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Old 12-16-2013, 10:36 PM   #1
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Wave piercing trimarans

Something about these things get me going, there quite cool if you ask me.
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Old 12-16-2013, 10:45 PM   #2
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I agree. They are the most efficient boats there are is my understanding. The extra speed sure would be nice to beat weather windows.
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Old 12-16-2013, 11:52 PM   #3
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Something about these things get me going, there quite cool if you ask me.
They are cool... except they are favored by those idiots from Sea Shepherd!

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Old 12-17-2013, 09:05 AM   #4
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there was an offshore race boat in the 80s of this design. It was called the Triton around 33 feet
ran over a hundred miles an hour. With 3 outboards . It seem like it spent more than its fair time upside down
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Old 12-17-2013, 01:03 PM   #5
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Wipers or Rain-X?
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Old 12-17-2013, 01:45 PM   #6
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Wipers or Rain-X?
Rain-X
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Old 12-17-2013, 03:06 PM   #7
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Nice flat water pictures, but what if waves are larger and from abeam?
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Old 12-17-2013, 03:10 PM   #8
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From Boatgm on this forum




carabao
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It ride well in big waves once you get the angles right.
Top speed is currently 23 knots, 20 knots is about a liter per mile, 15 knots is about half that and I donít think it burns fuel at 8 knots.
The engine is a 4 cylinder yanmar. The cabin is air conditioned with a simple automotive system with AC coming from inverters. My get home is a long shaft 6 hp 4 cycles outboard it charges at 6 amps, and steers with the autopilot and pushes us along at 6 knots, but that was not in any wind to speak of, just testing.
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Old 12-17-2013, 03:15 PM   #9
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Limitless budget tri?
Probably this




John Shuttleworth Yacht Designs Ltd.
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Old 12-18-2013, 06:24 AM   #10
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Nice flat water pictures, but what if waves are larger and from abeam?

No problem as the amas are low displacement and do not snap roll the boat , it simply rises up on the wave , as it passes under.

For an ocean crosser with an unlimited fuel budget , these Tris are a fine way to go,
BUT ,for the trawler crawl the slender hulls do little for economy , as slow speeds a fat boat has less wetted surface (at same weight) as these slender hulls.

And the difficulty when rafting or locking thru becomes a big PIA .
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Old 12-18-2013, 12:59 PM   #11
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Interestingly, Adastra (the Shuttleworth mega tact) is very economical at trawler, full-displacement speeds. I'll get some numbers and post soon.
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Old 12-18-2013, 04:36 PM   #12
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"Adastra" and Our New 12m Tri

The Adastra has a length/beam ratio (main hull) of 17:1 - this is extreme by any measure. But with a length of 42.5 m (over 139'), she still has plenty of room - not the same amount as other mega yachts her length, but more than the average trawler yacht.

Of more interest, is her efficiency at displacement speed - she burns 29 liters/hour (7-2/3 GPH) at 10.5 knots resulting in 1.37 NM/Gallon. This is "real" trawler economy and is her intended speed for ocean voyaging. Her top speed is 23 knots at over 8X the fuel consumption or 62 GPH. As a comparison, Island Pilot builds a 57', 60,000#, monohull that burns 8.4 GPH at 8.9 knots (we're both going slower and burning more than a 139 footer!!!) and at 30 knots, 66 GPH. These are apples and oranges - but interesting numbers.
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A Kadey-Krogen 48' with a single 200 HP Deere at 9.1 knots is burning 6 GPH or 1.5 NM/Gallon, a bit better than Adastra at 10.5 knots. Of course, if you slow down the KKY, she'll get better mileage, as I am sure you would with Adastra, too. But to say that this 139 footer is NOT economical at displacement speeds is incorrect. The entire design project was based on making her as efficient as possible for long hauls with a modest amount of top speed. Kadey-Krogen 48' AE

Regarding these long, thin, outrigger-stabilized monohulls (or trimarans, if you must) - the ones designed for off shore voyaging, seem to do fine. Earth Race (one of the photos posted) circled the globe in record time in 2008. Earth Race, renamed Ady Gil, was rammed by a Japanese ship and became a total loss.

My interest in this type of craft is to create one for the pleasure boater who is shopping for a 30 something, economical, coastal cruiser (Great Loop, East Coast, Bahamas, etc.). I am working on a design that has not dissimilar proportions as Adastra except for overall size, luxury and price - the goal is a trailerable boat that has a base price in the low $200s with super economical cruising at 6 knots and economical cruising at 12 knots. One reason for steering towards this type is single propulsion machinery keeping installations as simple as possible, making up in length what we lose from beam.

