Exhaustive reasoning, part 2

It's the most wonderful time of the year! Docklines at the ready.

The pins were barely in the steel before I was walking along the reassembled dock to put on my docklines. I've been told that, instead of every previous year when ours was one of the last boat in the water at launch (this year on April 28th), we would be one of the first, thanks to a change in the crane deployments. That means an extra emphasis on being ready to rock off the slings. Or at least, to motor sedately.

The angle is intentional: the waterlift muffler is not on the centreline. Blurriness unintentional.

Behold the stainless steel exhaust circuit shut-off. It's the culmination of a long-planned alteration to Alchemy's diesel exhaust setup, one that (after an appropriate real-life test period) will allow me to get rid of the dreaded anti-siphon loop, which I consider a weak spot in getting water out of the boat, having had them fail on me on two different vessels.

Yes, skipper, there is something called a "flash".  Seen on the right: the anti-siphon valve. Mine's a Vetus.

I got the idea from Dave Gerr's excellent Boat Mechanical Systems Handbook, which I endorse wholeheartedly as Damned Useful. In the picture above can be seen the fibreglass "T-fitting", a short run of exhaust house down to a SS ball valve, and a further length of hose down to the waterlift muffler. Also visible is the anti-siphon circuit, the purpose of which is to keep cooling sea water from backing into the engine once it ceases to use its exhaust to "push" it uphill and out of the boat. Well and good: my diesel is at or below sea level, and is more so on a heel. Water sucked in for cooling purpose via a seacock off the standpipe is perhaps one metre below sea level: anyone who has attempted to hold an inverted bowl full of air in a swimming pool can get a sense of the pressure involved. So the anti-siphon valve, by dissipating this pressure, allows the impeller to send seawater (and the heat it draws from the engine via the heat exchange) out of the boat, combined with the diesel's exhaust. It's why one's boat squirt out the stern, or, in our case, out the side.

Yes, I like to label. This shows the distance of the valve above the waterlift muffler. The top of the valve ball is just about at the waterline level of the boat at zero degree, or "no heel". This means that very little water can accumulate above it without draining to either side of the transverse exhaust.

Problems can occur with this anti-siphon valve, however, and I wanted to avoid complexity. Even though we sail in fresh water, I have had the "plunger and spring" part of the valve corrode and or stick shut and have had exhaust water back into the exhaust manifold, occasioning the dreaded "hydrolock" and extensive repairs and remediation. That's why I wanted to avoid the issue entirely: that's why, noting I already had an unusual starboard side exhaust, decided to go for a two-fer.

The new, port-side exhaust outlet being welded into place.

It got warm.

This involved some fabrication: Stainless steel "nipples", Sch. 80 and grooved to better accept hose-clamped exhaust hose, were welded in port and starboard. All credit to A. Barlow, my welder/fabricator of choice. As mentioned previously, he also did the new galley and head drain nipples in the same, robust form factor.

Back to the bare metal. It won't be the only time: we're having the entire bottom redone in Nova Scotia.

The idea was to dispense with the need for an anti-siphon loop at all. This installation means, in essence, that the area of the exhausts is effectively doubled (there's now two exhaust hoses, not one). This leads to less "back pressure"; the exhaust gases that propel themselves and the cooling water do not have to work as hard to get the mixture off the boat. The absence or negation of the anti-siphon circuit is compensated by the fact that the boat is nearly always heeled to some degree; the downward slope of one exhaust hose leaves the "windward" or "high side" hose open to the atmosphere, which allows the exhaust to exit properly.

That "T" is as high as it can go at present, but if it needs to be higher, I can make a box for it to increase the slope of the exhaust hoses out of the boat via that removable plate. As I've mentioned, I've been thinking of this for some time.

Now, this arrangement is neither common nor written about much, which accounts in part for the delay in implementation. Most sailboats have long hose runs to the stern and while that's fine in terms of function, unless the engine's in the saloon, an anti-siphon loop is essential, but the run is long and the possibility of having following waves flood the exhaust is real.  That's why I took this route and, let's face it, I was already, with a starboard exhaust out one side, conceptually halfway there.

About as neat a "bead" as I can manage in tight quarters.

Tests will follow once launched next week. In the meantime, I've finished the new bilge outlet. This is an above the waterline hole in the boat that takes a plastic fitting. It's bedded outside and in with 5200 Fast Cure sealant, which is the nuclear option for boat glues. But, as Mrs. Alchemy pointed out, one doesn't want the bilge outlet to leak, and so the big gun was brought out.

Recycled copper strapping. I suspect the hot water heater will go in the 'blank space'.

While I was down there, I gave extra support to the bilge pump hose, which is rather cheap and may be replaced before we skitter off the edge of the world.

The PSS "burp line" is better secured now.

In the process of strapping down the exhaust hose and ball valve, I secured the shaft seal's vent line high in the engine bay. It is not, in fact, the recommended two feet above the waterline, but coiled as it is, the water would have to be "extreme" indeed to crawl up that line. I have never seen it more than a few centimetres above the seal itself, in fact. Should this become an issue, however, I can easily raise it significantly higher...and drier.

Just because I often get asked about costs, the four nipples (two drain, two exhaust) cost about C$400; the run of corrugated exhaust hose (about 3.5 metres) was about $180; the AWAB SS 44-51 size hose clamps were about $60 and the stainless steel ball valve and tailpieces were about $230. We will soon learn if this was a wise investment.

