deck prism

[HoffaLives]

i've been given one, and the ones i've seen on boats are beautiful, but am leery of cutting into my deck to install it. has anyone ever done this?

[teshannon]

I've not installed one but I have 4 on my boat and they are really nice. They let in an amazing amount of light.
BTW, been to the city of Victoria a few times and it's one of my favorite places. I always remember the parade of lights around this time of year. You guys are lucky to live there. I hope to get back some day but it's not in the cards in the short term.

[Faster]

Originally Posted by HoffaLives

i've been given one, and the ones i've seen on boats are beautiful, but am leery of cutting into my deck to install it. has anyone ever done this?

Cutting into the deck is a scary thought, but done properly there's no real problems with the idea. If you are only installing one, then you really have to pick your spot. Also, depending on the overhead treatment (molded liner vs attached finishes) how you finish off the inside is another issue.

The prism could also put a good dent in your head so if headroom is an issue you want to pick your spot carefully for that too.

The CS36 has relatively small ports, and I can imagine you'd appreciate a little more light.

When you cut the deck be sure to cut/dig out at least a 1/2 inch of core material all round the cutout and refill that with filled epoxy (try to go far enough that the fasteners are sealed from the core too). Getting a good bond with the inner and outer skins is important and will eliminate the possibility of subsequent wet core, even if your installation were to leak a bit.

Dry fit the prisim, mark the area of the flange on deck and then mask that off generously before bedding the prisim.. it will make clean up a lot easier and result in a much tidier looking install.

You might want to wait for some warmer weather

Good luck.

[teshannon]

My prisms are flush with the interior. There may be different size prisms but if not flush they certainly could be a head knocker. You might check to see if there are different mounting hardware kits available.

[Faster]

I think a true deck prism is just that, the prism effect refracts light over a wide area. The ones I've seen are triangular in cross section, pointy end down.

We have a couple of deadlights over our aft cabin, lets in light, a surprising amount, but I don't consider them to be deck prisms per se.

[teshannon]

Faster,
Mine are like that however they are mounted in a fitting that is flush with the interor such that the point is recessed very slightly but not enough to interfere with the light. Oviously you need a certain thickness of deck to do that and the fittings may have been custom made when the boat was built.

[teshannon]

Faster,
I should have been more specific - mine are triangular in cross section inside the cabin, flat on deck.

[Faster]

You've got the real deal then...I'll wager your decks will be a tad thicker than Hoffa's

[camaraderie]

We have 6 on our Tayana and they work great at bringing in lots of light down below. Ours are rectangular glass and it is really a 3 piece mounting. The first piece is a plastic and mounts from the cabin side flush to the "ceiling" in the hole cut for the prism. the actual glass prism is lowered through the deck so that the triangle portion goes through the plastic piece while the plastic cut out supports the underside edge of the prism. Resting on this edge the top surface of the prism is flush with the deck and the deck opening is trimmed with a stainless steel plate. All edges of the opening are epoxied to prevent water ingress...and the prism is bedded using copious amounts of silicon putty.
I'm sure something similar could be worked up out of wood for any prism with some care.

[HoffaLives]

this doesn't have any hardware; just a blue pyramid of glass with about 5/8 thick hexagonal base that fits in the deck. i was thinking of cutting the deck the same size and shape as the base, but with no metal "holding" it, just glueing it in place, i would be afraid of someone's heel landing on it and pushing it through the deck. are they usually just bonded in place or should there be a metal bracket screwed to the deck (from the inside) that supports it? what cam describes sounds more like finishing rather than structural support.