Albatross 7.5 wooden light trimaran schooner (hemp fabric on frame and veneer sandwich)

Hi, this is a sailboat I designed with freestyle design (using a dragonfly 25.2 template and a deckhouse from other monohull I designed) the other day and it seems that I had similar approach than Grainger design, and I checked his 42 trimaran hull curves when i went to make the final hull freeboard curves and realised Dragonfly are ugly just to make more internal space.











LOA: 7.5 m
S.A.: 22 m²
Beam: 5.80 m
Displacement: 400-600 kg ( fabric on frame compared to 1 ton fiberglass shell dragonfly 25)
Max Draft: 1.50 m
Min Draft: 0.30 m

The hulls bows are gentler than today's shapes to avoid pitchpolling. The akas or crossbeams (green) have airfoil profile and reasonable angle of attack to lift the boat and I choose three akas to redistribute loads and create good attachment to the amas and avoid fluttering and also reducing structural weight

The cross beams can be made of good ductile bended steel and the shape with wooden frames besides having steel tension ropes inside too, the crossbeam safety is a big issue



This boat can be built with wood and ultralight construction just by making watertight wooden hull just over the waterline and using just tensioned hemp fabric and webbing on frame (no lindseed or hardening material, just some natural treatment) and veneer cold molding sandwich. Flexible fabric on tension is strong and and flex on impact and gives a good complement to the frame compression structure while usually fabric on resin is not pre-stressed before applying resin and cannot be tensioned again so most of tensile properties of fabrics are lost when doing these toxic nanoplastic shredding petrol chemicals while a resin adds unnecessary thickness weight to compensate resin brittleness.

The trimaran has also a good rope tensegrity structure with hemp ropes to create tension between the amas and main hull while the akas or beams add compression.




Also the the akas could have different angles of attachment depending of added displacement weight and wave conditions


This sailboat can also be built with a donor sailboat hull adding the the main water line hull and redesigning the curves with light frame construction




I like this boat and can be made almost for free with recycled wood and fabric

The three free standing masts have similar sail area as the dragonfly 25 and they diminish capsize risk (shuttleworth has some good aeticles about multihull wave, wind, pitchpole and reverse pitchpole capsizing) and also reduce structural weight by redistributing loads just as i did with the akas or beams, and using existing hull frame reinforcement

To recover after capsizing one ama could be flooded and emptied with a good pump when it makes the 180° rotation back to position. Also a stern arch with inflatable bag similar to RIBs righting systems could be added

There's also a hatch on stern to escape during capsizing


Also it has stern plates for storm series drogues and i could add pivot daggerboard or two asymmetric leeboards, and make round sterns to avoid reverse pitchpole



Trimarans are reckless and this is just an attempt to tame this design i suppose, the design and stability appeal is the only thing worthy, rather than the advertised speed.

The 3d model is on sketchup warehouse and i will try to upload to grabcad

3D Warehouse https://3dwarehouse.sketchup.com/model/18d0f746-25be-4431-a374-5f4fbed6b0c5/Albatross-75-trimaran-schooner-wood-veneer-and-fabric-on-frame-Ayoze-M-design

 

Apart from the materials my biggest doubt are the waterstays. This is a truss . The big crossbeam stresses are at the hull where the waterstays meet crossbeam.It should be rather the other way around, the waterstays should meet the crossbeam at the ama.

 

Good to hear that opinion. This is a design I had in mind and have read about tensegrity so I just placed some random ropes as an example and placed more than the usual waterstays. I suppose this a design section where trimarans could be made safer and tensegrity discipline could help on this. So eventually to build this trimaran i would do some testing and ask advice to trimaran designers besides people with tensegrity and bridge dynamic loads knowledge for example

The usual loads in sailboats are torsional and flutering hulls that's why some trimarans have 45/45 X akas crossbeams instead usual 90° so maybe plenty of waterstays from top to bottom both ways and from several angles can bring safety and reduce structural loads, still this is a coastal cruiser as trimarans and even monohulls shouldn't venture in blue water even if they have a lengthier coastal passage

For the crossbeams akas I think a discarded bent steel light pole could do, and making steel attachments with plenty of steel plates in the hull and amas, this is a place where safety factor should be more than usual

 

Exactly. That major and very obvious flaw shows that the "designer" has zero understanding of the loads and stresses involved.

It's ridiculous that someone who knows so little can insult real designers and pretend to know so much.

 

You aren't a designer, you only praise designers without having any real idea and designs are just some drawings and calculations while there's a real world there. In aviation all aircrafts are developed in tunnel winds and fly with scale models to test everything hundreds of times even with today software and calculations.

Sailing is about safety not breaking reckless attitude records and I'm glad of bringing safety discourse to multihulls which are pretty dangerous

I have designed and built anchors and stern series drogues plates and studied tension structures, that's just about checking material specifications and safety loads

If you haven't realised yet I'm bringing more compression and tension elements to a trimaran just for the sake of safety besides load sharing and structural reinforcement reduction

You seem not to have any idea at all

 

Shuttleworth last trimaran with semi-hulls

Maybe i could redesign the akas crossbeams

 

Hull section view shows odd configuration for a multi. What's the purpose of the keel pod on the main hull?

