Cargo Booms for Cruisers

CERES unloading, using her sprit as a Cargo Boom.
Note the 'universal joint' is a simple snotter.

Boom boom boom boom
A-haw haw haw haw
Hmmm hmmm hmmm hmmm...
-- From Boom Boom by Johnny Lee Hooker


Cargo Booms for Cruisers

A Cargo Boom is a durn handy thing.

Boarding or off-loading cargo (including groceries, luggage, tools, flotsam, what-have-you), a dinghy, an MOB, a pet. Raising a mast, a large hatch, an anchor. Heeling the hull to lift clear of that rock ledge you clipped...

A Cargo Boom is a durn handy thing!

The jargon of cargo handling is extensive and not always perfectly standardized. Here, I'm going to use terms as I've heard them used in my area. For those who care, there are many fine hairs to split.

A fully rigged Cargo Boom

Boom Derrick

The derrick (referring to the whole setup) pictured above is very common, though on small boats, seldom so thoroughly rigged. Essentially, it has a universal joint more or less fixing its derrick/boom heel to a mast, a topping lift to control lift aka hoist (vertical lift/lower) and guys to control swing (horizontal rotation).

A sailboat already has a mast, halyard (generally with multiple purchase) and likely a boom (and/or spinnaker pole). Thoughtfully rigged, the halyard can be transferred to the lift point of the boom (if not already so rigged) and guys added, and shazzam... you've got your cargo boom! Best yet, this kind needs no additional stowage when not in use.

Once set up, the boom can be more or less short and horizontal (preferred for amateurs) or more or less long and vertical (preferred by professionals). In both cases, the topping lift should be at near right angles to the boom.

In the short, horizontal case, the topping lift should be at an acute (sharp) angle to the mast (which then supports the load mostly in compression. The boom is only holding the load away from the mast, in this case, and is under much less stress than if it were near vertical.

Consider a halyard attachment which is easy to shift, with enough extra length to drop the boom end to deck level. Consider a universal joint that can handle the full range of potential boom movement. Consider bungee lines to gather rigging (such as lazy jacks) that go slack during boom operations. Consider supplemental backstays to support the masthead (low stretch line or wire in all stays... nylon is stretchy and can be dangerous!).

Stowing a dedicated cargo boom can be inconvenient. Rigs with spars set on one side of the mast have a section along the mast side opposite the spars that will never be swept, called the chimney. A boom may be stored vertically in this location. Consider using the boom as a side rail (like a lifeline) when not in use.

The pole isn't labelled... it's lower center and angled... the load is hanging from it.

Gin Pole

A gin pole is simply a near vertical boom with no mast.

Essentially, the heel is securely fixed to the deck, and the head inclined over some useful hoist point.

It can be rigged to hoist and swing around that point, but operation is complicated. More commonly, it is guyed (stayed) in one position, and lifting tackle used to hoist the load.

This type is less useful for cargo, and is generally improvised for raising a mast.

A-Frame

An A-frame derrick is a spread pair of poles lashed at the apex, and working in compression. Tackle hoists from the apex, and the fore and rear (aft) guy swing a load up and along a line perpendicular to that of the legs.

On board, this can be set up on the sheer, and cargo hoisted, then swung inboard.

Be aware that the guys can develop immense tension loads if their lead becomes too acute, and the threshold is reached and surpassed in surprisingly short order. If overloaded, something is likely to give - a guy or your sheer structures, most likely - and the A-frame can whop flat like a mouse-trap. Ya feel me, Mouse?

Be sure to limit the swing to short hops, keeping the A-frame near vertical at all times. Consider raising the guy anchors to improve their lead to the apex (closer to right angles).

Downside of A-frames is that they're a lot to stow. On the other hand, they work well at barge ends. Many rigs can be improved by A-frame masts, so it can pay its way between jobs.

I sometimes dream of an aft A-frame, flying a double stays'l rig on roller furlers. Whatta toy!


Cautions

Keep in mind that, even with relatively light loads, some wicked forces can develop.

As cruisers, our setup is likely to be DIY and... well... funky. Do familiarize yourself with forces involved and safety procedures, and follow them scrupulously! Do not pass under a load or allow anyone else to do so. Move slowly, with good communication among all present. Keep lift/lower and swing in/out operations separate.

