Super-Lightweight displacement boats Vs. old fashioned heavyweights.

[MapisM]

I see what you mean, but there are obviously other economic advantages in a smaller boat, if TCO is the key factor.
Besides, since you mentioned sea motion, don't you agree that "old fashioned heavyweights", as the OP called them, are bound to be much better in this respect than any much lighter and narrower hull, for any given LWL?

 

[rustybarge]

I see what you mean, but there are obviously other economic advantages in a smaller boat, if TCO is the key factor.
Besides, since you mentioned sea motion, don't you agree that "old fashioned heavyweights", as the OP called them, are bound to be much better in this respect than any much lighter and narrower hull, for any given LWL?

that's been my limited experience, the heavier the boat the smoother the ride.

following up on the concept of the slim long hull, and going back thousands of years, the polynesian canoe with outriggers is the ultimate hull shape, but as many people have observed a total nightmare in the modern marina environment that charge multihulls up to twice the premium for the extra beam.

.....i seem to remember there was a design of trimaran that had folding out riggers.
imagine the scenario, as you cut through the chop in your tri with it's super slim hull slicing through the waves, totally stabilised by the outriggers. as you approach the port, the outriggers are retracted to transform your boat back into a mono......whooosh.

so you could take the ultimate hull shape, something that looks like a narrow barge, with deep deep deadrise, i'll guess 8' beam by 11.9mtr length (less than 12mtr), a single small 100hp diesel to give 15kts max, 12 kts cruise, and a 20hp outboard as standby (8kts).

no problem getting hydraulic rams, or electric, to retract the outriggers......
View attachment 36195View attachment 36197

if you've ever been on a narrow boat, there's a surprising amount of room!

last year a monohull aluminium 'around the world record breaker' that was being build in the uk, and was destroyed in a fire, looked very narrow and long. iiirc it took a massive fuel load.

 

[rustybarge]

someone's already thought of this:

Described by Boat International as "one of the world's most amazing super yachts, that could spell the future for efficient long range cruising", the striking 42.5m Trimaran Adastra was launched on the 11th of April 2012 in China for Hong Kong clients Anto and Elaine Marden.

Measurements taken during the sea trials show that her fuel consumption at 10.5 knots is as low as 17 litres per hour when carrying 10% fuel and water. At cruising load (20 tonnes fuel and water) she uses just 25 litres per hour therefore on delivery trips her range is 10,000 miles starting with 30,000 litres of fuel. Her slender hulls and streamlined exterior allow her to travel faster in the open ocean and at 17 knots she has a 4,000 mile range so can comfortably cross both the Atlantic and Pacific oceans at hi-speed.



http://www.john-shuttleworth.com/adastra.php

lumishores eat your heart out:

 

[Deleted User YDKXO]

someone's already thought of this:

Described by Boat International as "one of the world's most amazing super yachts, that could spell the future for efficient long range cruising"

Yup it might spell the future if you're minted enough not to worry about the cost of commissioning a one-off 42m superyacht trimaran and you have your own harbour to park it in. When this design is scaled down to, say, a 15-20m range which mere mortals could hope to afford, I suspect that the interior accommodation will tiny. In fact, I'm not sure where the sleeping cabins will go since in both monohulls and cats, the sleeping cabins are usually placed in the hull(s). Still, I'm all for innovation and this is an interesting design

 

[rustybarge]

Yup it might spell the future if you're minted enough not to worry about the cost of commissioning a one-off 42m superyacht trimaran and you have your own harbour to park it in. When this design is scaled down to, say, a 15-20m range which mere mortals could hope to afford, I suspect that the interior accommodation will tiny. In fact, I'm not sure where the sleeping cabins will go since in both monohulls and cats, the sleeping cabins are usually placed in the hull(s). Still, I'm all for innovation and this is an interesting design

looks like you could park the average 24mtr mini-superyacht underneath the outriggers!

here's a smaller tri with folding hulls:

concept could be converted to power...

View attachment 36202

ignore the usual saily Bs........
folding on this vid at 1 min 20 secs:http://m.youtube.com/watch?feature=c4-feed-u&v=Kngm-NhfSJ0

 

[Nautorius]

I'm with you on that!

so, if only you could built on the cheap a nice fat f/b sailboat at around 40-45ft with decent aft deck and an airy sliding door saloon with standing height and floor level 1+m above waterline. Yep, 8knot hull speed with 1.0+mpl would make a perfect kit.
Have another 15yrs before I can start thinking about it
And don't mention cats as they're too expensive to moore or keep on the hard.

cheers

V.

Vas,

Except for the F/B this would fit the bill: http://www.beneteau.com/Sailing-Yachts/Sense/Sense-46

Slightly weird but great Med style boats for a couple or 2+2.

Paul

 

[rustybarge]

Vas,

Except for the F/B this would fit the bill: http://www.beneteau.com/Sailing-Yachts/Sense/Sense-46

Slightly weird but great Med style boats for a couple or 2+2.

Paul

that's a beautiful boat.
6kts cruise with saildrive?

 

[tadr]

I see what you mean, but there are obviously other economic advantages in a smaller boat, if TCO is the key factor.
Besides, since you mentioned sea motion, don't you agree that "old fashioned heavyweights", as the OP called them, are bound to be much better in this respect than any much lighter and narrower hull, for any given LWL?

Yes, a smaller (though not shorter) boat of lighter weight should cost less to buy initially and less to push through the water.

Motion is complex, and everyone reacts differently to it. A boat moves in six ways, surge, sway, heave, roll, pitch, and yaw. Any boat can be comfortable or uncomfortable in any of these motions. Changes in speed, course, or load distribution can change motion. The military has a big interest in crew performance and have studied motion a lot. One of their findings is that the speed of the motion is what fatigues crew and eventually induces seasickness. Heavier displacement might be better if the motion is slower, but wider boats tend to have high initial stability and a snappy roll, as do mutihulls. Power tris reduce the Ama (floats) size to "tune" the stability for better comfort. Narrow boats generally roll more deeply but slower. Perceived motion is dependent on where you are on the vessel. I've been aboard 3-story heavyweights where I couldn't stand up on the flying bridge in a small short chop.

 

[Nautorius]

that's a beautiful boat.
6kts cruise with saildrive?

Actually more like 7.5-8.5kts. these Benes are quite Slipery.

 

[rustybarge]

Actually more like 7.5-8.5kts. these Benes are quite Slipery.

i've watched boats off Cowes coming past the ferry terminal on a choppy day.(i've only visited once)
the mobos were rolling like pigs, yet the sailboats were as steady as a house, maybe a little bit of pitching.

so the idea of a motor sailer type craft could make perfect sense. the weighted keel will stop any rolling, the hull is hyper- low resistance drag, it has sails to help with fuel consumption.....7.5-8.5 kts ain't so bad!

lifting keel would allow access to shallow bays, cheaper than stabilisers that's for sure!