Backpackers Cruising Boat: Kea 5.4
Hello
After terrorising all the brave forum members I think its time to present my project:
I was strongly inpressed when I read the “Less is More” thread of Rick. With this philosophy in mind I began to rework my concept catalogue for the design of my proa for further simplifications and reductions.
My design brief :
Philosophical:
A minimum cruising proa for a singlehander, or a daysailer for a couple.
Very light, very cheap, very simple, very nice and sexy lines.
Stored at the habour where the beach cats have their place. Sliptrailer brings it into he water.
A fully decked Vaka for lots of dry stores, maybe a “emergency bunk” inside the hull
Beams and trampoline way high over the waves for a dry ride. A “throw” tunnel tent on the trampoline as living space.
Technical Data and Details so far, design work is just beginning
Vaka: LOA/LWL 5.4m (17’9’‘) BOA 0.83m (2’9’‘), Height 1,05m (3’6’‘), Draft(ama flying) 0.22m (9’‘), BWL (1’ 7 1/2’‘), LWL/BWL 11, Displ.(ama flying) 280 kg (616lbs)
Ama: LOA 4,8 (16’), BOA 0.41 (1’ 4’‘), BWL 31 (1’); LWL/BWL 15.5 Displ (normal loaded). 85kg (187lbs) Total volume: 400Litres (880 lbs) Ama will become smaller ... to much volume and weight now
The whole boat: Weights: Ready to sail: ~ 140kg (308lbs) Payload 140kg (308lbs), BOA: not decided, Sail area 10.5 to 12.7m” (112 - 136 sqf) working sail,
Details:
Construction:
Vaka: 4mm ply sidepanels tortured over 5 permanent bulkheads and fir stringers, flat bottom 6mm, 5oz glass over all, deck 4mm ply. 4mm subdeck as bunkflat
Ama 4mm all over, single chine V-hull, store compartment for anker and ropes, maybe waterballast.
Rig: not decided yet:
Option 1:one freestanding mast with a balanced lugsail similar as on the goat island skiff, one reef and then stormjib. Temporary auxilary shrouds 4mm Dyneema to support a genacker.
Option 2: Big windsurf sail (10.5m²) attached to a freestanding stub mast. These lightwind sails for windsurfers can be purchased as a complete rigs quite cheap on boat shows.
Lateral Resistance: Daggerboard in Ama
Rudders: Newick/Brown-style Daggerrudders with Skeg, attached to the sides of the Vaka with kickup ability. (nessecary in my homewaters).
Beams: 80mm aluminium tubes.
Unfortunally Iam new to cad design, so in the moment I can only picture the renderings of the hulls separatly, not the whole arrangement. I will prepare some handmade drawings next week:
So far ... open for comments ... Michel
Renderings:
Hello Michel,
I really like where you are going with this boat. You are giving it enough volume and freeboard to get through a chop without taking the tops off the waves and the shapes are quite beautiful. I like the section shapes. I would probably go for a narrower flat on the bottom and push in a bit more beam at the chine.
Dick Newick uses a piece of solid lumber for the bottom flat. This has the advantage of having a thick edge to attach the planking to and makes for a strong keel. Could be cedar.
It sounds like you are planning to build really lightly, and with as much volume as you are planning, it could be fast in chop. I would suggest using a rig that could take advantage of the potential of the boat. Maybe a beach cat rig (Hobie 18?) and use just the main, like an A-class cat. The rudders would have to be moved a bit aft to combat weather helm, but the flat in the bottom lends itself to moving the rudders toward the ends.
The over all length seems pretty minimal, but it would be light and easy to power up.
Anyway, that’s what I think.
All the best,
Russell
Hi Michel,
What a sweet looking little boat!
After reading Michael’s advice about stepping up to a bigger boat in gradients, I have, myself, been considering a one man, 12-16 foot boat as a test platform. I like your ideas. I like the shapes of your curves.
What software do you use for the lines, by the way?