Consider familiarizing yourself with vector diagrams to help assess loading. Consider which forces are acting in compression, and which in tension. Consider keeping your boom either short and close in (when used horizontally), or long and close in (when used vertically). Consider hoisting only modest loads.

Cultivate a state of healthy paranoia!

A Day in the Life

"Maybe you're getting into the rhythm of sailing life," says James. "You know, the tides going in and then out, the wind blowing east and then west, the high of a perfect day out on the water, the low of a thunderstorm or a wind that won't go your way."
― From Unbreak My Heart  by Melissa Walker

A Day in the Life

Okay. Several of you have requested a 'typical' day in our life. Not so sure there is such a thing. But if a day like this were to happen, I wouldn't be in the least surprised. Here you go, in all its gritty detail.

*****

RIIIIIIIIIIIING! Bam!! Groans.

The alarm wakens us and I kill it with a swipe. It's still dark in the wee hours, with a light lip,lip of water against the hull. As time and space return to our groggy minds, we recall that we're anchored along one of the 'walls' of Chatham Strait, waiting to catch a fair tide. We've got about an hour to get underway.

Morning. Mmm... kiss, kiss... mmmm.

We've got a few minutes to spoon and cuddle, and make the most of it. A little later, we sing:

It's up in the morning drinking gin...

Hey! Ho! Chicken on a raft!

To have another would be a sin...

Hey! Ho! Chicken on a raft!

Dunno why... it's our 'gotta get up and go' song... it's driving rhythm helps get the blood flowing, I guess.

With an effort, I roll out of the bunk to look around. Wind is light and, of course, contrary... if it had been fair, I'd get us underway, over-running the last of the tide, and Anke would make breakfast when she's ready. As is, we'll wait for the tide to turn before beating into it.

I load and light the woodstove, using kindling split fine and drying in a can beside the stove. In minutes, it's crackling, cabin temp is rising and my breath ceases to steam.

Grind coffee. Set water boil and rice to cook. Saute some greens and spices in a cast iron pan. Slice cheese. When the rice is done, stir it in, part a hole in the middle and add three eggs, then deal cheese over the top. Cover with a lid, and the lid with a towel. Voila! A 'standard' breakfast. More water on for the 2qt thermos and hot drinks through the day.

Anke dozes until she hears The Sound.

Chhhhhhhhhh-shhhhhhhh-hhhhhh...

That's me, imitating Anke's preferred Italian Expresso Pot as I plunge the French Press. When we moved into SLACKTIDE from LUNA, the smaller galley meant keeping one or the other. The FP handles company, so the other had to go. Turns out, the sound was the critical component of expresso, so far as Anke is concerned; so long as I make The Sound, her coffee tastes right.

We sip our coffees, interspersing thoughts about the upcoming day with quiet appreciation of pre-dawn.

We're vaguely heading for a favorite estuary about 20 nm north. Weather is s'posed to be mild, so we don't have to push ahead of high winds. On the fair, rising tide, we will sail further out to take advantage of stronger current, undiminished by friction with the 'walls'. We note on the charts any rocks, coves, shallows and points of interest along the route, and recall the last shelter behind us (ya never know). We listen to the marine weather forecast (if in range).

Spit bath? Too late... get one tomorrow. Dishes in a bucket for cleanup underway. Start the day's log. Bail the dory. Drop the boards. And time to go.

One of us hauls anchor while the other takes the helm. Today it's Anke's sailing us off. She frees the sheet and raises the mizzen, letting the sheets run (the junk rig hauls sheets vertically on raising) and spilling the halyard in a puddle at one corner of the cockpit. She watches her ranges as I haul, ready to act if we begin to slide before she hears from me.

Anchor's a'trip (Anchor's a'trip)... the flukes just broke free; I can feel it through the line.

Anchor's away (Anchor's away)... anchor is free and I'm hauling hand over hand.

At this point, we begin to slide aft in the light headwind, bow held up by the slack sheet mizzen. Anke backs the helm – shunting the stern opposite our intended course - and begins to raise main.

Anchor's aboard (Anchor's aboard)... cleated taught-set in its roller, ready to drop.

