Adagio Design, Requirements and Specifications

It’s surprising that our original requirements still hold today. Yes, we could write a more comprehensive requirements document today — but that is really the role of specifications, which we developed over a four-year period while awaiting building to begin.

For the record, there is little of the 1993 requirements that we would amend today. The only item that comes to mind is “resistance to striking floating trees”. We simply had no idea that British Columbia {and to a lesser degree, Alaska} have forestry policies that allow timber companies to just forget about any logs or whole trees that are left for other vessels to ram. That requirement would probably have eliminated our choice of saildrives and spade rudders — both important contributors to performance.

We worked hard on the Adagio specifications [PDF] before construction started — from 1994 through 1997. After construction began we continued to update, expand and detail-detail-detail the specifications in cooperation with the builder and designers. Please feel free to take these specs as a starting point for your own project!

Scd28 Accomodation Plan

The Accomodation Plan/Interior Plan [152 kb PDF] shows the general layout of the bridge deck, and port/starboard hulls [click on the thumbnail for the full-size PDF file — there’s a lot of graphic detail so expect a while to load].

We could link to the original-original interior plan, but the as-built Adagio is very different in many ways. Other than the original, in our CAD library we do not have the traditional architect’s “accomodation plan”. Because the Adagio design was developed largely in 3D, what we have in our library cannot be displayed on the web without having 3D CAD software installed on the user’s client. As in other drawings on our website, what we’ve done here is to display a working drawing — one of many, that show our communications with the builder, Allan Legge Boatbuilders.

This is actually a “Door Cutouts” working drawing, showing Allan the final decisions on exact locations and dimensions of all the interior doors — including the notes-to-builder on any changes from the previous “Door Cutouts” drawing.

Note the “Status: Final” in the lower right of the title block. That tells the builder the owner is done making changes to this detail!

1999: Design: Power Cat Tender


The Adagio tender “Allegro” has been a workhorse. The Morrelli & Melvin custom powercat is the most sea-kindly small tender we have encountered. Just under 13-ft, she carries 4 adults, 2 kids, and various gear on a comfortable plane. In flat water with just a driver she does about 23kn with the 25hp four-stroke Yamaha.

What is not obvious about a modern powercat design is the cushioning effect of the air-water froth between the planing hulls. We have cruised across Twofold Bay at the bottom of Australia’s “big island” in 6-ft seas plus wind chop very comfortably.

Another much-loved attribute of Allegro — the driver and passengers do not get “wet bum”, the usual outcome for those on RIB/rigid inflatable, or worse, ordinary inflatables, where driver and passengers sit on the tubes. Allegro carries four adults sitting on the center tunnel as shown in the thumbnail-linked drawing. So when we go out for dinner on Allegro, we do not have to endure an evening in salty underwear.

Other conveniences, there is a solid foredeck for boarding, which conceals the anchor locker. There is dry storage under the hydraulic steering wheel center console, under the foredeck starboard-side, and two “dry” lockers aft — each side of the engine.

There is also another much-loved convenience, an easily raised-stowed Bimini-top awning. As we get older we more and more appreciate ways to keep out of the sun — besides just keeping cool.

Sadly, we had no way to store the molds for Allegro. Someday we may build a sistership by taking a female mold off the Allegro hull. That will make it much easier to laminate her all-Kevlar/epoxy hull quickly before the resin begins to kick off. Allan Legge built Allegro as his first Kevlar uni-directional laminate — attempting to laminate the entire hull in one step. The Kevlar unis are VERY ill-behaved, so Allan ran past the “clock”, resulting in a resin-rich laminate. Next time we’ll achieve Gino’s design goal of about 78 pounds for the hull and wing laminate.

1998: Build: Turnover day

Turnover Day

This was one very exciting (and somewhat scary) operation. You realize how big Adagio really is when she is hanging from a construction crane. But, knowing how thoroughly Allan planned the turnover operation, there was no reason to be nervous!