Cheers,
Rick
Michel, I like it a lot. As others have noted, the lines are sweet, and you seem to have enough hull displacement to carry a decent “backpacking” load. I’m personally fond of the hull section you are using, the 4 chines are a good compromise between ultimate hydrodynamics and ultimate ease of construction in plywood.
Rick - I’m going to build a 16’, one man test platform first. Skip is doing that with his Bionic Broomstick, and it makes so much sense to me.
Hi Russel, Rick, Michael and all the others,
many thanks for the compliments. It seems that a lot of people like the apppereance of the old Dick Newick Proas.
The rendering with the red underwater sections is ok, but I should have wondered why the sub-surface of the linesplan is blue. I did the attachments in a hurry and picked the wrong one.
The main difference between the two is, that the Vaka will not have a chine above the CWL. The sidepanels are far under 4’ wide and can be cut without problems from the width of a plywood panel. They will be tortured over the permanent bulkheads and stringers, making the sides rounded without a chine.
The good news is that the bunk in the center of the Vaka can be done. The measures are 7’ long, 22’’ wide with 23’’ headroom over it. Just big enough not to become claustrophobic.
Russel,
Iam in favor for a relativly wide bottom and slightly flared sidepanels to have better numbers for rockerline, LWL / BWL ratio, and wetted surface.
I know that you like a bit more “V” in in your designs and you have drawn very succesful and beautyful boats to prove this right. But your designs (I know of) are 30 foot + and these are no small boats anymore. It is very difficult to get the needed volume into a small V hull. I think the penalty for wetted surface is to big in a small boat like mine.
(The same applies to the rising 24 footers here on the forum. The mainhull has to carry the load of two people, motor, gear, some stores and a leepod. A 24’ proa cannot be re-righted by the crew after capsize and needs some anti-capsize support. Thats a lot of wheight for such a small hull. For example “Madness” is 31 foot long and has the same payload schedule)
A thick bottom made from cedar is no good way to get a lightweight boat. A chinestringer or a epoxy panel connection with some fibreglass will do. The same is for theLength. I know that 17’ 9’’ its pretty minimal, but if you want to get a light boat its best to keep the longest measure as short as possible without compromising the ratios. My LWL : BWL is 11 and for my feeling this is the fattest for a low resistance proa mainhull.
The kind of rig is totally undecided by now and a beachcat rig is for sure one option. Eeverything you can purchase cheap and “ready to use” cuts down building time and costs. Hobie 14 seems to have the right size, the mast of the 18 is far too long and heavy, difficult to re-right after capsize.
On the other hand I have very good experiences with the balanced lugsail of the “Goat Island Skiff” that I have built for a customer. This is the second option. It has a very low CE and provides lots of power with a perfect control. The sail could be pretty big for good light air performance, because reefing is a matter of seconds. The short mast would make it easy to upright the boat after capsize.
My third option is a idea of Michael Schacht, shown here on the inflatable proa:
http://www.proafile.com/archive/article/teh_pookie
The lightwind rigs of the windsurfers are up to 10.5 m² big, they are light, aerodynamical very effective and quite cheap if you buy a complete rig with mast, wishboom and sail from the last years edition.. The big drawback is that you cannot reef. If the wind gets stronger you have to “dismantle” the wole rig and then go to stormjib set on the stub mast.
We will see, this decision is far far away.
Rick,
I use free!ship for design and I started to do CAD this year. I think its the best freeware programm available. If you want to design with it expect one or two mounths training time before you get some useful results and its a good thing to know what you are doing.. CAD makes no sence if you dont know your numbers. There will be a lot of calculations outside the design software. The big plus is that you can check a chined hull for developability of the panels and it gives you the flat panel offsets. You can print them out, scale them up at the copy shop and have ready to use templates for modelling.
Michel
Hi,
ok, I changed the linesplan of the vaka (look above), so that you now see the updated hull. If you scale up your screen a little (press ctrl + simultaneously) you can see the compounded sidepanels. Please notice that the linesplans have different scales. The ama will be shorter as shown, around 4.6 metres long. the vaka is 5.4metres.