I step to the main halyard and help raise the last of the mains'l. We've angled off on our tack, by now, and the lax main fills. Anke trims and makes fast; the vessel comes alive – heeling a bit – as we begin to slip forward, about 45deg to the apparent wind. I close and dog the anchor hatch before coming aft to help tidy halyard ends into their stowage buckets.

We note the time in the log, along with actual windspeed and direction and barometric pressure. We'll enter these every hour until anchored. Underway, five minutes into the young flood.

And a glorious morning it is!

First light dilutes blue black to blue greys, dark greys to silvered. Mother-of-pearl, opalescent highlights in rose and gold begin to define the clouds before giving way to full day. Today it's squally, stone sky with shafts of golden rays in the breaks. Our sister calls them God's Eyes.

We start slow and pleasantly in light wind and little current before picking up to the day's breeze and mounting tide. Long tacks out (the good one) and short tacks in. Short tacking along the edge of the rain, parallel to and inshore. Where there's something of interest 'longshore, we pull in further than is strictly efficient. Sometimes, we're becalmed, checking out a beach behind a headland and scull our way back to the breeze.

A squall or two bluster by. We drop the sails a panel or two to reef, then sheet to trim. Once past, we ease sheets, raise 'em back and trim again.

By late morning, the tide has maxed and waned. Slackened and fouled. We shift inshore, 'wall-crawling' where the opposing current is slower. Riding back-eddies behind the points and shooting a goodly ways out around them to avoid the counter rush at their tip.

Cold lunch – a rice and pickle salad – and later, coffee and a spoot (peanut butter, brown sugar, chocolate with cinnamon and/or vanilla and thickened with milk powder) to fuel us through the afternoon.

We've made good progress. Rounding a bluff, we see the berm – a twelve foot wall of sand and gravel running perpendicular to the river and parallel to Chatham – embracing our estuary under the watchful eyes of Lynn Mama (one of our favorite mountains). We plan to round that berm and anchor behind it, neaping out for a week or so.

We reach and pass our river entrance, slightly, to a point just upwind and current. We round, and, unopposed, approach with full control and good power to fight the river current (extra strong as the ebb is with it).

We watch our ranges as we enter, pointing counter-intuitively high upstream to track straight for our goal. We slip in behind the berm. As usual, the current is very strong, here. as the flats empty, funneled by the berm. Anke shoots as deep in as she can, then bunks the bow against the steep backside. As she drops sail, I jump ashore with the anchor (pre-cleated) and run it in.

Using the pole at the bow, we position ourselves mid-creek (the flats are narrowing down to drainage creeks), checking with the the pike pole on all sides for equal depth (we want to settle down flat, and can't see through the glacial water). One of us rows out a second bow anchor, then one off the stern. We'll explore our options while the tide is out, then shift the boat on the next incoming tide.

Now it's time for a glass of wine on deck as we take this new place in and wait to ground out. We hold our wine loose as we settle in little lurches, the not-quite-down chine digging in as we sweep back and forth over the bottom. Then a feeling of resignation as she takes her feet; afloat no more.

We're a little low on firewood and it's not raining. When the water's down to ankle depth, we wade across with wood bags (nylon navy surplus sea duffels), saws and axe and walk the berm. We spot and note a muddy flat, perfect for a week's stay in all weather.

Once in the woods, we find a standing dead tree – not so thin as to waste effort; not so thick as to require too much – and drop, buck and split it. A little less than two bags worth, so we split the load. We only carry them near water's edge... we'll pick them up with the dory near high tide.

The sky's clearing to a beautiful sunset, reflecting in from the Pacific on the ocean side of the islands. We decide on a beach fire, and whip up some Dutch Oven delight. Not a lot of small, dry wood on most berms, but always seems to be enough for a week or so, if we don't go crazy.

Well fed, we watch the clouds lose their scarlet ribbed radiance. Shy stars show one by one, regarding themselves in Chatham's now glassy water. The world hushes down in that moment before the night hunters announce themselves to their prey.

We'll have to shift the boat to the flat we spotted sometime after mid-night, riding the incoming tide. Pick up our wood before it rains again. So we dowse the fire and head home.

If we've any juice left, Anke may draw while I doodle a barge. We might read a little, separately or aloud, one to the other. Or play a little music. Or a game of Scrabble?

Like as not, I'll look over and she'll have nodded off. Watching her face - relaxed and flushed in sleep - I'll feel that familiar, warm rush of love and gratitude...

