A Proper Test Run

Working on my boat is intrinsically worthwhile, but to see it perform is a new level of satisfaction. Taking your boat any distance from land is to trust in the quality of your work, as well as your skill and composure should something go wrong.  Usually anyway, in my case it was more of a strident disregard for safety and an irrepressible need for instant gratification; in this spirit we set forth!

I had the displeasure of hearing Bon Jovi's "Blaze of Glory" earlier in the week, and whilst the musical aspect made me naueseous, something about the  lyrical content resonated with me, and I decided that Saturday's adventure would take place across low tide. This meant that we wouldn't be able to get home between leaving at 7am and 2 in the afternoon, and if serious trouble arose we'd have to beach the boat or fix it out there. This minor concern was also outweighed by superior fishing compared to an afternoon session, and it was settled!


The details will be omitted herein, simply because they aren't very interesting.  We didn't go "Down in a blaze of Glory", and thus its just not bloggable. We did decimate fish stocks and just generally have a rad time though. Every outing in this boat has been radder than the last, and every moment of radness is doubly rad because its been such an involved and challenging journey to get it to this point. RAD RAD RAD!

One more Bodge Job, then its Fishing Time!

With the platforms covering the lower half on the transom, there was now nowhere for the exhaust to exit below the engine's manifold. This is something of an issue, as the cooling water is injected into the exhaust immediately after the manifold to keep it cool, and if the exhaust runs straight uphill then seawater will seep back into the engine when its shut off. This is obviously an issue, so some engineering is required to move the water up and safely out of harm's way.

Fortunately, someone else has already solved this problem, when they invented the waterlift muffler. These use the pulses of exhaust leaving the engine to lift a column of water to heights well in excess of what we need here, and I set to making a temporary one.

As the water level covers the bottom of the exit pipe, a seal is made, and that water sitting in the bottom of the pipe is shot out with the next exhaust pulse. The process reaches equilibrium at high engine load, whereupon the water is shot out in super thin sheets, or even a mist, and thus the back pressure should be minimal.

The problem was what to make it from. I had some PVC pipe of about the right size, and I declared this suitable, but the main container/resonator part was less obvious. We had a look for paint buckets but couldn't find any that were empty, so I popped home and had a look for a strong container with reasonable heat and pressure resistance. All I found was a plastic petrol can, and whilst not quite the volume I was hoping for, I figured it should be strong enough, plus less prone to cracking than other plastics.

My home-made waterlift muffler

Two holes were made with a holesaw, and the pipes fit snugly into them. The surrounding area was degreased, and sanded with 60 grit, and the pipes glued with thick epoxy. I think the petrol can is vinylester, which isn't the best substrate for epoxy from what I understand, so extra care was taken to ensure a good bond.

The next day it was dry, and ready to fit after trimming the exit pipe.  This was then bent slightly with a heat gun (I don't reccommend this, buy the right elbow) as we only had a 45 degree elbow rather than a 90.

It performed entirely satisfactarily in testing; the noise reduction wasn't huge, but it was noticeable and took the sharp edge off the exhaust note. There was no problem with the lifting aspect, and a check after the engine was off confirmed that there was no danger of water ending up back in the engine, YUSS!

Under cruising power the water is largely atomised :{D

I'm unsure what could be done to make it quieter. I suspect incorporating baffles would help, as would a larger volume container. From what I have seen so far, I find no reason why this couln't be made from plywood and fibreglass, though I'd suggest incorporating a thermocouple and a basic heat alarm in case there are water supply issues. I think much of the sound level in this case is mechanical noise from the exposed engine; when this is boxed in I expect a larger reduction.

I plan to give this a good test before a redesign - its more than adequate for the moment. I was quoted around $300 for the correctly sized commercial equivalent, I can make at least twenty more prototypes for that sum and I'm sure I'll have something that's as good, if not better.

Rad work team, I'll see ya next time for more DIY adventures!

Introducing Chemical Dependance to an Already Strained Relationship:

The boat before me was not the one I'd loved before. From the end of its glossy white exterior, the grafts sprouted as a bulbous mutation; their appearance not altogether unattractive, but alien, and altogether incongruent with everything that made that vessel what it was. Their host was not intrinsically different however - in construction and shape they couldn't be more closely related. Yet all that connected them were two dozen zinc-plated screws. What, I asked, could resolve these tensions and unite the two forever?

Answer: Thermoplastic and woven glass extrusions. Duh.

