Deck Construction

They are long, heavy and hard to transport. Depending on the boat and type of construction, they can take up to 600 hours to build (including all the ginger bread on the deck). Why would anyone want to build and campaign a J model?

The answer is simple! They are one of the most beautiful models in the AMYA today.

There is nothing more spectacular than a J under sail that was built as a scale replica of the original yacht from the 1930s. These models are stable and very fast in all wind

conditions.

In this article, several building options will be presented. These step-by-step building tips come from years of large model construction.

Which J should I build?

There is no easy answer to this question. The good news: there are some 20+ designs for modelers to choose from. These include not only the yachts built for the America’s Cup but the large yachts that were converted to the J class in the 1930s as well as several of the unbuilt designs from the late 1930s and 1940. We suggest a little research before making that choice. An excellent resource is the book Enterprise to Endeavour by Ian

Dear, ISBN 1-5709-091-7. No J skipper should be without a copy. This book contains a wealth of information on the J Class, including history, many valuable photos, and some line drawings. All of the J designs are competitive as models and perform slightly

differently in varying wind conditions. It may boil down to which model is the most

attractive to you, the builder.

Fiberglass or plank on frame?

Again this is a personal choice. If time is an issue, a fiberglass hull may be the way to go. For the traditionalist, it’s got to be all wood. A fiberglass hull can greatly reduce the building time. There are budget considerations with building either a wood model or one with a fiberglass hull. The cost of a fiberglass hull is within reason, but the shipping costs can be quite expensive. The wooden hull will require more building hours but can be considerably less costly. 

 Several of the maritime

museums such as the Mystic Seaport Museum offer J drawings. These may take a little investigating on your part to get exactly what you are looking for. 

Time to begin

For this article, Bob chose an Endeavour fiberglass hull. Endeavour was a British J that

competed in the 1934 America’s Cup. The hull for this model was manufactured by Bob Sennott and delivered at the 2007 J Nationals in San Antonio, Texas. This particular hull is gel coated in white and has a one inch lip at the sheer. The lip is rolled inward and adds greatly to the hull holding its shape once it is removed from the mold. Unfortunately Bob Sennott is no longer manufacturing hulls for the J models. 

The first step was to check the hull for trueness prior to installing the sheer clamps where the deck meets the hull. The hull was true and we decided to leave the lip intact. For the sheer clamp, poplar was the wood of choice. Poplar is quite hard, but our first choice, spruce, was not available. The poplar was cut into 3/8 x 3/8 inch strips. Two are required for the sheer. I was fortunate to have an 8 foot board from which to cut the strips so they

were installed in one piece. The 3/8 x 3/8 inch poplar was installed under the fiberglass lip with 60 minute epoxy and many clamps. You will have to be sure that you install both port and starboard clamps at the same time to avoid having the tension in the wood distort the hull. (Note: If you purchase a fiberglass hull minus the lip, do not assume the sheer is straight. Let the sheer clamp follow the curve of the hull as the clamp is glued in.) 

With the clamps installed, it is now time to shape and install the deck beams. We decided on a 3/8 inch crown in the deck. We cut twenty nine deck beams from pine and sanded them to shape. The beams were notched to accept the king plank and the sheer clamps. The beams were about ¾ inch from top to bottom. The deck beams were installed on 3 inch centers for the length of the hull.  Completed deck beam installation. Three of the deck beams were constructed from 1/8 inch plywood. These three are located at the mast step location and extend on two legs from the center of the deck beam down into the bilge area of the hull to act as compression struts. 

 Additional support at the mast step. The two legs allow the center of the

hull to be open and unobstructed, a great benefit when installing or removing the lead ballast. When the boat is under sail, there is a tremendous amount of compression force in this area of the deck. With all of the deck beams in place, the king plank was installed.

The king plank was ¼ x ¾ inch and cut from a piece of poplar.

Referring to the full size plans, it is time to decide where the hatch/hatches will be installed in the deck. There are many factors to consider when laying out your hatch

arrangement; where the mast will be stepped, where the cabins will be placed on the deck, and whether or not there will be more than one hatch will all determine where the

hatch/hatches will be place. Be sure the main hatch is large enough to allow for easy access to the radio tray and the removable weights. Once these locations and their sizes

have been determined, it is time to frame in the hatch/hatches. The hatch covers will be created as you plank the deck.

The deck is planked in 5/32 x 3/8 inch pine. This lets you sand and the finished planking to about 1/8 inch with out having to worry about getting the planking too thin. I chose to run the planks the full length of the hull rather than make them shorter. The full length planking greatly reduces the building time for the deck. The decking on all of the Js ran parallel to the gunwale in a smooth arc that followed the shape of the sheer line.

Installing the planking this way will produce a great looking hull. (see ph

Begin your planking with the king plank and the waterway planks. The king plank is installed on the center-line of the deck, on top of the king plank that you glued to all of the deck beams. The waterway planks run down the side of the deck at the sheer line and serve as a frame for the decking. The planking used for these is usually wider than the rest of the deck planking. I often use a different species of wood for these planks to add more zing too the completed deck.

You may want to build simulated caulking into your deck. The easiest way that I have found to do this is to use colored construction paper between the planks. I have used

black, primarily, but you can use any color that suites you. The construction paper is cut

in ¼ inch strips and sandwiched between the planks as they are glued in place. I use thin CA glue for this, and the construction paper works as a wick to draw the glue into the seam and form a tight joint. This can be done whether you are using full length planking or shorter planking. When the planking is finished, the paper that is above the wood is trimmed off and the deck is sanded for a smooth finish. 

Your hatch covers will be incorporated into the deck as you plank. Simply build your

hatch frames parallel to the direction that your planking will run. When you get to the hatch do not glue the plank edges together at the hatch edge. Once you have planked over the hatch edge, then resume gluing your planking as before. You will need to cut the

planking at the fore and aft ends of the hatch after every second or third plank is installed. You will also need to glue a paper strip to the edge of the plank that is the hatch edge if you are using paper between the planks. This method will produce an almost invisible

hatch that blends in with the rest of the deck. 

Once the deck is in place and sanded, you will need to seal the underside of the deck to

prevent excess moisture from collecting in the deck. The easiest way that I have found to do this is to turn the boat upside down and support it at both ends so that you can reach the open hatch/hatches. When the boat is in place, use a can of oil based spray varnish or

Varathane, (a polyurethane product), and reach up into the open hatch/hatches and spray

the underside of the deck. Get as far into the ends as you can and really saturate the wood. The spray will carry to the narrow ends of the hull and will do a reasonable job of

sealing the wood. Do not worry about runs as you do not care about the visual quality of the finish, what you do want is the wood to be sealed. Keep the hull upside down over night to let the varnish or Varathane dry thoroughly. This should provide protection for the underside of your newly planked deck.

When you have completed planking your deck and it is sanded smooth, it is time to think about the finish. I prefer an oil-based finish as opposed to a water-based product, as I feel that it provides a better finish and is much more durable. You have two choices here; do

you want varnish or Varathane? It depends on the look that you prefer. Varnish yellows as it ages, while the Varathane has much less color change as it ages. You also have a

choice among finishes, gloss, semi-gloss or satin. Again it all depends on the look that you want. Regardless of the finish that you choose for your deck, your planked deck will greatly enhance the beauty of your model J.

A 55 minute “How To” decking video is available for $10. Contact either John Hanks or

Bob Eger for a copy and they will mail one to you.