The keel bonding areas have been prepared for glassing the keels in place. The keels are a complex composite laminate because they have more than the obvious hydrodynamic function of lift — they must also support and stabilize the vessel on ships ways, on dry docks, and of course on the beach. And they should survive skipper-screwups, such as unplanned reef soundings. The keels will be one of the very last big laminates because once they are permanently bonded to the hulls Adagio will be much higher off the ground — and thus more difficult for the construction team.

An essential point — in terms of buoyancy, the keels are completely separate from the hulls. So in case of a serious reefy accident, the keels may give us extra time to get the yacht off the reef. I.e., we could grind off 2/3 of a keel while awaiting arrival of a suitable tug.

At this stage the hulls and wing have been faired and undercoated. All that remains to complete the gloss finish of the topsides and wing is the Awlgrip application {which will be Snow White}.

1997: Build: the REALLY BIG molds


In this photo, Adagio’s male mold is being constructed to laminate both hulls and the underwing as one continuous structure. We used the underwing section of the mold as a large laminating table to build all of the structural bulkheads.

That is why the right hull in the photo (the port hull mold) is unfinished at this stage. Because the cabin-back bulkhead is so large, we built the underwing mold/laminating table to extend through the space that will become the port hull mold. Once the cabin-back bulkhead was completed we could finish the port hull mold.

1997: Design: Electrical Systems

Following are the online documents of the parameters driving Adagio’s DC and AC electrical systems”

Energy budget – DC (PDF)

Energy budget – AC (PDF)

AC system requirements (PDF)

Ground design – Lightning, AC/DC, HF radio

12/24VDC battery parallels/disconnects

Following are the basic online documents of Adagio’s electrical design:

Runs: Geometry of each major cable routing (PDF)

Cables: Circuit/cable definitions (PDF)

Conds: All connections to every device (PDF)


Adagio’s electrical design has been developed using a relational database design tool that I developed using FileMaker Pro®. The philosophy is that documenting a moderately complex design using only schematics is time-inefficient and not that helpful for either installation or trouble shooting.

This system has worked very well for us so far. Our electrician loves it, and wants to borrow my Powerbook for use on the job while wiring (because you can so quickly find things, trace circuits, etc. in the dbms – as opposed to searching through a book of pages).

A brief overview – the dbms is comprised of 12 relations which I’ll call tables. For those using the dbms design for the first time, following are the core tables and concepts:

1. The Runs table defines the physical routings of all the cabling. This corresponds to CAD drawings of same. Many different connections can use same run, or series of runs. Note that the Conds script “Report Runs Summary” shows you every connection going through any ducting, along with the OD size of the cables.

* I use the naming convention nn.1, nn.2, …, nn.M for Runs IDs where there are various cables going through the same ducting “nn” but which have different run lengths. This is just to force them to group together in the report.

2. The BOM table defines all the components [about 100 pages, a bit too big to put on the website] – from consumers to panels to buss-bars. Therein are defined the electrical characteristics (V, A) and terminal sizes if relevant (like 10-32 screw). This is also the bill of material for purchasing everything except terminals and wire.

* Because each BOM entry defines a physical device/location, you will notice multiple entries with Qty=1 for the same thing (say an 8-gang panel, or a sump pump). Find all the Blue Sea parts, sort by mfg part#, then look at the VendorsDetail report – you’ll see how I’ve summarized these multiple references to the same part#. The VendorsSummary report just shows the total qty lines.

3. The Conds table defines all the connections in terms of an Input Device and Output Device – the devices being referred to by their BOM IDs. I.e., Input == From, Output == To device. I use the convention that the load is defined by the Output Device – which simplifies describing common situations like lights, fans, … supplied by a panel. The Conds table is just a wirelist as used in electronics biz – you can wire and trouble shoot the boat with only this document.

Note that there are some subleties in defining multi-core connections:

* simple cases are such as a duplex wire from a panel to a device. The panel pins will be something like “2,2N” where the device pins will be “P/N” for both pos/neg. The #cores will be 2, the cable type “Dup” for duplex. The computed length/weight/resistance of the wire to be purchased will be 1-way length defined in Conds.

