Boat Design Forums

Boat Design Forums (
-   Multihulls (
-   -   An extremely cheap, easy to build proa, cat or tri for Okinawa island hopping? (

paradoxbox 10-01-2011 11:47 PM

An extremely cheap, easy to build proa, cat or tri for Okinawa island hopping?
I'm throwing around this idea in my head of island hopping in Okinawa.

The distances between most Okinawan islands are around 20nm or so, and the distance between the westernmost Okinawan island and Taiwan is about 50nm.

I want a proa, cat or a trimaran that meets the following criteria:

1) must be absolutely cheap to build
2) must be easy to build. example, stitch and glue plywood with fiberglass, or possibly even a skin covered frame (little bit scary tho)
3) should be able to carry 3-5 people including gear without much trouble.
4) ideally can be taken apart relatively easily for storage or when not using it
5) although it's basically intended as a "daysailor" it should be able to do overnight trips and it should handle a little rough weather (but i don't expect it to handle typhoons or gales)
6) rig i don't care about, could be lateen or marconi, even a junk rig, whatever

so far i've been leaning towards a proa design but a tri looks interesting too. catamaran may offer more space on deck but i dunno.. with a trimaran, maybe could give it some beefed up amas and then throw up some taut netting or something similar and use it as seating or extra storage space.

the kind of design i have been thinking of is very simple - hulls made of 3mm plywood with fiberglass overlay, everything would be lashed together (no nails or bolts). the mast materials i'm not sure about - have thought about bamboo but have heard people say it might be difficult.

any advice, tips, experience etc appreciated - flames are not, and don't need people telling me it can't be done either. looking forward to your ideas!

Corley 10-02-2011 01:24 AM

How cheap is extremely cheap? Do you have a budget in mind? Often you can make things cheaper by decreasing durability but that increases the longterm cost of ownership/maintenance of the boat.

paradoxbox 10-02-2011 01:43 AM

I'm thinking under $1000, better if cheaper. An optimistic budget would be around $500 for everything but I'm not sure I can find enough freebies to do that.

I priced out 4x8 3mm marine ply at around 30$ per sheet. I don't know how much I'll need as I haven't really even decided a good length for a boat like this as I have no real experience with multihulls, I just like the idea of them.

Everything will be made by myself including the sails so it's just material cost of the plywood, fiberglass related stuff

The durability of the hulls needs to be decent - I want to be able to drag the boat up out of the surf by myself or with the help of another person, but the sails, rig and rudder will all be lashed onto the boat with rope so I'm fully prepared to consider those as "consumable"

i should probably clarify a bit - this thing is, in my mind, going to sort of resemble a polynesian voyaging canoe but use cheaper/easier hull construction techniques (i don't exactly have access to huge original growth logs to hollow out...) that's why i'm lowballing the budget. painting etc. are not important to me. just needs to be a functional, speedy boat capable of island hopping and some minor offshore sailing (northern and southern okinawan islands are about 120nm apart)

Corley 10-02-2011 03:10 AM

Gary Dierking has some interesting sailing outrigger designs I'm not sure you could build them for that low of a budget.

What comes to mind for me as a very low budget boat is creating a tortured ply type of hull scarphing your ply panels together to create the hull and insert bulkhead and stringers to stiffen the panels you will need quite a lot of framework to support 3mm ply and stop the panels from "panting" in wave action. You have to stick to pretty high fineness ratios with this type of construction and the hullshapes that can be achieved are a bit limited but it could work.

A good way of experimenting with hull shape is to make some hull shapes in stiff card and see if they will translate into a good fine hull without requiring a lot of force. Its all an experiment with a small design, fun though.

The book the Gougeon Brothers on Boat Construction has a detailed chapter on tortured ply construction.

Turnpoint 10-02-2011 08:28 AM

I think a Wharram catamaran would be the closest match.... You should look at the Tiki 21 design.

Richard Woods 10-02-2011 11:54 AM

Look at requirement 3. A Tiki 21 is too small to carry 5 people and their gear even if just coastal sailing.

The cheapest way to build a multihull is to do what I did with my Strike 18 trimaran. Use a beach cat for the rig, outriggers and deck gear. That way you only need build the main hull. The Strike uses 10 sheets of 6mm plywood. So our Strike cost under USD2000 sailing and was built in under 200 hours. But then there are a lot of cheap beach cats available in N America, which is not the case elsewhere.

