Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors
  #1  
Old 12-25-2016, 08:41 AM
Jmooredesigns Jmooredesigns is offline
Junior Member
 
Join Date: Aug 2004
Rep: 10 Posts: 21
Location: midwest
Question about completely foam filled hulls

Do these manufacturers use stringers? or is the foam filled hull the stringer? Boston Whaler comes to mind here. when they put the deck and hull together and fill the area with foam do they first install stringers or does the foam become the stringer system as well?
Reply With Quote
  #2  
Old 12-25-2016, 09:47 AM
mydauphin mydauphin is offline
Senior Member
 
Join Date: Apr 2007
Rep: 575 Posts: 2,160
Location: Florida
Not sure about Boston whaler but most boat builders that are not using wood anymore are using fiberglass to make the stringet. There may be a foam mold but the strength is in the fiberglass not the foam . And of course that use different fiberglassing techniques and layering systems to create the strongest stringers possible. These foam Frameworks are made from a very dense foam and act like the steel frame in a car. These Framework skeletons many times are bought from specialized manufacturers that make them for the boat builders. it is amazing what they do now with computers and CNC
Reply With Quote
  #3  
Old 12-25-2016, 10:36 AM
ondarvr ondarvr is online now
Senior Member
 
Join Date: Dec 2005
Rep: 506 Posts: 1,290
Location: Monroe WA
The foam may or may not be structural, it all depends on the manufacturer and the design of that exact boat. It can be done either way.
Reply With Quote
  #4  
Old 01-02-2017, 08:28 PM
jorgepease jorgepease is offline
Senior Member
 
Join Date: Feb 2012
Rep: 71 Posts: 798
Location: Florida
I can't see fill-foam being a stringer. If you make a foam sandwich that will give you a lot of stiffness, that fill foam doesn't give you much.
Reply With Quote
  #5  
Old 01-03-2017, 06:04 AM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3967 Posts: 17,802
Location: Eustis, FL
In most cases, production boats use the foam to add to the boat's overall stiffness, as well as address buoyancy requirements. Even 2 pound floatation foam offers some reinforcement to an enclosed space.

As to percentages of how much reinforcement they're looking to gain, well this would be applications specific, so individual boat designs have to be evaluated independently.
Reply With Quote
  #6  
Old 01-03-2017, 09:51 AM
redreuben redreuben is offline
redreuben
 
Join Date: Jan 2009
Rep: 349 Posts: 1,447
Location: Beaconsfield Western Australia
When I used to work on boats full time, repairing or just working with foam filled compartments was a nightmare.
I would be avoiding it if at all possible.
Reply With Quote
  #7  
Old 01-03-2017, 09:46 PM
SamSam's Avatar
SamSam SamSam is offline
Senior Member
 
Join Date: Feb 2005
Rep: 971 Posts: 3,425
Location: Coastal Georgia
I was looking through blared's gallery and ran across this. There doesn't look to be anything but foam in there.

Reply With Quote
  #8  
Old 01-03-2017, 10:28 PM
Mr Efficiency Mr Efficiency is offline
Senior Member
 
Join Date: Oct 2010
Rep: 677 Posts: 5,313
Location: Australia
That would be more a structural type density, probably.
Reply With Quote
  #9  
Old 01-03-2017, 11:03 PM
ondarvr ondarvr is online now
Senior Member
 
Join Date: Dec 2005
Rep: 506 Posts: 1,290
Location: Monroe WA
It doesn't take a high density foam to greatly increase the stiffness in a hull. Plus, the density of the foam increases when used in an enclosed space where it's not totally free to expand.

The other thing is while these low cost foams work very well for a while, they degrade over time, the rate of degradation can be affected by many things, so it's at sort of an unknown rate.
Reply With Quote
  #10  
Old 01-03-2017, 11:31 PM
Mr Efficiency Mr Efficiency is offline
Senior Member
 
Join Date: Oct 2010
Rep: 677 Posts: 5,313
Location: Australia
Countless shock loads will cause the PU foam to break down, especially low density stuff, it must be contained in such a way that water cannot infiltrate, or eventually you will be finishing up with soggy mush.
Reply With Quote
  #11  
Old 01-03-2017, 11:40 PM
Mr Efficiency Mr Efficiency is offline
Senior Member
 
Join Date: Oct 2010
Rep: 677 Posts: 5,313
Location: Australia
Quote:
Originally Posted by ondarvr View Post
Plus, the density of the foam increases when used in an enclosed space where it's not totally free to expand.

.
Which is/was the case with the pictured boat. I'm not sure what the density would be, but I'd guess much more than free-expanding 2lb/cu ft.
Reply With Quote
  #12  
Old 01-04-2017, 10:00 AM
upchurchmr upchurchmr is offline
Senior Member
 
Join Date: Feb 2011
Rep: 579 Posts: 2,324
Location: Ft. Worth, Tx, USA
The foam shown above would be a fairly significant weight to the boat.
Stringers would "probably" be lighter.
Reply With Quote
  #13  
Old 01-04-2017, 11:12 AM
ondarvr ondarvr is online now
Senior Member
 
Join Date: Dec 2005
Rep: 506 Posts: 1,290
Location: Monroe WA
Quote:
Originally Posted by upchurchmr View Post
The foam shown above would be a fairly significant weight to the boat.
Stringers would "probably" be lighter.
You still need foam for flotation, so it's not like it's being totally eliminated by using stringers.

Add in marketing strategy and labor to put the stringers in and it may all balance out for the desired finished product.

I’m not saying it’s the best way to do it, only that Whaler has done well with the design.
Reply With Quote
  #14  
Old 01-04-2017, 11:46 AM
PAR's Avatar
PAR PAR is offline
Yacht Designer/Builder
 
Join Date: Nov 2003
Rep: 3967 Posts: 17,802
Location: Eustis, FL
Whaler's use 6 pound foam and it is considered part of the structure.
Reply With Quote


  #15  
Old 01-04-2017, 03:46 PM
Barry Barry is offline
Senior Member
 
Join Date: Mar 2002
Rep: 158 Posts: 652
Quote:
Originally Posted by upchurchmr View Post
The foam shown above would be a fairly significant weight to the boat.
Stringers would "probably" be lighter.
Stringers (weight) might be lighter than the foam IF only the panel/hull skin would be strong enough to support the structure. If you had to increase the thickness of the skin to gain rigidity in the area between the stringers, then there might not be any weight savings going to stringers
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
Foam option(s) for prototype hulls? jasonvi Boat Design 5 11-11-2016
07:33 PM 
thoughts on using spray foam inside hulls seadreamer6 Boat Design 6 10-13-2012
11:47 AM 
Foam filled ply for sole blakey1973 Fiberglass and Composite Boat Building 9 07-19-2007
05:04 PM 
Foam filling alluminum hulls Guest Materials 12 12-24-2004
12:03 AM 
Structural Foam for Aluminum Hulls jprev Metal Boat Building 3 08-30-2004
09:51 PM 

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.

All times are GMT -5. The time now is 02:01 PM.


Powered by: vBulletin Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2017 Boat Design Net