In-Depth, Aluminum Boat Design & Selection, Part III
By Guest Writer, Colin Speedie
Index
Part I
Introduction
Turning the Dream Into Reality
Choosing A Suitable Boat, New Versus
Old
A Boat Built to Travel
Making the Most of Aluminum
Part II
Self-Defence in Harbour
A Practical Interior at Sea or in Harbour
Limits to Complexity
Are Spade Rudders Suitable for
Ocean Crossings?
A Practical Cruising Rig
Part III
The "S" Word—Stability
Anchoring in the Modern World
Self-Sufficiency in Power
The "C" Word—Corrosion
Electrical Systems and Aluminum Boats
What Has Worked So Far—Domestically
The "S" Word—Stability
From the first time I saw one, I thought that one day I’d like to own an OVNI for long distance cruising. Living and working for part of each year in France meant that I encountered OVNIs and their sisters from Garcia and other builders regularly, and saw them return battered but proud from distant shores again and again. Listening to their skippers only made me more envious—all of them had nothing but the highest regard for the seakeeping abilities of these quirky craft. One day, I thought, one day…
So when the time came to put our money where our mouth is, there was no hesitation. And I can honestly say that the vexed question of the supposedly limited stability of the OVNI was never an issue for us. I simply thought of Jimmy Cornell taking his OVNI 43 Aventura III to the Antarctic and Alaska, and then crewing aboard Igloo, an OVNI 39, to Spitsbergen. I also thought of many other well known high latitude boats, Pelagic, Seal, Parati (to name a few), all lifting keelers that have made equally illustrious voyages. Now, we’ve a long way to go before we dare to include ourselves in the company of these immensely capable boats and their crews, but you have to aspire to something.
Nonetheless, I thought it would be interesting to check the numbers. The OVNI 435 has an EU category A (Ocean) rating, and that’s good enough for most people over here. Being no naval architect, the complexity of the formulae needed to come up with comprehensible figures made my head spin, so when I heard about the excellent Sailing USA web pages, for example, where simple data entry can be calculated to give a wide variety of figures that might be pertinent to ocean cruisers, it seemed a good place to start. So using the manufacturer's data from our owner's handbook, the website allowed some basic calculations to be effected.
The OVNI 435 has a ballast ratio of 135%—about average for today’s cruising yachts, and has high form stability, as we found when we sailed her home recently. The stability value is 34.15, and the Angle of Vanishing Stability (AVS) is 126.57, within the boundaries deemed acceptable for ocean crossing. The capsize screening value is 1.84, anything less than 2 being considered good. So looking solely at the stability numbers there is little to be overly critical about.
In terms of performance and comfort, the OVNI shows up well. The displacement to length ratio is 258, firmly in the moderate category, whilst the sail area to displacement ratio (with the standard genoa) should provide more than enough power for fast passage making at 22.42—ours will be lower, though, as we are having a yankee rather than a genoa as our working headsail, giving us a rating of somewhere just under 20—more cruiser territory. And finally, she has a motion to comfort ratio of 31.17, which when combined with the soft ride associated with internal ballast should make her a comfortable boat to make long passages aboard. All in all, a steady, middle of the road design built for long distance cruising.
Of course, these are “dry” figures, so we’ll be making sure that we don’t overload our boat. She has been kept deliberately simple, and even with only two of us aboard for most of the time, we’ll still be watching the weight. We’ve also kept weight down aloft—radar on the stern arch, hanked on staysail and so forth to keep the stability levels up, and in keeping with all our previous boats, we’ll be stowing everything possible below decks on passage. Keep it low, keep it light and keep the decks clear is a good way to go, we believe.
Another factor we’ll be looking to exploit is the ability to lift the centreboard when going downwind, not just to gain extra speed (although that’s good, too) but to avoid “tripping” on the keel and broaching. Many experienced OVNI sailors report lifting the keel in bad weather, allowing the boat to slide when hit by bigger waves, rather like a multihull. Well, if and when we have to face that, we’ll find out how well it works!
But at the end of the day, these are all just figures, and as it’s not unknown for well respected ocean cruisers to get into serious trouble if caught in the wrong place at the wrong time, we’re not kidding ourselves that we’ll be any less likely to suffer if it’s our turn one day. And so we’ll be out as soon as possible learning how our new boat likes to heave-to, run or work her way upwind in strong winds, and what survival tactics or equipment will be most suitable for our boat, so that we’ve at least a good working idea of where to start when the going gets really tough. There’s nothing like empirical experience, as the sea soon deals with the complacent, and at the end of the day it’s down to the way the crew handle the boat in so many cases, and staying away from the most dangerous places and conditions if at all possible.
