Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors

Go Back   Boat Design Forums > Design > Powerboats
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-13-2012, 10:34 PM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
GB 42 or 49 re-powered

I've been taking a good look at some Grand Banks 42. I like the layout, and am happy enough at displacement speeds. Efficiency isn't great - after all its basically a planing hull, built heavy. Typically 35000 lbs lightship.

Searches showed what seems a bit of an anomaly. GB 49's, older ones, often listed for similar prices. So the thought occurs - why not get a GB 49 for the extra space, standing height engine room and a bit more hull speed. But instead of feeding the 2 x Cat 3208's at 375 HP that they typically have change the power. Either re-power or rig up a chain drive/clutch system to run just one of the monster engines but turn both props, and then cruise at 10 kn at low fuel consumption. The 49's lightship are 60000 lb.

Am I missing something?
Reply With Quote
  #2  
Old 02-14-2012, 05:52 AM
keysdisease's Avatar
keysdisease keysdisease is online now
Senior Member
 
Join Date: Mar 2006
Rep: 205 Posts: 442
Location: South Florida USA
The system exists as an off the shelf product. Called Geared UP it uses gearboxes to run twin shafts off one engine.

I have seen it installed in one Dusky 33 with I/O's and a Mainship.

http://floridasportfishing.com/magaz...sherman-3.html

and here:

http://www.boattest.com/resources/vi...px?newsid=3230

There was also a discussion about this here, but I can't find it right now.

Steve
Reply With Quote
  #3  
Old 02-14-2012, 07:10 PM
WestVanHan's Avatar
WestVanHan WestVanHan is offline
Senior Member
 
Join Date: Aug 2009
Rep: 413 Posts: 657
Location: Vancouver
I guess you could do chains but it seems a bother.Why not just take one prop off...and then change back when you feel?

I think you would be quite surpised at the mpg at low speeds..even my 21 ton, 1280 hp twin engines running at 7 knots its a bit over 9 lph.

But get those 3208 Cats checked...seriously checked.

In trucks they were poor engines,IIRC they have only 2 rings,so lots of blowby and sludge.
In boats they seem to do better.Also if not loaded properly-they are very succeptible to the usual problems associated.

The good news is if they are shot, Cummins 6bt or 4BT are dirt cheap and last forever.

But first of all,realistically figure how many miles/hours you will put on vs. gph vs. cost to change and you may find it will take you 20 to 150 years to pay the new engines off.
__________________
I think it's bad luck to be superstitious.
Reply With Quote
  #4  
Old 02-14-2012, 07:44 PM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
Quote:
Originally Posted by keysdisease View Post
The system exists as an off the shelf product. Called Geared UP it uses gearboxes to run twin shafts off one engine.

I have seen it installed in one Dusky 33 with I/O's and a Mainship.

http://floridasportfishing.com/magaz...sherman-3.html

and here:

http://www.boattest.com/resources/vi...px?newsid=3230

There was also a discussion about this here, but I can't find it right now.

Steve
Thanks Keys, I'll check it out.
Reply With Quote
  #5  
Old 02-14-2012, 08:48 PM
Stumble Stumble is offline
Senior Member
 
Join Date: Oct 2008
Rep: 604 Posts: 1,086
Location: New Orleans
Brian,

In line with Wests suggestion of taking off a prop, you might also consider putting a feathering prop on the boat. While normally reserved for sailboats, if you are going to run one engine at a time, this would allow you to switch back and forth, and have both engines if you ever needed them for something.
__________________
********************
Nothing is half so much fun as screwing around with boats, except screwing around in a boat.
Reply With Quote
  #6  
Old 02-14-2012, 10:02 PM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
Good comments WestVan
Quote:
Originally Posted by WestVanHan View Post
I guess you could do chains but it seems a bother.Why not just take one prop off...and then change back when you feel?
I would like the option of running two engines, for maneuvering or for those times that I'm in a rush. But mainly want a long range cruise capability

I think you would be quite surpised at the mpg at low speeds..even my 21 ton, 1280 hp twin engines running at 7 knots its a bit over 9 lph.
Impressive!

But get those 3208 Cats checked...seriously checked.

In trucks they were poor engines,IIRC they have only 2 rings,so lots of blowby and sludge.
In boats they seem to do better.Also if not loaded properly-they are very succeptible to the usual problems associated.
To me having one 3208 is a disadvantage, let alone two! I want an in-line 6 that sips fuel at low rpm. Part of the idea of running two props for cruise is to increase engine loading at low rpm to avoid problems that could arise from extended low rpm running.

The good news is if they are shot, Cummins 6bt or 4BT are dirt cheap and last forever.
Yes, my engine of choice!

But first of all,realistically figure how many miles/hours you will put on vs. gph vs. cost to change and you may find it will take you 20 to 150 years to pay the new engines off.
Exactly. Better to get the engines of choice & avoid time, cost & hassle of re-power. GB 46 or 49 with anything but the dreaded 3208 is seems rare
If I buy a GB 42 I will struggle to get enough range to get home, even with some fuel bladders. California to Hawaii is a bit over 2000 nm, then to Samoa is a little further. After that its just island hopping and easy.... If I ship West Coast to Brisbane its in the order of $50k for cradle & shipping. Plus 15% import cost on that freight.

