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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Boat bending

29th December 07

The 28th was cancelled due to extreme rain and wind, Today a small lake surrounded the boat.
We managed to raise the 4th side piece on the 27th, now to fit it.
The opposite side fitted better than this one. Looking at the initial offering up, it looked like it would never fit, too high in places and too low in others. Nothing lined up... (to other potential builders.. a word of advise... dont panic and relax, let the boat build its self. The kits are extremely accurate but on this side the boat its self wasnt the right shape to have this part fitted, its that simple. So on my own and with a lot of 5000kg span sets I went about lowering the centre of the boat by over 12mm.. as its only tack welded it will move.



Below: These parts were out of align by nearly 10 mm. I used 3 x 5ton straps to the RSJ frame and a 6 ton jack to rise the lower of the 2 bits.. and yes, the boat came into shape. its really mind over matter.


Bottom lined up, and later the top came into line,


All the straps pulling the floor of the boat to suit the side sheet. Remember the side sheet will not bend, but the boat will.




All the internal lines, markings for the frames lined up 100% inside. if you look closely, frame 10( ST10C-2) will have to come up 5-7 mm.. and once I have the next piece offered up it will..

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New Central Heating

Last Tuesday I set about installing a new central heating and hot water boiler.  Although the Mikuni MX60 originally fitted has done sterling service for 2 winters, it did run hard and long which is actually good for this type of heater.

I decided the replacement would be a Hurricane SCH25 as it has more function and control.

I gave my self a couple of days to do this.  First job of course was to remove the Mikuni which took about 2 hours.  

With that safely removed and packed away the next job was to drain the engine calorifier coil as I would also be installing a flat plate exchanger to recover engine heat into the radiators which the SCH25 control system is able to do.

 20 plate 44kw heat exchanger

This is placed in series with the calorifier coil. The left hand (blue) pipes are from the engine the right hand (white) go the the central heating system and the SCH25 calorifier coil.  

Once the engine water has reached 70c this aquastat switches on the circulation pump and feeds the harvested heat into the CH system but without firing the SCH25.

This of course can be used in reverse to preheat the engine from the Hurricane but this would need another pump.  There is a small amount of thermo siphon already so I might consider putting in a 1 way valve to stop this as heating the engine without the option is wasteful.

Once the system was up and running I was getting (from the engine alone) 56c of water through the CH system.  Basically free heat when cruising or charging.

Reading taken from the towel rail

After 3, yes 3 days! I had all the plumbing done, and the heater installed and the wiring put through.

I had to cut a larger hole for the exhaust.  The old one was 1 1/2" and the new one is 2".  I didnt want to put yet another hole in the boat so how to do it?  My plan was to clamp wood either side of the hole and run a new pilot. But no theres a much better way shown to me by Garth at Ely Boat Yard.  This has to be tip of the year so far. So obvious really!

Use the previous hole saw as the pilot
 by mounting both on the arbor   

How neat is that?

New exhaust fitted

As always putting in wiring neatly all takes time.  The previous room stat had only 1 pair of wires the new one needs 3 pairs + I heft a spare for an extra frost stat but probably wont be needed.  This involved taking down one of the kitchen cupboards, the one with the most stuff in it of course!

Followed by the wiring back to the control box.

There are 3 extra wires here too, one for the GSM remote for the controlling the heater by TXT, one for the extra but probably not needed frost stat, and another for a room stat in the bedroom if it proves necessary.

Then finally all connected.

And with permission from the manufacturer in Canada the GSM remote wires soldered on to supplement the  switch on the system remote panel.  Special permission to not void the warranty

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And here with the panel switch off but the GSM switch on, system working.

So that was that.  It was a bigger job than I expected and if was presented with a bill for the time it took me I would be questioning very seriously.  I would think it probably took me 30+ hours.

All I need to do now is learn how to program the room stat/timer controller.  Its too cleaver for its own good so they provide tutorial videos on the Heatmiser website.