That she lets it be me.

*****

PS. There are other days, of course. Not all go this bucolically. It's even been a while since any day under sail is typical (building for a while, now).

And there are lots of days when I'm the one slug-a-bed and nodding off at the end. It ain't so purty, themdays!

Mix and Match

The Hobie Mirage Drive in Action
All KINDS of things come to mind!

Lesser artist borrow,
Great artists steal.
-- Igor Stravinsky


Mix and Match

One of the wonderful aspects of designing on so versatile a platform as the box barge is that almost any idea afloat can be appropriated and adapted.

Used to be walking the docks, or perusing library classics was the way to scan for ideas. Nowadays - with so many classic boats and good books gone over the bar - I stroll the internet. Most search engines allow image searches. With the right keywords, it's amazing what you can find.

Here are a few sources I've found attractive...

Gilmer BLUE MOON
From the UnlikelyBoatBuilder

From early on, I've admired Thomas Gilmer's BLUE MOON. One of the attractive features is the flush mid-deck with a trunk cabin aft and large hatch forward. Cockpit and foredeck are sunk below sheer height for secure work decks. I've used this layout in LUNA (based on Bolger's AS29) and WAYWARD (ex T32x8 LUNA).

*****

Once you have the mast, why not make a crane of it?

Howzabout an A-frame mast that doubles as a crane? And speaking of salty work barges, Tad Roberts doodled this next one around an old engine he came across...

Doodle by Tad Roberts

*****

The possibilities of what we could build on top of 'em are endless!

Traditional fishing boats on Lake Como

Hmm...

From Kerala India

If ya can fold out a trailer, why not a barge?

Waste Not!

*****

These are but a taste of what's possible!

That's the joy of building a box... it frees you to think out side of one.

 

Magic Triangles: Handy Math Trick for Befogged Brains

Mathematics is a collection of cheap tricks and dirty jokes.

-- Lipman Bers 


Magic Triangles: Handy Math Trick for Befogged Brains

Magic triangles are a handy little mental trick that helps with some of the math we boaters frequently encounter.

Anything that makes math simpler helps in those wee, hypothermic hours of pre-dawn fatigue! Anything that makes math simpler helps cut down on error, even when wide awake!

I first read of these in Miner Brotherton's 12V Bible for Boats (one of the most accessible DC12V sources around), who learned them in the Army. Apparently, some go so far as to tattoo them on the back of one hand.

Magic Triangles work for any equation of the form X = Y x Z.

Consider the Speed, Distance, Time calculations a navigator must face, if only in the rough. There are three, related formulas:

D = S x T ......... If we know Speed and Time, we can find Distance.
S = D / T .......... If we know Distance and Time, we can find Speed.
T = D / S .......... If we know Distance and Speed, we can find Time.

Got that? I don't! This kind of thing doesn't stick in my brain.

Each of these is a variant of the others, transformed by simple, algebraic balancing acts. Right.

I used to remember that car Speed is given in familiar miles per hour (aka Distance / Time), so S = D/T, and then work the others out as needed. But this doesn't come easy in the bleary hours, and paper helps at the best of times.

Here's the equivalent magic Triangle:

To use, cover the one you WANT TO KNOW. Of what's left showing, one over another means divide; side by side means multiply. 

Let's say you want to know S. Cover it with a finger, and we see D/T. Shazaam!

Three formulas in one. Better yet, I find I can do this in my head without breaking a sweat.

Any mnemonic works that puts the top letter first, followed by the other two (their order isn't important... DST or DTS works the same). 

What's important is that you start with the variable that stands alone, and equal to two multiplied variables. 

EXAMPLE:   Xamine Your Zipper    =>    X = Y x Z    =>    Magic Triangle with X on top.

Here's a couple others that are handy afloat or ashore:

These handle most marine electrical calculations.

So there ya go... MAGIC Triangles... making smart fellers of fart smellers since 1906.

*****




Extra Credit:

As with a spreadsheet, you're not limited to a simple variable within triangle spaces. Consider the following, common navigational trio:

 
 
Angles can be measured by sextant, compass, pelorus, cross-sticks or fingers. Distance may be known from fixes on the chart. Spread may be known from the chart, topo maps or average heights (an example in our area is trees, for whom average height is about 100ft). Other clues may be pressed into service, such as roughly 10 vertical feet per story in modern house construction. Tangents can be looked up in tables, on the web, using scientific calculators (many phones can handle these).

