Fiberglass sheet

Sy-Revolution

Sy-Revolution

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Does anyone know where I might get hold of some fiberglass sheet (5mm thick) in the East Anglia area? I'd like to make up a water tank and holding tank and I'm sure I saw an article somewhere where prefab sheet was used and bonded with GRP to form the tank.

Any ideas?
 
G'day RECUSANT2,

Don't do it......

Having seen a few of the home made single sheet tanks I can only comment that:

They can have sharp edges.
They can look like [--word removed--] with poor finish at joints.
But worst of all they tend to sweat with condensation forming on the outside leading to fresh water entering your bilges, not a good thing at all.

However you can avoid all of the above if you glass over foam:

Start by cutting the foam to the required shapes, and radius the corners and edges, tape together and glass the inside and outside using standard resins and CSM (Chopped Strand Mat). add a single layer of roving's last to give a smoother finish and ensure no strand ends are exposed. when cured sand the outside smooth and apply closed sell balloons mixed with resin to fill any low areas as required then flow-coat the outside, (standard resin and pigment).

Now go back inside and apply 4 or 5 coats of epoxy resin wet on tacky to avoid sanding between coats, then after curing a light sand and apply a high build epoxy primer.

Now make up the lid and treat as above making sure the inside top edge is covered with epoxy, add a little epoxy mixed with micro-fibres and drop in on. when cured add a little more filler and sand then finish the flow-coating.

Don't forget to add the plumbing and a removable inspection cover as you go. You can make fibreglass stick to PVC pipe by rapidly heating it with a flame till you see small black balls form on the heated surface, wipe with Acetone and do not sand it.

Hope this helps.

Avagoodweekend.
 
Hi Oldsaltoz,
Thanks for that, I've already sucessfully made myself a 140l fuel tank the 'traditional' way that you've explained above but it took quite some time and alot of mess. I've moved into a new house with no workshop facilities and was hoping to make the next two tanks using a simpler method. I might just have to bite the bullet......
 
Hi Brian. I think we should elaborate on foam types and resin types.
The classic polystyrene foam is not the best and will dissolve with polyester resins. Ok I think with epoxy. if you can find urethane foam that will be OK with polyester resins and even better is pollyester foam.
You need a closed cell stiff small cell foam.

Of course most chopped strand mat is not suitable for epoxy as the filler will not dissolve. Use a fillet on the inside corners and smooth the outside corners to leave a nice radius. Then a cloth may be easier to get to sit in corners. A twill weave bends easier. however if you use cloth you will need more layers.

Double check on my suggestions of materials. But resin types and compatabilities are important. olewill
 
<<<<<<Hi Brian. I think we should elaborate on foam types and resin types.
The classic polystyrene foam is not the best and will dissolve with polyester resins. Ok I think with epoxy. if you can find urethane foam that will be OK with polyester resins and even better is pollyester foam.
You need a closed cell stiff small cell foam.

Of course most chopped strand mat is not suitable for epoxy as the filler will not dissolve. Use a fillet on the inside corners and smooth the outside corners to leave a nice radius. Then a cloth may be easier to get to sit in corners. A twill weave bends easier. however if you use cloth you will need more layers.

Double check on my suggestions of materials. But resin types and compatabilities are important. olewill.>>>>>>

G'day Olewill,

For tanks I much prefer Klegacell foam, it works with all resin types and unlike many other foams will not crush and is not brittle; you can also apply heat and bend it into shape if needed.

The problem with urethane foam is that it can crush under impact so not used much anymore for hulls or exposed structures.

When weight is not a major consideration and you need the cost down then standard poly resins are fine, However you must complete and joints between existing poly structure and the new item with an epoxy for "most" applications.

The use of epoxy in this case is only to ensure the tank is waterproof and chemical resistant, and to ensure the epoxy also covers the joint between tank shell and top cover.

As for resin rules and cloth: Epoxy will stick to just about anything, but poly resins do not stick well to epoxy. even sticking new poly to old needs care as the bonding is not as strong as with epoxy, fine for things like backing plates and lifting eyes as the structure is under compression, but avoid joints under tension.

Avoid the use of CSM (chopped strand mat) with an epoxy because the binder may bot dissolve, but more important is the fact that the voids in CSM will not only mean you use a lot more epoxy resin, but end up with a weaker joint or structure at a greater cost.

Only use cloth designed for epoxy when using epoxy resins, aim for a ration of 1 to 1 resin to cloth by weight.

Standard resins and CSM require a ratio closer to 3 to 1, 3 resin to 1 cloth by weight.

Re corners and the use of fillets, good point Olewill, filling the corners will not only make it stronger but a lot easier to coat and clean later.

I hope this helps.

Avagoodweekend......
 
[ QUOTE ]
I would stay clear of GRP tanks completely as the GRP will de-laminate over time. Go for a plastic tank or aluminium or 316 stainless steel in that order of preference.

[/ QUOTE ]

There must be thousands of GRP tanks out there and many well over 20 years old that I built and I have seen one delaminate yet.

I have seen tanks fail because the design, application or location wall wrong or the lining failed or was never applied in the first causing the failure.

Delamination is caused by poor layup or bad practice like too much humidity when curing, over flexing can also cause delamination but not common in tanks as the baffles built in create enough stiffness to prevent it.

Avagoodweekend......
 
I am just after looking at a rib that has a built-in fiberglass tank and it has de-laminated after 10 years and is now unusable which is just one of many I have come across. Currently the owner is using a portable tank on deck. The only way to salvage the space used by the built-in tank is to cut the helm station out and slot in a plastic tank. A well respected marine engineer from Spain also confirmed that it is a major problem in the Med too.
 
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