The Sailing USA website makes this abundantly clear, quoting the 1998 Sydney/Hobart race review report that gave the following as one of the significant findings:
There is no evidence that any particular style or design of boat fared better or worse in the conditions. The age of yacht, age of design, construction method, construction material, high or low stability, heavy or light displacement, or rig type were not determining factors. Whether or not a yacht was hit by an extreme wave was a matter of chance.
The numbers for the OVNI are reassuring, and may be one of the reasons
why so many experienced sailors over here choose them for ocean crossings,
which is good, but it is surely only a small part of the picture. We always
felt we had chosen wisely long before we looked at the numbers though,
and felt that as others had gone before us and come back to tell the tale,
then with time, experience and humility in the face of the sea, maybe we
shall make it too. So now it’s down to us, a good strong boat and yes,
that indefinable entity—luck.
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Anchoring in the Modern World
The first sailors anchored using heavy stones, attached to long ropes, and often with an army of slaves to pull them up. Thank God those days are over, and that we now have excellent choices of anchors available, and powerful windlasses to retrieve them.
There can be few more important decisions to make than what ground tackle to choose when planning a long term cruise. We placed the highest priority on selecting the right gear for our new OVNI, knowing that we’ll have to rely on those decisions for most nights over the coming years.
The standard boat comes with a 1000W Lofrans windlass, which might be fine for most purposes, but not for a heavy anchor and plenty of chain we feel, so we’ve upgraded to a 1500W unit. We endured a fruitless chase to find some G70 high tensile chain in Britain, and in the end had to give up, but we did (finally) manage to track down some 10mm G40 chain calibrated for our windlass, so we’ve had to settle for that. The main cable will therefore have 70m of this chain, with another 30m of 18mm nylon anchorplait spliced to it. The second cable will have 30m of the chain with 100m of anchorplait, and a third with 10m of chain and 100m of anchorplait. This should provide ample capacity for most situations.
For our anchors, we have gone down a tried and tested route, at least for us. In 2005, fed up with our 45lb CQR and its variable performance we imported a 25kg Rocna from New Zealand. Having used it for two seasons in the Hebrides, anchoring on an almost daily basis, we found it to be a revelation in terms of speed of setting and holding power in a wide variety of substrates. So we’ve gone for a 33kg Rocna, backed up with a 25kg from the same manufacturer as our usual bower and kedge. Backing this up we have an FX-37 Fortress, which whilst less than perfect in some situations (hard sand, weed) is so easy to handle from a dinghy as to be almost indispensable.
For many owners the CQR has achieved near mythic status, and for many years I would have agreed it was the best anchor on the market, having spent hundreds of nights safely anchored by one. Having worked hard to perfect the technique to set one effectively, we felt we couldn’t make much improvement, but over time, the weaknesses—slow setting, poor holding in hard sand, easily choked by weed—became a real annoyance, and I became dubious about their ultimate holding power. So, although the Rocna was very costly (we imported it independently before there was an importer in the UK) we felt it would be worth the risk. Reports on the abilities of the “new” generation of anchors like the Spade and the Rocna were so positive we felt we had to try one for ourselves. And I have to say that the reports are true as far as we are concerned.
The Rocna is such a good all rounder that we’ve decided that for the first time, we’ll carry two anchors of the same type. We may also buy a big fisherman as an emergency hook, and for use in rock and kelp (where we would not normally choose to anchor), but that’s a straightforward trip to the local shipbreakers and little expense. Many people have commented that the new anchors are expensive, but when compared against what? Our new Rocna has cost us about the same as a month in a marina berth here, and we have it for use in perpetuity, so let’s keep things in perspective.
These anchors have their own drawbacks in some ways, though. There is a need to learn a new technique when setting them to allow for their rapid digging in to avoid strain on deck gear and the windlass. And while the large lateral area gives phenomenal holding, it does make it hard to carry two anchors in twin bow rollers—they are very huge. But as a wise man once remarked; “every time someone walks past our boat and laughs at the anchor, I reckon I’ve got it just about right”. And most bow rollers are still set up for the CQR or similar, so we’ve a list of planned modifications for ours to be carried out over the next few weeks to allow us to deploy and secure the Rocna effectively.
