Construction

Should You Build?

There is much to enjoy about building a boat, and a lot of satisfaction. Not everyone can afford a production boat like the F-28 or F-33, and the only answer may be to build your own from a set of plans. It is a slower process, but is made easier by highly detailed plans and can be considerably speeded up by hiring occasional labor, and by purchasing ready-made parts.

I received the F-82 plans today and have only had a quick look at them. Without a doubt they
are the most detailed plans I have ever seen. I don't think there will be much guess work in
building this boat unlike others I have built. Andrew Downing, NSW, Australia

All F-Series designs feature a unique method of building the hulls split vertically down the center, in simple female form frames. This was first used over 14 years ago with the F-9A, and immediately halved the amount of work required for temporary building frames. The Full Size Patterns are only used once, there being no need to mark their reverse side and then flip them over for marking the opposite hull side. The building frames are instead just flipped around to build the other hull half - much easier and faster - half the work in fact.

Once both hull halves are complete, they are joined down the centerline, the ideal place for extra reinforcement. Gunwale is no longer a join, and can thus be clean and well rounded. The considerable time required to later 'frame up' for the deck and cabin is also avoided.

Material options include strip planked Cedar or Durakore®, or a new system of vertical foam stripping as developed by Farrier Marine 10 years ago, which is now well proven, and gives a significant saving in both weight and building time.

With cedar or Durakore®, the strips are edge glued in the form frames, and then given a covering of a reinforcing fabric both sides with epoxy resin. This forms a lightweight and stiff shell, without losing any room to internal framing or stringers. However, wood boats are heavier, take longer to build, and can be difficult to insure these days, so foam core is now strongly recommended.

Vertical foam stripping is the most advanced and fastest procedure, and the advantages apparent from boats already built have now made it the primary and preferred method. Vertical strips are easier than the usual fore and aft strips, with much wider, easy to handle short strips, considerably fewer glue lines, and a much fairer hull.

Other advantages of foam include avoiding the tendency of wood strips to move with differing humidity levels, and the now lower cost of foam in many areas. Less expensive polyester or vinylester resins can also be used, which can be an important advantage to those with an epoxy allergy.

How Much Faster Is Vertical Foam Stripping?

A good comparison is to consider a square foot of hull core (300mm x 300mm). Such an area on an F-9A would require 6 to 9 fore and aft wood (or foam) horizontal strips or glue joins, but only one, or two at most with vertical foam stripping. If any doubts still exist, then actually make such a square foot of hull core and see the saving in time and material (glue) possible with vertical stripping. There's around 935 sq.ft of hull/deck area in an F-9A so the saving with vertical foam stripping is real and significant.

Compared to fore and aft 'bead and cove' foam strips, vertical strips require much fewer form frames, and there is no need to use a thicker than specified foam as is recommended, in order to leave sufficient thickness once all the multiple fore and aft 'flats' have been sanded out. Thus foam cost is much lower with vertical strips, and better, one doesn't have to sand such flats.

What About Pre-Made Panels?

Pre-made panels were initially going to be used on the new F-22 hulls, but feedback from builders using this method, plus growing concerns as the F-22 construction details were worked on, were sufficient to decide against it. It just proved to be too slow with the extensive taping required, plus having to fair exterior taped joins is hard to do, and slow. One range of such kit panel boats was even withdrawn from sale after complaints that construction was taking much longer than the claims, so be very careful of this.

Other designers are also switching over to the Farrier vertical strip foam planking system in vertical halves, as they realize the advantages. It really is fast, plus gives the best hull shapes. Better still, all the internal bulkheads and many panels are available as DXF computer files, so that all these parts can be pre-cut from ready made panels, and this does offer a true saving in time.

Building the hulls can actually be the easiest and quickest part of a boat, most time actually going into fitting internal bulkheads/panels, and then assembly and fitout. Most of the internal bulkheads are already fitted in vertical stripped hulls when removed from the form frames, whereas they have to be done later with many pre-made panel systems. The resale value of true round bilge hulls with optimum hull shapes, and their superior load carrying ability, is also far higher.

A foam/glass F-36 float half with beam bulkheads (made from full size patterns) fitted, and ready to remove from temporary form frames. At this stage, hulls are rigid enough to handle easily. Once the first two float halves are finished and removed, the form frames are then just turned around to do the other halves. Once done, the first halves are dropped on top, with bulkheads and join seams being taped as required. The floats are then complete and ready for fairing and painting. Clean, simple and fast.

The folding trimaran connecting beams, and associated Central Mounting Modules are made from either fiberglass or carbon fiber with foam core, or it is possible to purchase the beams ready made on some models if wished.

The Folding System Struts can also be either self made from the plans or purchased ready made.