Propane Locker Build

[Flying Knight]

I've decided to save myself about $500 and build my own propane locker. I've already gone over the requirements but don't have much experience building with fiberglass. I'm going to use a concrete form and a few other materials to create the shape, then lay fiberglass over that to make the actual locker. What can I do to ensure the fiberglass and the form separate after construction? How many layers of mat do I need to use for proper construction?

[valhalla360]

Never heard of using concrete as a form but assuming you can get it nice and smooth it should work. Make sure the shape is continously sloped so once broke free, it's not wedged around the form.

For one off tasks, I would use a stitch and glue method. Since it's not a structural item, I would use foam rather than plywood for the core to avoid concerns with rot. A foam cored construction will likely be lighter for the same strength compared to a solid fiberglass.

[Flying Knight]

Thanks. Not concrete but concrete forms. They're just cardboard cylinders of various sizes.

Why have a core at all? Why not just glass?

[valhalla360]

That makes more sense. A sonotube should work fine. Probably easier to just seal it inside and not try to release it.

The idea of using coring is similar to using an I-beam in construction. You can get far more strength for the same weight.
- If you keep it very light weight with solid fiberglass, the result is very thin and easily cracked due to flexing.
- If you thicken it up to resist flexing it gets heavy very quickly. Also resins and fiberglass are getting expensive and you need more of them.
- Instead, by using a core, you can apply 2 thin layers on either side to resist flexing very well while still maintaining a very light design.

Of course for a light duty use as a cover, it's not overly critical to go from 10lbs to 5 lbs. I was mostly suggesting it as construction would be simpler than a solid concrete form.

[Flying Knight]

Ah, that makes a lot of sense. I don't know that sonotube is readily available locally but quickcrete makes forms that HD carries. Same thing.

Only concern is getting the cardboard out after. Is there anything I could line it with or apply so the glass wouldn't stick?

[valhalla360]

Breaking it free from the form will be a problem. It's a constant diameter so poping it free and sliding it out isn't a good option. More likely you will need to grease it up good and then tear it up to get it out.

[HansSolo]

Covering the mold in clear packing tape first will help.

[knottybuoyz]

Originally Posted by Flying Knight

Only concern is getting the cardboard out after. Is there anything I could line it with or apply so the glass wouldn't stick?

Soak it in water. It'll eventually just fall out. I'd use something stiffer than just mat for a reinforcement though especially on the bottom. It's likely to take a bit of a beating on a boat.

[ShipShape]

Originally Posted by Flying Knight

I've decided to save myself about $500

hehehe If you want to save any money then get rid of the boat.

Originally Posted by HansSolo

Covering the mold in clear packing tape first will help MAKE LIFE HORRIBLE.

I tried using clear packing tape over a dowel when trying to preserve some boltholes through my deck - epoxy makes the adhesive on the tape dissolve - since the adhesive was compromised the dowel came out easily, but the tape was embedded in the epoxy and removing it was a nightmare and screwed up the holes.

Epoxy (assuming you are using epoxy, I don't know about polyester) will not stick to PVC, cover your mold with a trash bag and it will separate without too much hassle, then you will just be left with some annoying wrinkles inside your locker.

Why do you want to hassle with a fiberglass locker?? Assuming it is going on your deck, make a box out of outdoor plywood and protect it with paint or epoxy. Quick and easy and that WILL save you $ome. Just make sure the tank and locker are well-secured to your boat, and the drain set-up conforms to ABYC recommendations and you are good to go.

[Matt sachs]

You could build it with marine plywood and fiberglass it?

[boatpoker]

youtube.com

[ShipShape]

Originally Posted by Matt sachs

You could build it with marine plywood and fiberglass it?

1) Maybe for some people double the work and expense = double the pleasure and fun.

2) Bad idea - plywood and fiberglass structure expand and contract at different rates for the same temperatures and humidity.

[knottybuoyz]

Originally Posted by ShipShape

2) Bad idea - plywood and fiberglass structure expand and contract at different rates for the same temperatures and humidity.

Huh?

[boatpoker]

Originally Posted by ShipShape

1) Maybe for some people double the work and expense = double the pleasure and fun.

2) Bad idea - plywood and fiberglass structure expand and contract at different rates for the same temperatures and humidity.

Huh ???

[Matt sachs]

What they said....HUH?