We believe that the new generation of anchors mark
a major improvement in safety, security and offer priceless peace of mind.
Human invention is limitless, and so things develop over time, so the conviction
that anchor development stopped with the CQR simply flies in the face of
reality. For if we followed that logic to its conclusion, we’d still be
driving cars with cable brakes, flying the Atlantic in biplanes, and—anchoring
with stones.
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Self-Sufficiency in Power
When we were planning our new boat, one of the first aspects we discussed was our preferences for power generation, and our desire to have as much “free” energy input as possible. There were three reasons for this: our desire to avoid the complexity of a diesel generator; our own commitment to renewable power after so many years of both working in the environmental field; and a chance to agree on something—it’s always a good idea to establish some common ground first!
Top of the list was a wind generator. Having owned one of these devices on a previous boat, my views on them are straightforward. None of them are the quietest things to live with, so if you must have one, then its output must justify the discomfort factor. So we opted for a Superwind, and having lived aboard for the last few weeks it is a revelation. Not only is it quiet (enough not to annoy the neighbours), but with a maximum 350 watt output when there is enough breeze, is well worth having. Being German, it is nicely engineered and built, and looks like it should be a real asset in the long term.
We also wanted plenty of solar, so we have two long slim panels with a combined output of 90 watts on the OVNI arch at our stern. Following good advice we had these mounted so that they can articulate. Two more semi flexible panels with a combined output of 96 watts are about to go on the coachroof ahead of the mainsheet where they will not be subjected to too much foot traffic, and hopefully will not suffer too much from shading by the boom. Finally, we have a very nice 80 watt solid panel which can be articulated on the guardwires for maximum output when in port or at anchor. All of the panels were carefully selected for reliability and sustained output, as opposed to peak, so we feel that we should be able to make a solid contribution to our daily needs in this way.
The aim has been to achieve a balance between wind and solar. In the higher latitudes we tend to frequent, wind will generally have the upper hand, but solar can still contribute due to the long hours of daylight, and, very occasionally, when the sun shines. The best we can hope for is that each technology works at its best for some of the time.
Our engine is fitted with a high output alternator, rated at 105 amps, and we are going to see how we get along with this unit without any “smart” type regulator for this season. With a battery capacity in excess of 600 amp hours we may have to consider fitting a second alternator in any case, so once we have tried it out over an extended spell living aboard, we’ll know more. We really want to avoid running our engine at anchor, which is not only unpleasant to live with, but is death to a diesel engine in any case. If all else fails, we have a neat little Honda petrol generator that we’ll use.
We are planning on buying a towed generator for longer passages, as these units are reckoned to offer the most amps per buck, normally around 1 amp output per knot of boatspeed. Being simple, robust units, we have high hopes of running the engine as little as possible on passage, as long as fish don’t go for the spinners too often.
Finally, we have tried as far as possible to audit our requirements, and reduce our daily power consumption. We are slowly going through the boat checking what lights in the interior can be fitted with LEDs and which not. We have a masthead combined tricolour and anchor LED unit to conserve energy when sailing or overnight, but have not bothered with our running lights, as we’ll be under power then, so little will be saved. And we have no freezer unit, simply an efficient coolbox, so that’s another significant drain we don’t have to worry about.
We
are aware that none of this has come cheap. If we added it all up it, including
installation, would amount to perhaps two thirds of the cost (and installation)
of a genset. But we think that if you have a genset, then the next thing
will be that you will have more need of it—your power requirements will
increase in line. Then there are the spares, and so forth—and don’t even
mention reliability. And we accept that we may have to live more frugally
than some others out there, but feel it is all relative, and that living
simply is a tiny price to pay for the huge privilege of going long-distance
cruising.
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The "C" Word—Corrosion
If there is one simple word that springs to mind amongst the uninitiated in relation to aluminum boats it has to be corrosion. If we had a pound for every time someone warns me against bringing spare change aboard and then dropping it we wouldn’t have to worry about a cruising budget—we’d have money in the bank.
Just as all construction materials have their benefits, so do they have their weaknesses, and we were well aware of the potential risks with aluminum. But the French (and others) have been building alloy yachts for decades now, and most of them are still afloat, so there can’t be that much wrong with them. In any case, we none of us stop to question the wisdom of using aluminum for spars, do we, so why worry unduly about a hull and deck?