* where you build a circuit with multi-core wire leading to various devices/pins, you describe each single-wire connection in a separate Conds entry. E.g., look at all the Conds entries for inDev = 2071, the mastbase terminal block. There you’ll find 4 separate entries for the 4 core cable running up mast to Tricolor/Strobe/Anchor light. Then look at buyLength in the data dictionary – you’ll see that in such cases the length is divided by the # of cores because of the 4 references to the same piece of cable.

4. The Cables table defines multiple Run and/or multiple consumer loading cases. The Cable (same as Circuit) ID, when referenced in a Conds entry, defines the AWG wire size – i.e., overrides the from-to AWG computed by the Conds table. You simply enter a list of Run IDs, then a list of consumer device IDs which you have decided represent the worst case operating load in shared conductor situations.

5. The allowable voltage drop, as %, is defined in Conds (and Cables if an entry subsumes a given connection). The ABYC wire size computation is the same in either case – the wire size is the larger of that required by “inside engine space ampacity” (conservative) or by the specified drop”.

6. You have to decide what type of wire, color code, and number of conductors to be used – all defined in the Conds entry.

7. Similarly, you have to decide what type of termination is used on both ends for each Conds entry. The default terminal type is RT = Ring Terminal. The allowable types are defined by the TerminalTypes table (bet you already figured that out <g>). I also use the type “SOL” for soldered terminations where we don’t use any kind of terminal.

8. Note that I use the convention that PT = Pin Terminal, which is how wires are terminated that are secured in a hole by a screw (a common AC connection). We actually use Ancor pin terminals, but some folks just tin the end.

9. Wire size priority scheme, from highest to lowest: Conds/BuyAWG field – where you enter what you want, the Cables/reqdAWG field described above, last the Conds/reqdAWG field.

10. Other key CAD drawings (these are layers with variations for voltage – i.e., 24VDC Panels, 230VAC panels). Every drawing shows physical locations as well as logical design, and tags the devices with their BOM IDs which appear in the Conds table, etc.

* buss terminations/distribution points

* panels

* ground system design for DC/AC/lightning LPS & Bonding/HF

* nav and deck lights

* pumpsSump, pumpsSea, pumpsFuel

* 12/24V Batteries/Charging


There are only about 15 key schematics, because most simple things are fully described by the Conds table.

11. A slightly complex issue is the generation of correct terminal part#s. The Conds script PopulateTerminals does this. It creates the Terminals table based upon the Conds entries in conjunction with the AncorTerminals table definitions. Ancor terminals which use diff wire sizes will have multiple entries, but same part number.

12. If you want to generate a list of all the terminals you need to buy, as we did so we can order everything from Ancor/US, you have to do a bit of work to find out what gizmos are on each device and tell the Conds table what to use if not a ring terminal. This includes the screw size if it is a ring terminal. Note that BOM can only define one screw size. When a device has different screwsizes for diff pins, you override this in the Conds table. A special case is Blue Sea panels, with have #10 screws for feeds, #8 for buss bars, #10 for breakers. I hard-coded this logic into the ScrewSize script.

The Terminals script “Report Summary” generates the purchase order for terminals.

13. The purchase order for wire is generated by the Conds Script “Report Wire Purchase Summary”.

14. Because Conds defines each wire or cable as from/to, how do you analyze a printed report to find everything connected to a specific device/pin? Run the Conds script “Report Explode” (and be sure to run “Explode Delete” after you have your report). Report Explode mirrors every Conds entry, reversing the from/to fields – creating a table with 2x the original number of entries. In this report you will find in the first column (inDevID) in sorted order every device in the dbms, so you can quickly trace out any circuit and be sure you didn’t miss something because you didn’t know whether it was an “in” or an “out”. Note that mirrored entries are identified by an “x” in the DeleteMe field in the report so you can tell which are “phantom” entries. These will not have their AWG size calculated because the load device is now in the “in” position – e.g., a 100A panel supplying a 3A motor.

