hans
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Posts: 166
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Post by hans on Oct 21, 2011 14:08:13 GMT -5
Martin,
just today I started to build the mold for my aux tank. I only need an aux tank when I'm flying solo, so I planned a delivery tank type of thing that is located on the front seat. I too want to keep the turtle deck storage space.
My aux tank will be laminated with vinylester resin. All the connections (fuel line, vent line, etc.) will be be located in a top mounted inspection cover. I have not yet decided on what I'm going to use as a transfer pump.
cheers
Hans
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Post by wannabe on Oct 21, 2011 19:43:05 GMT -5
I had a friend who built a motorcycle tank out of Polyester vinyl resin fiberglass and it did not hold up to the fuel he ended coating the entire inside of the tank with Pro-Seal (expensive). Epoxy Resin would be better. I am not an expert, maybe someone else can speak to this.
Also, are you putting an aux tank in an in a straight SII (not stretch)? Is that part of the plans? I only have stretch plans.
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Post by oahupilot on Oct 21, 2011 22:09:56 GMT -5
The proper resin for fuel tanks is vinyl ester resin. Polyester and epoxy have issue with fuels, this was discussed before in on the s.net archive.
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hans
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Posts: 166
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Post by hans on Oct 22, 2011 4:34:24 GMT -5
Wannabe, my resin choice was made for the reason Oahupilot mentions. His reference and a few others I came across document that only vinylester will hold up long term. Apparently it's a bit more messy to work with than epoxy, but I'll have to come to terms with that when the time comes.  This delivery tank is going to end up in an Sonerai II. It's not part of the regular S-II plans that came with my ship. I have made a number of pics of my mold building and will continue to do so through the entire build process, so perhaps our new Sonerai.net home to be will one day contain a 'how-to' on this very topic... Hans |
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Post by oahupilot on Oct 22, 2011 11:59:54 GMT -5
Hans
vinyl ester becomes very tacky or sticky quickly, 10-15 minutes, mix small batches at a time and work quickly.
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hans
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Posts: 166
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Post by hans on Oct 22, 2011 15:53:38 GMT -5
Hans vinyl ester becomes very tacky or sticky quickly, 10-15 minutes, mix small batches at a time and work quickly. Thanks! I'll do some test laminates first before tackling the delivery tank. Hans |
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Post by oahupilot on Oct 22, 2011 19:17:22 GMT -5
Hans,
How do you intend on building the mold? Are you going to do a 2 part female/male mold?
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hans
Full Member
Posts: 166
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Post by hans on Oct 23, 2011 3:42:08 GMT -5
Hans, How do you intend on building the mold? Are you going to do a 2 part female/male mold? one mold for the tank, one mold for the lid which is going to contain an alu inspection cover. I've got 4mm (0.16") 2024 lying around, so it would be most cost effective to use that for the inspection cover and it's mounting ring. So far I have a sticks & glue frame set up that defines the tank perimeter. This thingy was assembled in-situ. From my yachting years (I used to dabble in sailing yachts and be a delivery skipper) I know that the simplest way would be so simply take plywood, glue a box from that and simply cover its in- and outside, ie. in that case it would become a composite structure with a plywood core. This afternoon I'm again going to work on it, this is one of the decisions I'll take this afternoon. Hans |
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Post by oahupilot on Oct 23, 2011 11:09:01 GMT -5
I suggest you use polyurethane foam for core instead of wood, should be much lighter that way. You could also build a single wall tank from a sealed and waxed mold.
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hans
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Posts: 166
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Post by hans on Oct 23, 2011 12:20:21 GMT -5
see the JPG file in the attachement, which shows the sticks & glue contraption that defines the outer perimeter of my future delivery tank. I'm going to use it to take measurements from. These measurements will end up in a CAD system, trued up to make it symmetric and be used to plot the individual panels. This thingy was created on top of the front seat and could be taken out and inserted again, which, as you may gather, is a desirable property of a delivery tank  Also, my feet fit adjacent to it, so I'll still have the rudder to play with when this tank gets installed... cheers Hans Attachments:
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Post by martinroy6100 on Oct 25, 2011 17:17:02 GMT -5
Hans:
I would look at purchasing a tank from an out board outfit or take a look at race car catalogs. They have a great number or tanks in varying sizes, by the time you build you will have more into them than you care to admit. Some items I will absolutely build, others I buy already done.
I saw a 4 gallon tank built to racing specification that would work great for $99.
Martin Roy
N61QC
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Post by raceair on Oct 25, 2011 17:49:47 GMT -5
Martin....Very often, these inexpensive, beautiful race car tanks are VERY heavy....Check with them before you get serious....I have seen them welded up from 1/8" aluminum......Ed
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Post by hairy47 on Oct 25, 2011 18:47:59 GMT -5
Hi
I just built a wooden frame, sat a outboard fuel tank in it,used the seatbelts to tie it in and used it for a 2000+ mile trip.
Just needed to be high enough for gravity feed; hand through hole in back of front seat to change tanks and modify the vent to suit both tanks.
It gave me an extra 25 litres.
Dave
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hans
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Posts: 166
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Post by hans on Oct 26, 2011 15:24:49 GMT -5
I've looked into pre-fabricated tanks for boating, both welded job as used for outboard engines and roto-molded fixed tanks. I wasn't too impressed, especially the rotomolded jobs are rather heavy and the welded tanks were not in sizes & volume that I would prefer to have. As to tank volume: this sticks & glue contraption has a volume of over 50 liters / 14 gallons. Even subtracting the volume of the structure, I'll end up with at least 45 liter, which more than doubles my current 10 gal. tank. There will be a transfer pump that transfers the fuel into the main tank.
cheers
Hans
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Post by o2koold on Oct 27, 2011 19:15:34 GMT -5
Hi Hans, Have you considered using the old one-off foam block trick? I am making my own main tank with this technique. I have Styrofoam blocks that I am shaping, and will then seal with clear packing tape. Once I know the shape of the top and have it taped up, I will wax and use PVA this one off plug/mold. After glassing the whole thing, I will cut out the hole for the filler neck and dissolve the mold with gas. Then just clean out the tape and glass in the filler neck. I will try and post a picture off the bottom shape so far. Scott R Attachments:
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Also, my feet fit adjacent to it, so I'll still have the rudder to play with when this tank gets installed... 