To come:-  The new prop has arrived.

And some new seating and storage for the stern deck.

This is the template to build to

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What happens if you make a mistake

Are you scared to start a boatbuilding or other project in case you mess up, in case you make a mistake? What will people say, will your friends joke about it and embarrass you?

Nearly everyone makes mistakes. Those who say that they dont make mistakes are either lying or are not pushing the boundaries of their own ability. As long as we are trying new things, taking on new life experiences, we will make mistakes. It is an essential part of the whole learning experience. Sure, it is nice to learn from the mistakes that are made by others but we learn more lessons, we learn them faster and the message sticks better when we make those mistakes ourselves. The more painful the mistake, the stronger the lesson that we will learn.

When I designed the Paper Jet, I had a particular building procedure in mind for the boat. As it turned out, the Paper Jet could not be built the way that I had envisaged. So, I had to go back a few steps and think of a different way to assemble it. I did that and went ahead and built my boat by a different method. I had a few other smaller backtracks and eventually had my boat complete.

Did I make some mistakes? Yes I did but so what? I made those mistakes because I was doing something that I had never done before. I was doing something that nobody had done before. I needed to learn the lessons that had to come out of building this prototype so that I could write the building instructions in the best way that I could, to enable other builders to get it right without making those same mistakes.

If I was scared of making mistakes I would not be trying new things. I designed and built the first radius chine plywood boat, my own "Black Cat", and made some mistakes along the way. Every time I was able to recover the situation very quickly and move on to the next stage of building. Overall, the project was a great success. Along the way I shrugged off the comments and criticisms of others because they were of no consequence unless I allowed them to be. They were generally from people who have never built anything major themselves. It is normal that the people who will laugh when someone makes a mistake are those who dont achieve much themselves. Disregard those people.

While building "Black Cat", one evening I was working with a spindle router shaping some small plywood parts. I was annoyed about an interruption unrelated to what I was doing and which had broken my concentration. In my distracted state of mind, I put my right thumb through the router bit, which was spinning at 20,000rpm. It made 11 cuts to the bone in the space of 1/2" and I was spraying blood. Within a minute or two I was passing out from pain and shock and was hauled off the the doctor. She said she had never seen such neatly done damage to human flesh and described it as sliced like deli meat. She was able to fix it with one stitch threaded through all of the slices. The worst impact from my mistake was a couple of weeks knocked out of the middle of my already tight building schedule.

OK, so we all make mistakes. Hopefully most of them will be to your boat rather than to yourself. How do you recover from your mistake? First you need to know what your mistake was, i.e. what it was that you did and what you should have done differently. That should help you to figure whether or not you can take apart the incorrect work. If you can take it apart then do so and rebuild it correctly. If you cant take it apart then you must figure the best way to modify the structure to correct it.

When you buy a set of quality boat plans you get access to a support system as part of the package. That includes being able to ask the designer for advice when needed and to steer you along the best path whenever you have a problem. You may think of a way to correct it but the designer, from past experience, may be able to offer some other alternatives and to say what will be best. It is likely that the designer or someone else has made the same mistake before.

The important things to understand are:-

1. You will occasionally make mistakes.
2. Some of those mistakes will be silly ones and may embarrass you. Laugh them off. Take control of the situation and correct it, dont allow the mistake to take control of you.
3. The designer of your boat should be available to help. Contact him, explain your mistake and ask for advice.
4. You can recover from most mistakes. It may take a bit of application on your part but you can do it.
5. When your boat is finished you will know where your mistakes are but most other people will never see them.

When prospective builders tell me that they could not build to the standard that they see in my Paper Jet, I sometimes point out some imperfect workmanship so that they can see that my work, like theirs, is not perfect. We all make mistakes. Fix them, then get on with life.

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Bottom Draw Hatch Covers

Remember the days when mostly girls started a bottom draw for the day they would marry and set up their new home.