Here's how we were situated, with a hull extension like the one pictured (left) on each side of the boat. These were not strong enough to cope with any of the forces they were designed for, as all that was holding them together (and on to the hull) was a few screws. Plus there were significant gaps on some joins, and the likelihood of any aspect of them being functional was fairly slim. Luckily, this was considered in the design process, and there was always going to be another step before their boat ramp baptisation - fibreglassing!

In case you were wondering, I mean with epoxy resin and woven boat cloth. As far as I'm concerned that is the only kind of fibreglass. Polyester resin and chopped strand mat existed only so that we'd all have time to practice and hone our skills before the real deal came along. I did not use polyester resin for glassing this boat for the same reason that I did not use Lego to make the engine mounts; both may be "easier to work with" but I would quite like a functional boat at the end of this. Ok!

Hull planed flat with extension, this was done on every contiguous surface

The first step was to plane across where the extensions met the hull, which provides a good surface for the resin to adhere to, and ensures that extension and hull meet at exactly the same level. The latter is crucial for performance and the former is crucial for strength, and with the electric plane it didn't take long.

Well, its now the part of the story where I talk about actual fibreglassing. If you have yet to try fibreglassing the bottom of something, I'm afraid I can't express the misery involved in normal prose, and suggest you imagine yourself trying to escape from a disused well that local residents use to dispose of surplus marmalade and net curtains. Hamish and I did the 'wet lay-up' method, where you brush on resin first, then try and push the cloth up onto it. It was tricky and we ended up with a couple of creases and bubbles on the first side, which appear opaque and white, whereas properly wetted out resin is transparent. These can be sliced or sanded off and then filled, so all was not lost.

The other side went much better, though I'm not sure why. We then glassed strips over all the joins that weren't already coated, then did another coat of resin over the rest. Wherever glass cloth wasn't hard up against ply there were more opaque spots, and these seem much more prone to having pinholes with no resin, so much care was taken in the resin coat to fill these little squares and ensure waterproofness. And that was that, woo!

And thats how two became one, and no stress (hydrostatic or hydrodynamic) would ever turn them apart (probably, don't want to jinx it!). I haven't taken any photos post-fibreglass, but here's what the extensions look like, see ya next time!

Unacceptable Stern Freeboard Ends Here!

After much conjecturing about how much of what force needs to be applied where (see below post), I arrived at the conclusion that making hull extension/swim platform things for each side of the boat would solve the stern heaviness issue. I worked out the exact torques and their net sum, and was able to calculate that they would "probably work ok" as long as they were "quite big." I was now completely convinced and set to make the modifications in accordance with this consummately specific brief.

The first step is always to make a template from wherever your modification will be affixed. I make a habit of doing this first part in a mad rush and with only partial concentration, so that the first piece is always completely useless and must be remade. By doing this I ensure that any excess enthusiasm is quashed, and the fact that I can't make things out of wood very well remains at the forefront of my mind until the project's completion. Once this is out the way things generally go much better. The second attempt at the first piece is on the left.

I nailed a bit of ply to the transom and traced around it, then popped it off again to cut. Its important for performance that there is a smooth transition between the hull bottom and the extension, so I deducted 12mm from these areas, so the ply that runs back from the transom should be close to the same level as the hull. This may not make sense now, but you'll see it in the other photos.

The vertical bits were then measured and cut. These had to fit closely since they form the gussets that hold the extensions rigid when their buoyancy is pushing upwards, or people's weight pushing downwards. Needless to say not all of them were perfect first time, but they were soon sorted, and I could start the longitudinal pieces.

The bottom piece needed careful lining up to ensure its angle was near identical to the hull's angle. I screwed the front end, then adjusted the back with a car jack, till both looked good against a straight edge. After screwing this rigid, I made the side piece, then the angled part that joins them. They had 20mm overlaps at this point, and cutting the shallow angles was a bit of a headache. In the end I used a handsaw, and by holding the blade against the upper piece of ply (in both cases) I was able to get the angle very nearly perfect, as seen in the photo to the left. Woo!

It took me two days to finish this first one, and I was very happy with the result. I figured it should take me like 4 hours to copy it and make the other side - just got to make careful measurements and cut the same thing reversed, right? Wrong!

Both sides nearing completion

It took the remaining three days of the week to make the other side; almost every piece required two attempts (or more), plus I was running out of 12mm ply and had to scavenge what I could from around the place. Hence my work bench is now missing 1/3 of its top surface, and one my mum's shelves in her office has mysteriously transfigured itself into 18mm ply (Shhh!).

