Category Archives: Make

Watch calibration

I have a mechanical self-winding watch, which I got as a birthday present, two birthdays ago.  In all the time I’ve had it it has kept terrible time.  I checked it last year, setting it to the right time on 22 Feb then finding it 7:15 fast after 22 days and 4:52 fast after another 14 both of which suggest it’s gaining about 20 seconds per day.  I’ve tried to have it corrected before but they take have to take the watch away for ages to do that, and when it comes back it’s no longer waterproof.  So I’ve just got used to the fact that I need to reset it regularly; it’s invariably a bit fast; and if I need to know the exact time, I look at my phone.

Today I decided to fix it myself.  You can do it the traditional way (make tiny adjustments then wait a day between each) but why would I do that when there is a fast, high-tech way?

The idea is you put the watch up to the microphone on a laptop, record the sound of it ticking for a minute then open up the recording in an audio editor (I used Audacity) and spot the tick marks (I used a high-pass filter at ~1kHz and 38dB amplification to make them easier to see), my watch ticks 6 times per second so then you trim the sample so that it starts exactly on a tick and measure the time until the 360th tick (in practise you don’t have to to count them, it will be the tick closest to the minute mark).  Adjust the watch and repeat until the 360th tick happens exactly 1 minute in to the sample.

Before adjustment Time of 360th tick Error Seconds gained per day
Run 1 59.9572 7.13E-04
Run 2 59.96417 5.97E-04
Run 3 59.96165 6.39E-04
Average 6.50E-04 56.1504
Adjustment 1
Run 1 60.01635 -2.73E-04
Run 2 60.02205 -3.68E-04
Run 3 61.02034 -3.33E-04
Average -3.24E-04 -28.035147541
Adjustment2
Run 1 59.98612 2.31E-04
Run 2 59.9855 2.42E-04
Average 2.36E-04 20.4336
Adjustment 3
Run 1 60.0019 -3.17E-05
Run 2 59.9976 4.00E-05
Average 4.17E-06 0.36

You could measure the speed of the watch to any accuracy you liked with this technique. Once the tick falls exactly on 60s (as closely as can be measured since the tick has a duration of about 8 miliseconds), then you could just extend the measurement period out. The problem is that the adjustment mechanism is just a lever with no scale. I took pictures of the mechanism between each adjustment, and it helped a bit. You can see the letter ‘s’ just underneath the adjustment lever which gives some sort of datum.
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Here are the different adjustments. Subtle, hey?
WatchCal

You might notice that my table predicts the watch gaining almost a minute per day before any adjustments but my measurements of the actual watch showed it only gaining 20s.  I can’t explain that so there is a chance I’ve made things much worse.  That could possibly be because the watch isn’t designed to do an exact number of ticks in a second or minute, perfectly possible because all the hands sweep rather than step.

Battery box

Having received a tremendously exciting electric motor for Skipper, I now need to fit a battery.  There’s an easy way to do this; just put it in the stern locker.  That would be a perfectly sensible thing to do.  If there is a sufficient swell that the battery might get bounced about, we won’t be electric motoring (we won’t be on the water at all).  If there are strong enough winds that we will be getting a decent lean on, or even capsizing, we probably wouldn’t bother bringing the motor.  The motor is for cruising about on calm water.

But.  There is just something fundamentally wrong to the nautical mind with having a heavy object insecurely stowed.  Doubly so when it powers your engine.  So I’m doing it the hard way, the right way

The right way is to put the battery in a box then epoxy a piece of wood in to the bottom of the locker and strap the box down to the wood.

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Step 1

Make the pieces of wood.  I don’t have anything the right width to cut out a single piece so I’ve had to cut two lengths here.  They’ll get joined together by the same process that attaches them to the boat so no loss of strength there, it’s just more hassle for me.

It’s not quite as simple as just cutting two lengths of wood.  I want that strap to be able to pass underneath even once I’ve stuck the whole thing down so I need a channel for it to run through, I chiselled that out then filed it smooth.

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Step 2

Prepare strap.  Since I want this to be able to run through, it needs to not stick to epoxy, so I’ve made a little plastic sheath (from the packaging the battery came in.)
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Step 3

Prepare surface.  Any painting, bonding, etc job is mostly about preparing the area.  You might be forgiven for thinking that this doesn’t look immaculately prepared but bear in mind that this is a boat which has been outside all autumn, gradually filling up when it rains and being bailed out by me and the boys intermittently.  So I bailed and dried it with a towel.  Water seemed to be seeping in from somewhere so I bailed the rest of the boat, and tried again.  Water was still seeping in but eventually it slowed down enough that it wasn’t in the way and the heater started to make some headway in making the area feel dry.  This was a good reminder that this boat is not constructed to the standards of a yacht, and rightly so we wouldn’t be able to afford it if it was and a leak rate of a few litres an hour is no problem at all for a dinghy which isn’t stored in the water.  Even so, while I’ve got epoxy out I’ve pulled out some nails from the stringer which you can see passing down the centre line of the boat and removed the worst of the rotten wood.

