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15-04-2010, 18:19
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#1
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Registered User
Join Date: Apr 2009
Location: West Palm Beach
Boat: Parkins Herreshoff 28
Posts: 932
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A Fiberglass Tankage Thread
one of the projects im most looking foward to this summer is building a huge f.g. water tank under the v-berth, and a 20 gallon f.g. holding tank in the head.
i have a pretty good idea of how im going to go about it, but the few questions i have are...
Baffles - is there some standard to use to determine how many baffles? how close they should be? do i need them in the 20 gallon tank?, maybe 1 i suppose
fittings - those of you that have built one, what do you do for fittings, for the holding tank i will need 3 x 1-1/2" fittings and 1 x 5/8" can i get pvc that will fit 1-1/2 hose well and glass that it on? this would be ideal for a cost effective standpoint. if that will not work, how do you do the fittings?
access plates - i understand they should be big enough to provide access to (almost) all of the tank, are they plastic hatchs that are affordable and reliably water tight? or am i better off building my own? if i do build my own, is it as simple as glassing in some threaded rods, a nice fat rubber gasket and using wing nuts to hold them down?
thanks guys, and you all know a picture is work a thousand words so if anyone has and tankage construction pictures they could share that would be invaluable
all the best,
Ben
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15-04-2010, 19:31
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#2
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Registered User
Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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You may find the info here. Its been a long time since I read it but it should be of interest to you.
http://www.epoxyworks.com/18/pdf/tanks.pdf
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15-04-2010, 22:48
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#3
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always in motion is the future
Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 18,760
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For fittings, I would use fiberglass exhaust pipe and glass them in.
ciao!
Nick.
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16-04-2010, 19:13
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#4
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Registered User
Join Date: Apr 2009
Location: West Palm Beach
Boat: Parkins Herreshoff 28
Posts: 932
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thats all you got for me nick?
thanks for the west article, i have put it in the file, interesting that they do not outright endorse f.g. tanks for potable water, i thought the general concensus was that they are fine if painted with a FDA approved coating??
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17-04-2010, 07:15
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#5
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always in motion is the future
Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 18,760
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Quote:
Originally Posted by pressuredrop
thats all you got for me nick?
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It ain't much, isn't it? ;-) It was the only smart thing about fittings I could come up with...
Quote:
thanks for the west article, i have put it in the file, interesting that they do not outright endorse f.g. tanks for potable water, i thought the general concensus was that they are fine if painted with a FDA approved coating??
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West describes a wood-epoxy composite construction for the tanks, not fiberglass. However, all the remarks they make are concerning the properties of epoxy as in any method used for building the tanks. Basically they say that when you mix the epoxy "resin-rich" and thoroughly, there shouldn't be any leeching of substances from the hardener.
So yes, if you coat it with a FDA approved coating, which adheres well to epoxy, you are okay.
ciao!
Nick.
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17-04-2010, 07:54
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#6
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Registered User
Join Date: Aug 2006
Location: Shelter Island, California
Boat: Stevens 47 Komaru
Posts: 440
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Pressuredrop, I built a 80 gallon fuel tank in the bilge of my boat and 2 water tanks 1 on starboard under the settee the other on port. They are about 60 gallons each. They are all built with epoxy and biax cloth. The tanks are all built in place with a 90 degree flange glassed in to accept the lids, those are pre-cast onto a piece of melamine that was waxed and buffed. For the inspection ports I purchased 2 aluminum ports (expensive) for the fuel tank. I made my own for the water tanks with the method you have described using Buna rubber as a gasket glassed in the bolts. For fills you can use the method that Nick describes, I did use barbed through holes for mine. The pics are of the fuel tank built into the bilge.
I do not think you will need a baffle for your holding tank but if it is long and skinny you may want to put in one. From what I have read, after about 30 gallons you need to start adding baffles.
Jack
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17-04-2010, 07:59
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#7
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Registered User
Join Date: Oct 2008
Location: Puget Sound
Boat: Irwin 41 CC Ketch
Posts: 2,878
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All 3 of my water tanks are all fiberglass...all have baffles but I can not tell you how many or their configuration...as are my fuel tanks.