The current design is hovering at 12m (39'6") with a waterline beam of 3'0" - If we can bring the waterline beam down to 28", we will be close to Adastra's 17:1 lenth/beam ratio, a good goal. Beam across the outriggers (amas), is at 15'0" - not too beamy to fit in many slips. Since the accommodations are long and lean (width of interior is 7'0"), we will end up with similar spaces as a typical monohull thirty or so feet long - and since boats are priced like steak (you pay by the pound), we expect pricing to be similar, too. If possible, we'll have 2, stand-up cabins (one queen & one twin) - one in the bow and one in the stern with a deck house between and an exterior bridge/sun deck aft (over one of the staterooms).

We built a 1/4 scale model and towed it at speeds up to the equivalent of 12 knots, full-size. Our 6 knot cruise was to our expectation using 6 kW/8 HP - with a modern diesel, we would expect 12 NMPG. At 12 knots, we see 65 kW/86 HP - 2.5 NM/Gallon. (See video of model being towed.)

To keep the price competitive, we are thinking of offering her with a variety of propulsion packages and are considering the following:

1. Single outboard
2. Small diesel for displacement speeds only - maybe 30 HP?
3. Plug-in electric power - 10-15 kW with 4 hours battery
4. 110 HP modern, computer-controlled diesel
5. Parallel Hybrid - 13 kW electric with 110 HP diesel (as above)
6. Serial Hybrid - 10-15 kW motor with variable-speed DC generator
7. Solar option - PV array for charging the battery - any of the above
8. Wind option - Wind turbine for charging the battery - ditto

All the electric drive/hybrid options would include a sizeable Lithium battery at 48 VDC.

Like Maltese feels there's a market for his efficient 52 foot cat, I feel there's a market for a smaller, ultra efficient cruiser with a price to match.

The outriggers (amas) are designed to be retractable for both trailering and for world-wide shipping in a standard 40' shipping container.
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Old 12-18-2013, 09:24 PM   #13
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BUT ,for the trawler crawl the slender hulls do little for economy , as slow speeds a fat boat has less wetted surface (at same weight) as these slender hulls.
What rjtrane said

Plus from above, this from Boatgm
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Top speed is currently 23 knots, 20 knots is about a liter per mile, 15 knots is about half that and I donít think it burns fuel at 8 knots.
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Old 12-19-2013, 06:39 AM   #14
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A 17-1 LB is optmised for very high speeds , which are very expensive , so very rare .
I would think optimising for lower speeds with about 8-1 would be cheaper at modest speeds and double the interior room at almost no cost.

Of course once you get to 8-1 the use for Amas becomes questionable by simply using low engine and battery weights, in a box keel.

When I ran a design drill , my conclusion was a NJ Seabright hull with an Atkin style box keel and reverse deadrise 40loa, 5 ft BWL, 8ft BOA would make a safe sea boat and delightful cruiser.

Speed on the pin would be no more than 18K , but at 12K genuine economy at almost double trawler crawl would be acceptable and at 6-8 should be measured in pints not gallons / hour.

Beachable , or at least the ability to take the ground during some period of the tide would aid cruising in crowded waters.

With a bit of BOA trimming the boat could roll into a long container so world cruising (a circumnavigation ?) at tiny cost would be a snap as the boat would not need offshore scantlings oR tankage.
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Old 12-19-2013, 07:27 AM   #15
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I designed a box keel sailboat years ago - the Peep Hen - a micro cruiser 14' x 6' - and built well over 100 units. Most likely my favorite project.

More recently I designed an expandable box keel motor boat, the longest of which has not dissimilar dimensions to your suggestion. I'll dig it out and post later. Never got built.
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Old 12-19-2013, 09:42 AM   #16
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Box Keel Cruiser

This concept was not as lean - 7' beam at the WL - 39'6" LOA and LWL - ratio is 5.65:1 - not exceptionally narrow. But sized for shipping by standard 40' container.

The box keel is the width of the walkway and approximately 14" deep. Total draft under 24". Designed with tooling in sections so a day version 6m and a single stateroom 9m could be built from same molds.

The bridge would be enclosed with Eisenglass - the canopy on lifts to lower for trailering and shipping.

Here's the 12m profile and plan views. We were planning on branding her "E-Solar." The late Phil Bolger was a big fan of box keels.
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