But I wouldn't recommend a Strike for the trip paradoxbox is thinking of. Because of his load carrying requirement and cruising plans I would suggest a minimum of 25ft. Although the minimum boat I'd recommend would be something like my 28ft Gypsy catamaran.

Richard Woods of Woods Designs

jamez 10-02-2011 12:06 PM

Not that I am suggesting you should build one for ocean sailing, but to give an idea of what your budget might run to, it MIGHT be possible to build a couple of Wharram Tahiti Wayfarer 21 hulls for a grand (10 sheets 6mm ply, 20l epoxy, some solid timber) and it is designed to use tree branches for beams and spars, steers with a paddle, has lots of flexibility for home built sails rigs of different configuration etc. Can be built as a single hulled outrigger too, but this halves the payload (approx 360kg as a catamaran). It won't take 5 though, so possibly this requirement could/should be reassessed. Or the size boat/budget. Generally little multihulls don't like to carry a lot of weight. I had a Wharram Hinemoa which moved along quite well with 1 or 2 people, the one time I had 5 on board the deterioration in performance was very noticeable.

Turnpoint 10-02-2011 06:26 PM

Although I think one of Richard Wood's designs would be a better all around boat if Paradoxbox wanted to increase his budget... it seemed the cost of under $1000 was the most important aspect for his design brief. Its more likely that this could happen with as small of a boat as possible.

I thought of the Wharram Catamarans because Paradoxbox said he wanted a Polynesian type design with everything lashed together, and simple rigs. I also think the Wharram designs are geared towards construction using cheap materials that could be found anywhere.

rayaldridge 10-02-2011 06:55 PM

I'm not sure this is a realistic budget for a boat to be taken offshore. My little 16 foot open cat, Slider, cost me 2000 bucks to build, and that was with a homemade mainsail, a mast made from a couple of construction grade 2X4s and using underlayment instead of marine ply. The hulls were glassed only to a couple of inches above the waterline, and there was a lot of creative scrounging involved. I wouldn't want to take Slider offshore. I'd probably survive, but I'd be scared. We've taken 3 people camping, but that's pretty much the limit-- 4 is too many.

jamez 10-02-2011 11:55 PM


Originally Posted by Turnpoint (Post 491113)
Although I think one of Richard Wood's designs would be a better all around boat if Paradoxbox wanted to increase his budget... it seemed the cost of under $1000 was the most important aspect for his design brief. Its more likely that this could happen with as small of a boat as possible.

I thought of the Wharram Catamarans because Paradoxbox said he wanted a Polynesian type design with everything lashed together, and simple rigs. I also think the Wharram designs are geared towards construction using cheap materials that could be found anywhere.

The original classics can potentially be cheaper than the other series as they can be built without epoxy or glass. however there is still a bunch of materials - something like 25 sheets of ply in a Hinemoa which costs $$$. The wayfarer is relatively cheap simply because there is less of it and doesn't need commercial hardware. So if you can afford the hull materials and you have access to a suitable tree :rolleyes: It could probably be used for island hopping by an experienced 1 or 2.

I know PDB you asked for no negative opinions, but on reflection, someones got to say it. Its a big ask to build any worthwhile multi for a K, let alone one you can can go into deep water with.

Alex.A 10-03-2011 05:06 AM

Something like Gary Dierking's te Wa would be more appropriate but no plans as of yet...... Whatever you end up with is going to cost more than your budget.

peterchech 10-03-2011 02:13 PM

I have had the same idea
I have built a 24' wa'apa outrigger canoe by Gary Dierking. See the link here:

here's a little video

Although I modified it greatly, and used s&g where chine logs would have sufficed, total cost after modifications was $1500, and the initial build was about $1200, pretty close to your budget. If I did it again, I could do it for 1K for sure.

It comes apart into 8' sections. It is extremely seaworthy for its size, and I have taken 4 large people on it, plus a large cooler and some other gear, without unduly slowing it down. (I have a relatively large lugsail-sloop on it, which is slower overall but gives more power so this may be why it can punch through surf with 4 aboard). To go island hopping or even offshore, I don't know, but I have had it out in significant swell/chop with no problem at all. If going out of sight of land, you def need to deck over the front and rear sections.