My holding tanks are Polly...If I were building them out of FG I would not put baffles in those...Marine sanitation is full of enough problems with out adding more to the mix.
Edit:...Nice work Stevens
__________________
"Go simple, go large!".
Relationships are everything to me...everything else in life is just a tool to enhance them.
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17-04-2010, 10:20
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#8
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Registered User
Join Date: Feb 2010
Location: UK
Posts: 834
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Huge tank in V Berth.... huge = 50 gallons?
One point - weights and balances. By my reckoning 50 gallons is about 225 litres which (thanks to the metric system) is 0.225 tonnes which is as far from the centre of balance of your boat (in the V Berth) as you can get so that's going to push the bow down a bit particularly when you have guests in thge Vberth. You might have 1/2 ton in there.
Just a thought...
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17-04-2010, 10:32
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#9
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Registered User
Join Date: May 2006
Location: Nicholasville, Kentucky
Boat: 15 foot Canoe
Posts: 14,191
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Aloha Ben,
I can't tell you exactly where I read it but a baffle should be added every 18 inches which is what I'm intending to do. Minty's post is important. If it is a large tank for the v berth then the weight will be high and in the bow. If you also store an anchor and chain there and have a windlass above it might not be good to have a really large tank too.
kind regards,
__________________
John
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17-04-2010, 10:38
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#10
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Registered User
Join Date: Nov 2005
Posts: 1,156
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So generally speaking, one wants fuel and water tanks in the middle of the boat. But holding tanks in the ends is not as bad because when one is at sea they are generally empty. Plus holding tanks are smaller anyway.
Regarding baffles, I assume they are needed only in the horizontal dimensions... I need to replace a largely vertical fuel tank that holds about 60 gallons and I don't think the old one has any baffles.
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17-04-2010, 17:45
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#11
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Registered User
Join Date: Apr 2009
Location: West Palm Beach
Boat: Parkins Herreshoff 28
Posts: 932
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jack - pretty work indeed, at 80 gallons, you must have some baffles in the tank... got any pictures of those? and your homemade cleanout ports? while your at it
mintys - appreciate the concern, my v berth is a little further aft then unsual, the front is not exaclty pointy, i have a huge anchor locker then small sail locker then v berth. i was going to put it towards the front, but youve deffinetly made me recondsider. if i move it to the back of the v berth i will get more tankage and be pretty close to amidships, but it will be more on one side then the other
p.s. big is > 100 gallons
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17-04-2010, 23:05
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#12
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Registered User
Join Date: Feb 2010
Location: UK
Posts: 834
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Quote:
Originally Posted by pressuredrop
p.s. big is > 100 gallons
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100 gallons = 455L = 0.45 tons (if US gallon then 0.38 tons)
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18-04-2010, 05:04
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#13
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Registered User
Join Date: Apr 2009
Location: West Palm Beach
Boat: Parkins Herreshoff 28
Posts: 932
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correct, should be about 800lbs when full
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18-04-2010, 06:57
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#14
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Registered User
Join Date: May 2008
Location: SW Florida
Boat: Bristol (Alden) 35 Sloop "Zephyr"
Posts: 508
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My 35' Sloop has a 30+/- gal tank under the v berth, and a 50 +/- gal tank under the stb settee.
Neither have baffles. Baffles or not, you need to be able to clean the whole tank, thru the inspection cover.
The tanks in my boat are orig, and the inside surface of the hull acts as part of the tank. It's worked for 40 years so far.
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18-04-2010, 06:58
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#15
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Registered User
Join Date: Aug 2006
Location: Shelter Island, California
Boat: Stevens 47 Komaru
Posts: 440
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Quote:
you must have some baffles in the tank... got any pictures of those? and your homemade cleanout ports? while your at it
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Look close at the top right pic the green strip is the top of the baffle there is a 12x2 plank after obscuring the view of the second chamber. I am having problems with my camera and can not get the pics of it, has the ones with the access ports on it plus tons of others Jack
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