koen's blog

RIB competition

While waiting on the final KeyCreator (CNC) blueprints for our new surfboat, I decided to have a little competition. I want to know if it is still possible these days to build a wooden boat, that can compete with a similar RIB (Rigid Inflatable Boat) not only on price, but also regarding maintenance, ease of handling under oar (the RIBs are awful!) and motor, weight and aesthetics (sorry, can't help it, a thing of beauty is a joy forever).
LOA Length Over All has to be more or less 4 metres, and she has to be able to carry 4 adults with load easily.
Also, she has to be light, easy to construct and seaworthy.
I know that a roundbottom boat (like the Lawley tender) complies to my wishes, but this type of building would definetely increase the building costs - read building time. A flatbottomed bank dory however would be very ease to construct but she wouldn't row that well in rough conditions.
Browsing the endless archives of master boatbuilder John Gardner, I came across the 12 feet Chaisson dory. This little boat has it all: great looks, she rows very well, and is not too difficult to build. She will last a lifetime and she will bring her owner and his/her family anywhere they'd like.
I decided to build my first one like the old chap Chaisson would've done: a clinker built, flatbottom craft with sawn oak frames and copper rivets as fastenings.
The only thing I changed was the amount of strokes: 5 instead of 4 at each side. This to eliminate the really wide boards needed for the true Chaisson dory, which are very hard to find these days.

My idea is to optimize the building process by taking notes, and pictures - in order to obtain my competitive goal of selling this boat for 3500 euro.

At this stage of building - see pictures - these are my notes/changes:
- stripplanked instead of clinker: you save a lot of wood
- laminated frames and stem instead of solid sawn wood: less timeconsuming to make (especially the gussets took way too long to fabricate)
- started right side up, I turned the boat at this stage to make it easier for shaving the bevels. Although, when stripbuilding I think I would go for right side up.
- when glueing the bottom plank, there is no need for putting in the rocker at this stage. It can easily be done afterwards.

More to come..

Chaisson Chaisson Chaisson

Hot news - surfboat with CNC routed frames

We're making a boat in collaboration with the Technical Institute of Tielt, the VTI.
They will provide us the frame of a prototype surfboat, completely CNC routed!
This time I want to build a light boat that will litterally click together like the famous dinosaurs models do. So I got to the drawing board and sketched the lines of this new surfboat. Evert Lataire, homie and naval architect, ran these lines through his computer and enabled me to make a paper model.
Nice, like a giant fishbone!

Next, Bram Van Oost, a VTI student and computer wizzard, got in action and redrew the hull in KeyCreator, a highly specialized CNC program.
And that's where we have to take a break, for a while at least. Bloody exams!

No worries, news will follow shortly.

Ella sketch Ella paper model

The frame that refused to be laminated

September 14th, 2007
Recently I faced a problem and since for once it had nothing to do with customers not paying, I think it's worth sharing with you.
A boat with laminated frames was brought back to my shop because four of the laminates had failed.
Indeed, at the turn of the bilge the glue joint had failed and even the stainless steel screws, used to fasten the frames to the battens (this was a batten seam boat), didn't keep the laminate together! What did this guy do with my baby?!
It turned out the boat was left uncovered for a week. Unfortunately, more rain fell that week than in an entire year, and the boat was filled with water, 20 centimeters high. After pumping the water out, the owner noticed the laminate failures. OK. Time to take my lazy brain to the gym for a serious workout. The oak frames had been under water, swelling for more than a week, and oak is known for twisting a lot when exposed to different levels of humidity. For these four frames, the swelling must have been too strong, causing complete glue failure. So did I use an inferior glue? But I used seawater-proof polymere glue that can handle forces of 50 kilo per square centimeter. Pretty OK, no? And what with the screws? They were literally torn out of the wood! And why did only these four frames, at different places in the boat, fell apart, while the other sixteen frames remained completely intact. The brain was boiling.
Suddenly old stories of other oak-glue failures came back to me. Like that heavy oak transom, made up from several thick planks glued with epoxy, that broke under the force of an outboard engine. Or that guy who spent six hours of circling, trying to get back in the harbor with a broken oak rudder...
An idea started to bubble up! Not the glue was the villain but the tannin, a substance which gives oak its resistance to rot. Maybe my four oak frames didn't spend as much time in the steamer as their siblings, and therefore contained more moisture - read tannic acid. The acid made the oak less receptive to gluing and this could be thE reason for glue failure.
Now, since more woodworkers, not only boatbuilders, but carpenters and cabinetmakers will start using epoxies, polymeres and other 'modern' glues, the more information will come to our ears concerning the oakgluing business.
Anyway, this whole thing is highly hypothetical, and I promise some testing and updates on the results!

ps. How did I fix the problem:
I resteamed the four frames in the boat, using a tarpaulin cover and a tube, and refastened them with stainless screws. Simple as pancakes...
(with the same glue)

Halfmodels and computer programs

August 20th, 2007
The construction of our new boats always starts with the making of a halfmodel, as was done centuries ago.
By making this halfmodel, the boatbuilder gets a 'feel' of the performances of the boat and the way the shape of the hull will behave under motor, sail or oars. The model is carved from one piece of hardwood, straight grained and dry. The boatbuilder tunes the shape of the hull with spoke shave until it is perfectly sanded and can be finished bright. Completely finished, the model is now cut in pieces, vertically from the baseline, and the pieces are numbered, from stem till stern. The lines were the model is sawn, will become the different frames of the future boat.

Now, every piece is individually put on a scanner. They are scanned, and with the aid of a computerprogram virtually glued together to form the lineplan of the boat. Here tradition finds the digital age and forms a magnificent team. When the CAD program has checked the hull for anomalies, it gives us further information: waterlines, buttocks, weight etc. When all parameters are set, the fullsize prints are a piece of cake.

halfmodels

Hardcore or woodcore?

August 3rd, 2007
The hardcore traditionalist claims there is no boat like a wooden boat! And I think he's right.
Seeing a beautifully made wooden boat cut through the waves is simply breathtaking and no PPP (Plastic Production Potpourri) will ever beat that. There is only 1 problem: from the professional point of view, you have to keep up with them. That's where the new generation of epoxies, polymere glues, and other slimy stuff comes in. We can still make a beautiful wooden boat and limit the cost of solid wood, limit the production time and yes, we can even build our boat lighter. Hip-hip hurray for the woodcore boatbuilding, some say. A little explanation: a wooden core is sandwiched between layers of glass cloth and epoxy. The whole thing is vacuum bagged and thermally cured to form a strong unit. Most boatbuilders nowadays use plywood for the hull's core because it is cheap and easy to get. We don't. A Whaleboat woodcore boat is made of solid wood - larch. I believe that the plywood core system has one major drawback: when a sharp object hits the boat really hard and penetrates the glass clothing damaging the ply core, you have serious problem. The ply will soak up water between its layers of (different) veneers, and it will eventually result in failure of the glues or even worse, rotting of the inferior softwood veneers. The once so stable ply is becoming very unstable now. When using a solid wooden core, these problems simply don't exist.

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