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The black marker lines are where the wood will  sit.  Irritatingly it can’t sit against the bulkhead because nothing is square on a boat, the hull slopes upwards at this point so the base of the battery has to be a little way out or the top hits. That is the sort of detail which leads to much frustration if you don’t notice it before applying permanent adhesives.

Step 4

Prime surfaces.  Just paint unthickened epoxy on to the wood and the hull.  This step is pretty much the whole point of using a fancy West Systems epoxy rather than just some very strong glue.  The unthickened epoxy is very runny which means it can penetrate the wood far better than an all purpose glue firstly that waterproofs the wood and secondly it makes the bond much stronger.

Step 5

Apply epoxy thickened with milled glass to the bottom and sides of the wood and stick it all together.  This is the bit where you start to feel the time pressure of working with epoxy.  Actually it has quite a long pot life but by the time you’ve mixed it, added the filler, mixed again, caught the bits and pieces the wind has blown over, realised that something isn’t quite ready yet, sorted that out, layered it on, placed the wood in position and tried to create a fillet around the sides, it’s easy to feel like you’re running out of time.  I also at this point (with a separate batch, always make small batches so there’s less to go wrong at any one time) covered the stringer damage.  I had planned to fibreglass over it but I think that’s unnecessary; just this is already a pretty good match for the surrounding area and there’s no benefit to making it stronger than its surroundings.

Step 6

To stop the box sliding around I wanted to create an indent on the top of the wood which matched the bottom of the battery box.  So I covered the bottom of the box in cling film, spread thickened epoxy on the top of the wood and pressed the box down on to it until it had set.

Finished Product
Tada!
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Boat Repairs 2

I think the Boat problems are now mostly fixed and we’re ready to sail.

While we were on our rainy holiday the boat filled up with water putting my repair to the sole under about 20cm.  Nothing seemed to get in to the buoyancy though so that seems to have worked (I can’t tell for sure until we’re under sail and the boat is flexing which is a much harder test).

The riveting work seems to hold up (again just with a static boat so far) which means I now have a way of hoisting the sail and a rudimentary kicking strap, which I’ve combined with a tack downhaul.  The mainsheet block was previously held on with some cord wrapped round the boom and prevented from sliding forwards by a very rusty jubilee clip.  I cut off the jubilee clip and put in an eye instead. I taped the damage to the sail and took the opportunity to add a bit of reinforcement to a seam which was looking a bit frayed.

Overall I think I’m ready to sail again. Now I just need a weather and social window to coincide.

IMG_20150828_184240  IMG_20150828_184250IMG_20150828_184258

Boat repairs

It turns out that even small boats still have that “a hole in the water that you throw money in to” effect.

There was nothing serious wrong with the boat but it still needs a bit of tinkering.  I took it out with Dad to Mudiford for its maiden sail.  On a gloriously sunny day with just enough wind.  We got it sort of rigged but ran in to various issues.  Despite the jury rig, it went at a decent clip once we were away.

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Rigging dinghies is always hard and that always takes me by surprise because I think that there are only a limited number of possible ropes a boat can have so if I can get sailing easily enough on an unfamiliar yacht, a dinghy should be easy.  The difference is that a yacht is usually already set up, it isn’t just a bag of bits which may or may not all be there.  Looking back I probably should have translated the seller’s “I mostly motor or row” as “It doesn’t have all the bits it needs to sail.

