Reply
 
Thread Tools Search this Thread
 
Old 30 August 2009, 13:29   #1
Member
 
chewy's Avatar
 
Country: UK - England
Town: Up Norf
Make: Avon SR4,Tremlett 23
Length: 4m +
Engine: Yam 55, Volvo 200
Join Date: Apr 2007
Posts: 5,217
Under deck buoyancy, what to use?

Have got a new project and wondered whats best to use for underdeck buoyancy. Have seen some polyurethane foam which is two part and provides 27kg of buoyancy per cu ft. I know Powercats use some sort of small ball a bit like a ping pong, and the HR223 used empty coke bottles.
Any one else used something different or which would be best?

Thanks
__________________

__________________
chewy is offline   Reply With Quote
Old 30 August 2009, 16:20   #2
Member
 
Country: UK - Scotland
Town: Ardfern
Boat name: Moon Raker
Make: Humber Destroyer
Length: 5m +
Engine: Honda BF 90 D
MMSI: 235035994
Join Date: May 2006
Posts: 694
Quote:
Originally Posted by chewy View Post
Have got a new project and wondered whats best to use for underdeck buoyancy. Have seen some polyurethane foam which is two part and provides 27kg of buoyancy per cu ft. I know Powercats use some sort of small ball a bit like a ping pong, and the HR223 used empty coke bottles.
Any one else used something different or which would be best?

Thanks
IMHO I think foam is the very worst stuff to use. Whatever the manufacturers say, it does soak up water because the closed cells are rigid and they get progressively crushed as time goes by. Dell Quay Dories suffered badly from this. Provided there's a hatch to get them out if you need to, I would go for ping pong balls or plastic bottles.

Or, as with my boat, nothing at all.
__________________

__________________
alystra is offline   Reply With Quote
Old 30 August 2009, 18:02   #3
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Do NOT use foam!!!!!!!!!!!!!!!!

I wouldn't bother - that's what tubes are for. If you must fill a void another fuel tank is a great way to do it. Even when full of fuel they will keep you afloat but when empty they provide even more lift.
__________________
www.speedshift.co.uk
codprawn is offline   Reply With Quote
Old 30 August 2009, 18:50   #4
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
the amount of scrap boats that our club has broken up over the years,sailing/ power/ply /grp have showed that a lot of so called foam filled would have been death traps ,ok most boats were from the 60s 70s and a few from the 80s so they were old ,but what was worrying was the amount of open cell foam used in bouyancy tanks ect,voids ,any leaks into these area s and the water just stayed there or very little drained back out again ,the amount of water weight was brow raising, and we have seen the home d.i.y using empty coke bottles/ gallon containers most which over the years had gained water .though having said that the cavity wall foam used in building seemed to fair up well .
__________________
m chappelow is offline   Reply With Quote
Old 30 August 2009, 18:56   #5
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
the amount of scrap boats that our club has broken up over the years have showed that a lot of so called foam filled would have been death traps ,ok most boats were from the 60s 70s and a few from the 80s so they were old ,but what was worrying was the amount of open cell foam used in bouyancy tanks ect,voids ,any leaks into these area s and the water just stayed there or very little drained back out again ,and we have seen the home d.i.y using empty coke bottles/ gallon containers most which over the years had gained water .though having said that the cavity wall foam used in building seemed to fair up well .
__________________
m chappelow is offline   Reply With Quote
Old 31 August 2009, 01:41   #6
Member
 
chewy's Avatar
 
Country: UK - England
Town: Up Norf
Make: Avon SR4,Tremlett 23
Length: 4m +
Engine: Yam 55, Volvo 200
Join Date: Apr 2007
Posts: 5,217
Quote:
Originally Posted by codprawn View Post
Do NOT use foam!!!!!!!!!!!!!!!!

I wouldn't bother - that's what tubes are for. If you must fill a void another fuel tank is a great way to do it. Even when full of fuel they will keep you afloat but when empty they provide even more lift.
I know this is in the RIB section buts it actually for a Tremlett 23. I can do anything at the movement as its a bare shell.
Am I best just having sealed compartments wiith inspections hatches?
__________________
chewy is offline   Reply With Quote
Old 31 August 2009, 03:24   #7
Member
 
Country: UK - England
Boat name: Seashell
Make: Redbay
Length: 7m +
Engine: Inboard diesel
Join Date: Jan 2004
Posts: 5,261
Polystyrene is a good option if you do decide to fill it with something. Buy a big sheet, break it up and stick it in. I think I personally would seal it all up, put hatches in and leave it empty.
__________________
Tim M is offline   Reply With Quote
Old 31 August 2009, 03:47   #8
RIBnet supporter
 
Jizm's Avatar
 
Country: UK - England
Town: Southampton
Boat name: Hissing Sid
Make: Ross Smith Cobra
Length: 6m +
Engine: 200HP Optimax
MMSI: 235038046
Join Date: Jun 2002
Posts: 3,803
Ask a packing company (spare parts) for a couple of sacks of the polystyrene chips that look like wotsits!
Jizm is offline   Reply With Quote
Old 31 August 2009, 05:22   #9
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,113
Quote:
Originally Posted by Jizm View Post
Ask a packing company (spare parts) for a couple of sacks of the polystyrene chips that look like wotsits!
If you do go down that route then (1) make sure they are Polystyrene - many places now have moved over to biodegradable ones which slowly dissolve in water! (2) think about the implications of a fire in that space.

Personally I would say that anything small like that is fairly pointless - as a big hole will let them all out! I agree about foam filled being a giant sponge.

I would tend to leave it empty - and consider fitting a bilge pump (or fitting where you could connect a self priming pump - with tube to the bottom of the void on the inside) - if you are really worried.
__________________
Poly is online now   Reply With Quote
Old 31 August 2009, 05:33   #10
Member
 
Country: UK - Scotland
Town: Glasgow
Length: 6m +
Engine: Yamaha
Join Date: Jan 2009
Posts: 134
dont fill it with foam, like everyone else has said, it will get waterlogged, heavy and it is a nightmare to remove. i would fill the void with air. best not put anything there. the less stuff you have on the boat, the less stuff you have that will go wrong.
__________________

__________________
Heart-trouble is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 03:45.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.