Tuesday, August 7, 2012

Making a Storm Dodger for the Aft Cabin Hatch

Nothing is worse than hanging out down below in the rain with the boat closed up and no ventilation! If you’re anything like us, you want to keep your boat as open as possible while onboard and maximize airflow whenever you can. Our 4-way wind scoop is great in fair weather, but we needed something a bit more substantial in a squall. We’ll make a storm dodger for the foredeck in the coming months (with a much different design), but since the aft hatch is directly over the bed in our master stateroom, increasing ventilation and keeping it dry was a top priority.

Our aft cabin hatch is essentially square, has a 3”rise off the deck, and opens aft to help draw the air out of the boat. We toyed with designing it to open both fore and aft, but our hard top dodger and bimini spoil the airflow over the aft cabin, so we kept it simple and minimized the extra hardware.

Aft Hatch closed
Another consideration was overall windage – we already have plenty of that! So a hatch dodger seemed a better choice than an awning or boom tent.

We began by looking at several different design options and finally settled on one we found in Karen Lipe’s book more Boat Canvas, but with a few modifications of our own…  (As an interesting side note/coincidence, we learned that Bruce Bingham did the cover illustration for this book when he was here for the Andromeda party).

Step one was to determine how high we’d like the hatch open underneath the dodger. Approximately 45° seemed about right to us the maximum and we can always lower it if the winds are really blowing. Then came the measurements. We started by measuring the basic hatch dimensions, as illustrated below.

Opened and ready for measuring

Note that the length “A” is determined by the distance you want your dodger to extend out away from the hatch, “E” is the height with the hatch opened, “G” is the width of the hatch at the closed end, and “F” is the width at the base on the open end, which will come into play if you add the optional “splash guard” panel we’ll describe later.

Once our measurements were complete, we laid out our Sunbrella fabric and mapped out 3 panels (using measurements A through E) – one top panels and 2 sides – and added a 1” hem allowance to all edges. The panels were cut out, stapled together, then checked for fit on the opened hatch.

Stapled and checking for fit

When we were satisfied with the fit, the three panels were sewn together and the edges hemmed with ½” double hems. Since we installed twist locks (aka common sense fasteners) to the base of the hatch for our everyday hatch covers, we were able to use the same fasteners to secure the hatch dodger. With the dodger in place, I marked the location of each twist lock stud, sewed a 1”wide piece of webbing to the inside of the dodger in each spot for added reinforcement, and installed the corresponding eyelets. An additional length of 1” webbing was used to secure a stainless steel O-ring to the top edge so we could tie the dodger’s overhang to the stern pulpit.

Dodger in place, facing aft
After looking at the design, we decided we needed a “splash guard” to prevent any driving rain from bouncing off the deck and down the hatch. We played around with different heights, and finally decided that a finished height of 4” would be enough to keep water out without reducing the airflow too much. Using our previous measurement “F,” we mapped out a rectangular piece of Sunbrella to fit, added our seam allowances, cut and hemmed the piece. We checked for fit, attached the new piece to the two sides of the dodger, added the webbing reinforcement and eyelets, and our creation was complete!

Side view

Splash guard in place