Many people who see an OVNI out of the water expect to see them covered in anodes, and are amazed to see how few there are. Instead the hull receives two good coats of epoxy paint to act as a barrier layer, which has to be replaced every five years to ensure its integrity. Anodes are placed in areas where there is a risk of dissimilar metals reacting with one another, such as the rudder (stainless pivot pins) and propeller. And that’s it, largely because dissimilar metals have been kept to a minimum.
For example, all seacocks fitted to OVNIs are plastic, thus avoiding a major galvanic threat. In keeping with this policy, when we fitted our Echopilot forward looking sounder, life was made easier by the manufacturer offering a transducer housing machined from solid aluminum billet. Part of the answer with aluminum is undoubtedly in planning to avoid problems from the outset.
Above the waterline the hull is unpainted almost up to deck level, only receiving a light coat of Owatrol before delivery, after which it’s up to you whether you keep replacing this coating—we have already decided not to, preferring to allow the aluminum to oxidise and fend for itself—we want to avoid unnecessary maintenance wherever possible, and in the event of a scrape, the 5083 H111 marine grade alloy used in the construction will self anodize rather than allow corrosion to attack the aluminum under a damaged surface coating.
The topsides band, deck, coachroof and cockpit area are all painted with two pack epoxy paint, a hard and durable finish, but as with even the toughest coatings the risk of chipping the paint is ever present, and so as with steel boats it is best to keep paint and brush handy, ready to deal with any chips as they occur. The days when metal boats were all sharp edges with accompanying paint vulnerability are over, too, so lessons have been well learned over the years.
In keeping with our aim of avoiding drilling holes (and so giving corrosion a place to start) in the deck, we are working out the best ways of attaching all mobile deck gear, such as spinnaker sheet and guy blocks, using simple Spectra (Dyneema) strops. So far we haven’t had to drill one additional hole in the deck, another step in keeping water out of the boat at all costs. All fittings in stainless steel (such as stanchions) are isolated in plastic sockets to avoid corrosion, and all bolts are isolated with nylon washers, and liberal use of Tef-Gel to avoid seizures between dissimilar metals is essential to allow future maintenance.
Internally, the inside of the hull receives a coating of epoxy paint, but this is really more cosmetic than a barrier coat. One of the supposed benefits of solid metal hulls is how dry they can be—the old joke about “dusting out the bilges” may prove to have some truth in it after all! The whole of the hull and deck below the waterline have been insulated, so it’s difficult to check behind the insulation (though not impossible), but from inspecting the hull during construction we know that there are limber gaps and holes on all fore and aft stringers to avoid water gathering, and causing problems.
Finally,
it is possible to inspect nearly the entire internal hull surface below
the waterline by lifting the cabin sole, even if you do have to be a contortionist
to get into some corners. As a result we’ve been getting acquainted with
some of the far flung corners of the bilges well in advance, looking out
for potential water traps. We’ve also taken to thoroughly vacuum cleaning
after all work internally, and clearing up carefully, checking we’ve left
nothing lying around that might cause problems some time in the future.
And perhaps that’s a large part of the message here—in keeping potential
problems at bay, an aluminum boat needs care and attention—just like any
other material in fact. It’s simply a question of getting your head around
the likely threats, and staying on top of them. And then there are the
electrical circuits—but that’s for next time.
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Electrical Systems and Aluminum Boats
All of the yachts I have sailed over the last 20 years have been simple boats with fairly minimal electrical equipment. Not one of them (even up to 80ft) had an autopilot—sail training vessels often don’t, as they are set up to be sailed “handraulically” as we say over here.
So when we approached the planning for Pèlerin, we were mindful of our desire to have a simple boat, yet at the same time capable of meeting our wish for self-sufficiency at sea or in harbour. Another factor also nagged away in the back of our minds—the risks of electrolysis with aluminum, a subject upon which we’d heard a great deal of negative comment.
There is no doubt that there are risks inherent when mixing electricity and a material like aluminum, but we reasoned that Alubat have built thousands of OVNIs over the last 30 years, and we’ve never heard of one disappearing! So we did our homework, and made a few changes, and trusted the builders to do the rest. Now that we have her afloat and working, we can make some initial comments on what we have found.
The first thing is that the wiring installation has been done with great care at the factory. OVNIs, like most alloy yachts, have a two wire insulated wiring system, which means that there is no earth to the engine or hull as in a more conventional GRP boat. Each wire goes out and returns to the positive and negative sides of the battery bank. As a result, extra care has to be taken to ensure that there can be no grounding to the structure of the boat that would set up a galvanic circuit. Every OVNI is fitted with a leak meter, which can be used to make a daily check that no stray currents are making their way to ground and thus compromising the boat. If when tested there is any sign of a leak from either the positive or the negative side, it should be possible to identify which circuit is at fault by working through every switch on the panel in turn to identify the circuit, and then setting about finding the leak itself wherever it is in the wiring.