Woodworking on boats is especially tricky. When making house modifications everything can be level, vertical or 45 degrees usually, whereas here there is no way to get a reliable level, and thus no way to get either of the other angles. Hence all the crucial measurements were made with a straight edge off the hull, and then a sliding bevel was used for any subsequent cuts. The starboard side took much longer, since as well as matching the hull, it also had to match the other side. Eventually both sides were within 5mm of each other, and most dimensions were within 2mm. It was the most mentally challenging part of this whole project thus far, but I'm sure the results will be worth it.

Next time: The Wee Guys get her glued, glassed and gorgeous - stay tuned!

"Sternz up, Bowz Down!"

If you don't have at least a mild interest in half-baked physics, skip this post

Those were Snoop Dogg's exact words when I called him to ask for advice on our boat's weight distribution. I thanked him earnestly and began thinking about the situation. As far as I could surmise, the problem was that the moments exerted by the motor, stern leg and (to a lesser extent) the battery, were all significantly behind the boats centre of buoyancy; the pivot about which these torques are applied.

I ran a string line along the boat's bottom and its current waterline, and worked out the rough cross-sectional area every 0.5m. By averaging these and mutiplying them by the waterline length, I came up a point 1.2m from the transom as the boat's centre of buoyancy. I then worked out the torques on the sketch below:

The negative number reflects the torque's direction, ie pushing the stern down. I estimate (based on no evidence whatsoever) that if that were reduced by half or more then the boat would sit about right. But how?

A few options spring to mind:                

1. Move the engine forward

2. Add ballast to the front of the boat to balance it

3. Find a lighter engine, or even modify the transom for an outboard

4. Add displaced volume behind the centre of buoyancy.

I am lucky to have a buddy who works for a prominent yacht building company, and he suggested considering extending the hull, but boxing in the stern leg where it is. I had had a bit too much to drink at the time that this chat took place, so possibly missed some useful tips that might have made the process easier, but I came up with this the next day:

Essentially the plan was to build two hull extension box things, to around half the transom height, and pass it off as a swim platform. I sketched them and came up with dimensions, and found they'd add around 70kg of buoyancy each when submerged. Those with experience in reading kindergarten-quality technical diagrams will see above that they restore net torque on the system to just -20Nm, in conjunction with the battery being moved to the bow.

I can't be sure this will work, since its an assumption made upon previous assumptions, but it will definitely help. If need be the issue can be mitigated with other measures from the list above.

Snoop will be so pleased :D , see ya next time!

Second Test Launch Day!

Wee Dave!

Mine and Hamish's excitement was of such incredible magnitude that it actually threatened to tear the universe apart at its salty epicentre, so its lucky that we were able to get a launch in on the next Friday afternoon. In doing that we believe we've saved humanity, but we may not be completely absolved from blame if 2012 actually happens, we were THAT excited.


I thus had four days between test launches to get everything tickety-boo. I reluctantly conceded that installing the correct number of bolts in the stern leg was neccessary, and sealed the exhaust and the other glaring sinking hazards from the week before. Before I knew it, it was Friday and it was all on. In spite of this, things felt much less rushed than last time, everything felt very ready, and the purchasing of bait and ice was closer to being justified.Things went smoothly in the marina. She came off the trailer fine, and I set to driving around in circles by the boatyard while I waited for Hamish to park. I swung back to pick him up, and we began to learn how boat-driving and car-driving are not tantamount to the same skill. I think a diagram will help here:

1 - Beginning to grasp the beginning of boat driving here. 4 - Hamish has to run to the front to grab a post we're about to hit and push us off again.   2 - Ran aground.   3 - Ran aground.   4 (upper one - haha!) - Notice temp gauge very hot.   5 - Realise flushing tap open so water pump has been pumping mostly air, slowly turn back on and decide to head back to shore believing we've blown the head gasket and cracked the heat exchanger. Whoops!

Haha no but its not all bad! It was probably a good 20 minute trip, as we did about 1kt out the marina (paranoid about another accidental speed record attempt), at 400rpm and as many decibels, and had a grand wee time! Also we did try and get the boat on the plane once we were past the breakwater, and it almost did! There is something of a problem though, in that the motor weighs a lot and is very far back, and thus will undermine our attempts to do maritime things effectively until something changes there. Or somewhere else... (spoilers!)

So anyway that was that. I'll leave you this picture and the weight problem to ponder, until next time!

Test launch Day!!