1997: Design: Hydronic Heating System


For a catamaran the common forced-air diesel heaters don’t make much sense — there is too much distance between all the cabins. We think hydronic heat is the efficient solution — routing of the 20mm heater hose takes up little of your valuable storage space. And if thoughtfully routed, keeps your storage dry as a side effect of the radiated heat.

OTOH, if you are not concerned about warming the storage areas, consider insulating the heater hose. I once calculated the thermal losses through our 120-ft of hose — it is significant, and it really does not contribute to the space heating goal.

Adagio has a 40,000 BTU Webasto diesel boiler — just about right for our volume, but possibly a bit undersized considering our huge glass area.

One design tip: ensure that your hydronic ballast tank is BIG, and as high as possible above the otherwise highest point in the loop. The bigger/higher the less likely you are to get air bubbles in the liquid flow around the boiler’s heat exchanger. The Webasto does not like air bubbles, as we discovered after replacing 3 motors. Then in 2003 I designed a new stainless tank — never a fault since.

1997: Design: Pressure Water System


Adagio’s pressure water system is fairly straightforward — though we have not seen some of our design solutions — such as our hot water loopback scheme on any other boats. As the schematic shows [click the thumbnail] it only takes three valves and a bit more pipe. The valves are situated each of the places you will want hot water — when opened the valve simply routes the hot supply back to the starboard tank. Thus, you can have hot water “immediately” without pumping precious fresh water down the drain while waiting for the hot.

Other design features we appreciate:

Triple parallel pressure pumps

As the schematic shows, the primary pump manifold is comprised of parallel Shurflo 2088 Baitmaster pumps. These are controlled by external heavy duty pressure switches set for staggered on pressure trips:

Pump#1 controlled by — HI switch: 25 psi on, 42 psi off.

Pump#2 controlled by — LO switch: 15 psi on, 42 psi off.

Normal conservative use only activates Pump#1. But if we have guests aboard –> simultaneous showers, then Pump#2 will double the supply volume.

The external pressure switches eliminate the most commonly reported failure mode — internal pressure switch failure.

Live Redundancy

The other big benefit, as for all or our parallel pumping systems, is that if either pump fails we still have pressure water until we get around to fixing the fault — which will hopefully not be at sea.

In this design, we went one step further to achieve triple redundancy. The Port -> Starboard transfer pump is another Shurflo 2088 Baitmaster. The port-side 3-way valve shown is normally set to connect the port tank to the pressure water main line. So if we have a glitch with the main pump manifold {like a suction-side air leak} we can just turn on the transfer pump, turn off the main pumps –> fresh water service continues.

5-way Redundancy

We strive to use the same pump model everywhere it makes sense. Then in the extreme case we can just “borrow” the same pump type from another use. In this case, our salt-water washdown pump is #4 Shurflo 2088 Baitmaster. And #5 is stored in our spares inventory — and sometimes used as a utility pump.

The Plumbing

We originally planned to use the Whale Quick Connect Plumbing System. On our builder’s recommendation we elected to use a NZ-made household-standard polybutylene plumbing system. Allan has used this system for some twenty years now — never a leak or fault. A critical detail — all the connections should be crimped using a serious professional crimp tool.

If you Google “polybutylene plumbing” you will discover the power of the tort lawyers in America. I understand there was a problem decades ago with a particular USA vendor supply defective pipe — even today the free-lunch continues.

It has been a good choice for us — 100% reliable so far.

If you are retrofitting an existing boat I would probably choose something similar to the Whale system. Unlike polybutylene it is flexible and easy to modify.

1997: Design: Fuel System Reliability

Updated 20 August 2008: Adagio is obviously a sailboat. Still, certainly our comfort, and possibly safety, depend on reliable electrical supply. And there are definitely times when safety can be compromised by unexpected loss of propulsion. If you feed a diesel engine both clean air and clean fuel it is rare to have an un-heralded failure. Over the years of meeting with long distance cruisers we’ve encountered several cases of fuel problems – often at bad times – like heavy weather. Almost all of these trace back to contaminated fuel reaching the injectors. The heavy weather faults were usually due to water, dirt or biological debris being disturbed in a fuel tank sump, then sucked by the fuel intake.