All subjects covered elsewhere (though not by me). 

Go get 'em, Tigers!



PS. Astute reader JOHN caught me with the wrong magic triangle for the extra-credit (now repaired)... thanks, John!

As it turned out, I'd already realized it, as the same afternoon, Anke and I used it to lay out our sails, but it wasn't making any sense!

Just goes to show, easier is still a challenge for some of us!  8)  

Duet Together

Photo by Dorothea Lange
See more of her work here

We hail from a time when,
If something gets broke, ya fix it.
Ya don't just throw it away.
-- An Elderly Couple's Secret to Long Love



Duet Together

Sad news percolates through the grapevine; another couple, once very much in love, has grown apart and split the sheets.

Now, we don't think of these as failed partnerships, and shy away from the judgement implicit in the word. There are as many reasons why couples part as for coming together. Rather, it's a time to support friends who are most often hurting, and helping, where we can, to facilitate their transition from love to simple amity.

 But there's a pretty common thread, running among these partings; often, the couple spent a great deal of their waking hours apart. Work and commute, domestic chores, hobbies and pastimes, social activities, social interactions, toob time... many of these are activities pursued separately. These take a toll on time and energy that might be invested in partnership. These run lovers along paths which can, and so often do diverge.

There are other possibilities.

Anke's about to head out to renew her passport – for about a week – while I stay at our winter care-taking gig. It occurs to me that, from 26 years, this will bring us up to total of one month apart. I hate it; she hates it. Gotta be done.

One of the most frequent questions we're asked about living aboard is, “Don't you need some time and space away from each other, now and then?” Answer, “Umm, no. Why?”
 
I suppose we do take time apart, in a sense.. We both like to read, and only sometimes in the same subjects. I write, she draws. She hits the hay earlier than I do, most days.

But this all takes place within reach of conversational tones. It's easy to share, and check in, and steal a kiss 'n' a hug. We're not walking in lockstep, but neither do we lose contact.

When we're home, we live close. Life onboard is ... well... intimate. The needful goes better with all hands, pulling together. The pleasures of the life are shared by all aboard. One is never further than voice can carry, and thoughts and laughter are easily shared.

When we work, we work together. Bad enough we have to work, now and then... but to work apart from each other?? Package deal or no deal. This can deliver a hit to our economic potential, of course. A job like care-taking pays the same, whether for one or two. Or working possibilities are limited to the overlap of our skills.

When we travel, we travel together. No separate vacations for us. Most of our travel is just moving around with the wind; travel without really leaving home. Travel overseas to see her family is an arduous and risky venture. If anything's gonna happen, we'll face it together.

If something gets broke, we fix it. We may fuss and we may fight, but it ain't like that all the time (line from Ruby Pearl by the Hackensaw Boys)! We work at this as hard as anybody, and with as much cause. We're not always fair or patient with one another, but we notice, and talk until we get there.

I'm not bragging here. These approaches won't work for everyone. This is a way that works for us, and we like it. I merely suspect they might avoid some of the growing apart that goes around.

That, and stay in touch with why you fell in love.

***





PS. What got me thinking about this was a task we've been tackling, together, these last few days. A generator is failing, and its 500lb replacement needs to be swapped in. This entails getting it out of storage, across a couple of separate docks, up a tidal ramp, across boardwalks and a gravelled path, through some woods and over stones and boulders, up two levels of powerhouse porches, through a narrow door and crowded machine room, then wire up its three phases and presto! I'll spare you the reverse trip for the old one.

The job entails chewing gum, baling wire and a whole lot of odds and ends. It's a little dangerous, and if we drop it, we've bought it. Alone it would be doable, but tedious. Together, it's doable, and yet another bonding experience, replete with laughter and copious opportunities for growth.

She is my 'buddy from work', and so much more.

Another day at the office!
Anke running the hoist.

Footwear's Footprint: Problems and a Solution?

From Thomas J. Elpel's Primitive Living Skills
Article contains tire sandal pattern and instructions

 

Sell a man a boot, you boot him for a while.

Teach a man to boot, you boot him for life.

