: I have made magnetic flush hatches for my CH16, and I have read in past posts
: that if you do not put a layer of fibreglass over the magnets they will
: rust.
: My idea to stop this, is to put a layer of glass over the magnets but i need
: the layer to be as thin as possible so I thought vacumn bagging would
: achieve this but getting a pump and attachments in New Zealand(where I
: live)is extremely expensive so I am wanting to know if anybody has built a
: vacumn bagging setup at home and if so would you like to impart your
: knowledge to one how knows nothing.

If all you need to cover is a few magnets, why bother with any of this stuff?

Buy a minimum purchase of the thinnest glass cloth or non-woven glass mat veil material you can -- probably a yard -- and just use that.

You can find glass cloth in very light weights at hobby stores. Anything at 2 ounces per yard or less will be very thin, and should be suitable.

Glass the hatch over as you normally would, drill out the holes for the magnets, add some epoxy resin to hold the magnets in place and drop in the magnets. Then cover each magnet with a coat of epoxy resin, and paint the resin to about a two inch circle, centered on the center of the magnet. Drop on top a 2 inch diameter piece of your very thin glass cloth. It should wet out almost instantly.

Set a sand-filled plastic bag (like the kind used for sandwiches, or kitchen food storage) on top of this patch and walk away for a day. The plastic bag won't stick to the epoxy, so you can just peel it back after the resin sets up. the smooth plastic should leave a smooth finish over your patch, minimizing sanding and reducing the need for additional coats to fill the weave. In fact, if you use something like 3/4 ounce (that's 0.75 ounce) non woven mat you won't have a "weave" pattern to fill.

Defender (http://www.defender.com/cgi-bin/Web_store/web_store.cgi?cart_id=) has these lightweight materials in their catalog -- which is acessible online, but not in their online store.

While you may not wish to order from Defender, the information in their catalog may help you in trying to find similar materials at stores closer to you.

Strangely, you have to go to their online store to get access to their online catalog. This is confusing, I'm sure, but just copy the URL above and when you get to the page, scroll down on the left side of your screen to the line "Catalog in PDF", and click on that. The next page asks you if you want to search by name or page. select "Search by page" and find fiberglass on page 50 in the list.

You'll find their "Angel hair" glass cloth listed under the heavier materials on that catalog page. It is US$1.05 a yard. One yard is more than you'll need for dozens of magnets and hatches.

By the way, when they scan in their new catalog the page number may change.

Have fun with your magnets.

PGJ