Like chafe-free parachute anchor bridle attachments, clean fuel is fairly easy to design into a new vessel, but can be difficult and expensive to retrofit. So we gave a lot of attention early on in the design process to the objective of “zero defects” in the fuel department.

Adagio’s fuel system is the result of several years of research, all targeted on the question “how do we ensure we never have an engine/generator/diesel heater fault due to bad fuel in the tanks?”. E.g., one or both engines stop when we are negotiating a narrow reef pass with no wind, under power? Or under sail at night in nasty sea conditions — we are charging batteries, freezing down the reefer and freezer — the generator stops.

The design theme has been simply “always 100% clean, dry fuel in every tank”. Touch wood, but after some 30,000nm, we’ve had two cases of unplanned fuel filter changes. Both were due to a design oversight which I’ll explain after reviewing the original Fuel System Reliability specifications. For the original system schematic, click the thumbnail at left. Here’s a summary from the SUMMARY OF VESSEL SAFETY PROVISIONS section of the Adagio Specifications:

** The reliability of the vessel’s electrical systems is dependent upon the supply of quality diesel fuel to the three engines. Every effort has been undertaken to ensure the reliable supply of clean diesel fuel by means of the Fuel System.

** The fuel supply is isolated in five tanks having a total capacity of 430 USGal. 400 USGal are stored in four integral epoxy tanks, two in each hull. Fuel is directly gravity-fed to all diesel consumers from a central 30 USGal “day tank” sited on the bridgedeck. The system is designed so that at least 20 hours of cruising speed operation can be supported by pristine fuel loaded in the central day tank.

** Fuel filtration and transfer is controlled from a central Fuel System panel located on the bulkhead separating the workshop from the forward machinery space. The Fuel System is comprised of:

** Three parallel, independent pumps. Two are 24VDC continuous-duty Shurflo 8000 series industrial pumps. The third is a diesel-rated manual Whale diaphragm pump.

** Filtration is accomplished via two series-connected industrial grade high-volume filters. The first filter is an RCI Purifier RC 400-E centrifugal filter which removes at least 95% of free water and particulates. The second filter is a depth-type Gulf Coast Filters model F-1. This filter removes 99.9% of any free or emulsified water present, and all particulates larger than 0.5 microns at flow rates up to 2 USGal per minute.

** Fuel can only be transferred between any of the vessel’s five tanks by processing through the RCI and GCF filter manifold. The Fuel System valve manifold provides for fuel transfer from any of four hull tanks to any other and to the common day tank. The forward-starboard hull tank is also plumbed to the fuel manifold such that fuel can be loop-back polished through the filter manifold to this tank. New fuel loaded aboard is always isolated in this tank and is treated with Biobar and DFT#1500 to eliminate bacterial contamination. It is then tested and polished before transferring to another hull tank for storage. Onboard polishing can be accomplished either by loop-back polishing, or by transferring once between any pair of tanks via the RCI and GCF filter manifold.

** To simplify refueling in remote areas, the Fuel System can also pump fuel from containers on a wharf or adjacent vessel. anual Whale diaphragm pump.

** Vessel operating procedures require that all onboard fuel except the daytank be recirculated through the filter manifold weekly.remote areas, the Fuel System can also pump fuel from containers on a wharf or adjacent vessel.

** The common day tank is managed by an automatic level control system. Two magnetic reed-switch float sensors start and stop day tank resupply at 75% and 95% full, respectively. The day tank can also be resupplied by manual override of the automatic system. In the event of failure of both Shurflo fuel transfer pumps, the day tank can be resupplied via the manual diaphragm pump. All fuel supplied from the day tank is filtered a third time via a Racor 500 FGSS2 filter with 2 micron element (60gph rating, approximately 30-times oversized). While this filter is intended to protect against any small amounts of condensation in the day tank, it is also a third level of insurance of fuel quality.sociated fault. The fault indicators are as follows:

** To ensure that water does not enter any fuel tank in extreme sea conditions, each tank vent line is protected by a high-capacity water-separator which admits only dry air into the tank from vents located just below the sheer.