Droning on about drones

Vista enhanced: The view from a drone. Photo still (c) http://www.captaincurran.com/2014/11/how-to-fly-drone-from-your-boat-1.html

Small, reasonably priced, remotely controlled (by either smartphones or dedicated console) camera drones are not just for annoying people and pets in public parks with their high-pitching whining. For the cruiser, they offer some practical advantages...if you can keep them free of the rigging. Not to mention your delicate flesh.

The advantages of the drone aboard the cruiser go quite a bit beyond boat selfies and bringing a bit of local colour to one's passagemaking blog. Some of them can be flown in fairly stiff breezes (although retrieving them can be tricky), and a range of several miles, using drones as "eyes in the sky" could reveal approaching weather or marine traffic, or even, when used as a "virtual crow's nest", reveal potential obstacles, such as wrecks or coral heads, that could ruin an otherwise beautiful lagoon visit.

It's important to note, however, that most drones are limited by their software as to the altitudes to which they can ascend; this is for practical reasons, such as the safety of aircraft, which also restricts drone operators as to where they may be flown at all. At sea, however, and away from land-based air traffic, there are fewer restrictions beyond battery runtime. Even so, a height of 100 metres is significant from sea level and is five to six times higher (and therefore gives a great "height of eye" distance to the observable horizon under fine conditions) than even the view from the top of the typical mast. For instance, our approximately 15 metre tall mast on Alchemy allows me to see an object of sufficient size on the horizon at 13.8 kilometres away; 100 metres of altitude on a drone would allow nearly 36 kilometres. And that's for relatively low objects; a ship of sufficient height could be seen even farther away, and a squall line thousands of metres tall would be obvious even further away and long before those on deck perceived the dark line of it approaching. This interests me, and not just because I've yet to install a lazyjack setup.

Mast steps galore: The smaller one's feet, the smaller the step can be; but the shorter the crew, the closer they'll have to be. Photo (c) Don Street/Cruising World.

In the past, the only way to get this sort of vantage point was by sending up the sharpest-eyed crew on mast steps, which was more convenient than just a bosun's chair alone and arguably safer as the last ones at the mast top gave the crew a place to more or less stand while repairing light fixtures or other mast-top fixtures, or examining standing rigging or freeing a snagged or damaged furler part.

The most esthetically pleasing mast step, as well as the least-likely to snag sails or lines, is the folding type.

But mast steps add weight and complexity aloft and can be expensive to purchase (depending on how many you require, which is a function of leg length and mast height) and laborious to install. (In the link provided, the fasteners are rivnuts, which I use with the solar panels; rivets or tapped machine screws are also possible choices). There's also a concern present in my mind of putting so many holes in one's mast and whether that has a compromising effect on its strength.

I would not hesitate to place a pair of mast steps near the mast top (particularly ones that are simple to fabricate, would be unlikely to snag anything, and would fit my huge feet), because I can see the point of that when combined with that bosun's chair. But installing mast steps all the way up just to get a better view? Perhaps the drone as nav aid makes more sense. Much as AIS complements RADAR, it strikes me that a live feed from a drone ahead of the boat would complement the forward-looking sonar we are already using. 

I think that the most productive use of drones at sea, apart from littering one's blog with stunning aerial shots, would be in noontime approaches to gaps in reef walls to confirm the least-tricky turns and the presence of uncharted coral heads. It was about two years ago that I realized drones were becoming cheaper than a full set of mast steps, and, because they can look directly down from well in front of the bow, are better for spotting keel-threatening hazards. I can easily see when an overlay of GPS co-ordinates and virtual AIS markers could use live drone inputs sent directly to the plotter so the tech-savvy could steer safely in undercharted areas by "live charting". Perhaps someone is already doing this: it seems like the future.

Logically, the most compact drones with the longest ranges and flight durations would be preferable for onboard use, but compact and long flight times don't always appear in the same models. Another consideration is the danger of losing something that costs one thousand dollars or greater into the salty sea; few current drones are capable of water landings (or take-offs or easy COB-style retrieval) and that's also going to restrict their use to fair weather and plenty of on-land practice prior to on-deck snatches) and the ones listed here seem too toy-like (or expensive) to take to sea, or to crash into it.

This is indeed wee. Photo (c) Steve Mitchell/Sailbits.com

Ocean cruising is a niche activity, and drone use during it is a niche of a niche, so word gets out quickly as to what works and what doesn't. A popular drone maker, and not just at sea, is DJI; their Mavic Pro and Phantom models seem to have quite a few fans, and I like how compactly the Mavic model can fold down to the size of a shoe for stowage. In January, I attended a rigging seminar with Andy Schell and Mia Karlsson of 59 North.com and the good ship Isbjörn. Andy and Mia run a popular charter business aboard their Swan 48 and they travel to some seldom-frequented latitudes worthy of shooting in high-definition with their DJI Phantom drone.

The DJI Phantom 4 drone: It's the handles you want to reach for.

After the seminar, which featured quite a lot of cinema-grade footage of Isbjörn underway, I asked Mia about the Phantom's performance parameters. She suggested the "big loops" of the Phantom model seemed superior in terms of safe retrieval; its maneuverability, being a larger drone, made it easier to control. I was surprised to learn that the drone could be flown easily at 15 knots apparent wind speed, although Mia suggested this was a big power drain and made retrieval increasingly difficult. 

There's plenty to consider before we ante up for a drone, but I think before we leave, I will have it sorted out for consideration as another useful tool in the navigational armoury. After all, if it's good enough for Paul and Sheryl Shard, who am I to disagree?