Well building a new boat is much like setting up a new home.  We however have a bottom draw ROOM.

Pretty much everything in this room is destined for the boat, from furniture to, fire extinguishers and home entertainment stuff to kitchen ware as well as loads of boaty bits like solar panels, ropes, navigation books, even a bloody Rosie & Jim.

Deb is particularly pleased with the cushions that arrived today.

Meanwhile I am still doing all those jobs Ive been putting off.  Today is was grinding off the old holding paint on the fore deck ready for final finish which will be nonslip.  Also painted now are the hatches for the weed hatch and mud box and the clamping bars.

Oh and I fitted the cover for the hydraulic steering ram.
(Blue bit with silver screws 9 oclock)

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Dressing up The Annie Buck in The Eye of The Storm

Phase II of the Annie Bucks change over from her summer outfit to her winter outfit occurred as two incredible storms were on our doorstep: Hurricane Sandy (otherwise known as Frankenstorm) and the 2012 Presidential Elections. As I write this, the hurricane is bearing down on us, so if my writing seems a bit off, its because Ive got my mind in a few different places. This story is about yesterday and as I write it I dont know what the outcome of today will be...

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David pointing to the winch on the boom. The mast is the pole
with the "whiskers".

It has to be done when it has to be done and on the day the rain bands were arriving in advance of Hurricane Sandy, it was necessary to install the mast and boom used for oyster dredging into the Annie Buck to be ready in time for the season.
 

About a month ago, I wrote about the removal of her canopy, a coordinated task involving the efforts of a number of Watermen and neighbors. This is a similar type of task. The mast is made of steel and, although I dont know exactly what it weighs, it weighs at least several hundred pounds. It is the long pole with the “whiskers”, which are steps to climb to its top for whatever maintenance might be required. The Boom is made from aluminum and it weighs somewhat less, but the winch attached to it adds a lot of pounds.

The boom comes out of the truck first.

All of the work was again supervised by“Keeper”, who knows all corners of the boat. Our part starts when we meet David at his truck, where he has somehow managed to load both mast and boom. They are precariously balanced, the weight bolstered by some people sitting on the truck-cab ends as if on a see-saw. The trip to the boat is about 500 yards and uneventful.

The mast has to be installed first, but the boom is on top, and so it is the first off the truck. It is placed out of the way, as much as it can be, on the dock.

 

The mast is all steel and quite heavy.

As it was when we removed the canopy, you find that its a long distance from the decks of the boat to the floor, especially when you are carrying something heavy and even more so when there is a momentum to the object being carried, because of all of the people involved. Everyone has to be quick and careful and to be aware that if you are at the wrong part of the dock, or boat, it is easy to step off onto nothing and end up in the water.

Board being bolted to mast bottom.

The bottom of the mast is attached to a board which is bolted to the floor just behind the pilot house. That board is bolted to the mast first and then the mast is brought upright. There is a bit of finagling to get the bolt holes in the board to line up with those in the floor. When the holes are aligned, lag bolts are set in, but the mast is by no means secured.

Raising the mast.

What really controls the stability of the mast are the various lines running from the top of the mast to the bow of the boat and to points near the sheer line in the forward half of the boat. These lines are made of “wire rope” and their tension is controlled by long turnbuckles.

Securing the mast.

 

After the mast is in place, the boom is brought aboard and attached to its mounting point by a very sturdy assembly made of stainless steel. Of course, as we are doing all of this, there is a wall-like line of clouds in the SouthEast sky; probably the first part of Sandy... 

???

Bringing the boom aboard.

 

The boom is not raised yet to its normal spot. It doesnt need to be today. Its time for everyone to go and batten down the hatches at home.

I just want to say that its clear as I write this, that  a lot of people that we know and love are going to be hit hard by this one. I hope that everyone fares well in Hurricane Sandy...

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Family Time

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