This was very useful when it came to wiring up the new electronics such as the autopilot and the radar, as after each item was fitted the leak test could be conducted to ensure that no fault existed as a result. All electronic units had to be isolated from the hull structure during installation, once again to avoid any chance of leaks to the boat's structure. We did, in fact, have a small problem during installation, which was traced back to a faulty AIS unit and rectified, so the leak meter is a vital component on this type of boat.
Another area which we approached with caution was the shore power circuit. Having heard of (and seen) the effects of galvanic corrosion on boats kept in some marinas, we were particularly aware that this was an area for concern for us. Not that we intend to base Pèlerin in a marina, but who knows where we may decide to overwinter her at times. We finally opted to fit an isolation transformer, a device that is virtually unknown in Britain, at least, but by all accounts is common in the USA, and should be fitted to all metal boats, not just aluminum. Of course, we may never know just how effective the transformer is—if it’s working then we should see no problems, and I don’t suppose we shall turn it off to find out otherwise! It is a heavy and costly item, though, so we hope that it will prove its worth.
So far we are well pleased with our new home.
Not that we haven’t had our share of glitches, but these have been overcome
with support from the Agents. We have had her out in a maximum of 30 knots
of wind so far, when she was stable, comfortable and easy to handle, so
we’re looking forward to our first decent passage in her very soon, when
we’ll be able to report back in far greater detail on our impressions.
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What Has Worked So Far—Domestically
Well, we’ve finally moved aboard and are on our way, and although we haven’t travelled very far yet, or even in the direction we had initially planned, it’s a definite relief to be off. This is largely due to the “summer” the South of Britain has been enjoying—certainly the worst in terms of relentlessly poor weather in my memory. And even though it’s early days yet, we have had the chance to evaluate some of the equipment we have chosen for domestic life aboard, as well as the general layout. After having agonised over the minutiae for so long in the planning stage, it’s been a little nerve wracking waiting to see whether we had got it anywhere near right.
Well, it’s good to report that so far it’s far more good than bad. The interior layout works very well, and the saloon is comfortable and airy with lots of natural light and ventilation. The Webasto heating system (in August!) is excellent, and coupled with the insulation makes the boat cosy and warm even when the temperature drops very low. The only condensation we have seen at all comes from the aluminium inner surrounds of the hatches, which is something we knew we’d have to tackle somewhere down the line, especially as winter nears.
As we have a lot of computer equipment aboard for our work (consultancy and photography), when we are in harbour mode we tend to use a lot of amps. But we were determined not to have a diesel generator or to use the main engine for charging when at rest, so we have tried to maximise power creation from renewable sources, whilst at the same time minimising our consumption. And we’re really impressed with our power generation from a combination of wind and solar at this stage.
We have an articulated solar array of 90 watts mounted on our OVNI arch (what a brilliant structure that is) and we have fitted two 48 watt semi-flexible panels on the deck forward of the dodger. Add to this an 80 watt panel that we bring on deck in harbour and orientate towards the sun, and you have a powerful combination which makes a substantial contribution to our day to day needs. The Superwind generator, whilst not the quietest unit of all, has an amazing output—it’s not been unusual to see 10 to 15 amps output when the wind is fresh, although like most of the larger units it is weak below 8 knots of wind. The upshot of it is that we have never once had to run the engine to charge the batteries at rest—so we’re close to our goal.
The Force Ten cooker that was specially ordered at great expense works well, but seems to suffer from small weaknesses that let it down at times. But the oven is great, the burners are powerful, and once we have ironed out the bugs (mainly to do with a temperamental thermocouple) we think it will give a long life of good service. The only really negative thing to say about is that the supports supplied for the gimbals are far too flimsy. John & Phyllis found the same problem with their stove (see this post), and have very kindly sent me the drawings of the ones they had fabricated as replacements, and these are far more substantial. We’ll definitely replace ours this winter.
All in all, we’re very happy indeed
with our new home. We’ve still got a few reservations about the galley
layout (linear down the starboard side) once out on the water, but other
than that we’ve few complaints, and we’re looking forward to getting some
real miles under our belt.
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