Water Levels for Boatbuilding

In my recent post about building stocks for wooden boats I mentioned using a water level for getting things aligned on the building stocks but I didnt explain how it works.

A water level is the most basic of measuring instruments and is very easy to use. Properly used it is very accurate but there are some principles that need to be taken into account in order to achieve that accuracy. If you ignore them then you can work on blindly assuming accuracy that is not really there.

A water level works on the basic principle that water will always find its own level; it will flow from where the surface of the water is highest to where it is lowest, until the two are equal. It is a simple tube with water inside it, open at the ends so that atmospheric pressure can push down on the exposed surfaces. It can be done with a simple length of clear plastic tubing, or it can be an ordinary garden hose with a length of clear plastic tube attached at each end so that you can see the level of the water.You will need about 500mm (20") of empty tube above the water level, to prevent water from running out one end when moving the tube from one bulkhead to the next.

To get two equal-level points on any structure, place the tube against the structure both at your reference mark and where you want to place the new mark. Raise or lower the tube at your reference mark until the water surface inside the tube is exactly at the level of the reference point. At the other end of the tube, draw a mark on the structure exactly in line with the surface of the water inside the tube. Ideally it needs two people working together, with one at each end of the tube to make fine adjustments to get the reference level correct but it can be done by one person if the tube ends are secured against the structure.

You can use this when setting up a bulkhead so that it is level across the boat. First, the bulkhead must have the waterline drawn accurately on the face, which should be done on the workshop floor when drawing the bulkhead for cutting. Position the bulkhead on its legs with clamps, with the centre of the bulkhead at the centrepoint of the building stocks. Position your water level so that the water is at the level of the waterline at one end. Raise or lower the other end of the bulkhead until the marked waterline is exactly at the level of the water in the tube. Check the transverse alignment of the bulkhead on the stocks with a plumb line attached to the centreline string above your building stocks, as described in my previous post about building stocks for wooden boats. Similarly, use the water level to set up other bulkheads at the same level as the first one.

Simple isnt it? But, it has potentials for error that you must take into account, or your new mark will not be accurately placed.

1. Dont use a tube that is smaller than about 12mm (1/2") diameter. The smaller the diameter the slower it will be to react to adjustments in level, due to friction of the water against the wall of the tube. The larger the tube, the more easily the water will flow and the faster it will react. The large tube also has more water surface exposed to atmospheric pressure, helping to speed the reaction. A tube of 16-20mm (5/8-3/4") diameter is ideal.
2. Dont use a tube that is excessively long. Ideally it will be long enough to reach the most distant point to be marked, with a bit extra to allow the tube to lie on the ground. Any additional length increases the friction in the tube due to increased surface area. It also allows the tube to lie in loops that will slow the movement of the water and possibly trap air to form airlocks. An airlock can stop movement of the water almost completely.
3. Purge all air bubbles out of the tube before you start. Air bubbles will affect the accuracy of your readings and will slow the movement of the water inside the tube. The smaller the tube, the more that it will be adversely affected by air bubbles.
4. Try to do your work in fairly stable conditions, so that the tube and water are not heating up and affecting the readings. Warm water will flow more easily than cold water and a warm tube will expand in diameter, holding more water. You dont want the tube to be moving between sunshine and shade because the expansion/contraction of the tube and water are likely to affect accuracy. This is particularly important if you are using a dark-coloured garden hose with clear plastic ends because the hose and water will expand considerably in sunlight.
5. Dont be in a rush to mark your new reference line. It takes a few moments for the water to find its level before you can make your mark. It will first surge up and down a few times before it stops. This is when you will see the importance of a tube that is not too small because it is possible for the friction inside a small tube to overcome the atmospheric pressure and give inaccuracy of 20mm (3/4") or more for awhile before it very slowly equalises.
6. Flick the tube with your fingernails before assuming that it has found its final level. The shock waves running through the water will help it to stabilise at the correct level.
7. Dont do this work in windy conditions. Wind blowing over either or both of the open tube ends will exert a venturi effect and change the readings. The air flowing across the mouth of the tube forms a vacuum inside the tube. That sucks the water up the tube, so the level will be higher at that end than the other. Even if the wind is blowing over both ends, it must be exactly the same speed over both ends at all times to have no effect, a very unlikely situation. If you must work in the wind, make sure that both ends of the tube are well sheltered from the wind. If the wind is strong then just dont do it because wind blowing over a bulkhead will cause high pressure on one side and low pressure on the other, so you will be unsure of the accuracy of your readings.
8. Tie a length of string to each end of your tube. Between readings, tie the strings to something at about the same level as your reference line. This will prevent the tube from dropping down and emptying some of the water unexpectedly.
9. When you have one bulkhead that is accurately set up and secured so that it cannot move in any direction, use that first bulkhead as your point of reference for the waterline when setting up all of the other bulkheads. Dont move the reference point to any other bulkhead because you could end up with a cumulative error, which is minimised by always working with the same origin as reference.
10. Buy or make some tight-fitting  bungs to plug the ends of the tube. It does not matter whether they are rubber, plastic or wood, but they should be non-porous. Use them to keep the water inside the tube when not in use.