-- Ancient Chinese saying, sort of 

 Footwear's Footprint: Problems and a Solution?

As coastal cruisers in temperate climes, we are oppressed by our mountain of footwear.

Here's our current list by type and purpose; 

• Rubber Boots – Edge-of-the-water and wet hikes ashore.
• Leather Boots – Longer, more rugged hikes.
• Hip Waders – Wading for repairs or thin water maneuvers... chest waders would be nice, instead.
• Winter Boots – Insulated for cold weather sailing or snow ashore.
• Sandals – In and out of water in warm weather... good soles allow doubling as street shoes.
• Slippers – Sheerling for lounging and fair-weather sailing, while high soles allow short, wet deck excursions.
• Snow Shoes – Snow and occasionally mud.

Times two! Sheesh!! This adds up to a bulky heap o' gear.

Shoes get a lot of wear and tear, and replacing them adds up, over time, to a pretty penny. 

If not given prime storage, they tend to mildew, no matter how well cleaned.

Our vital rubber boots, in particular, only last a few seasons at best... we face a choice of carrying a spare set or patching (mixed success) until pulling into a town for replacement. And over the years, they leave a trail of unrecyclable garbage. Can sometimes cut them down to 'garden loafers' and pass out to friends, but most of them are doing the same, themselves.

My hip waders are heavy rubber whose tops fold down and up again, like old-fashioned sea-boots (this makes them near impossible to use with pant-style raingear, and a short rainjacket doesn't cover their tops). While I like them in dry weather, they are too heavy and expensive for general use. Anke uses a lighter set, but they're still not economical for frequent use.

In general, we go for robust treads for afloat/ashore use. Not for us the sliced sole, deck-gripping yacht tread... they just can't cope with a slimy rock or mossy log.

But I've come across some ideas that might help reduce our footprint.

Leather has some distinct advantages, with DIY potential.

Well made, maintained and oiled, leather boots are reliably waterproof. Irving Johnson, in Around the Horn, reports that professional sailors preferred leather sea-boots to rubber. Apparently, they kept feet warmer and overall dryer. I'm guessing it's because rubber doesn't breath, and feet are soon dampened from condensation, even on dry days. 

Boot leather is tough stuff. We wear out our resole-able rubber treads, but the uppers just keep on going.

A friend directed me to this brilliant idea: 

Make DIY sandals from old tires. Add a moccasin. Add good socks. Go. 

This system has been reported to be extraordinarily comfortable on thousand plus mile treks in rugged terrain. In our case, we'd be looking at boot moccasins (or moc + tall, waterproof socks?). 

It's a modular system (my favorite), which confers high versatility. Each component can be used separately or in combination. The sandals provide solid, sure, cheap soles to the boot mocs, while the socks layer up to moderate weather.

In our case, we would need the boot leather to be selected, treated and built for waterproof service. At best, waterproofness is pursued from the tanning process on. 

To this basic system, I would like to add a roll of light, water-proof or -resistant fabric to the boot top. Waxed cotton, for example, dampens when immersed, but will not flood through. It would normally be worn furled, but could be unrolled as hip-waders. This avoids the weight and volume issues of folded leather. Having them always available would be a big asset. 

Insulated overboots from sturdy fabric for cold-weather can be DIYed, again using the sandals for soles. Weather cold enough for insulation is generally dry. With care, these can be used ashore. With luck, the overboot could double as a lounging slipper?

In-soles are a low-profile accessory. Wool insoles provide cushion and insulation from the ground without over insulating the foot above. Specialized insoles increase shock absorption. 

The only sticking point is that, while moccasins are easily made by the home craftsperson, waterproof moccasins are not (they can be DIYed, but it's skilled work). There are a few professionals who offer these, custom made, but they cost considerably more than one normally expects to pay for common footwear. 

Still, I'm guessing that a custom crafted boot moc will pay for itself with decades of life if faithfully protected by the sandals. We waffle, but my guess is that this is one skill we'll not acquire unless forced by circumstance.

If this works, we'd be down to the modular system and snowshoes... 

That's more like it! 

Considering Multihull TriloBoats

T40x20 CATAMARAN

Verrrrry interesting.... but STUPID.

-- Arte Johnson (I'm half kidding) 

Considering Multihull TriloBoats

Judging by the amount of correspondence I field on the subject, there's a fair amount of interest in multihull TriloBoats – catamarans (cats), trimarans (tris) and proas. 

Here, I'll lay out the modest benefits and considerable pitfalls I see in this approach at cruising sizes, along with an impressive example of a smaller scale project that I consider highly successful.

I warn you... this is rather dull going. Unless you're particularly interested, I'd bail.

A bit of jargon: Amas are the longitudinal 'hulls' composing a multihull. There's some variation in use about the net, but it seems a pretty generally accepted term.

NOTE: The T40x20 CATAMARAN, shown above, was a 'cartoon' made on request for relatives who'd fallen in love with Phil Bolger's DOUBLE EAGLE. It's way beyond my engineering skills to even put it out as a design, but gives a taste of a square boat approach.

I should emphasize that this approach is not our taste, in general. Anke and I would be off on a Wharram TIKI, or at least a dory-ish trimaran if we ever succumbed to the allure of polyhullery and warm waters.

Multihull Principles

The use of multiple hulls is primarily to greatly improve stability. They may follow one or a mix of two strategies:

Float the leeward ama – Its reserve displacement resists heeling moment, tending the whole to low angles of heel. Its wetted surface and resulting drag, however, slow the vessel and induce lee helm.

Hike the windward ama – Its weight, lifted at the long end of a lever arm, resists heeling moment, tending the whole to low angles of heel. Lifting up and clear of the water's surface reduces wetted surface and resulting drag, as well as hull-dynamic weather helm, optimizing speed.

Cruising catamarans favor the first strategy, while proas favor the second, as do most racing or speed maximizing craft. Trimarans mix the strategy, and tend to work with shorter lever arms.

The longer and leaner the hull(s), the faster the vessel can be. Wharrams suggest a minimum of 11:1 length to waterline beam ratio. Such hulls are easily driven to higher-than-displacement speeds. Extremely narrow hulls with very high freeboard (over low draft) are enabled by the amas, which keep them from flopping over onto their sides.

Circular hull sections are fastest, but have low lateral resistance and can't be easily built of sheet materials. Rectangular sections carry the most load (assuming equal beam and draft), and have high lateral resistance. V sections have good lateral resistance and speed, but low displacement on a given draft.

Long and narrow has ergonomic consequences. In order to have a wide enough interior to fit even a snug double berth within a fast hull, the hull quickly gets long. Flare above the waterline can help, but a platform must be placed high to take advantage, reducing its headroom. The interior is linear, in shorter hulls, with little opportunity for circular social settings below-decks.

A common solution is to live largely on top of the hull/ama(s)/deck. But this generates considerable superstructure which adds weight and windage.

A mixed strategy is often employed... low superstructure to provide headroom over the narrow hull, into which, perhaps, only feet may dangle. It may overhang the sides to help provide 'elbow-room', storage or even low headroom bunks.

Wharrams recommend a 3ft sea-riding height for bluewater cats (I take that as applying generally to multis), measured from the waterline to the underside of decks between amas.

Caveat to Multihulls vs Monohulls

Here are some for DIY builders to consider when comparing types:

For a given footprint, a multihull adds cost, complexity and engineering challenges.

You are building two to three monohulls, cross beams to join them, with one or more decks and/or superstructures over. Each of these components represents a fair chunk of the effort required by a monohull. Special challenges – like mast steps, Ackermann steering, high leverage forces throughout – make design daunting to dangerous for the amateur. Everything multiplied x multi.

In terms of square sections, things get scarier... the initial and reserve buoyancy of a slab is much higher than usual sections. Larger forces develop faster than the usual rules-of-thumb were evolved to handle.

If one joins the very few pioneers in this field, I recommend a cautious approach, backed by modelling, certified expert advice and incremental sea-trials.

The payoffs are speed(!) under sail, humongous decks and undeniably cool. For the pure of heart, able to run lightly through the world, multihulls can more than pay their way.

So, with that caveat, let's continue...

Simple Conversions: Adding Outriggers to Square Boats

Adding amas to a full-width TriloBoat designed as a cruising hull, I feel, is a losing proposition.

Triloboats and other box barges already have the highest monohull form stability possible on a given footprint (length x beam x draft).

