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

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

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 07-24-2008, 04:24 PM
Bruce Hess Bruce Hess is offline
Junior Member
 
Join Date: Jul 2008
Rep: 10 Posts: 31
Location: Alaska
Weight concerns about a boat I'm considering purchasing

Can anyone give me some advice on a 32 downeast yacht I am considering making a offer on?

It is a BHM 32 hull designed by Spencer Lincoln powered with a 260 HP 3208 cat. My concern is that this hull and power configuration normally has a 14 knot cruise and normally weighs about 14000#. This is based on conversations I've had with a current manufacturer of this design, Atlantic Boat Company.

The boat I am considering was laid up extra thick and has some other characteristics that have increased the weight to 20,000# and has a cruise of 9 knots at 5 gph.

Is there anyway to know whether this extra weight has caused detrimental effects or repowering the boat with a more modern lighter weight diesel could a achieve a moderate increase in speed without a considerable increase in fuel consumption? It seems, at present, that the weight may have negated some of the positives usually achieved by the semi-displacement aspects of its downeast design.

How expensive would it be to have a NA run some calculations and are there any recommendations of someone with downeast hull experience that could do this for me?
Reply With Quote
  #2  
Old 07-25-2008, 10:45 AM
Tad's Avatar
Tad Tad is offline
Yacht Designer
 
Join Date: Mar 2002
Rep: 2006 Posts: 1,638
Location: Gabriola Island, B.C. Canada
Fuel use comparison.xls

The attached table compares a range of Maine Lobster boat type hulls, various lengths and weights, showing fuel burn differences at expected speed.

A 32' weighing 20,000 is seriously overweight, these hull forms are designed around speeds of 15-25 knots. The shape is all wrong for 9 knots. Different engine may help, probably a different gear and prop may be more to the point.

This boat is not an efficient runner, therefore I would stay away.
Reply With Quote
  #3  
Old 07-29-2008, 07:41 PM
juiceclark juiceclark is offline
Previous Member
 
Join Date: Oct 2007
Rep: 71 Posts: 373
Location: Fort Myers, FL
A plastic surgeon friend of mine just spend a million bucks on a 40' Cabo sportfishing yacht. He hates it because it's too "corky." I've heard this from several people lately in these new, heavily cored to be light boats. When you get out in the slop the weight helps buffer the beating.

I'll bet you can find ways to lighten the load a bit if you really like the boat. But Tad is right, there seems to be something else wrong...like prop size, bottom growth, a heavy and wet cored deck somewhere, engine problem, etc. etc. etc. A survey is the only way on a deal like that if you think it's worth it.
Reply With Quote
  #4  
Old 07-30-2008, 10:29 AM
Bruce Hess Bruce Hess is offline
Junior Member
 
Join Date: Jul 2008
Rep: 10 Posts: 31
Location: Alaska
I'm suspecting that the prop is sized incorrectly. Could the wrong prop slow a boat like this 6 knots.
Reply With Quote
  #5  
Old 07-30-2008, 10:44 AM
juiceclark juiceclark is offline
Previous Member
 
Join Date: Oct 2007
Rep: 71 Posts: 373
Location: Fort Myers, FL
....sure it could. And that's a lot of "extra glass!" Was something patched or a flaw over-compensated with strength? Who know...but you'd better have a survey check all that out before jumping-in.
TC
Reply With Quote
  #6  
Old 07-30-2008, 11:44 AM
Bruce Hess Bruce Hess is offline
Junior Member
 
Join Date: Jul 2008
Rep: 10 Posts: 31
Location: Alaska
Thanks for the advice on the survey. I do have a survey from 7-07. It doesn't report any patching or other damage. The original owner has indicated the boat was laid up extra thick because he wanted the boat extra stout. I'm also suspecting the weight has been overstated. I'm having present owner weigh the boat to verify. If the weight comes in in the 15,000 pound range I'm going to have Tad Roberts do a propulsion analysis to identify any problems with prop size and or reduction gear issues. If this detects that the speed could be corrected with adjustments to these items I'll pursue a survey and possible offer.
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
Self-steering concerns- multihull vs monohull Seafarer24 Sailboats 5 03-02-2008 10:01 AM
environmental concerns using boat yard paints and other chemicals Kaptin-Jer Fiberglass and Composite Boat Building 44 01-26-2008 11:26 AM
Average Human Weight, Safe Excess Weight, &c. Free Pirate Boat Design 12 03-14-2005 02:40 AM
help in purchasing 1st sail boat bc22 Sailboats 0 08-05-2004 03:31 AM
Mast base laminate concerns Craig_Hastie Fiberglass and Composite Boat Building 3 06-28-2004 10:32 AM


All times are GMT -5. The time now is 12:47 PM.


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