Deck Hatches
Image Gallery
Project Logs
Coming soon…
Questions
+Don Casey says to wait for the polysulfide to cure for 1 week, then tighten the nuts on the through bolts all the way down, is this the way to go?
-> Casey also said on an online article to…
Snug But Don’t Tighten – Assemble the parts and “snug” the fasteners enough to squeeze seal-ant out all the way around. The most common bedding error is fully tightening the fasteners while the sealant is soft. This squeezes out all of the sealant, leaving a dry joint that will soon leak.
-> I’d like to ask Eric about this. I also want to know if he thinks I could use the epoxy method he mentioned on 3/12 for this hatch. -> On 4/3 I spoke to Eric about this and he mentioned that the whole idea is to try and make a gasket. To do so, put on sealant, snug it down to where it squishes out, but not completely out. Let it cure for whatever curing time (1 week) then go back and do another 1/2 or 1/4 turn on nuts below to finalize the installation. If I tighten the nuts (don’t turn the fastener!) this won’t rip the caulk and break the seal. I asked if he thought I could use epoxy and he said sure.
+ Is it Ok to just secure cockpit hatch with #10 x 1 ¼” screws, not through the cockpit sole?-> Yes, because there will be a cockpit grate on top of this for added protection and most forces on the hatch are pushing down. -> However, later on, I read that it should definitely be secured using through bolts.
Research
- When equipped with good gaskets and dogs, these hatches can act both as skylights and as vents (as, in the case of the forward hatch, as a passageway for crew, sails, and gear). Preferably the hatch should have hinges fore and aft so it can be opened in either direction to be used as either an intake or an exhaust. (Desirable and Undesirable Characteristics of Offshore Yachts)
- The hatch sides should be straight (with no flare) and should be close to the deck when the hatch is closed so that lines won’t catch under them…in particular, the corners of forward hatches can easily snag a jib sheet during a tack or jibe. A sheet under great strain may bend up a hatch corner, which will leave a gap…so make sure all hatches are dogged loosed (or left all the way open) before tacking. If there’s any change that a hatch corner will hook a sheet even when the hatch is closed, install a guard at the corners. (Desirable and Undesirable Characteristics of Offshore Yachts)
- All hatches should be installed as close to the centerline as possible (in the event of a knockdown, an open, off-center hatch can let in a huge amount of water in a very short period). (Cruising Handbook, p. 94)
- I like to see aluminum-framed hatches installed on a molded-in, raised base because the base helps deflect water away from the seals.
- All locker-access hatches within the boat should be locked in place to prevent them from flying off in a knockdown. In particular, hatches in cabin soles tend to be heavy and are potentially quite dangerous…In addition to the sole hatches, there are numerous locker lids beneath and behind settee berths and in other locations….On ocean going yachts, they too should be locked in place. (Cruising Handbook, p. 121)
- Mask the deck around the perimeter of the hatch and mask the edge of the flange. You can let the tape stand vertical; its purpose is to keep sealant squeeze-out off the frame. Remove the hatch and completely coat the deck between the tape and the cutout with sealant. Use polysulfide if the hatch frame is metal…Put the hatch back over the cutout and wiggle it gently to distribute the sealant. Insert the bolts or screws and snug them all. Now tighten them, following a patter of each screw in sequence being as opposite as possible to one before (e.g. right side, left side, front right, rear left, etc.) Tighten enough for some sealant to squeeze out around the full perimeter of the flange. Do not over tighten the screws or you will squeeze out all the sealant and the resulting metal to fiberglass joint will soon leak. Allow polysulfide to cure a week, then tighten the nuts on the through-bolts about half a turn to put the sealant under compression. Do not tight screws or you will break the seal on them. Trace a razor knife around the perimeter of the hatch frame to separate the squeeze-out from the sealant under the frame. Peel the tape from the deck and the excess sealant will come with it. Finally, install the trim ring below. (This Old Boat, p. 95)
Cockpit Sole Hatch
- Whether this hatch will be hinged or lift up, the coamings make it absolutely watertight (see images from same pages as source). This feature requires the lower bedlog to be of 1 ¾” stock. Then ¾” high lips on it shuld be high enough to stop all the water and low enough to remain not too fragile. The inner coaming should be 1 inch higher than the first bedlog. Then if any water makes it past the first one, the inner will surely stop it. (From a Bare Hull, p. 331)
- Half-inch drain holes in the four corners of the bedlog will easily let brave water drops drain away. (From a Bare Hull, p. 331)
