C-Dory 25 Deck Sole Hatch Installation

[journey on]

ok, here we go. 3M 4000 is a Silane Modified Polymer and is easier to remove. 3M 5200 is a polyurethane and offers some structural benefits.

I used 5200 because I wanted those hatches to be as strong as the deck. Also I feel it seals the screws against seepage into the core. If you only want to lay a bead and don't care about the structural rigidity or sealing, use the 4000. I've used it to caulk around fittings which are bolted in such as the windlass.

Which brings us to the question of the 22 screws holding the hatch down. You realize that the screw only holds through the fiberglass and not through the balsa. So, you have 2 choices: through only the top layer of fiberglass or through both the top and bottom layers. As mentioned above the 5200 helped hold the hatch to the deck, so I only got screws long enough to go through the top fiberglass layer (there are 22 of them.). That said, once the screw is through the fiberglass to its full diameter, longer isn't going to help holding. I forget the exact length, but since the screw goes through the hatch and deck, I think I used 5/8" screws. I do know I got 316 ss screws from Bolt Depot, since the regular 304 screws rust on a wet deck.

There, I beat that to death.

Boris

[thataway]

Be sure that you route out and seal with thickened epoxy any exposed balsa core before you put the new hatch in place. You want to pre drill the pilot holes for the screws so that the area under these holes are part of the epoxy rim which you will form around the cutout for the new raised hatch. I have not done mine--I added more gaskets which helped, plus keep a slant back over the cockpit when the boat is not in use.

If you don't epoxy seal the core, and do the plugs there is always a worry that the core will get wet thru the screw holes as well as the rim of the hatch.

Boris used 5200, and I have also used 5200 with plastic hatches in the past. If you have to ever pull that hatch, it will be difficult. The sealant recommended for plastic and fiberglass together is Boat Life, Life Seal, which is a urethane/silicone hybrid. I used this for the new plastic access hatches on the fuel tank top, the bilge pump and the step access to the fuel lines on each side replacements. This has worked well there.

[Bob&Alicia]

[ssobol]

I would use 4000 or 5200 sealant and tighten the screws all the way to get a good seal (wiping up the excess that squeezes out). This will also seal the edge of the hatch frame to the FG. The 3M stuff does not work the same way butyl does.

Be aware, if you need to remove the hatches for any reason (say one gets damaged), 5200 will make the job harder. Not impossible, just harder. You might remove some of the gelcoat too.

[thataway]

Agree, tighten down the screws with the 5200. I usually tape about an 1/8" or less outside of where the sealant will be, so that it can be easily removed. Same for the top and most of the side of the new hatch--leave about 1/16 untaped, fold the tape over the edge, and then cover the rest of the rim of the hatch with tape.

Good on the epoxy--you can just pretrial the holes, and then route deeper, to get the size plug you need.

[Bob&Alicia]

My new GL Skipper hatches have a slight gap on backside where hatch lid is not really flush around the edges. You can force the gap to close some but not totally. This leaves the screws partially exposed on rear edge when lid is installed. I don’t want another water issue so this concerned me. I can’t really tell from online pictures if this is normal and could get a reply from manufacturer Innovative Solutions.

For those that have installed is this normal?

(Can’t figure out how to upload pic with iPhone)

Thanks
Bob

[thataway]

Is this the photo?



Boris can tell you if this is correct or not--his photo looks like it may over lap some.

But did you seal the core, with epoxy, and and be sure that there was plenty of "beef" to screw into?

[Bob&Alicia]

Yep that’s the photo. Thanks! The lid fits right along the frame on the front and sides but not the rear. I just have it dry fitted and even in the workbench can’t get the rear snug against frame. Maybe that’s the design??

I still have to drill holes and core it out. Was dry fitting it before I did all that.

[thataway]

The proof will be if it the hatch does not leak...

[Bob&Alicia]

I am going to install them. I would think they would fit flush all the way around but the gap is how they came from the supplier. They came in two parts but there is only one way to assemble them. I just have them on the workbench so there is no issue with the boat cutout putting pressure on the frame.

[localboy]

I can tell you all this: I can wash the entire cockpit with a running hose, tilt the boat up to drain and the bilge remains 99+% dry. It's possible that water can leak down via the side wall storage boxes, which are not sealed off. But these hatches make a huge difference. Make sure the sealing surface is clean before you close them, as grit seems to find its way in there.

That back joint looks similar to mine, since the hatches don't have "hinges" and snap into the frame at the rear. Remember, if you cut out the hole to the correct size, the back frame will be parallel to the front more as it won't flex out as much.

FWIW, I used 4000 as that's what I had. I also completely sealed off the balsa with thickened West Systems epoxy, even every screw hole.

[jkswor]

I installed these last fall. Had to add a small strip of gasket. They do not leak a drop of water. Had 3 in of water covering them yesterday as I hosed off deck. No leak
When it rains however I get water in it. Don’t know from where but not from floor hatch