In summary, clean fuel supply is assured by preventing seawater and bacterial contamination, by immediate onboard polishing of all new fuel, by weekly repolishing of every tank, and by processing all fuel through three filtration stages before the fuel reaches each engine’s factory fuel filter, and all particulates larger than 0.2 microns at flow rates up to 2 USGal per minute.

Sounds good – so how did we twice manage to gum up the Racor FG-500 on the day tank output? Well, Adagio is heated by the diesel-fired Webasto hydronic boiler – whose return line leads to the day tank. After a winter of daily cycles of heat/cooling the fuel in the day tank, condensation accumulates in the stainless day tank. Even though the fuel is always treated with DFT-1500 Hammerdown, a tiny amount of bacteria grow in that water — enough to create a bit of vacuum at the Racor two micron “final safety belt” filter. I say a bit of vacuum because it is too small to read on the remote filter vacuum gauge mounted on the shop fuel system panel.

And how did we rectify that oversight? There are two errors:

1. I didn’t realize that clean fuel pumped into the day tank might be contaminated by “new water”.

2. Though I specified a duplex filter on the day tank output, during construction we decided it was a poor use of the machinery room space. So duplex became simplex, not a problem in light of assumption #1.

We’ve addressed #1 by modifying the fuel control manifold so that the day tank can be a source, and thus can be polished like any of the four hull tanks. By routinely polishing the day tank fuel we remove any water by means of the massive GCF F-1 filter.

I am still studying solutions to #2. There is no point in a duplex filter manifold that is not easy to service. And all the high-rent locations in the machinery space are already occupied.

Click to embiggen

Updated 10 Nov 2010: When I rebuilt the Panda generator in New Zealand this year it gave me access to the bulkhead behind the genset. So the simplex Racor was replaced with a duplex Racor FG-500 plus an in-line Facet solid state fuel pump. The Facet serves either as a primer pump for the two Yanmar propulsion engines, or as a “hot spare” for the Panda genset fuel pump (an identical Facet pump).

1997: Design: Sample 3D interior renderings


From 1994 forward we continued to refine the specifications as we translated the concepts into CAD drawings and 3D renderings of Adagio. The rendering above shows a version of the bridge deck arrangement which is quite close to our final design. Note that the cocktail and dining table tops are interchangeable between the cockpit and saloon spaces. We switch the table tops to suit when the weather invites outdoor dining.


The interior and cockpit shapes are visually integrated — when the sliding doors and windows are fully opened, the interior – exterior spaces are completely united by the granite countertops, and continuous varnished American Ash.


After a couple of years of ocean passages we decided we could remove the cooks-belt padeyes in the galley. The spaces + Adagio’s gentle motion at sea are perfect for rough weather cooking. Like the weather-cloths we fitted to all six berths — the galley cooks-belt proved completely unnecessary.

1997: Design: Interior Plan

Scd28 Accomodation Plan

The Accomodation Plan/Interior Plan [152 kb PDF] shows the general layout of the bridge deck, and port/starboard hulls [click on the thumbnail for the full-size Acrobat file — there’s a lot of graphic detail so expect a while to load].

We could link to the original-original interior plan, but the as-built Adagio is very different in many ways. Other than the original, in our CAD library we do not have the traditional architect’s “accomodation plan”. Because the Adagio design was developed largely in 3D, what we have in our library cannot be displayed on the web without having 3D CAD software installed on the user’s client. As in other drawings on our website, what we’ve done here is to display a working drawing — one of many, that show our communications with the builder, Allan Legge Boatbuilders.

This is actually a “Door Cutouts” working drawing, showing Allan the final decisions on exact locations and dimensions of all the interior doors — including the notes-to-builder on any changes from the previous “Door Cutouts” drawing.

Note the “Status: Final” in the lower right of the title block. That tells the builder the owner is done making changes to this detail!