As cruisers, box barges skim upright downwind, benefitting from shoal draft relative to their displacement (don't have to push much water aside). On the wind, they benefit from heeling by presenting a V section to the water.

A simple, multihull conversion detracts from both. The outrigger(s) add displacement and drag off the wind, and force the hull more upright on the wind. Plus, they clutter the deck, increase the beam with high windage, vulnerable bits, and – starting from the high mono-deck – don't offer usable sidedecks.

Lose-lose-lose.

Critiquing the T40x20 CATAMARAN

Let's take for granted that my T40x20 CATAMARAN can be well-engineered to be affordably and soundly built.

Even so, the two amas together total only 8ft hull beam. Displacement is roughly equivalent, then, to a T40x8 square monohull. But the monohull wouldn't require the two, inboard ama sidewalls. We'd be able to live within the T40x8, rather than on top of it, eliminating much of the superstructure with its weight and windage.

If a large living platform were the goal, converting to a barge by hulling over between amas would increase displacement by roughly 250%, and likely halve construction effort.

Box Section Approach to Multihulls

So let's look at it from the other direction. Could a 'square' multhull be worthwhile, designed from the ground up? This, to my mind, shows much more promise.

Triloboat approaches that might apply:

• Square sections
• Constant section
• Whole and even fractions of sheet materials

These are independent, and can be considered throughout the design.

We'd likely want to start with a long, slender hull, as per multihull normal, for an easily driven hull.

Square sections carry the same weight on less draft than all others. That can be useful. Their right angle chines provide good lateral resistance. They're easy to build, and interiors are easier to fit. Hull mid-bodies benefit most.

But flat bottoms forward – especially when held upright by amas – pound when slapped by the water's surface. What to do?

Fining down the bow - and maybe adding a cutwater (a sharp, faux hull bonded under the bow) - helps a lot with this. I'd consider matching the forward curves in plan and profile (TAB) for least turbulence.

I doubt the stern needs to narrow, and full width preserves precious deck space at the transom. I'd consider a very easy exit, with the bottom of the transom at or slightly above the waterline. Being a multihull, we're not going to heel much (so won't drag the transom corners), while the release wave depresses to help match the exit angle. Never actually seen this in square hull action, so needs experiment.

Constant sections – of whatever shape – naturally develop parallel longitudinal lines (such as the sheer) along the constant section. This is especially useful amidships, with superstructure planned and fit along this stretch.

Constant section amas , with shaped foam ends (where shapes get complex) and glassed over, show promise, I think, for easy construction and good performance. I'd personally favor assymetrical V sections (especially Newick plow-style), with the leeward face(s) oriented vertically for lateral resistance.

Whole and even fractions of sheet materials can be applied to hull, superstructure and decks, for economies of effort an material.

Another approach to square sections might be to rotate the square sectioned hull 45deg, for an upright V section. We'd end up with a diamond-style section resembling Superman's chest logo (variations are possible). The right-angle keel would run the entire centerline, eliminating any need for a cutwater at the bow. Downside is increased draft for the same displacement.

A Square Trimaran: (Mostly) A Success Story

Mark Meyer designed and built an upright box section trimaran at 27 feet. It is wicked fast, fun, good looking (I think) and carried his family safely across the waters of northern Southeast Alaska. He used it extensively to fish Tenakee Inlet for at least a decade.

Notably, he used square section, aluminum girders, rigidly mounted, for cross-beams. These worked very well.

His only disappointment were the flat-bottomed amas – skimming across the water they pounded hard. He added a V section cutwater toward the bow, which improved the situation, but not much. Apparently, flat-bottomed, flying amas proved to be a poor choice.

NOTE: Wharram Designs abandoned flat-bottoms for their catamarans for the same reason... the windward ama raised enough to pound badly. Nevertheless, they safely travelled far and wide.

Mark definitively proved the concept for the main hull, and new amas were in the works last I checked in. 

My personal opinion is that  square sections are a viable choice for hulls that stay immersed, especially when building quick and dirty or on a small scale. 

I, myself would opt  for other shapes in any project large enough to represent a significant investment. It seems to me that, beyond a certain point, the savings in construction effort cut into long-term multihull values.

But that's me.

*****

So there you are, dear Readers. For those of you interested in these exotic pursuits, I wish you happy doodling.

And keep me posted!