Hey, folks! I am planning to use magnetic deck hold-downs for the transports I am building. Has anyone else done this? Does anyone know where to get bunches of small rare-earth magnets?
They have lots of the rare earth magnets at my favorite ship store Axe-man Surplus. But unless you're in MN you would have a long drive. I have seen them magents used of decks and for turrets. They worked well. Just make sure the turrets can float or are tied one the ship. I have seen one get hit by a bb and fly off.
Greg's Tirpitz is built like that... I quite like it, no screws to hold on to or drop in the water. The decks 'snap' into place with a reassuring click. Not sure what "rare earth magnets" are compared to "regular magnets"
"rare earth" are like super-magnets. They're much more powerful for a given size, compared to regular magnets.
Check out this topic I launched some magnetic information in there http://www.rcnavalcombat.com/rcnavalcombat/forum/topic.asp?TOPIC_ID=1180&SearchTerms=hold,downs
Harbor Freight has small round rare earth magnets in packs of 10 for something like $1.50 They are about 5/16"X1/8" thick.
Wow, this is an old thread. All the way back in 2008. I do have rare earth magnets now. They worked well enough, and that's all that matters. Kun2112 has an interesting idea about magnetic chalkboard paint, though. I wonder how well that would work.
My local Menards has Rustoleum Magnetic Primer for ~$18 a quart. My local ACE has rare-earth magnets out the wazoo. I already have about 15 or so small magnets. I just wonder if the pull would be enough for a deck seal...
So I broke down and got some of the "magnetic primer" tonight. It is an enamel paint with iron filings embeded in it. It is a VERY thick paint that requires a lot of mixing. They recommend three thin coats--the first is down. Will provide an update.
Well...the results are underwhelming. Magnets hold with direct contact with the paint, but do not hold if seperated by 3/32" of plywood. Right now, I am not sure if even direct contact is strong enough for a deck seal. Sinking, and the air trapped inside, would probably pop the deck off. I also have concerns about how this stuff will react to prolonged contact with water. During cleanup, the bottom of my jar of thinner had a very distinct layer of sediment. Sure enough it looked like the old Wooly Willy game when I got a magnet near it. That much iron would tend to produce a lot of iron oxide if not sealed properly.
I made a thin sheet of fiberglass board by pressing a couple layers of glass between a couple sheets of wax paper. This is thin enough that I can bed metal in resin below it and the magnets stick really well to it. The magnets are imbeded in the bottom of the deck and are flush with it. By bedding the metal, I keep it from rusting. The only problem is when I got behind a cruiser and it let fly - blew all of the superstructure (three separate sections) off the Mogador! Since the superstructure is all foam, it became a tugboat action to clean up.
Well, the good news is that a prolonged submersion test resulted in zero rust. Considering I dropped $30 on the paint, thinner, and a mini roller (perferred method of application), i will let this simmer on the back burner for a while
I painted the inside of my deck tonight. I have 28 3mm x 9mm rare-earth magnets on hand. My sub-deck lip is 1/8" or .125" and 3mm is .118" so I will be gluing an arm to hold the magnets to the bottom of the "lip" and attaching the magnets that way. There should be less than ten thousandth's space between the paint and magnets vertically. Horizontally, I will place a magnet every 4-6 inches--the combined pull should be enough for an effective deck hold down. This is a Treaty boat, so no prop-washing the decks, therefore a water tight seal is not necessary At $0.40 each at the local mom & pop hardware store, the magnets with the paint look to be economically on par with the most common forms of deck seal hardware With the paint, don't bother with a roller, use a cheap-o 1" foam brush or acid/epoxy brush. You could do 10-20 boats per quart if you just painted around the edge of the deck. The can says 16 ft^2 coverage with three coats, so maybe a club's total construction for a few years? Not sure... I used about 10% of the can so far, but a lot was wasted in the roller tray (and soaked up in the roller) and a lot used for testing... Again, don't waste your time with the mini-roller if you decide to try this. The good news is there is only a 30-40min dry time in between coats, so much easier to work with than marine varnish in that regard.
I wasn't going to say anything until I had a chance to test, but the paint does not inhibit radio wave propagation ( at 2.4 GHz ). There may be issues with 75 MHz because of the longer wavelengths, as there is a metallic component to the paint.
I would not think so as you are just painting the narrow strip were the magnets will attach not the whole deck.
