Deadlights & Deck Prisms

[Ronin NW]

Here's a trying-to-save-some-money-by-cutting-corners question (how rare!). Don't be turned off though, I still think it's intriguing...

Ronin formerly had a big ol' solid fuel stove in her galley, long since removed by a previous owner. Last summer I installed the new 2-burner (w/oven) Force 10 propane unit, and we love it. There's only one thing remaining to be done in the overall galley/stove settup: the old charley nobel deckring is still tucked away on the deck (not the housetop) behind the stove.

My original plan was to remove the deckring and replace it with a skylight of similar size. This would provide ample lighting to all of the galley supplies and whatnots stored behind (outboard of) the stove. I've had this in mind and have been looking around for a while, but darned if they're not around $200.

So now my question is whether I can install a deadlight in the same place for a drastic savings in cost. The lighting aspect here is not perhaps the most crucial element, more an added bonus. I'd really just like to clean up the deck and finish the job. A deck prism would be ideal, and they're pretty beefy since designed for the job, but a deadlight my be sufficient... would a deadlight (with a lexan or similar glass) be up to the possible abuse it could take from above in a relatively high traffic area?

Thanks for your thoughts,
Scott

[Dan McCosh]

Deadlights are plenty strong, but they get scratched with traffic. If it's a high-traffic area, it seems as if you would trip on a prism. I used to have a 9-ins. circular prism that probably would work, so I know they make them.

[ssor]

I just googled "deck prisms" and got a ton of hits. The first one offered a bare green glass 4"x4" pyramid shape for about thiry five bucks. Just have an aluminum or bronze "angle iron" frame made for it and set it with 3m 5200 sealant first in the frame and then set the assembly in the deck in your favorite bedding compound.

[ssor]

I forgot to add the almost obvious, the pointy end always goes down and thus spreads the light inside the cabin.

[Andrew Craig-Bennett]

We have three circular deck prisms of the "grapefruit squeezer" type, and five rectangular ones.

The circular ones pass much more light, and are well worth it.

The glasses fracture erratically, probably due to stresses locked in in cooling. Carry a spare.

Are you really sure you no longer want the ventilation?

[Ronin NW]

The hole in question hasn't been ventilating anything for some time. There's a porthole on the house side just above (and about 2 ft aft of) the stove, which is usually open. The old chimney was long gone, the charley nobel covered (quite snugly) with a plunger. You can understand the aesthetic issues here.

I love those grapefruit-juicer style prisms, and they're in a variety of sizes so I know I could find one (pointy bit down of course), but they cost an arm and a leg. The green pyramids are sold everywhere as paperweights, but how do they actually compare to the grapefruit juicers as a functional prism?

Dan, what was the material in your scuffed-up deadlights? Would something else work better?

Thanks thus far...

[rbgarr]

This item may be too pricey, large or in the way, but it might prevent scuffing of a glass or lexan deadlight if that concerns you.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4520728503&rd=1&sspagename=STRK%3AMEWA%3AIT

[Andrew Craig-Bennett]

1 grapefruit juicer type = 3 pyramid types.

[Ian McColgin]

Is it really a good idea to put something that slippery in a high traffic area? Most deadlights and prisums I've seen were installed in places where the foot was less likely.

[paladin]

You can use 1/2 inch or 3/4 inch lexan....or three or four layers of automotive glassepoxied together using epoxy from a glass shop.....it's optically transparent...and use to bond prescription glass to diving masks...and make your own decorative rings from bronze or brass...

[Bob Cleek]

Those green glass pyramid deck prisms sold as paperweights are just that... paperweights. Somebody started copying one they copied at Mystic that supposedly came off the Morgan. Problem is, they are no where near finely finished enough, and they are slippery. It sounds like you are going to need to fill at least a three inch hole, no? Have you considered making your own? It doesn't take much to melt glass and it doesn't take any special glass to make a prism. Now, I'm not saying I've made one lately, but all it takes is a mold to pour the glass into. Coke bottles ought to do just fine. If you know a glass blower or potter with a kiln, it may be useful. In this way you can get the exact shape you need, citrus juicer or whatever, and figure some way to put a non-skid finish on the top. It doesn't matter that you can't see through it... translucent is what it is about. Add a trim ring and you're done.

[TimothyB]

Here's one that looks like a legit deadlight:

http://www.columbiatrading.com/cgi-bin/columbia/18685.html

[Alan D. Hyde]

You could rig up something, as Bob suggests... Use recycled glass, and mind the fumes.

The ancients did it with wood.

You could do it with charcoal and a hairdryer. IIRC, you may need somewhere between 1600-2700 degrees F. to melt glass.

Alan

[Hugh M.]

Someone once told me that deck prisms condense and drip when it is cold outside and warm inside the boat. Maybe this isn't a problem in a galley, but don't put one over your bunk! Could be especially bad with a propane stove making nice warm, wet air.
Something to consider.
On the bright side it could be an el-cheapo watermaker - kidding.
-Hugh

[ssor]

In my never ending quest for information I came upon this site for prisms:

http://www.boatdeckprism.com/cgi-bin/cgiwrap/boatdeck/cp/cp-app.cgi?pg=store&sub_pg=main_cat&ref=1

They seem to have a good array.
If condensation might be a problem, you could add a second glazing disk separated from the prism by a dead air space.

[PeterSibley]

Andrew
1 grapefruit juicer type = 3 pyramid types.
Why are the juicer variety so much better ? Brighter ? Better diffusion?

I had thought to mould the juicer shape or alternatively the pyramid from clear acrylic resin then bond a 3/8" or 1/2" layer of glass on top to protect it.How does this sound? Does anyone have an idea of the required adhesive....I assume the rates of expansion are different .

[Alan D. Hyde]

Here's an interesting discussion of glass-making:

http://www.unc.edu/courses/rometech/public/content/arts_and_crafts/Susan_Hampton/Roman_Glass.html

***

Alan

[PeterSibley]

Bump :D

Does anyone have a suggestion about bonding glass to acrylic ?

[Stargazer14]

Why not just 5200 to your this (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4208&item=377787421) to your deck.
It even has an anchor on it...... :rolleyes: