Ark - right!

With a little trepidation, I launched the Ark on the boating lake. I had picked a nice evening when no-one else was around. 

I was so worried that I tied a crabbing reel thing to the handle on top so I could pull it back out if all went badly. This wasn't so clever as two corners of the pool (you can see one in the background of the photo) are home to very tall plants and the cord kept getting caught. 

In the end, I gave up with it and took the risk. We completed a full circuit of the pool before  I pulled the model out and inspected the interior. 

Dry!

After this, it went back on the water for some more sailing and photography. Another 10 minutes sailing and still dry. 

So, it looks like this "quick" project is finally complete. 

What did I learn? 

• Projects always take longer than you expect. 
• When converting a toy boat, take it apart fully and then glue the bits back together. Keep thinking, "How do I keep the water out?"
• A short hull with a stupidly big propeller can work. I don't give it too much speed and the model tootles along fine. Even at full thrust, it's not going particularly fast, but then it is only a little motor. 
• Tubby hull, big rudder, excellent turning. Not quite so good at going straight. 

After all the trials, it's great to see the Ark sailing. On a sunny evening, it looks great on the water, every bit as good as I hoped. I couldn't help smiling as I pottered around with it, and that's what the hobby is about.

A lifebelt for the Ark

One last job before a return to the lake, make a buoyancy aid for the Ark.

My theory is that if I fill the hull with polystyrene, it can't fill with water. This might not save it on its own, but if it does start to sink, the sinking will be less dramatic and I can charge the bank to get within rescue distance.

To aid this, the receiver is sealed up in a plastic bag. I can't protect the motor or servo, and the speed control can take a dunking, but it's all about increasing survivability.

The foam is hacked away using a sharp knife (messy) and hot wire (clean, but limited use due to access issues). I kept pushing down on the foam to mark where I should cut next.

Fingers crossed I don't need this...

The Ark loses weight and gets back on the water

Sunny weather, a little less work pressure - I can get back to the Ark. 

With the middle sealed with epoxy, I ripped the lead weights out of the hull, waggling them with big pliers until the glue holding them in gave way, and set off down to the newly cleaned up garden pool. 

Handy hint: The filter sand needs changing every 5 years, not every 15. Makes a difference. 

Anyway, I wanted to let the hull sit higher in the water than before, but worried that all the weight of superstructure and animals would make it unstable. At the poolside, I added in a lot less lead, but as far forward as I could, until the boat sat level. 

At this point I had to make a decision - the elephants are heavy (who'd have guessed?) and so will affect the trim. From now on, they are the front of the boat so it can be weighted on this basis. 

After adding the lead, I sailed for around 10 minutes. Then looked inside. 

No water. OK, we've been here before but this time I'm more confident. With 8oz less weight, the model seems to sit on the water and be surprisingly stable. Bashing it against the pool edge didn't threaten to tip it over. Wobbling it about was fine too. Tight turns, and this boat can really turn, don't bother it.

If I really tip the model by hand to the point where the water is at the join between bulwarks and hull then water gets in. But the boat still plops back the right way up. Basically, if the deck is wet, there is water in the hull. I need to be careful. 

 However, things are looking good. 

Deep breath, epoxy time!

With a fresh battery delivering plenty of volts, the ark charged around the pool creating a bow wave. A couple of minutes later, there was a little pool around the motor support.

As I had thought, water is getting in in the join between hull and top of the hull. Sealing around the inside might have slowed the flow, but it still came in under the foam motor support. The only solution is to fill the gap around the hull.

I'd not wanted to do this as it's highly visible but better that than a sinking boat.

In my toolkit are some syringes and needles. I wondered if I could put epoxy in one of these and squirt a very thin bead into the join.

I couldn't. The glue wouldn't go down the needle. It did come out reasonably neatly from the needle-free syringe but quickly blocked the nozzle.

It was no good, I had to mix a fresh batch of glue and apply it as neatly as possible with a small screwdriver. As it happens, the result wasn't too bad, but not as good as I would like.

I'm going to try cleaning this up a bit once it is fully hard, but if this fails, it occurs to me that a length of yellow Trimline tape would look OK and cover any mess. If I'd thought of that earlier, I'd have tackled this job earlier.

Lights on, no action

Having ascertained that the electrics in the ark were working, my plan for a good long sail was thwarted.

Switching on the model after charging the battery overnight, the Viper speed control showed both red and green lights and the servo had the jitters. All the channels on the receiver seemed to have swopped around too.

How could this happen? The only thing I'd done since it had worked before was charge the battery.

After a fair bit of pugging and wiggling, I gave up and pinched a battery from another boat - one on charge for a visit from my cousins (who needed to be entertained) a couple of days later.

This seemed to cure things, but then I put a meter on the batteries.  The good one gave over 6V, the duff one 4.something. At a guess, not enough for the receiver or speed control.

Diagnosis, my charger is faulty.

Digging around, I found a Thunder Tiger version and a suitable lead to connect it to the battery. A few hours later, the meter said 7V. Not sure how that works, but I'm thinking this proves it can hold a charge.

More importantly, I managed to get the boat on the water and find out how it leaks. 

Looking for that leak

With the radio gear working, I need to find out where the water is coming in. Back on the pool (yes, it's gone green, there's someone coming to look at the filter next week) I sail the ark around for a while.

After ten minutes, looking inside, there is a tiny amount of water around the rudder tube.

A really tiny amount, but it's worked its way up the tube, I can feel it all the way up to the arm, which must be just lower than the waterline.

Unconvinced, I wanted to sail the model without the top, so added a bit of weight.

Another few minutes sail and again, a tiny amount of water. Certainly not a boat sinking amount, but it's the only wet stuff in there.

Ideally, I'd have sailed on, but the battery was on its last legs so this is on charge and I'll lightly grease the rudder post to try to keep things dry. Then have another go. 

Don't rush your modelling, it can save you money!

Work commitments have kept me away from the Ark, but I'm determined to get it on the water properly before the end of the summer.

With a few minutes to spare, I thought I'd dig through the stash of model boat bits and see what I needed to replace after the dunking. Out came a receiver and servo, but first, I fired up the boat.

And it worked!

OK, the Radiolink R8EF receiver doesn't look pretty, but it only works!

The servo seems happy too. So all the bist go back in the stash.

When I tried all this a few weeks ago, the servo chattered but didn't operate properly. Now all is well. I can only assume that in the interim, the electronics have fully dried out. So by waiting, I didn't bin perfectly good (if ugly) components.

Sealing the hull

Holidays and working have eaten nearly all the time I have had to work on the mystery as to why the ark sank. A bit of a shove on the pool didn't reveal any obvious leaks I'm sad to say, so it's back to guesswork. 

One possible issue is the hull is in two parts. The top ring is sperate from the bottom, so it the boat reaches that depth, it's going to fill up very rapidly with water. 

Ideally, I'd have separated the components and glued them together. With the motor fitted, this isn't an option so it was time for a less appealing Plan B. If I can't stop the water getting into the hollow bits of the hull, at least I can stop it getting into the main bit. 

Along the front edge (right-hand arrow above) I ran copious amounts of Poundland epoxy glue. It splodges nicely into place and will stop any water. 

Under the top edge, the hull is hollow, so I filled it with Milliput. Then, because I've never got on with the stuff, coated it with more epoxy. 

I don't know how much all this will help, but I reason at least if the boat starts to sink, it will do so slowly. 

Now I just need to find time to get back out on the pool and really sail this boat in a safe environment to see what else happens. There are some electronics to replace first though as the servo is chattering, which might be the servo or the receiver. Which I wish I'd waterproofed in a balloon.

Not an ideal maiden voyage

Look closely at these two photos taken 2 minutes apart.

You might think they look like a pretty boat sailing on the water at our boat club, and you would be right.

The sharp-eyed will notice that the model appears to be sitting slightly lower in the water in the second shot. I was not sharp-eyed on the day.

Fortunately, by the time the model had made it halfway around the lake, even I realised something was wrong and pointed the model at the bank. It made it, but then sank.

Running around the pond I reached the boat which had lodged on a ledge, I'm glad I left the handle in place, and I was able to haul it out. Popping the deck off, I emptied out the water and took the model back to the bench for further drying.

Back home, the good news is that the electric seems to have survived. I just need to work out what's gone wrong.

For what it's worth, the advantage of brightly colour models is you can spot them underwater.

2 by 2, they went for a sail

Loading the ark with figures proved to be interesting. I tried a few different arrangements but ended up with something very close to the first version. I wanted to keep the pairs of animals together, but there's not actually much deck space. As it is, the giraffes had to look over each other than the front legs of the elephants aren't on the ground.

Sticking them down was essential. I had considered fixing wood in their legs and screwing them down, but eventually simply glued them in place with UHU on some feet and clear silicone sealant on others. I might go for solvent eventually, but like the idea of being able to remove them if I decide, I don't like things later. UHU/silicone can be peeled away, or at least I hope it can.

After this, a quick trip around the pool was called for. All seemed well...

Time to put on weight

All wired up and ready to sail, the ark just needs a bit of weight to level it up. The heavy battery in one end brings the hull down a bit, but uneavenly. What the model needs is a spell in the sink and some extra lead.

Those moulded lines on the hull are very handy as a quide. Add to that a spriti level to make sure things are equal all round and the job only takes a few minutes.

At 1.2kg, this boat isn't going to have a problem in the wind, or when the fast boats make waves!

Surprise unobtainables

Things I'm surprised I couldn't buy at Cosford, from the wide array of RC parts suppliers.

A battery holder for a jelly cell. 

OK, the flyboys don't use heady lead-acid batteries, but I was able to buy the lump itself easily enough. I suppose not being able to buy something to hold it in the hull isn't that much of a problem since a few bits of Plastikard and some glue will work.

A servo holder. 

This IS a surprise. A simple vac-formed box to hold a servo, or something in laser-cut plywood out to be found on many stands, but apart from one plywood device to hold the servo against a wall, nothing.

With servos being fundamental to all forms of radio control, I really thought there wouldn't be any need to make something myself. It's not that I'm lazy, it's just that it's a bit of a faff as these things are a bit of a funny shape. You need a box which a wire can point out of the side of.

I'm sure someone is going to point me at a supplier. I'll be the one placing an order for several as there are many more servos in my future.

Foam motor support

With the driveline fitted in the hull using lashings of epoxy glue (Hint: Hwen using the Poundland stuff, buy fresh tubes) the motor was going to have to sit at a funny angle due to the whopper prop fitted on the end of it.

I contemplated making a plastic support but decided to try something new. With several lumps of grey styrofoam kicking around, why not use this? 

Chopping this to size worked well. I kept shaving bit away until the motor would fit with everything in-line. Half an hour's work and I had something that worked.

Thoe motor is fitted with UHU POR adhesive - a foam-safe clear glue. I wasn't sure about this, but it seems to have fixed the foam to the hull and motor strongly enough that when power is applied, nothing falls apart or even looks like it might. I wonder if the foam even provides some cushioning effects to keep things quiet?

Anyway, with things dry, I lashed up 6V worth of batteries and tried it in the pool. 

Short driveline

The ark needs a short driveline. From the back of the motor to the tip of the propeller is 18cm.

You can't buy a prop shaft that short - 6cm long - so I used a piper cutter to trim it. One of the plastic bearings was eased out of the end and then pummeled back into the new short length, not an easy job as these things are fitted tightly.

The shaft had to be cut down too. Tricky as while one end is threaded for the prop, the other isn't and I didn't have a coupling connector suitable for a plain shaft. Oddly, my 4BA die wasn't a good fit on the thread, I'm sure it should be, and I couldn't find a holder even if I wanted to use it.

In the end, I opened out a threaded connector with a cutting broach until the shaft could be friction fitted with a bit of percussive persuasion.

It all seems to work, I just need to fit the lot in the boat.  

Can I cram it all in?

As with any model boat, work starts on the Ark by taking a perfectly watertight hull, and making holes in it.

The rudder is easy enough - drill a hole, ream it out, screw the rudder tube in place. For a change, I haven't needed to mess with the length of this as the hull is so thick at this point it more then covers the plain section of the tube.

Fitting the prop tube is a little tougher. I've elected to use a 60mm plastic propeller for a few reasons:

• It's bright red and matches the hull (sort of)
• I had it to hand
• I like the cartoony idea of an oversize prop under this boat

The practical upshot is that the shaft has to be inclined quite steeply.

I don't see this as an issue. The short hull means little space for a motor but fitting it at an angle will help. OK, the drive won't be as efficient, but this is a pootling around boat so who cares?

One challenge will be shortening the shaft. 6 inch is the shortest one available and I reckon I need half that. Time to get the tube cutter out!

A dig through the stores

I want to get cracking on the Ark, so rather than place orders for components, I've had a dig through the Parker stash of bits.

I now have a speed control, motor, prop, propshaft, servo and rudder. There's a receiver in my new (OK, bought for Christmas and not used yet) radio set. A battery will be nabbed from the drawer, I'm not having jelly cells posted 'cos they weight a ton.

Some of this stuff was bought for other projects and will need to be replaced, but not for the moment. It doesn't do to hang on to some bits anyway, the world moves on and they never find a use. Anyone need a 26meg receiver? Not anymore.

One of the advantages of being in a hobby for a while is you build up component stocks. I remember when first working in 3mm scale model railways, it was a nightmare as every project required a buying session before I could get stuck in. Definitely a disincentive to trying something new. 

Thanks to all those who clicked on the ads, they don't pay a lot, but I've pretty much covered the speed control already!

Unboxing the Ark

You asked for it:

I'll get the parts required ordered in then start work on this project. If you want to help, please click on the advert on the right-hand side of this page. It doesn't cost you anything, but gives me a bit of cash to offset the parts required for this project.

Well, I'm sure it wasn't my idea!