Ideally I would ship to American Samoa, or some other US territory in the west Pacific. There must be some kind of semi-regular supply runs to these places
Reply With Quote
  #7  
Old 02-14-2012, 10:14 PM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
Quote:
Originally Posted by Stumble View Post
Brian,

In line with Wests suggestion of taking off a prop, you might also consider putting a feathering prop on the boat. While normally reserved for sailboats, if you are going to run one engine at a time, this would allow you to switch back and forth, and have both engines if you ever needed them for something.
This is also worth considering. But props are 24" or 28" diameter, so feathering versions will not be inexpensive. If I do end up with 2 x 200+ HP engines, preferably Cummins, then 2 x CPP would be an option. Not inexpensive either, but a good set-up and be very likely better than re-powering. The problem is, once I cross the Pacific the normal usage wouldn't justify the changeover. The journey itself has to give a lot of the payback. I'm trying to test various options, just have this horrible feeling that the checkbook pain of freight could end up being the way to go.
Reply With Quote
  #8  
Old 02-14-2012, 10:33 PM
Stumble Stumble is offline
Senior Member
 
Join Date: Oct 2008
Rep: 604 Posts: 1,086
Location: New Orleans
Brian,

I can tell you that often the cost to ship is much lower than the cost to take it over on its own hull. This is the way most mega-yachts move around the world. Some of the transport craft even have full ship yards to do dry dock work during the transit.
__________________
********************
Nothing is half so much fun as screwing around with boats, except screwing around in a boat.
Reply With Quote
  #9  
Old 02-14-2012, 10:40 PM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
Quote:
Originally Posted by Stumble View Post
Brian,

I can tell you that often the cost to ship is much lower than the cost to take it over on its own hull. This is the way most mega-yachts move around the world. Some of the transport craft even have full ship yards to do dry dock work during the transit.
In my head I know you are right. I'd love to do the trip, but its not without its risks either. It probably only makes sense in a sailboat, and take best part of a year to do it to enjoy places en route. Seems the Pacific Puddle Jump is a fun way to do some of it.
Reply With Quote
  #10  
Old 02-14-2012, 11:45 PM
sabahcat's Avatar
sabahcat sabahcat is offline
Senior Member
 
Join Date: Dec 2008
Rep: 257 Posts: 793
Location: australia
How about something more fuel efficient?

Quote:
49 ft long with a 6LX Gardner

After cruising the boat for twelve months we are consistently getting 7 - 8 litres per hour at 7 knots (1100 RPM) and we are ecstatic

http://cruisingunderpower.fastmail.net/index.html
Reply With Quote
  #11  
Old 02-14-2012, 11:57 PM
WestVanHan's Avatar
WestVanHan WestVanHan is offline
Senior Member
 
Join Date: Aug 2009
Rep: 413 Posts: 657
Location: Vancouver
Quote:
Originally Posted by Brian@BNE View Post
The journey itself has to give a lot of the payback. I'm trying to test various options, just have this horrible feeling that the checkbook pain of freight could end up being the way to go.
Try Dockwise- float on and float off.

There's yacht path,DYT, and seven star that I know of.
__________________
I think it's bad luck to be superstitious.
Reply With Quote
  #12  
Old 02-15-2012, 08:53 AM
keysdisease's Avatar
keysdisease keysdisease is online now
Senior Member
 
Join Date: Mar 2006
Rep: 205 Posts: 442
Location: South Florida USA
Those Yacht transport ships make regular trips to Australia and New Zealand, and you can stay aboard your vessel enroute.

http://www.yacht-transport.com/homepage.html

Ther are other yacht transport companies, but these guys use the floating drydock style vessel exclusively, other's are usually deck transports.

Steve

Quote:
Originally Posted by WestVanHan View Post
Try Dockwise- float on and float off.

There's yacht path,DYT, and seven star that I know of.
Reply With Quote
  #13  
Old 02-15-2012, 09:45 AM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
Quote:
Originally Posted by sabahcat View Post
How about something more fuel efficient?
I read their story a while back. Seems OK. Not that keen on a project like theirs. Could be fun when time comes to sell, and sooner or later it does.
Reply With Quote
  #14  
Old 02-15-2012, 09:47 AM
Brian@BNE Brian@BNE is offline
Senior Member
 
Join Date: Jan 2010
Rep: 140 Posts: 222
Location: Brisbane, Australia
Thanks folks, when it gets to the point of making an offer I'll contact Dockwise et al. Staying on board for the trip could be pleasant enough too.
Reply With Quote
  #15  
Old 02-15-2012, 11:28 AM
Tad's Avatar
Tad Tad is offline
Yacht Designer
 
Join Date: Mar 2002
Rep: 2037 Posts: 1,719
Location: Gabriola Island, B.C. Canada
According to some recent information, if you are flexible about timing and location of pickup/dropoff and can build a shipping cradle, Sevenstar can be "exceedingly affordable".
Reply With Quote
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pedal Powered Formatted Boat Design 2 12-26-2010 08:28 PM
Powered Trimaran hwbd Multihulls 9 05-06-2009 02:56 PM
Curious New Human Powered Sub Chris Ostlind Boat Design 3 04-17-2009 06:20 PM
Self-Powered wakeboard WakeBoardAddikt Propulsion 8 11-11-2008 03:53 AM
fiberglass outboard powered macka Fiberglass and Composite Boat Building 0 09-28-2008 06:39 PM


All times are GMT -5. The time now is 04:55 PM.


Powered by: vBulletin Copyright ©2000 - 2012, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2012 Boat Design Net