BUILDING YOUR OWN BOAT - PART 2

Roger Simpson (left) on building your own boat.. Our boats are real world boats. They can be built by ordinary people who just want to go sailing and enjoy the best that life has to offer or they can be built with ease by professional boatbuilders. Expensive tooling up is out as is unnecessary complexity and setting up costs. Given this there are four methods of construction that suit these criteria.

1. STRIP PLANKING

THIS IS THE MOST POPULAR, FAST AND STRAIGHT-FORWARD WAY OF BUILDING A ROUND BILGE HULL.

It is often made to sound lengthy and complicated but in reality is a very fast and simple method.

In essence, temporary frames are made using particle board or second hand timber. These are set up on the strongback and act as a mould for the planking to form the hull shape over.

The planking is laid full length over the mould fixed to the frames and edge glued as you go. On an average day up to 30 planks can be fitted by a couple working together. That's roughly 1.5 metres of hull side for one days work ... not bad. We've had a report that one of our 13m hulls was planked in a weekend by a crew of three ....again, not bad.

Western Red Cedar

A North American timber known for its light weight and atttractive appearance, it is easy to work and takes glue extremely well. The planks are "scarfed" together (an easy process) and as said are fitted full length to the mould. Edge gluing with epoxy holds. everything nicely in shape. A light sanding and detailing ollows and then you're ready to lay the fibreglass.

Western red cedar really comes into its own if you love a timber finish to the interior of your hulls. The inner laminate of glass is virtually transparent when wet-out. A coat of varnish over the epoxy produces a beautiful glowing wooden hull interior.

2. COLD MOULDING - COMPOSITE PLY

Cold moulding has been around for many years and is well proven the world over for achieving a round bilge hull. The main variation on this theme that we use in our boats is composite ply we use sheet ply for the topsides and a cold moulded girth or bottom section. This is a quicker and easier way to get a fair hull where it shows.

The principle of cold moulding is to lay thin veneers or plywood strips in layers orientated at roughly 45 degrees to each other. The exact angle is called the "magic angle" by cynics. It is determined by finding the easiest lay of a master plank somewhere near the midsection of the boat.

This angle obviously will vary from boat to boat and is determined on the job.

Cold moulding/composite ply are slower methods than strip planking but are cheaper. The stringers and frames remain and we do try to design them into the final accommodation as far as is possible. Above worktops they show and is you simply can't stand them, a thin layer of lining ply will hide them and give a smooth interior.

Many of our designs have been built using this method and now have thousands of sea-miles behind them. It is a good strong way to build a wooden boat.

3. SHEET PLY

By far the cheapest way to go is to create a chine boat using sheet plywood. Sheet ply is very strong and has great stiffness for its weight and is readily available.

Again the planking is supported by stringers and frames but this time the planking is sheets of plywood joined by either butt straps or scarfs joins.

We use sheet ply in our WOODWIND range of catamarans.

The WOODWIND principle of construction evolved from a growing desire of many amateur builders for an improvement on the older and now obsolete "V" style of hull. The drawing to the right shows a scaled overlay of the "V" hull and the WOODWIND hull. Note the shaded area showing, dramatically, the gain in interior volume of the WOODWIND hull. It is also easy to see the increase in waterline beam and room where you need it most ... at worktop and locker level.

The benefits gained:

• More internal volume, especially in the forward and aft ends. Increased waterline area results in a substantial increase in payload capacity.
• The underbelly shape is a close as possible to a round bilge hull without the extra cost of building one.
• The so-called "hobby-horsing" effect is reduced because of the greater reserve buoyancy in the hull ends. In the "V" style hull the shape tapers off far too quickly thus actually reducing the reserve bouyancy and contributing to the "hobby-horse" effect.
• The slight curvature in the topsides is considerably more attractive than a dead flat hull side.
• It is no harder to build a WOODWIND hull than a "V" hull and the benefits are greater.

4. FOAM CORE

If you feel more comfortable with a fibreglass boat then some of our designs have a foam core sandwich alternative.

In this method a temporary mould of frames and stringers is made. Its only purpose in life is to hold the foam to shape until it has been glassed. We have found that the best way to fix the foam is to screw it from the INSIDE. It's not a bad way of spending a day with one person holding the foam from the outside and the other screwing it from the inside.

The gaps in the foam are then filled (bogged) and the outside laminate of glass is applied. Fairing should be done before the hull is turned. Foam hulls are quite floppy until the inside glass laminate is applied so a cradle to sit her in after turning is well worth the time and effort. When all is set and ready the inside can be glassed and allowed to cure for a few days before any jigs or props are removed. Polyester resins shrink during the cure so be warned.

Once the hulls are built the fitout and completion are fairly straightforward...bulkheads first then floors etc.

My trimaran LIAHONA 40 was a foam core boat and I was very happy with the material. Heat and sound insulation are built in and it is stiff and strong. LIAHONA under several new owners has thousands of miles of cruising behind her, as do several of the same design, and there has never been a structural problem.

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BUILDING YOUR OWN BOAT .... a final comment

Building your own boat is much simpler than some would have you believe. Each individual assembly is straightforward and although there are a lot of bits to assemble, thanks to modern epoxies and materials, it has never been easier for the uninitiated.

I have built boats in every method described and therefore am able to help you through your project on a hands-on basis. I am very proud of the fact that our designs have been built by people who thought they would have trouble with a set of bookshelves. The cynic in me would probably say that building bookshelves is harder than building a boat.

Building your own boat is a time consuming affair. However, it can also be an absorbing hobby and learning curve, one which a family or group can participate in. The end result, using sound techniques and up to date methods, is a very good investment .... a waterborne nest egg if you like.

Today's multihull is an asset. Some of our designs have returned three times their building costs to the owners on eventual sale. This isn't a bad return on the fun and achievement of building and then the fun of sailing and using your own boat.

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"SIMPSON ON BOATBUILDING"

....the instruction manual

We have written a book on boatbuilding that is supplied with every set of plans. In a fit of original thinking we called it "SIMPSON ON BOATBUILDING". Subtle don't you think? You can buy this book separately if you want to study up on boatbuilding before you start (see the Online Shop).

In true style we've kept it very much a hands-on book. All modesty aside we've received nothing but praise for the book and so far no negatives. Here are a few comments from readers:

"SIMPSON ON BOATBUILDING has helped me understand the GOUGEON BROTHERS BOOK"

....... that one I liked.

"This is no coffee table wowzer, but just what I've always hoped would someday appear between two letter sized soft covers that will lay out flat on a workbench .... and finally before closing the book there's a full sized pattern for the goodly Joggle Stick. That's the samurai-like thingum used by those-in-the-know for determining the shape of irregular objects .... which alone, I think, is worth the price of the book." SEARUNNER trimaran designer Jim Brown in his revue published in WOODEN BOAT MAGAZINE.

"There's a page missing"... we replaced the entire book.

"How come others don't simplify things as neatly as you do?"...I wouldn't have a clue.

"Your book Simpson on Boatbuilding is the best I have read. Amusing, thoroughly informative and full of commonsense."

The book is written in a step one, step two, step three type sequence. We've attempted to cover just about everything a backyard builder needs to know to build our designs. A curious side effect has been that people building from other designers plans have found our book invaluable.

SIMPSON ON BOATBUILDING - Buy from the Online Shop.

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