guide to make boat

I have shown a few projects in this blog over the past few months with the hulls being turned using different methods. The bigger the boat the more critical this operation is. The risks of damage to property and injury to people increase exponentially as the boat becomes more bulky and increases in weight. Imagine the difference between turning over a plywood hull that is 6.4m (21ft) long, 2.4m (7'10") wide, 1.2mm (3'11") deep and weighing 200kg (440lb) or a 50% scaled up version of the same hull. At 9.6m (31'6") long, 3.6m (11'10") beam and 1.8m (5'11") deep, it will weigh 675kg (1488lb).

It has only increased 50% in all directions but the weight is more than 3x that of the smaller boat. The bulk becomes more difficult to manage and the weight to lift and lower becomes a major factor. If, at the same time as increasing the size, you also change to steel as the construction material, that same size hull could weigh 2500-2750kg (5500-6000lb). Now you are talking about some serious loads that can get out of control, yet the boat is still only 50% bigger in each direction.

Those smaller projects are easily turned over by hand, with friends and neighbours supplying the motive power and the boat having a soft landing on tyres or some other cushioning material. Years ago a client of mine in South Africa turned his 32ft hull by himself. He jacked it up on one side until it reached the balance point, then let gravity take it the rest of the way. It fell against a young tree, then slid down the tree and came to rest flat on the ground. Luckily his hull was relatively undamaged but the tree didn't survive the experience.

There are many ways to turn a hull but that is not one of them. I have a whole chapter on this subject in my book "Shaped by Wind and Wave", to give guidance on how to safely turn your hull. The two Didi 950 hulls that were turned recently in USA and Australia both used the spit-roast method. For each of my own big boats I have used a chain block to do the work, another of the methods explained in the book.

Turning the 38ft "Black Cat" using a chain block on a scaffold tower.

The book can be ordered either as a paperback or as digital for reading on whatever screen device suits you.

To see our range of designs, go to http://dixdesign.com/.

This seems to be a period of hull-turning. About 10 days ago I posted about the Didi 26 being turned in Hood River, OR. Now I am doing the same for Mike Vermeersch's  Didi 950 in Ohio.

Mike turned his hull this weekend and it went very smoothly and safely. It is a much bigger boat, with more weight that can potentially get out of control and more height needed to successfully accommodate the hull on its side as it goes through the process. Bigger and heavier boats need more care, preparation and equipment than is the case with smaller boats.

Mike chose to turn it using the spit-roast method. This is only one of many methods that I describe in my book "Shaped by Wind & Wave".

Turning by this method is done by attaching axles to both ends of the hull to suspend it on supports (Mike used engine hoists) while it is rotated on the axles. Care must be taken to get the axles on centreline and close to the vertical centre of gravity of the hull, to keep the rotational forces small. In this case Mike asked me for the position of the VCG, which he says proved to be spot-on. Once lifted, he turned it by himself, exerting about 20lb of force to rotate the hull. These photos tell the story.

Spit-roast axles ready to be fitted.

Axle bolted to transom.

Axle bolted to bow.

Axle in chain sling attached to boom of engine hoist.

Lifted on engine hoists and turn started.

Almost over.

Cradle ready for the hull, on castors for easy moving.

Safely settled in her new cradle and ready for interior work.

Thanks Mike Vermeersch for the great photo series.

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