I have no images of water levels of my own but Roy McBride of CKD Boats kindly supplied the images below, with permission to use them. His company is my agent in South Africa and supplier of plywood kits for many of our designs.

Two water level tubes. The one at left is discoloured by age but still usable. A simple plastic tube and water.

Both ends plugged with bungs to keep the water in.

This illustrates the principle. The tops of the lower two pieces of tape are level with the top of the water at opposite ends of the tube, so they are level with each other. Here they are close together but they could be 10m apart without any loss of accuracy.

Close-up of the tube and water surface.

 Thank you Roy and  CKD Boats for allowing the use of your photos.
 
To see our range of boat designs, for both amateur and professional builders, please go to http://dixdesign.com/.

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Amateur Boatbuilding Coming Alive Again

All things boating have taken a hammering over the past decade, with most people suffering to a greater or lesser extent through the financial woes that flooded the world. Initially, amateur boatbuilding seemed to stay quite strong, while sales of production boats went into a deep slump.

After amateur boatbuilding also started to weaken, it was interesting (but distressing) to observe the progression of the slowing sales around the world. First to go were the industrialised countries, led by USA and UK, then it spread to less developed countries. It is said that when America sneezes the world will catch the cold. When we lived in South Africa we could watch that phenomenon and knew that what was happening financially in USA, whether up or down, was likely to be mimicked in South Africa within a year or two.

The one market that seemed to stay remarkably buoyant was Russia, where amateur boatbuilding seemed to stay strong. Then war and politics stepped in, the Russian economy took a dive and sales of plans to amateurs in Russia also fell.

Boats are not an essential part of life for most people. For some they are transport or a work implement, for others they are a home but for most people their boats are toys, sporting equipment, or somewhere between, certainly not high on the list of essentials when money becomes tight.

Now we seem to be coming out of that slump. The US economy has been showing signs of life for a year or two and that now seems to be filtering down far enough that amateur boatbuilders are again starting new projects. If the normal pattern pertains, the upswing will spread out to the rest of the world as well.

Over the 35 years that I have been designing boats professionally, I have drawn mostly boats that are suitable for amateurs to build. This was not an intentional path in my design career but, in retrospect, was probably the most natural and logical one. My roots are in amateur boatbuilding, when I built a plywood 36ft cruiser/racer in my in-laws garden, based on a design by Ricus van de Stadt. My own first full design was the CW975 for a 32ft plywood racer/cruiser, which I also built after it won a design competition. The third design that I drew was the steel Pratique 35 cruiser for an amateur-builder friend. Next was the Coquette 39 plywood racer/cruiser commission, also for an amateur. Only after that did I receive my first commission from a professional builder for a production GRP boat.

My own 2nd big boat project, the CW975 "Concept Won", in my garden.

This depth of involvement with amateur boatbuilders and designs has resulted in a long string of commissions for amateur builders, mostly for plywood. My own third build big-boat project, in the form of the radius chine plywood Didi 38 "Black Cat", and my well-publicized voyaging in her, have reinforced that trend. For the past 30 years I have always had at least a year of work waiting in  line. That has now expanded to a 2-year backlog and I have had to turn away new commissions to keep the backlog somewhat manageable.

As the slump deepened, the average size of boats that people chose to build slipped lower, until we were selling only dinghies and trailer-sailers. Now that average size is starting to creep upward again, as builders move back into bigger boats. The most durable design that we have is the Argie 15, which has developed a good following that keeps it going strongly through thick and thin.

Argie 15 built by Andrey Borodikhin in Moscow, Russia.

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In trailer-sailers, the little gaffers, in the form of the Cape Cutter 19 and Cape Henry 21, are the ones that keep going. These lapstrake plywood boats are more complicated projects than a simple stitch-&-glue boat but they are just so pretty that they have attracted a good following. They have also proven to be quick in the light stuff and capable in the rough stuff, so they have grown a reputation for being desirable boats. That resulted in the upward expansion of this design range with the Cape May 25.

Beautifully-built Cape Cutter 19, built by Sergio Vianna of Curitiba, Brazil.

Newest in this series, and already generating much interest even before completion of the design, is the Cape Charles 32. Although not yet on our website and pricelist, drawings have already gone out to the first two builders. This one is a coastal and offshore cruiser, with shallow fixed keel and external ballast, whereas the smaller sisters have steel centreplates and internal ballast. We should have a web page for this design in a month or two. Until then, please email me for info on plan price etc.

Accommodation layout of Cape Charles 32 cruiser.

It is not only cruisers that are growing in popularity. One of the commissions that is waiting for attention is a bigger sister to the radius chine plywood Didi 950, at 11.4m (37ft). I have also been asked multiple times to draw a Didi concept to the Class 40 Rule but am not able to fit in the design in a reasonable time, so have turned down the commissions. Meanwhile other larger boats in our radius chine plywood range are also starting in various countries. This includes the first in that series, the Didi 38, with two new builds starting in Asia.

Didi 950 radius chine plywood racer/cruiser.