Hint

For weeks the boat had been creeping closer to sea-readiness, and it was decided that the coming weekend would be the one. Hamish's parents were away (always a catalyst for progress), so after working all Saturday we moved the boat to their garage and continued into the night. A few more jobs were taken care of on Sunday morning, until there came a point where we figured there was nothing more to do. It was terrifying.

We began the slow journey to the water, and stopped in at the petrol station for boat diesel and gas for the borrowed aux motor. We quickly attracted the attention of two old seadogs, one of whom was full of admiration for the thing, and one who could find nothing better to do than point out every possible flaw and sinking hazard. Though the latter was clearly just old and jaded, it increased my terror level to near breakdown point. I was running low on nails to bite also, and wondered how much of my arms I would consume before we arrived at the boat ramp. Luckily both legs of the journey total less than seven minutes so all limbs and appendages arrived intact.

I rolled one last, sparse cigarette, and walked ahead of the trailer, going through everything needing done before leaving the dry and then the trailer. The nerves had clearly spread to my crew also, as all of us were getting increasingly bitchy. Jumping in the boat as Hamish backed her down, I put her in neutral, checked the bungs for the ninth time, and attempted a deep breath.

Surprising how deep the water in the marina is

Water was creeping in the missing stern leg bolts that Hamish and I had deemed unnecessary, as well as through the unsealed exhaust hole which I'd assumed was above the waterline, not realising the stern floats lower on the boat ramp. Figuring we could just bail all that later, I pressed on. With water now a couple of inches deep, I found my temporary flylead and got the glowplugs going, then gave it a crank. After 10 seconds or so I began to suspect something, as it'd started beautifully every time since I put the primer bulb on, but this time not a murmur!

I opened the vent screw on the injector pump and squeezed through some diesel on the primer, but there were no bubbles. I cracked cylinder 1 & 2's injectors also, and cranked for another 10 seconds. Fortunately at this point a wrench fell and landed on the injector pump, and picking it up I noticed that the Stop lever was on. Thank Neptune! With that off she started up within a second, and after the injector nuts were back on she was purring. If that wrench hadn't landed there I might very well have dismantled the whole engine there on the boat ramp, lucky it did!

For better or worse, it didn't occur to me that if I was capable of that big of an oversight, then perhaps I didn't quite have all my faculties. That I should maybe cool off and have another cigarette, or take a general stock of the general situation (slowly sinking, controls too primitive, brain not working). Worrying.

Looking over the transom though I was pleased to see gallons of water spraying out the exhaust, and the engine chugging away merrily. At Rob's suggestion I tried putting it into forward, and that was all working ok.

From this point its something of a blur, though I distinctly remember saying "It's fine, don't panic" as much to myself as to Rob, after reversing off the trailer with a bit too much vigour, in the process breaking several water-speed records and almost sucking the transom underwater . The "above waterline" openings were spewing water inwards, but I dove for the throttle and gear lever at the same time and halted our journey underwater. The lack of throttle killed the engine however, so we were drifting haplessly away, and I really thought we were going to sink.

I am not ashamed to say that I have never been so afraid in my life. I assume I knew (don't really remember) that we weren't going to die, but I do love this little boat. What's worse is that it sinking would've substantiated every snarky remark I've ever received from defeatists who will never take a risk in their life, and who scorn me for backing myself to pull these things off. Some of my friends are these type of people, and I resent them expressing doubts about their own abilities, let alone about mine. Victory here is the only option, as they have to learn AGAIN,  that Wee Dave never doubts himself and that is why he usually wins.

Anyway, on to what happened next. I am pleased to say I remained reasonably equanimous, found the flylead and got her going again. Memory fails me slightly, but I think that in the preceding hysteria I had knocked her into forwards, so we took off at some speed and were almost on the plane before I could get to the controls, but I got there in time, cut it, and steered her gently onto the trailer. We covered that ten metres or so very quickly!

Just kidding, she's still above water! I just didn't take any photos and needed to keep things exciting.

The other guys couldn't figure out the winch, so I jumped out to the bank alongside and paid out some line, and we got her back on without too much hassle. Naturally the old miserable guy from the gas station was I-told-you-so-ing, but I really didn't care. We'd packed in a whole boat trip's excitement into three minutes or so, and had lost neither life nor vessel! The fishing rods and snacks may have been a bit ambitious though... Haha!

I'm smiling now just thinking about that launch, retrospectively it was the most fun I've ever had! Stay tuned for more Adventures of Wee Dave!