Like Tree0Likes

How much does added weight effect your speed ?

Reply
Old 07-21-2004, 06:45 PM
  #11
Registered
Platinum Member
 
Comanche3Six's Avatar
 
Join Date: Sep 2003
Posts: 9,273
Default Re: How much does added weight effect your speed ?

I slept at a Holiday Inn express last night and my boat will do 74 mph with a full 100 gallons of fuel and 82 with about 10 gallons left. Usually, regular unleaded gasoline has a gravity of around 58 and a weight per gallon of 6.216 pounds per gallon. Premium gasoline may have a gravity of 54, or 6.350 pounds per gallon
Comanche3Six is offline  
Reply With Quote
Old 07-21-2004, 07:03 PM
  #12
Warped & Twisted Member
Platinum Member
Thread Starter
 
Jamie B.'s Avatar
 
Join Date: Jan 2002
Location: 4 Miles Offshore, IL
My Boats: Cigarette Top Gun w/ V6's and Maxum 3000 SCR
Posts: 2,117
Default Re: How much does added weight effect your speed ?

Quote:
Originally Posted by 42MTI
Jamie'
I think it depeends on the type of hull as well as the brand. In my 42 fountains I never saw much if any difference. However in my can there is an noticeable difference. I think the formula for it is 1mph for ever 200lbs and the nortech is similiar.
Interesting. You have a much higher top speed in your MTI than you had in either of your Fountains, I assume. Thinking about that, you would think that the total top speed of the boat in question might also have alot to do with it (?) . . . will 200 pounds effect a boat that normally can do a 150 mph top speed the same as it does one that does a 65 mph top speed ?

How much does your MTI weight ?
Jamie B. is offline  
Reply With Quote
Old 07-21-2004, 07:07 PM
  #13
Warped & Twisted Member
Platinum Member
Thread Starter
 
Jamie B.'s Avatar
 
Join Date: Jan 2002
Location: 4 Miles Offshore, IL
My Boats: Cigarette Top Gun w/ V6's and Maxum 3000 SCR
Posts: 2,117
Default Re: How much does added weight effect your speed ?

Quote:
Originally Posted by CigaretteFirefox
I slept at a Holiday Inn express last night
lol

I round up to 7 per gallon
Jamie B. is offline  
Reply With Quote
Old 07-21-2004, 07:09 PM
  #14
Warped & Twisted Member
Platinum Member
Thread Starter
 
Jamie B.'s Avatar
 
Join Date: Jan 2002
Location: 4 Miles Offshore, IL
My Boats: Cigarette Top Gun w/ V6's and Maxum 3000 SCR
Posts: 2,117
Default Re: How much does added weight effect your speed ?

Quote:
Originally Posted by CigaretteFirefox
my boat will do 74 mph with a full 100 gallons of fuel and 82 with about 10 gallons left. Usually, regular unleaded gasoline has a gravity of around 58 and a weight per gallon of 6.216 pounds per gallon. Premium gasoline may have a gravity of 54, or 6.350 pounds per gallon
How much does this boat weight ?
Jamie B. is offline  
Reply With Quote
Old 07-21-2004, 07:14 PM
  #15
Registered
 
formula31's Avatar
 
Join Date: Mar 2001
Location: ohio
My Boats: 1988 Cruisers 2800 Rogue
Posts: 2,558
Default Re: How much does added weight effect your speed ?

Strangely, my boat is faster with a full tank of fuel, probably has something to do with moving the center of gravity to its optimum point. Then, cold air, 1-2 footers is the best.
formula31 is offline  
Reply With Quote
Old 07-21-2004, 07:29 PM
  #16
Warped & Twisted Member
Platinum Member
Thread Starter
 
Jamie B.'s Avatar
 
Join Date: Jan 2002
Location: 4 Miles Offshore, IL
My Boats: Cigarette Top Gun w/ V6's and Maxum 3000 SCR
Posts: 2,117
Default Re: How much does added weight effect your speed ?

Quote:
Originally Posted by Troutly
Well, lets see....200 lbs is about 32 gallons of gas.....and I have 194 gallons on board.....assuming I don't burn it below 32 gallons.... I might gain 2 MPH total.
How much does your boat weight dry ?
Jamie B. is offline  
Reply With Quote
Old 07-21-2004, 08:03 PM
  #17
Registered
 
dreamboater's Avatar
 
Join Date: Apr 2002
Location: Southern Maryland
My Boats: 2000 28 Skater
Posts: 1,234
Default Re: How much does added weight effect your speed ?

I have heard in twin engine O/B cats, 200lb can equal as much as 2mph. Some boats are just more weight sensative than others, Cats especially. Dont know if there is an exact formula for this. Our 37 Outerlimits actually has run faster loaded down than empty. I am pretty sure that has something to do with not having the right props, but weight has not slowed the boat down as of yet.
dreamboater is offline  
Reply With Quote
Old 07-21-2004, 08:21 PM
  #18
Registered
 
Join Date: Jun 2004
Location: Atlantis
Posts: 24
Default Re: How much does added weight effect your speed ?

I personally think that the more iced down cocktails we have on board the faster the boat seems to go
Lady X is offline  
Reply With Quote
Old 07-21-2004, 08:52 PM
  #19
Charter Member # 545
Gold Member
 
Beak Boater's Avatar
 
Join Date: Dec 2000
Location: Port Tobacco MD/Cape Coral Fl
Posts: 2,151
Default Re: How much does added weight effect your speed ?

I think the heaviest thing you can put in a boat is a GPS, the boat always slows down 3-5 mph when you add one of those!!!!
Beak Boater is offline  
Reply With Quote
Old 07-21-2004, 09:26 PM
  #20
Gold Member
Gold Member
 
Hydrocruiser's Avatar
 
Join Date: May 2004
Posts: 5,759
Arrow Re: How much does added weight effect your speed ?

http://www.go-fast.com/boat_speed_predictions.htm

I used this speed calculator and started with a 8500 lb (let's say 35' step hull) and T-500 HP engines. The calculated speed is 86 mph. For every 200 lbs you add you loose exactly 1 mph. If you go down to a lighter boat of say 4,000 lbs, even with the same power and size you loose 2 mph per 200 lbs added. So you are right, the heavier the boat the less effect additional weight has on speed even though the lighter weight boat obviously has a faster (112 mph in this case) top end. The boat does not have to be bigger it's a function of weight in a planing hull. Just as a side note by adding steps you may see an additional 10-15 mph on the top end and to get this same speed gain by decreasing weight using light weight composites it would take a weight reduction of 1,500 lbs to gain the benefit (10-15 mph) of steps. So a non-stepped 35' boat that weighed in at around 7,000 lbs would go as fast as a stepped hull weighing 8500 lbs. If you could get the weight down to 6,000 lbs a "traditional" non-stepped 35' deep V would go 92. So as I see it steps give higher MPH by a simple hull design change with no additional manufacturing costs whereas reducing weight is expensive.

I went the extra mile out of curiosity to figure this out for the fun of it.
Not an easy one to understand.

Last edited by Hydrocruiser; 07-21-2004 at 09:49 PM.
Hydrocruiser is offline  
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
scarabrun
Scarab
2
09-25-2007 01:10 PM
Daniel
Cigarette
19
09-22-2006 12:00 PM
Bad Girl
Fountain
6
07-18-2006 10:17 AM
Craney
General Boating Discussion
5
06-27-2006 08:52 PM
Toffen
General Boating Discussion
7
04-11-2004 02:26 PM



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 On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 04:28 AM.


Copyright 2011 OffShoreOnly. All rights reserved.