Pro Vee Race Boat Plans
Page One
Bulkheads and Coaming
Bulkheads
Do I need to point out the importance of deadly accuracy when laying out and cutting out your bulkheads? Errors here will haunt you for the rest of the project. Take the time to measure carefully, then check for accuracy, then check again.
The bulkheads, transom and stem can be drawn directly onto plywood, or you can draw them onto paper first if you prefer -- eighteen-inch wide freezer paper (dull side) works well; please see next photo.
Start each drawing with the centerline and the reference line, precisely at right angles to each other. All points on these plans are offset from these two lines. After cutting out the bulkheads, carry these two lines around the edge of the plywood and across the back side.
The curve of the deck is found by bending a batten (3/8" x 3/4" will do nicely) through five points: two at the sheers; two at the coamings; and one at the centerline. If by chance your batten describes a nice curve through the sheer and coaming points, but does not quite fall on the centerline point, then ignore that centerline point. (Although if it's way off, check your measurements.)
More about drawing curves HERE.
Bulkheads one, two, four and the transom are full width. Bulkhead three, on the other hand, consists of two pieces which will be permanently secured to the outside of the coaming, while a third piece will be temporarily fitted between the coamings and removed later in the construction process.
Draw bulkhead three as if it's a single, full-width structure, then cut it into three pieces as you cut it out of the plywood.
Again, you may choose to draw on paper first -- to save a copy of your work for instance. Transfer the drawing from paper to plywood with an awl or other pointy tool.
For the compound-curved bottom profiles for bulkheads three, four, and the transom, I strongly urge you to make a template such as this one, which is cut from hardboard.
One template will serve for bulkheads three and four. A second template will be needed for the transom.
You might also choose to make bottom templates for bulkheads one and two. However, these curves are simpler to draw and are less critical due to their locations away from the main running surface of the bottom.
Here is bulkhead number two. Note the notches for the carlins (along the deck line) and the coaming battens (along the bottom profile). Also the slots which will mesh with opposite slots in the coaming. (Bulkhead one has a slot on the centerline to mesh with an opposite slot in the stem.) The bottom glue blocks have been added. These blocks are cut from 3/4" softwood lumber and are approximately 3/4" wide. Note also the two limbers cut into the bottom-most edge.
This is bulkhead number four. Note the large cutouts along the bottom profile. If you are NOT going to race your boat, then a 3/4" x 1" slot will suffice here, to accomodate the coaming batten that will extend from bulkhead one to the transom.
But for racers, the coaming battens are interupted from bulkhead three to bulkhead four by 1.5" x 3.5" "lifting beams" which will anchor u-bolts used to hoist the boat for weighing. (More on this coming up later.)
Coamings
NOTE: At the time I cut out the coamings for my Pro Vee, I intended to have a high bulkhead behind the seat to accomodate driver restraints. I later changed to the version you see in the plans.
The greater part of both coamings can be cut from one sheet of 4x8 plywood, with the remainder scarfed on between bulkhead four and the transom. Include the reference line on each coaming, and carry it around to the other side. Lay out and cut the slots for the bulkheads -- not forgetting the limbers -- as shown on the plans.
Cut your coamings about 1/2" extra long at the aft end, to be trimmed later when the motorboard is installed.
Dry assemble your bulkheads, transom, stem and coamings. Bulkheads two and four and the transom fit together with the coamings egg-crate style. Bulkhead one and the stem fit together similarly. Bulkheads one and three attachment to the coamings with 3/4" x 3/4" softwood cleats. The stem attaches to bulkhead two with cleats.
Make certain the reference lines on the bulkheads precisely correspond with the reference lines on the coamings and/or stem.
At this time, make certain that the coamings are perfectly parallel with each other, and the bulkheads are square with the coamings. Then secure the coamings to the sawhorses, or whatever structures you have chosen to support them.
Now, close one eye and take a look along the ends of your bulkheads. The reference lines should line up. (I couldn't quite get the camera properly positioned to demonstrate the procedure, but I think you get the idea.) A very minor miss-alignment (say, 1/16" or less) can be corrected when the sheer clamp is installed. Otherwise you will have to stop and figure out where the error is and correct it.
Also take a sight down the centerline of the boat. The bottom of your boat should be dead flat from bulkhead two to the transom -- the four structures to which the keel will be fastened.
At this time your structure will be a bit speghetti-like, prone to lateral wiggle, and the centerlines on the bulkheads and transom may not line up. No need to worry at this point. The next step, the keel, will take care of it.
Before starting permanent assembly, cut openings in all these parts, as you see fit, to lighten the structure and/or to accomodate running wires and control cables below the deck. I actually didn't run any wires or cables through the hull, but kept it all in the cockpit. For this reason I cut four holes through the center section of bulkhead four (two holes would have been plenty, one port and one starboard). You may not want any holes between bulkheads two and three where flotation will be poured later. Another benefit to all these openings is improved air circulation below decks which will help to keep things dried out.
Start final assembly by gluing bulkheads two and four and the transom to the coamings. Strengthen these joints with 3/4" x 3/4" softwood cleats.
I suggest holding off for now gluing on bulkheads one and three and the stem. In fact, remove these parts (except the center portion of bulkhead three) from the structure to get them out of the way while you intall the keel.
