Joe,

I have put deck ports in both of the 6.0s I have owned. Properly installed they are as strong or stronger than the deck around them, will add to the overall strength and life of the boat by improving air circulation while the boat is stored, make great storage places for distance racing, and give you access to the board trunks , shroud anchors, and front beam area should you need to make any repairs.

I would recommend the Beckson 6 inch portals. I liked the ones with the textured non-skid surfaces.

west marine part number 106260 or 106254 depending on whether you like white or black.

I would place them exactly half way between the daggerboards and the front beam.

At a high level the installation process is:

1.) mark your decks
2.) cut your holes
3.) test the fit of the portal (always using the ring with the lid in place in it, otherwise the ring can be out of round)
4.) mix up some epoxy resin
5.) "paint" the foam and glass around the hole with resin, allowing it to soak into the foam core around the hole.
6.) add either micro-balloons or hardware filler to the epoxy until it is peanut-buttery consistency.
7.)glue the portals in. (make sure that the lids are in the rings when you do this or as I said previously you can end up with rings out of round, then you are in trouble. Make sure you do not glue the lids into the rings.)
8.) fillet the area around the rings using the thickened epoxy. (do not attempt to screw the rings down. The screws are not necessary and will only tend to bend the rings out of plane)

Once the epoxy hardens you are good to go. I additionally liked epoxying a small eyestrap to the inside of the hull somewhere near the portal. The Beckson portals have a fitting in the lid for a screw-eye. put a stainless steel screw-eye in the portal lid, and then tie a piece of light line from the screw eye to the eye-strap. Then, when you remove a lid on the water, you don't have to worry about losing it.

When storing your boat, leave the portal lids off and cover the portal with something that will let air circulate, yet keep rain and vermin out. Your fiberglass hulls will appreciate the extra air circulation.