Cobra Kayaks supplies a large A shape hatch for installations on their kayaks. The A Hatch may fit other kayak makes and models, but a careful assessment of the deck space will have to made.
The A Hatch requires a very flat deck; 15 inches at the widest by 23 inches long.
The Cobra A Hatch has eight toggles fastening the cover. This makes it very secure, but the many toggles may appear to be a chore to open.
Once you have the hatch installed and have gotten used to the toggles you will find that this hatch will open up great internal storage possibilities in your kayak. There are quite a few rivet/screw holes on the rim of the Cobra A Hatch, so plan plenty of time for the installation. All these rivets will secure the rim top the deck well with no gaps or leaking. This coupled with the rubber seal between the cover and the rim make for a very waterproof hatch.
Cobra includes instructions and a template with each A Hatch, as well as rivets. This article will help you see what the job entails and to provide some additional tips not found in the Cobra instructions.
Test fit the A Hatch to the kayak by putting the hatch upside down on the deck. Make sure that it is fully flat against the deck and is not crowded at the edges by contours in the deck.
This will ensure that the rim will seat properly and a buffer zone around the edge will allow for ""wiggle room"". You may want to make a couple marks with some masking tape.
Locate the cutout by placing the Cobra template on the deck and centering it in the space your have tested. Use a ruler as needed to place the template accurately. Hold the template firmly in place, a bit of masking tape, or a buddy can help.
Trace the outside edge of the Cobra template with a sharpie type marker.
Use a drill to make a hole that you can insert a jigsaw blade into, next to the line you have traced. Carefully cut along the line with the jigsaw. Cut along the line in a manner that cuts away ½ of the line you have drawn on the deck. The best blade for this work has moderate teeth, not too aggressive (for wood), not to fine (for metal) but somewhere in-between (for plastics and composites).
Test the cut out with the hatch rim, with the cover fully locked in place. It should fit snug, not too tight. Some trimming may be required. A Stanley Surform tool will be helpful, but a knife or the jigsaw can trim the edge too.
Pre-drill all the holes using the rim as guide. Drill each hole, one at a time and insert a rivet (or bolt) in each hole after it is drilled to maintain alignment of the rim. Drill a hole or two on one end of the rim, and then a couple hole on the other end, before you drill the sides.
Take the hatch cover off the rim and set it aside. Using 100% silicone sealant apply a thick bead or two all along the underside of the flange that contacts to the deck.
Create a thick, continuous bead, no gaps, in the corner where the flange makes a 90 degree turn from the flat to down ward portion of the rim.
Make sure you use enough silicone to fill in the low spots between the rivet holes. A small putty knife can be of use. Each "rib" should have a modest layer of silicone on it as well.
You may want to get a large size tube of silicone, or 2 medium sizes squeeze tubes. Read the direction on the sealant tube to determine the working time you have, silicone hardens fast, so plan well and have everything you need at the ready.
Place the rim into the cutout and press gently to ensure it is engaged properly in place. Install you first rivet.
Put a dab of silicone under the head of each rivet as you go.
Sticking the rivet into the tip of the silicone tube up the rivet's cap is a good method of coating the right part of the rivet.
(Stainless steel nuts with ny-loc bolts can also be used if you do not have a rivet tool. Well-nuts could be used, but are the not the best choice for working with silicone, the rubber nut gets slippery and hard to tighten.)
Place the first rivet on one end, at the top or bottom of the A. The next one should go a few spaces over, on left, then another on the right.
Next work on the other end in the same fashion. Fill in all the other rivet holes, staggering and alternating sides. This will ensure that the rim is evenly seated in the hardening silicone.
As you install each rivet you will squeeze out silicone from under the rim. This is good and means that you have used enough sealant. If you have used too little it will not squeeze out, and that could indicate you have gaps.
Reversing what you have done so far with the silicone and rivets will be an ordeal, so be sure to use enough.
This will of course make a big mess, and it will have to be cleaned up. Have rags or paper towels handy. The putty knife is handy too. Silicone sealant cures fast, so prepare well, work quickly, and a helper can be very useful.
Once the rim is bolted in place wipe the under-inside with a rag to clear out dripping silicone. Just get the drips, leave the rest in place. Test the fit the cover and remove it. Let the silicone fully cure with the hatch open. A well-ventilated work space is preferable.
The hatch cover can now be installed on the kayak and left in place. You can add a "leash" to the cover by installing a strap eye on the cover, underside or topside.
Install a second strap eye to the deck, underside or topside, adjacent to the eye on the cover. I would prefer to have the leash inside the kayak, but on the outside is ok too.
The cover can then be tied to an existing strap eye or to deck rigging, as long as the leash is out of the way of snags.
You can use a small sharp chisel to remove some of the bumps on the topside of the hatch cover for better seating of the rivets or eye.
Use a short length of deck line, about 18-24 inches to tie the cover to the kayak. Slip it through both eyes and tie a figure eight knot at each end.
Keep your hatch cover clean and free of grit as much as possible. Rinse well with fresh water after each use. Keep the toggles in the locked down position when not use. Toggles left standing up will be vulnerable to breakage. The toggles can be replaced if necessary, but it is best to prevent damage and corrosion.
Related Links & Articles:
Some helpful tools for kayak work are the Stanley Surform and a Marson HP-2 Hand Rivet Tool, which can be found at our affiliate link and using their keyword search: Amazon Market Place.
I highly recommend reviewing our article: Basics of Strap Eyes, Rivets, & Well Nuts For Customization & Repair of Your Sit-on-top Kayak.
You can also e-mail Tom @ TopKayaker.net if you need help, or have questions. Spare parts (lids & bags) are available by special order.
Viking Six Inch Kayak Hatch Installation Instruction also by Tom Holtey
Read our Kayak reviews of the Cobra Tourer and the Expedition that feature the Cobra A Hatch.
© 2008, Tom Holtey
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