Now that all of the hard work is done of installing the keel trunk, it is now time for the easy stuff. Putting in the deck beams is an important function for a model yacht. There must be good support for the mast, jib boom attachment, and other fittings. Without good deck support the model yacht will be prone to breakdowns while sailing.
Before a builder starts the job of putting in deck beams, there are some things to think about. One of the worst things you can do to a 36/600 is install a hard deck. To define what a hard deck is, it is a deck that is made out of a thin wood veneer. The main reason not to use a wood veneer is it makes it hard to remove and do repairs below deck. When removing a wood veneer that has been glued on, it damages the deck beams underneath. So if you have been thinking about a wood veneer deck, think long and hard if you want the extra effort.
The 36/600 model yachts that are doing well in a regatta have a "cloth" deck. The description of "cloth" deck is a mica film that is used to cover model airplanes. Using mica film as decking saves weight, is easy to apply (and remove), and is watertight. The only thing needed is where to place the deck beams.
The goal is to only use enough beams in the right place to do the job. At this point in the construction every bit of less weight means more speed on the water. Some builders use hard balsa wood, I like to use 3/8 x 1/8 inch spruce. It is harder than balsa, stronger, and almost just as light as balsa. When it comes time for the stress and strain of racing I never had a problem. To help you through this article on deck beams, look at Example 1 as you read, and match the beam number to the number in the example. With that in mind, let's get to work on installing deck beams.
Now that the keel trunk has been installed, the first beams to install are the two that will hold the trunk into place. Doing so will make sure the keel trunk won't be under any undo strain and break loose. When I shape the deck beams, I file the ends to fit the inwhale beam. This will insure there will be as much contact as possible between the inwhale and the deck beams ends. Another task that needs to be done before the deck beams are glued (I use 30 minute Epoxy for glue) in is to cut a notch at the center point of the beam where the centerline deck beam will be placed.
Install two beams (#1 and #2), on both sides of the keel box. Then install the two cross beams (#3), to add further support. Once that is done, the next beam to be put into place is the beam up at the bow (#4). Putting this beam into place will allow the forward centerline deck beam (#6), to be put into place. Don't glue centerline deck beam in, you just want to be able to take it out for future work to be done on it. Next, I install another deck beam (#5), to add support to the forward centerline deck beam. Also take note that the forward centerline deck beam goes right over the top of the keel trunk box. This is important because the forward centerline deck beam will be used to support the mast step fitting and will hold the keel nut, more on this in future articles.
Installing the deck beams aft of the keel trunk is the next step. The area aft of the keel trunk is the place where the deck hatch will be located. To be able to have something for the hatch to connect to, I want to do something different. I like to use wider beams (1/2 x 1/8 inch) than the ones I use for the other deck beams. I form fit two flat cross beams (#7), right in front of the aft deck beam of the keel trunk to attach the hatch to. Now I have a wide base to create a hatch with.
The next two deck beams (#9) used will be for the hatch itself. It is up to the decision of the builder on the size of the hatch. Too wide and it is overkill, too narrow and you won't have an easy time getting the radio board in and out. I make my hatch hole 4 ½ inches wide and 5 inches long. It is best to install beams #9 to beam #8 at the same time outside of the hull. Then when the glue has set I install the two beams #9 to beam #1 as well with beam #8. The hatch is now installed, and the aft centerline beam is next.
For the aft centerline beam (#10), I don't put any extra cross beams in, other than the T connection to the hatch beam #8. The reason for this is the only stress on the aft centerline beam will be the through-the-deck sheet pulley. One item to point out in the T connection to the stern inwhale (#14), I notch the stern inwhale so the aft centerline beam will be placed into it. Later, for added support I will glue in a small piece of wood to the underneath side to overlap the notch. Please note, do not glue in the aft centerline beam now, there will be later work on the aft centerline beam.
Next, I shape and glue in two small pieces of wood (#13), for the gunwale eyes to attach to. I use oak wood to do this with. Because of the small size, it does not weigh any more than spruce does. I like to use oak because it is a hard wood, and it holds up to the stress of the shroud lines that are attached to the gunwale eyes. When sailing, there is a lot of stress being applied to these two pieces of wood by the gunwale eyes. Not having good, strong wood for the gunwale eyes to connect to will cause problems when sailing, and you don't want that.
The last two deck beams (#11 and #12) will be put into place once I know where the mast step and jib rack will be located. I want these two beams placed at the other end of the mast step and jib rack for the most support. There will be a lot of stress at these two points, and this stress will be passed to the deck beams, so support is important. I will discuss more on this in an upcoming article. For now don't' glue these two beams in.
To date I have used this deck beam layout for five 36/600 class model yachts without any problems. You may have a better way or may have better ideas, use them! That is it for now, look over the photos and the deck beam example to get a good idea of what I am describing. Plan out your work by drawing a full size layout of your boat's deck (like example 1), to design your deck beam layout. Next time, I will describe the radio board mount. Happy building!