 

A step to climb the hull using the handles, i placed 2 steps stair embedded on the stern hull but then i remove them to place the capsize escape hatch

I think i will rather place a folding stair

 

This is a total different approach because what does shuttleworth trimaran is applying the akas crossbeams in a longer longitudinal plane in the amas outriggers while bringing them to the two main structure reinforcements in the companionway and mast. Also the semi-X shape would help with 2 akas crossbeams torsional loads however the trimaran has 3 akas with the other aka in the stern

So I have more freedom to chose main hull intersection with akas crossbeams since Albatross has small masts with little loads well redistributed (i can even place 4-6 masts with thinner flexible wingsails) and plenty of wooden structural frames across the hull

Hull fluttering is what causes structural damage and stress, its a problem also in aircrafts and most of sailplanes should bring safety tension cables like old aircrafts even if they create drag


Also Classic south-asian outriggers have several akas and longitudinal stringers too to create a big sandwich structure and waterstays amas outriggers rigging with poles



https://c8.alamy.com/comp/EAG422/tr...outrigger-canoe-islands-malapaskua-EAG422.jpg









https://c8.alamy.com/comp/2DYY29B/a...arangani-province-the-philippines-2DYY29B.jpg

 

Fabric on frame is probably the oldest boat construction method, used by arctic and tropical people and has been largely ignored by current sailboat design, and natural fibre fabrics as hemp or kenaf can be waterproofed with vegetable waxes and oil while remaining flexible

It can reduce weight from 30%-50% ( in bigger boats a flexible skin can reduce the weight a lot compared to a thick brittle shell) from a fiberglass shell while the advertised carbon shells only reduce 15% of weight,

Fabric on frame can be complemented with a wooden watertight structure under the waterline to keep the boat dry and bring additional sandwich structure

This is an old fabric on frame catamaran




current fabric on frame boats use mostly laced strips so they are lacking a Sandwich structure like current CNC frames used in wooden boat construction like comuzzi










Also there's fabric building structures















Even good streamlined 3D fabric structures



Mosquito velomobile

 

Yes, the real world is very different - which is why your drawings are so pointless especially when your understanding is so faulty that you can't even draw major supporting structure the right way around.

How many craft that have been launched and sailed have you ever designed? Drawings on computers don't count - we can all doodle all day long. How many multis have you sailed?

Of course you are not "bringing safety discourse to multihulls" - it has been going on for decades.

 

This 2024 new shuttleworth trimaran has a shorter ama outrigger while grainger and dragonfly use large amas outriggers, all of them with a different longitudinal angle facing downwards in the bow (used to avoid wave capsizing while falling in a wave slope)

Also he places weight distribution to the aft, probably to avoid pitchpolling

Shuttleworth has an extensive multihull safety blog posts that all people should read










Grainger Mauritius cabin

 

Do you think every 3d design is just some fancy random lines???

Precisely I'm in touch with real sailboats problems and all types of accidents and failures and lack of safety gear and standards beyond a radio call.

Different boats solutions and out of the box thinking to bring new things to sailboats just like aerospace has influenced sailboat design

Here's an aircraft I made that also looks like a fancy render but brings a lot of thought and university research behind

And aerospace students had plenty of positive feedback while other fancy monetised stol aircraft projects didn't had that feedback and following, otherwise sailplanes are real aircrafts but dangerous be playing with

https://www.reddit.com/r/AerospaceE...stable_flying_wing_design_setup_propelled_by/

Do you think a designer just pull off a superb design and sit back? Design is usually a matter of trying and changing things, you can see in thingiverse people create things and change the design with other people feedback and personal testing

Safety things I'm bringing here compared to some mass produced trimarans

+Lower mast height, no brainer this removes vastly the possibility of wind and wave capsizing and front and reverse pitchpolling. Also they create less heeling force so the ama outrigger keeps drier and has less structural loads upon it

+Additional aka crossbeam, increasing structural stiffness

+Watertight companionway and stern escape hatch

+Rounder bow profiles to avoid pitchpolling

+6 waterstays compared yo few or no waterstay at all in some trimarans, usually included in folding trimarans

+Stern series drogue plate

+Ama flooding upright capsize recovery

And Im going to add and change more things just as an example of amateur construction everyone can do

 

Do you have any real world data that supports the assertion that of 30-50% weight reduction especially on bigger boats?Do such boats have comparable strength and capacity characteristics? What is the nature (make up) of your sandwich structure? I’m particularly interested in your notion that this is possible with bigger boats; how big?

 

Weight reduction with fabric on frame canoes is usually 30% with bare strips and lacing and cotton fabric with lindseed oil

Usually petrol shell sailboats use the hull skin as structural part of the boat but because fiberglass warps it usually needs wood bulkheads and furniture interior as structural stiffener and compression, or fibreglass stringers and bulkheads

So in a current wooden boat construction the structure is composed by frames that act as a Sandwich structure leaving the hull skin more a as collision barrier and tensile structure rather than structural

That's why modern wooden sailboats save weight by concentrating on a multi frame structure

So in the case of using flexible fabric on frame it will bring plenty of tension to the compression structure, while also absorbing impacts, and so the weight reduction can be more noticeable in bigger boats where hull skin thickness is usually a lot







Also there's this sailing reverso sailboat that uses ropes as tension structure to hold the assembled hull parts, this potential of webbing and ropes used for staying structural parts has also a lot of potential to reduce hull weight too.






I remember the kevlar hull fallacy calling it bulletproof while kevlar only works when being flexible and with resin is just one of the brittlest materials along carbon that get smashed easily and would only used as sacrificial material to not compromise another material structure, instead building a hull of kevlar and resin which is the opposite material property for a hull.

When using thin skin hulls, a sort of external strings can be added at the sides and on the bottom as collision and puncture protection rails or to avoid hull skin contact, i suppose the old sailboat keels where also a sort of protection rails against reefs