We are also experiencing increased interest in steel cruising designs, which have been very dormant for the past 10 years. Overall, amateur boatbuilding is looking a lot more healthy now than it has for a long time. Now we all need the politicians in all of our countries to play nicely together. If they do that then life should improve for all of us. Lets all go play with our boats.

To see more of these and our many other designs, visit http://dixdesign.com/ or http://dixdesign.com/mobile.

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Cutting Boatbuilding Costs

I recently had a situation that comes up on a fairly regular basis, often enough to be worthwhile writing about it. It varies but the core message is the same; "Your plans are too expensive, I dont want to pay so much for a few sheets of paper". I end up having to justify the price of my product to someone who is expecting a cheap deal and it has never resulted in a satisfactory closing.

When considering building a boat for yourself, or having one built by a professional, please bear in mind that you want to build a good and safe boat, one of which you will be proud and hope to own for a long time.

~ The plans are not simply a few sheets of paper, the paper is only the medium used to deliver a tremendous amount of information. When the plans are supplied in digital form by email, the negative feeling of the customer may be aggravated because even the paper has disappeared from the package that is supplied. The value of the plans is in the information, not in the paper. You can buy a pile of paper at your local stationers but they cannot sell you the information that you need to build a quality boat.

DS15 sportboat built by amateur Jim Foot in Port Elizabeth, South Africa. Photo Glen Meyburgh.

~ A quality boat design is the result of many, many hours of work, work that has been done by someone who has spent the time, taken the trouble and paid out a lot of money to get the training and experience needed to do a good job of designing that boat. A 40ft boat can take 500 to 1000 hours to draw accurate and high quality detailing. That is what you are paying for in the price of the plans.

~ If you have chosen wisely, you are also buying the accumulated experience and knowledge of someone who has learned, through thousands of miles and decades of boating, what makes a good boat, one that can be built by an amateur, with efficient use of materials, a boat that looks good, moves through the water efficiently and will give you great joy to launch and voyage.
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Beautifully-built Cape Henry 21, by Dean Ivancic of Porec, Croatia

~ We all expect to be paid a reasonable wage for our working hours. The person buying the plans expects to be paid for his labour, why would he wish less for any person who is supplying a service to him? If we cannot get a worthwhile price for our work then we must abandon that work and move into another field of employment. I design boats for a living because I love doing so. I retrained myself from another profession that was not as enjoyable but would have given me much higher income. That doesnt make boat design a hobby nor a pastime that neednt pay a satisfactory wage.

~ If you want to pay a low price for a product then you must expect to receive a product of low value. That is the mindset that has resulted in our shops now being overrun with junk products from cheap manufacturers in the East, mostly not worth the price that is paid and not properly fulfilling the purpose for which they were bought. The purchase ends up being a bad investment purely due to hunting a low price.

Didi 38 cruiser/racer built by amateur Stas Pechenkin of Irkutsk, Russia

~ There are places in a boatbuilding project that money can be saved or the dollars can be stretched a bit further. But you have to be judicious in choosing the places to save money. You will be spending a boatload of money to build a large boat and you need that money to be well-spent, a good investment. All of that money will go into buying materials and equipment to go into and onto what is shown on the drawings. The drawings themselves are likely to cost 2-3% of the total cost of the project. If you buy your plans based on price rather than on the quality of the design, you may save yourself 50% of the plan price, which is only 1-1.5% of the total cost. That is a very small saving but it can have a massive effect on the quality and value of the boat that you build. If a particular boat or construction method really appeals to you then you have good reason to buy that design. Changing to another design that doesnt really do what you want but costs less is really not a good reason for the change. Even if you get the plans for free, if they are for the wrong boat then you will be wasting your time and money to even start the project.

~ You can save money on the expensive shiny bits, then upgrade later when more funds are available. It will irreparably harm your boating experience if you build the wrong design but it will be done no harm if you buy good used winches and other hardware at a large saving. Make sure that the used hardware that you buy is to the required specification and in good order, that it has a useful life ahead of it. In a few years, when available funds permit, you can replace with new and sell the used items to another builder who is in a similar position to what you were.

Dix 43 Pilot built by amateur Dennis Wagner of Empangeni, South Africa.

~ Beware though, if you are tempted to buy used that very costly item, the sailing rig. If you find a used rig that you think is suitable for your boat, please first run the dimensions, mast section, rigging diameters and configuration past your designer for advice. A mast that you might think suitable may really be totally unsuitable for your boat for a host of reasons linked primarily to strength, which might cause it to fall down on deck in a tangle of bits. Something else to take into account is that the insurance industry generally applies a service life to the rig and expecting much beyond that may prove to be foolhardy. The service life is generally 5 years for sails, 10 years for rigging and 20 years for spars. If the items that you are considering exceed these ages then they may not be worth buying, should be examined very carefully or maybe even dropped from consideration.

Few people who build their own boats have endless funds. We all want to get the best deals on our purchases. We need to spend judiciously within the limited budgets that we do have available. Part of spending judiciously is to save money where it wont hurt the overall project.

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