I also corrected the text of my last post a little, perhaps you read it again to get all the informations.
I worked a little further and calculated a basic material list for building the hulls:
The vaka will need 7sheets of 4mm ply and 3sheets of 6mm.
The Ama needs 3sheets of 4mm.
Have one addidional sheet (spare) you can make a cost estimation with:
14 sheets (11 x 4mm, 3 x 6mm) marine plywood to build the two hulls.
For Stringers: 68 metres (225’) of 3/4 x 3/4 fir (or similar), around 30 metres of 5oz woven glass and 30kg of multi purpose epoxy for glueing, laminating and sheeting.
This is a rough and generous calculation. It will be more exact after nesting the parts, when the design is finished.
Michel
Rick and Michael,
I think its a good idea to make a 16 foot test platform but its also a good idea to test a rc equipped model first.
A 16 footer will eat up several 100 Bucks and around 150 hours of work, even with a rough finish.
Mivchael, I would like to see what you have in mind for your 24 footer. Can you show us some concept drawings or are they secret?
Best Regards, Michel
Hi Michel,
I had a whole bunch of free and/or demo programs downloaded, and I was reeling with the complexity of many of them, but seeing the results you obtained with Freeship, I gave it a go. I’ve been able to produce—if not usable designs—some good results. I had been calculating displacements using old methods learned in high school, for example, and I must say that Freeship really makes it possible to see the numbers very easily!
So thank you,
Rick
Renderings:
Luckystrike, Surely you have seen the CLC proa Madness? Great similarity in the Newick style curves which I find personally appealing as well. I also saw a guy, Ron Falkey, used the vaka as a trimaran main hull.
Dan
Hi Everybody,
rain today in northern Germany and nothing to do. So its a good time for some design work. I have put the drawings together to show the whole arrangement.
The Sailplan shows the balanced lug rig with a sail area of 12,7m² (140sqft). Ithink this is the maximum for a singlehander sailing without trapez. I like to have lots of sail area for a good performance. Reefing is a matter of seconds, but small sails spoils your sailing fun for years. For the same reason its good to have a gennaker too. The sail must be brought in for shuntung, but this is a touring boat ... so it will work.
Beam has settled at 3,1 metres. I would like to have it a little slimmer, but the trampoline has to be 2m wide to have enough space to build up the tent.
The look from above
A friendly Hello!
Currently on my drawing board is a 7,5m Camp Cruiser/Racer and I want to present it here in my thread instead making a new topic. Maybe I will make a new thread when the design is better specidied *smile*
Design of the hulls is absolutly preliminary and just a first impression, especially the rockerline is far from being optimal.
This time it is a modern styling with radical reverse bows. I think they operate well with the sharpie hull. In fact from the bow to the middle of the boat it has the same characteristics as a modern beach cat. It will be interesting to see how the tail behaves in the real world.
The Vaka is very long but the boat shall have a very good performance on the one hand and on the other a good payload to carry two people and their camping gear.
Data:
Vaka:
Loa 7.5m, BWL 0.55 Ratio 13.5:1, Boa 0.7m, Draft 0.22 max.
Sharpie style hull
Ama:
LoA 4,8m, Beam 0.4m, Total Volume 280 litres..
Sharpie style hull
The Proa:
Wheight ~ 200kg, Payload 350 - 400 kg, Displ. 550 - 600kg (hopefully)
Beam over all: not decided, but aprox. around 3,5 - 4m
Details:
Beams will be Aluminium tubes, welded into a frame so that the trampoline can stay attached during trailering.
Rudders: Kick up Rudders at the side of Vaka, just as in Kea 5.4
Daggerboard in Ama
Beach Cat Rig, same as “Madness”
Open for comments:
Best Regards, Michel
Ama
Love the reversed bow vaka but curious as why you need / want a reverse bow ama
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