From building and sailing this boat, I have learned a few things.
1. Deck it over except for the center section, where you sit/put your legs. Possibly consider adding some freeboard too if rough stuff is expected. In a short chop/swell, the long narrow hull has less buoyancy than say a monohull, and has a tendency due to its length to plow into chop. A bow manu would help this alot IMHO. This is only a concern in the bigger stuff though.
2. For sailing comfort and safety, a trimaran configuration is best. The single outrigger is a bit uncomfortable and worrisome when the wind and swells pick up. Just makes you more tired at the end of the day, and also creates weird and quickly varying helm in certain conditions.
3. Top speed with the lugsail has been 9.3 knots, cruising speed with 2 aboard is 5 knots upwind and 6-7 knots on a reach/run. A beach cat rig would be superior, although beyond your budget, as the lug produces power and lots of heeling moment, but not as much speed. Still faster than a mono though, and more comfortable.
4. If seriously considering this for island hopping, the sectional route may not be best. I would build in one piece if possible, it would be lighter, stronger, less worrying, and would give more uninterrupted interior space, which is lacking on this boat.
5. You might consider extending it to 32', as waterline length generally = comfort at sea, according to gary dierking. He said it could be built to this length if required. He has also e-mailed me with an idea for a small coffin-cabin where someone could lie down for a bit if they wanted to. The French Berque brothers crossed the atlantic using such a cabin on their 6m outrigger.
6. Oh... and make sure you have at least 100% amas, the little ones in Gary Dierking's plans are minimal. There is general consensus on this amongst many proa/outrigger builders, that adding buoyancy to the amas is worthwhile.
7. A quarter rudder works well. Don't bother with a daggerboard unless you are doing the trimaran configuration, as lifting it in a timely matter when the ama is to windward in a stiff breeze is a real pita without capsizing... leeboard is prob fine, just make it super STRONG, lots of stresses there and I have had leeboard fitting strength issues...

I really like the idea of an extremely cheap and simple multihull. A double outrigger voyaging canoe seems to hit the spot for me. If you notice in that video, that narrow bit of wake behind the canoe stern of my boat as we are cruising at about 6-7 knots. I find that spot just magical, feels fast and efficient even if it is slow by beach cat standards...

If it were me, a 26' double outrigger wa'apa, decked front and back, with a foot more freeboard and a tiny cuddy is about the most boat you can get for the buck, gives decent performance and excellent seaworthyness to boot.

BATAAN 10-03-2011 02:47 PM

3 Attachment(s)
Just build a simple Wharram cat out of whatever you can find. Don't be stupid and do a good job. I loved Zamami, that was the best island. Spent some time in Itoman, working in the shipyard on tall ship KAISEI. Love Okinawa, would go back in a heartbeat.
Here's one project.
Also an alternative motor boat for the job.

Petros 10-03-2011 04:35 PM

Do not discount Skin-on-frame construction. You can build a good sized cat or tri using skin-on-frame for about $300 for total hull costs (about $100 each hull), less if you can salvage. Join that to a single junk rig with an unstayed mast, sails made from Tyvek or heavy poly tarp, you should be able to build it for about $500 no problem.

There is a false perception that skin-on-frame is not very damage tolerant, but I have found this is just not true. With a heavy 18 or 20 oz nylon or polyester skin it will be more durable than fiberglass over plywood, much lighter and cheaper too.

Make a stout frame from lumber selected from the hardware store, rip it into stringer size with a table saw, use plywood bulkheads, lash the frame together with polyester artificial sinew. Use 6 to 10 layers of one part urethane floor finish or oil based paint and you will have a very sea worth and strong hull.

I have built about 12 skin on frame kayaks and never had a skin failure, also built small sailboats using same construction. Very light, fast to build and low construction cost. I built a small tri with a junk rig sailboat for about $55 in materials and it took 2 people about 12 hours to built it (24 hours build time). I used Tyvek for the sail, using quality duct tape for the seams (faster than sewing). IT is durable and cheap, but I would count on reskining the hull and replacing the sail after 5 seasons of heavy use.

It think it is the only way you can reach your cost goal.

Check this thread out:

Richard Woods 10-03-2011 04:55 PM

But can you carry 3-4 people and sail offshore in a USD55 SOF boat??

To PDB a couple of questions:

What is your sailing experience?

Would you cobble together a car made from USD500 worth of scrap parts and then drive it across (say) the Australian outback, knowing that if you broke down you would not get rescued??

Do your three friends know how little you will be spending on the boat they will be risking their lives on??

Can you not borrow USD200 from each of them and so make a safer boat??

I know that you won't get far with a SOF catamaran in the English Channel. However the east coast USA and PNW have much more benign weather so SOF can work there, hopefully Japan is like that, although I have never sailed there so don't know.

Richard Woods of Woods Designs

All times are GMT -5. The time now is 07:02 AM.

Powered by: vBulletin Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2017 Boat Design Net