- The hatch I ordered is a Bomar cast aluminum inspection hatch, part # BOM-C4T1020, available at Hamilton Marine (order #147407; $357.99). The hatch required a 21″ x 12″ opening…machined aluminum, with two large locking dogs on one side of the hatch, and two stainless steel pins on the other side to lock it in place. (http://www.triton381.com/projects/smallprojects/cockpithatch.htm)
- The hatch has one weakness that anyone using this hatch (bomar cast aluminum) should be aware of. There are two pins in the forward edge of the hatch (the opposite side from the latch side) that fit into holes in the frame. The pins are stainless steel (it would have been better if Bomar had used aluminum pins). To prevent corrosion between the two types of metal, be sure to coat the pins and the holes liberally with Lanocote or a similar product. I also plan to coat the neoprene gasket with silicone grease. Once I determined that everything fit properly, I removed the hatch and slipped it into an old pillowcase for protection. (http://www.triton381.com/projects/smallprojects/cockpithatch.htm)
- I continued by placing the hatch in the opening, ensuring that it was centered and otherwise properly positioned, and then drilled small pilot holes at each screw location with a Vix bit (a self-centering, spring-loaded bit designed for this purpose). With the flange screw locations thusly marked, I removed the hatch again and, using a 1/2″ Forstner bit, enlarged the holes at each location, drilling through the top skin and core, but not through the bottom skin. In this manner, I removed all core material from around the eventual screw locations, eliminating the chance that minor leakage could saturate the core. I replaced the flange one more time and taped the deck off around it for protection. Then, I mixed a batch of loosely thickened epoxy and poured some into each of the 1/2″ holes I had drilled, filling them with solid, strengthened epoxy. The screws will penetrate through this epoxy, which is not only strong, but also isolates the screws from the core, preventing any moisture intrusion issues. Since any forces on this hatch will be from above–whether water, persons, or gear–I saw no reason why screws would be insufficient to hold it in place. I left the epoxy to cure overnight, as usual, before continuing with the installation. Once the epoxy had cured, I set the hatch in place temporarily and redrilled the pilot holes for the installation screws, once again using the Vix bit. Then, I installed the hatch in a heavy bed of 3M 101 polysulfide. The underside of the hatch flange features two grooves to ensure sound bedding in all areas. I secured the hatch with #10 x 1-1/4″ screws. I cleaned up the excess caulk, removed the tape, and the job was complete. (http://www.triton381.com/projects/restoration/cockpitstructure3.htm#COCKPIT%20SOLE%20ACCESS%20HATCH)
- The critical thing is to make sure you use marine grade anti-seize on the bolt and hatch threads.The only problem with many hatches is that they never used the anti-seize. (http://www.capedory.org/board/viewtopic.php?t=8204)
- Screwed-to-the-deck hatches are fine on a coastal boat, but on any boat headed offshore, the hatch frame must be through bolted all the way around. If you will be screwing the frame to the deck, take care that you use the correct bit for the screw size. (This Old Boat, p. 95)
- With the hole cut, I removed the core from the immediate area, scraping back about 1/2″. After cleaning, I filled this gap with thickened epoxy. (http://www.triton381.com/projects/restoration/cockpitstructure3.htm#COCKPIT%20SOLE%20ACCESS%20HATCH)
- I marked the shape of the new hatch on the cockpit sole, and made preparations to enlarge the opening as needed. (http://www.triton381.com/projects/restoration/cockpitstructure3.htm#COCKPIT%20SOLE%20ACCESS%20HATCH)
- I made some fine adjustments with a grinder till the hatch flange fit into place. Then, to prepare the opening, I removed 1/2″ or so of the balsa core material from the exposed back edge and filled the resulting gap with thickened epoxy, to seal the opening and prevent any possibility of moisture intrusion through the cutout. (http://www.triton381.com/projects/restoration/cockpitstructure3.htm#COCKPIT%20SOLE%20ACCESS%20HATCH)
- I cut out the hole, dug out the coring around the edges and filled the cavity with thickened epoxy, set the hatch in place and screwed it down. Well, I also drilled the hole for the mount screws with a half inch drill, filled with epoxy, and then re-drilled pilot holes in the new epoxy ‘plugs’ for the mount screws. This prevents further water intrusion into the core. This should always be done and really shouldn’t need to be mentioned every time. (http://www.triton680.com/Cockpit/triton680_cockpit.html)
Forward Hatch
- The foremost hatch should hinge on its forward face so that if a wave comes aboard when it is open, it will be knocked closed rather than ripped off. (Cruising Handbook, p. 94)
- At first sight, the hatch hinged on its forward edge seems to interfere with airflow, but as long as a windscoop is in use, the reverse is true; in fact, if there is an option about which way to open a hatch, it is best to do it this way. (Cruising Handbook, p. 126)