Adrift at Sea —Dan’s blog on dankim.com

One of the projects I’ve decided to do this year is creating a bridge deck on the Pretty Gee.

A bridge deck is a raised section in the front of the sailboat’s cockpit that is designed to prevent a pooping wave from entering through the companionway. Currently, there is no bridge deck on the Telstar. A lot of the water that gets in the cockpit ends up in the cabin unless you remember to close off the companionway—especially if you’re out sailing in strong winds and choppy seas.

Benefits of a Bridge Deck for Pretty Gee

First, it will reduce the volume of the cockpit, which reduces the weight and volume of water that can fill it when the boat gets pooped by a wave. I see this as an inevitable occurrence, so reducing the amount of water that has to drain is a good thing.

The new bridge deck will take up about four-and-a-half cubic feet of space from the current cockpit layout. That is about 300 lbs. of seawater in the case of the boat being pooped. It also prevents most of that from going down below, even if I don’t have any drop boards in place.

Second, it will give me some more storage inside the cabin. I am planning to have the bridgedeck only open into the cabin, and act as a storage locker. Storage space is rather scarce on a trimaran, which has effectively has no bilge or under-settee storage areas.

The upper half of the locker will be about 48″ wide, 15″ deep and 6″ high. The bottom half of the locker will be about 24″ wide, 18″ deep and 6″ high—giving me about four more cubic feet of storage. Currently, I don’t plan on dividing the locker quite yet. However, that too may change, depending on how I find I am using the new space.

Third, it should stiffen the stern of the boat, and help transfer the loads across the boat’s structure for the rear ama support arms. While I believe this is true, I don’t believe it is really necessary—it is more of an unexpected benefit—anything that makes a boat stronger is a good thing in my opinion.

Designing the Bridge Deck

Originally, I decided to make the bridgedeck the height of the steps in the Telstar’s cockpit, rather than the full height of the cockpit seats. This allows it to still function as a step when entering or exiting the boat’s cockpit from the amas. It also increases the headroom that you have to step up out of the cabin.

The new bridgedeck will have a companionway threshold that comes up to a bit higher than the cockpit seats and the cockpit transom, and really reduces the chance of water coming into the cabin from the cockpit, even without any dropboards in place.

I spent most of the day roughing out the layout of the bridgedeck.

Here are two photos of what I’ve gotten done so far. I still have to screw the cleats to support the structure in place, and then glass it in, but this should give an idea of what I’m doing.

The structure in the photo is not what I am going to be using for the final bridge deck, as I decided to do something slightly different for the final installation. Instead of using the smaller piece you see for the top of the bridge deck, I’m going to use a single 1/2″ sheet of plywood that goes all the way across, and fills in both step areas.

I only thought of running the piece all the way across after seeing how the preliminary model worked out. By running the top piece across the entire width, I will gain a inch of height in the locker, reinforce the boat for the ama-related stresses, and eliminate the need for putting in cleating blocks for the top, since it will be fully supported by the steps already—simplifying the installation. This will add a lot of strength and rigidity to the cockpit area and help reinforce the aft aka beam.

Doing it this way will also allow the remaining step to drain much better than it would have if I had just glassed in the smaller panel. I plan on fairing the top surface slightly to aid water in draining from the steps—which has been a minor annoyance since I got the boat.

The Construction Process:

The first step will be installing the new bridge deck main board. I am going to epoxy coat the top board, which will be 1/2″ plywood and then glass it in. The board will be epoxied to the existing steps, and it will be glassed in to the top of the steps as well as to the lower steps underneath. This creates a 3/4″ x 15″ fiberglass and plywood beam across the cockpit, which didn’t exist previously.

The second step is glassing in the new companionway threshold. The companionway threshold will be a 6″ high piece of 1/2″ plywood which will be routed along the port and starboard edges, so that it sits flush with the interior of the cabin side of the companionway. The threshold will be glassed to the back and front of the companionway, as well as the top and bottom of the deck piece. This should provide plenty of support for the bridge deck and eliminate any need for a frame or any additional support. This also makes the companionway opening much smaller and should make the aft end of the cabintop much more rigid.

The third step is installing the angled bulkhead. This is the bulkhead that seals off the cockpit from the bridge deck locker’s interior. I plan on installing cleats on the port and starboard sides as well as one on the cockpit sole. The temporary cleats will be made of either Starboard or composite decking material, and will be removed after the external glassing and epoxying is done. I plan on filleting the joints and then glassing the interior after removing the cleats. This also acts as another fiberglass and plywood beam, which will join and stiffen the two cockpit locker panels considerably.

The fourth step is finishing the exterior and interior of the bridge deck. I also have to either paint or gelcoat the bridgedeck. Currently, I am thinking of gelcoating it, and using a epoxy mold made from the existing non-skid surface of the cockpit sole. If I go this route, I will make the mold up on Saturday morning by spraying down the aft end of the cockpit with non-stick cooking spray and then pouring some thickened epoxy over it. Getting the gelcoat to match the existing cockpit gelcoat will be a challenge.

The fifth step is extending the water tank deck fill to the new bridge deck. I haven’t decided if I want it on top of the bridge deck or in the aft surface of the bridge deck. The aft surface would be less likely to get contaminated, so I am leaning towards that right now.

The sixth step is building or designing a new companionway ladder. This will have to be a three-step ladder, rather than a two-step ladder due to the increased height of the new threshold from the cabin floor. Currently, I am thinking of ordering one of these small 26″ step ladders and then hacking off the back set of legs and adding a way to attach it to the companionway.

The final task of this project—a door for the locker. I will be designing some sort of door for the new locker to keep the contents in the new locker. The design for the door has to work with the companionway ladder, so it is going to depend on what I come up with for a companionway ladder solution. What I’d like to have is the door setup with the hinge at the bottom—so it opens down and out, into the cabin. This way the locker door could possibly be used as additional counter space for the galley.