hi everyone,
I was wondering if anyone had made an Fiberglass diesel tank.
I was was considering making a custom job that sits down in the bilge out of the way/keeping the weight central & low (I estimate I can get 25 L which will be enough for a nanni diesel 14 hp)
I going to make it out of epoxy, using the turn of the bilge as a mould, have the bottom 15 or so cm above the keel, with a sump & removable top.
I was wondering what the regulations are etc/how would you went with surveys if I went down this way?
this is is the bilge
thanks
Hi G30. I believe fibreglass makes successful diesel tanks. One boat I know of has a 100 litre tank
and the boat is more than 20 years old, so it seems you won't have a problem with the material.
www.turtlepac.com/products/flexible-water-diesel-holding-yacht-tanks/
I have seen similar in surf club IRBs so i looked on google
Might be an option
Is that an encapsulated keel? My Currawong 30 has a fiberglass fuel tank [40 litre] at the rear of the keel. Sump in the middle and water tank at the front of the keel. Just another advantage to an encapsulated keel.
Yep the keel is encapsulated with concrete over the top of lead ingots/mixed with a resin filler/binder
Hi, before you start this project enquire about vinyl ester as the glue. Its not as strong as epoxy but it is resistent to chemicals / fuel. General rule is cheapest is polyester,epoxy is strongest but most expensive,vinyl ester is most chemical resistant and cost is between epoxy and polyester. Ask the suppliers and get a printout of suitability for intended use. Cheers Bottman
Hi Bottman,
I will ask re vinylester, I have about 4 kg leftover from the holding tank (online research all cases I could find were made from epoxy)
I've made a few diesel tanks in the past. Vinylester is definitely the way to go.
Just form up a plug out of polyurethane foam and glass her up, then cut the lid off, clean her out, baffle her up and tape it back together and you have a nice new, perfectly fitting tank.
Thanks for the responses guys, spoke to the Fiberglass mob, they said either epoxy or vinylester, though vinylester was a bit more chemical resistant, so I will use vinylester for the innermost lamination.
I actually was going to use the hull as a moulding surface & use cardboard to form the bottom/front & back of the tank, putting sign writing vinyl down first so it releases. Or that is the plan anyway 
I actualy did the fist tie layer today out of vinylester, I think I will do most of the tank out of epoxy until I pull it out of the hull as the styrene fumes were a bit much (I was wearing a mask but I kind of feel like I am a bit sunburned).
The hull is the sides of my fuel tank. If I was going to make one in that situation I would cut pre laid fiberglass panels to shape to form the ends and a baffle and glass it in with epoxy. Epoxy over the fiberglass hull sides and the cement base. I would leave a gap at the rear and room for a sump in the centre of the keel. Glass in a plastic piece of conduit on the bottom of the tank as a limber hole so the bilge water can drain to the sump. Glass in a copper fuel pipe from the rear so it ends up about 25mm above the bottom near the front. The top needs to be high enough so the average bilge water does not get to it. The top needs to be removable for cleaning. That size tank the whole of the top can be the removal lid. This is pretty much what I have and most yachts of that era have. It's important to make it easy as possible to clean the interior of the tank.
Hi Ramona,
Thanks for that, the top of the tank is 350 mm above the height the float switch in the sump activates. (Sum/Bilge will take about 100L before flooding into the cabin & then about another 200L before hitting the top of the tank/battery connections)
I was going to
-have an access panel in the middle/back 2 thirds of the tank so I can remove it with the engine in place
-have all fittings on the top
-use polyethylene fillings for the pick up, diesel return, air vent & filler
-have the filler with a tube to the bottom to avoid foaming
-pick up tube to the bottom
-the bottom of the tank is 60mm up so that the manual bilge pump pick up can go under to the sump
-have 2 baffles that are removable for cleaning (held in slots when the lid is closed)
-have it so it is removable if I pull the engine out
I was considering putting an additional access hatch on the front so that cleaning is easier, (would just have to remove the battery bank to access), but would not be a deal breaker as I could clean 90% from the top lid & get to the rest with a rag on a piece of dowel etc 20cm long
Note if you are intending to race, that the Australian Sailing Racing Regs 2.24.9 specify :
" (b) Diesel fuel tanks shall be metal or other material certified as suitable by the manufacturer. "
Currawong has a stainless diesel tank under the cockpit floor and a 75L water tank in the bilge. I hope I never need to replace the plumping as it is solidly glassed in.
Ramona, do you know if this rule was in place when your boat was last seriously racing as Katinka ?
A
Select to expand quotetony10 said..
Hi, before you start this project enquire about vinyl ester as the glue. Its not as strong as epoxy but it is resistent to chemicals / fuel. General rule is cheapest is polyester,epoxy is strongest but most expensive,vinyl ester is most chemical resistant and cost is between epoxy and polyester. Ask the suppliers and get a printout of suitability for intended use. Cheers Bottman
I did hear some time ago that if using West systems epoxy for fuel tanks, go with a slightly resin rich mixture
e.g.: when using the Wests metering pumps , go 6 pumps on the resin and 5 pumps on the 206 hardener (something along those lines)
Stay with the vinyl ester, use peel ply and you will get far less pin holes than epoxy. Vinyl ester is used for avgas on some light aircraft.
Select to expand quoteAndrew68 said..
Note if you are intending to race, that the Australian Sailing Racing Regs 2.24.9 specify :
" (b) Diesel fuel tanks shall be metal or other material certified as suitable by the manufacturer. "
Currawong has a stainless diesel tank under the cockpit floor and a 75L water tank in the bilge. I hope I never need to replace the plumping as it is solidly glassed in.
Ramona, do you know if this rule was in place when your boat was last seriously racing as Katinka ?
A
Last measurement certificate I have is for 2004. No mention of fuel tank construction. I presumed all Currawongs would have the same set up.
