to have less regulation (less safety) than if they were measured according to the law. As I said, I hope this is no longer true
...
Don't worry. All San Francisco ferries are now purely passenger (not car or railroad) so there shouldn't be any question about doors.

__________________
markpierce is offline   Reply With Quote
Old 13-03-2013, 23:31   #22
Registered User

Join Date: Dec 2009
Posts: 3,016
Images: 4
Re: Displacement???

Objects that are "floating" are "weightless", no? It is that simple. So we call it "displacement". Mostly to discriminate between our elite selves and the dockwalking riffraff.
__________________
daddle is offline   Reply With Quote
Old 13-03-2013, 23:55   #23
Registered User
 
lateral's Avatar

Join Date: Apr 2011
Location: NZ
Boat: S34 Bob Stewart - 1959 Patiki class. Re--built by me & good mate.
Posts: 703
Re: Displacement???

Out of all my mates the only ones concerned with their displacement are skippers?
Odd.
__________________
lateral is offline   Reply With Quote
Old 13-03-2013, 23:59   #24
Registered User
 
markpierce's Avatar

Join Date: Aug 2010
Location: Central California
Boat: M/V Carquinez Coot
Posts: 3,416
Re: Displacement???

If you just "googled" it, you'd save us all the trouble.

Displacement (ship) | Ask.com Encyclopedia
__________________
markpierce is offline   Reply With Quote
Old 14-03-2013, 00:00   #25
Registered User

Join Date: Nov 2011
Location: Fethiye Turkey
Boat: Lagoon 440
Posts: 3,164
Re: Displacement???

Quote:
Originally Posted by Coops View Post
She would probably tell you that her "displacement" is being with you. She would much rather be elsewhere.

Coops.
Your absolutely correct some one will get "displaced"..... LMAO

Cheers
__________________
"Political correctness is a creeping sickness that knows no boundaries"
Lagoon4us is offline   Reply With Quote
Old 14-03-2013, 09:09   #26
Registered User

Join Date: Mar 2011
Posts: 88
Re: Displacement???

Thanks for all the enlightening answers. I gather from them that there is no standard formula that builders adhere to when publishing the displacement weight of their boats. Thats really all I wanted to know. I kinda thought that most people would assume, since I was using a computer, that I was of normal intelligence and consequently would know all the elementary stuff, volume of water displaced=weight of displacing object, etc. Still, I did learn what I wanted to know. CF is a great resource.
__________________
nial is offline   Reply With Quote
Old 14-03-2013, 09:20   #27
Registered User

Join Date: Dec 2012
Posts: 449
Re: Displacement???

Do you mean you've got more than you were hoping for?

CF is a great resource ... no doubt ... but like with everything on Internet, you need to know in order to know what you read ...
__________________
Richard_W is offline   Reply With Quote
Old 14-03-2013, 09:21   #28
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Displacement???

That's what keeps this forum going--for most questions there is no single, correct answer. And, for those questions where there is a correct answer, there will always be someone who disagrees purely on principal.
__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 14-03-2013, 09:28   #29
Registered User
 
jeremiason's Avatar

Join Date: Oct 2010
Location: Punta Gorda, Florida
Boat: Sea Ray 270
Posts: 1,427
Images: 2
Send a message via ICQ to jeremiason Send a message via Yahoo to jeremiason Send a message via Skype™ to jeremiason
Re: Displacement???

Quote:
Originally Posted by gjordan View Post
Displacement = weight____except when the Coast Guard is involved, and then it gets much more complicated. Registered tonnage is a measure of volume of the enclosed spaces of a vessel,less the spaces that are considered machinery spaces. This has lead to many ways to cheat on tonnage to get under rules that only apply to larger boats. I was told many years ago(I hope it is no longer true) that the SF bay ferries used to remove the rear doors on the lower decks at measurement time so that they were not considered enclosed spaces, and after the measurement was taken, put the doors back on. This allowed them to have less regulation (less safety) than if they were measured according to the law. As I said, I hope this is no longer true, but I saw some very large vessels being run by 100 ton masters and safety rules that applied to 100 ton and smaller vessels. Your CG tonnage on your documentations has little or nothing to do with the weight of your vessel. __Just something to think about.____Grant.
You are now referring to Gross and Net Tonnages, which is very different from Displacement.

Gross Tonnage, the total internal volume and Net tonnage, the volume of the actual cargo space, basically refer to what the vesel can carry, at least theoretically. Yes, you can play with hose numbers by removing hatches or adding them.

You are correct, that a USCG Deck Officer's License is based on Gross Tonnage and that most SF Bay ferries are rated at 99 GT and I suspect that much of that has to do with costs associated with operation.

For example in my experiences, the USS Potomac is rated at 412 GT, which requires a Master with a license of a minimum of 500 tons and an addtional licesed crew of 4, but only carries 148 passengers. On the other hand the Red & White Ferry Fleet are all rated at 99 GT and only require a 100 ton Master and a crew of 3, but carry over 200 passengers. Go figure?
__________________
Tom Jeremiason
Punta Gorda, Florida

jeremiason is offline   Reply With Quote
Old 14-03-2013, 09:29   #30
Registered User

Join Date: May 2010
Location: Elsewhere on the Water
Posts: 571
Re: Displacement???

Quote:
Originally Posted by nial View Post
I gather from them that there is no standard formula that builders adhere to when publishing the displacement weight of their boats. Thats really all I wanted to know.
If the boat is to be USGC Registered, the tonnage has to conform to the USCG measurement standards per their regulations. With that said, I also know that many vessels are USCG Registered with nonconforming tonnage reported.
__________________

__________________
St. Elsewhere is offline   Reply With Quote
Reply

Tags
displacement

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 16:54.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.