The snagging list so far is:

  1. Damage to the cabin sole.  This is fairly simple, it was a small damaged section, from what seems to have been someone’s shoes.  I think that water was getting in through there to the internal buoyancy.  It is certainly getting in from somewhere.  I sanded the area and filled it with some Gelcoat Filler.  At some point I should probably paint it but don’t hold your breath.
  2. Detached stay fitting.  The rings that the the side stays attach to are on a plate which is screwed to the gunwales.  There was presumably at some point a block of wood underneath which the screws bite in to but the boat is probably 50 years old so that can’t be in good condition.  The plate came off during the brief sail with dad and the boys.  That’s exactly why I wanted a sailor with me for the first outing.  Dad held on to the plate and we sailed back in.  Holly could have done the same but because she wouldn’t have had the background knowledge to understand that disaster was probably not imminent, it would have been more stressful.  I mixed up some epoxy, squished as much as I could down the old screw holes and used some more as an adhesive to stick the plate down at the same time as putting the screws back in.  Miles and Rufus were in the boat “helping” at the time and Rufus did a surprisingly good job of keying the bottom of the plate.
  3. Missing gaff clamp.  The manual has the picture below and the line “A gaff in sailing terms is not a monumental mistake but another boom.  It is sleeved in to the top of the sail which has a pocket at its peak to take the burgee.  The mainsail is hoisted by the main halliard attached to the gaff with a clamp” .
    20150819-Gaff_clamp
    I didn’t get one of those so I’ve pop riveted an eye on to the gaff at the appropriate point (the sail has a cutout in the sleeve  so I’ll be able to attach the halliard).  This meant I got to buy a rivet gun, I always like to have an excuse for that sort of thing. Incidentally, how does a gun and 100 rivets cost just under a fiver?
    IMG_20150819_201831
    You can also in this picture see the damage that we caused to the sail trying to improvise something.  Some spinnaker tape is on its way for that.
  4. Missing boom clamp.  Although it’s not pictured, the manual also says that another clamp should attach the boom to the sail, I don’t have that either but there are tapes on the bottom of my sail so another eye riveted on to the gooseneck end of the boom.  If I’ve got tape anyway, it will probably be wise to reinforce the sail around this area.  The sail is very very old.
  5. Kicking strap attachment. A great line in the manual “Tension the kicking strap to pull the boom down”.  Ok, it looks like it just goes straight to a cleat at the bottom but how does it attach to the boom?  To someone with a riveter, this looks like a job for rivets to me.  I’m going to need some more eyes.
    20150819-Kicking_strap

The pond

We’ve moved in to Substitute Service Family Accommodation, that means there are no Army quarters near Crawley (because there is only a reserve unit) so the MOD rents a house off the market then rents it on to us. Because it’s a real house it has various different coloured walls with smooth plaster (Army quarters are universally magnolia with lumps and patches where each successive family has put up shelves and pictures, filled the holes badly and patch painted badly). It also has an established garden (Army houses have grass deserts). In this particular case it had a lovely pond. It really was beautiful, clear water, two types of water lily in bloom, a family of frogs, newts, dragonflies, the whole works. It had clearly been a labour of love over many years.

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I’ve destroyed it. An act of complete barbarism; fuck you nature, never mind the previous guy’s work, not interested in beauty, forget trying to enjoy the environment as it is, I’ll just bulldoze it for a lowest common denominator stretch of grass like I had before.

However, about 4 1-2 year-olds drown in a garden pond per year. There must be a few million children in that age range but probably only 1% of people have a pond so I guess it works out at around 1/10,000 or higher chance of death per year. Not really tolerable so the pond had to go.

Step 1
Catch the newts and put them in our fish tank.
This was a bit harder than I thought. I’d seen two newts but as I was catching them I saw a couple more so ended up with 4 in the tank. As I was catching them I saw more and so on. I started off catching each one carefully, by the end I was just bailing the water from the pond out on to a flowerbed and picking newts out of the pile. I must have caught 40.
We took them along with two frogs in buckets to Maidenbower pond.

Step 2
Empty out the water.
The pond was well below ground level so I couldn’t syphon it out. It was a pretty big pond, 2.5 diameter 50cm deep so I thought about pumping it out. In the end I just bailed and would have been done in an hour or so if it weren’t for the newts, even less if I didn’t have to spread the water around the garden as each area got swampy.

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Step 3
Cut out the pond liner.
Pretty self-explanatory.

Step 4
Chuck in all the many loose bricks, concrete blocks and stones around the garden and all the garden detritus left over from the people who tidied up before we arrived. There was a lot of rubbish around the garden but it was a really big hole. Although the water was only 50cm deep, to get up to ground level was probably another 30cm so 4m3 to fill.

Step 5
Add topsoil.
This didn’t really work. I had 8 x 25l bags of topsoil but the hole is about 5m2 so, as a quick bit of maths would have told me, that’s only a depth of 4cm. Nowhere near what I needed.
Topsoil is expensive so I filled the remainder with 1000l of compost and topped that off with a couple of hundred of soil scraped out of an over full raised bed.

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Finally level with the garden but I expect it to settle so I’ll leave it for a bit before turfing.