Reply
 
Thread Tools Display Modes
 
Old 06-15-2015, 11:50 PM   #21
TF Site Team
 
Peter B's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Lotus
Vessel Model: Clipper (CHB) 34 Sedan/Europa style
Join Date: Jun 2008
Posts: 6,669
Send a message via Skype™ to Peter B
When I bought my Celica GT4, I knew I didn't need 155kw (about 200hp) and a top speed of 240kph, (=~150mph), but I felt that was it was designed as a rally car, with all that implies, then if I just drove it sensibly, it would not even be breathing hard in normal use, and should be bullet-proof. This philosophy has been proven correct. I still love it and it's still going strong 25 years later, in near perfect condition at 270,000 km, (=~, oh bugger it, you do the damn US math).

Anyway, I sort of feel that boats are not that different. As I have on occasion been darned glad of the extra power to get me out of trouble, (and on occasion, as it is 4WD), tow someone else out of trouble, so also am I glad that my boat at hull speed is not really breathing that hard, has reserve, and on occasion I have actually used this to tow other grounded boats off. As I see it, as long as it's up to operating temp, further load is largely irrelevant, and it is so frugal I don't mind buying the bit extra fuel for that reserve. The fact it is still effective purring, and 'using no oil', (I know - they'll use a bit - gotta, right), at some 5000 hrs plus, I think I'm not far wrong - just saying'.
Attached Thumbnails
Click image for larger version

Name:	Image 3.jpg
Views:	44
Size:	94.4 KB
ID:	41120  
__________________
Advertisement

__________________
Pete
Peter B is offline   Reply With Quote
Old 06-16-2015, 08:17 AM   #22
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,887
Hope everyone in the discussion understands the difference between displacement weight and documented gross tonnage....they can be quite a bit different.


http://www.uscg.mil/hq/msc/docs/CG-5397.pdf


http://www.qualitymaritime.info/Pres...mplified_0.pdf


Definitions from Wiki....but the above shows the diff....


Tonnage is a measure of the cargo-carrying capacity of a ship. The term derives from the taxation paid on tuns or casks of wine, and was later used in reference to the weight of a ship's cargo; however, in modern maritime usage, "tonnage" specifically refers to a calculation of the volume or cargo volume of a ship. Tonnage should not be confused with displacement, which refers to the actual weight of the vessel.
Measurement of tonnage can be complicated, not least because it is used to assess fees on commercial shipping.
__________________

psneeld is offline   Reply With Quote
Old 06-16-2015, 09:07 AM   #23
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,711
Thank you Scott,
I suspected as much.

We're up early for a road trip to get a new trans oil cooler so not much time.
So for our purposes tonnage numbers have no value. Would be nice to know what Early Spring weighs but I don't think it will come to pass. In this case guessing is probably about as close as we'll come.

I tried to find some comparable boats w displacement numbers but didn't do well at all.

For me I'd do well to study QB and dannc's previous posts and see if I can learn more. Anyway when I said "WAY" over powered I a bit off or more and I WAS WAY off re Duwam's size. However I do think Early Spring would be better served w a 3-53.

QB wrote "Eric, displacement goes like length cubed. (33/30)^3 * 8 = 10.6 tons." My guess for Early Spring's weight was 10 tons. Maybe I was not far off. My estimate for Willy's power requirement is 30 to 33hp. I put 40 in her and it seems very close to ideal. That's 5hp per ton. Skeene says 44hp. Dan's conclusion of 50hp seems extremely correct but w my own experience I finally decided I could actually do w 6 to 8 hp less. But if I repowered again would I have the guts to go to 4lbs per hp (33 for Willy) ..... probably not.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-16-2015, 11:34 AM   #24
QB
Senior Member
 
QB's Avatar
 
City: San Diego and Gabriola
Country: USA and Canada
Vessel Name: Skookum Maru
Vessel Model: Ed Monk design #1924
Join Date: Dec 2011
Posts: 215
Quote:
Originally Posted by psneeld View Post
Hope everyone in the discussion understands the difference between displacement weight and documented gross tonnage....they can be quite a bit different.
This is true. Also USCG and Transport Canada rules for measuring gross and net tonnage are somewhat different, and here we are comparing a US and a Canadian boat.
QB is offline   Reply With Quote
Old 06-16-2015, 11:50 AM   #25
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,887
Quote:
Originally Posted by QB View Post
This is true. Also USCG and Transport Canada rules for measuring gross and net tonnage are somewhat different, and here we are comparing a US and a Canadian boat.
fair enough...just a reminder for those that didn't know that for US vessels...

Do you have a link for Canadian Vessel measurement so I can compare the calculations?


One quick glance at one source showed the measuring to be similar as it is about volume vesus weight....


http://wwwapps.tc.gc.ca/wwwdocs/Form...408-10_E_X.pdf
psneeld is offline   Reply With Quote
Old 06-16-2015, 02:34 PM   #26
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,734
Quote:
Originally Posted by psneeld View Post
Hope everyone in the discussion understands the difference between displacement weight and documented gross tonnage....they can be quite a bit different...
Hobo has a design displacement at 1/2 load of 17.63 tons and her gross tonnage is 36 tons and her net tonnage is 29. When we were overseas on our last boat, sometimes port fees were calculated on the net tonnage and in our case it wasn't very much.
Larry M is offline   Reply With Quote
Old 06-17-2015, 12:04 PM   #27
QB
Senior Member
 
QB's Avatar
 
City: San Diego and Gabriola
Country: USA and Canada
Vessel Name: Skookum Maru
Vessel Model: Ed Monk design #1924
Join Date: Dec 2011
Posts: 215
Quote:
Originally Posted by psneeld View Post
One quick glance at one source showed the measuring to be similar as it is about volume vesus weight....http://wwwapps.tc.gc.ca/wwwdocs/Form...408-10_E_X.pdf
Yes and the corresponding simplified US method is here: http://www.uscg.mil/hq/msc/tonnage/d...-1_Current.pdf. They use different shape factor coefficients, account for above-deck structures differently, etc.

Then there are various non-simplified formal tonnage measurement schemes that have been used in the past. These days the US and Canada are supposed to be following the International Convention on Tonnage Measurement of Ships and large commercial vessels' measurements should be updated to that by now, but not necessarily for smaller boats.

You are right that all these tonnage measurements are volume based and don't actually involve weighing the vessel. Since a floating boat's displaced volume of water equals its weight, one might hope that they should be comparable, but that is not often the case.
__________________

QB is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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





All times are GMT -5. The time now is 07:50 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012