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woods designs catamaran

Richard Woods

Woods Designs specialise in the design of sailing catamarans for both home and professional builders. Founded in 1981 we now boast possibly the largest and most comprehensive range of catamaran designs in the world. Designs range in size from 14’ to 45’ and types include beach catamarans, open deck cruising catamarans, bridgedeck cabin cruisers, racing catamarans and trailable boats. Boats can be built in a range of materials of which the most popular include sheet ply, cold moulded ply, strip plank cedar and foam sandwich. Email: [email protected]

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Introduction to Woods Designs

Woods Designs specialise in the design of sailing catamarans for both home and professional builders. However we also have a small range of dinghies, trimarans and power catamarans I tend to own a fleet of multihulls. Sometimes I just go for a day sail, sometimes I race for the weekend, while most years I spend a long time living on board (I spent most Christmas' living on board a boat from 2001 - 2020, on many different boats and in seven different countries). I have now cruised and raced in over 40 countries. All this experience means that I have personally faced nearly every situation you can meet when sailing and I use that experience in my designs. At Woods Designs we have always believed that designers should build and sail their own boats. As a result, since 1980 we have built a total of 18 catamarans, ranging from a 14' beach cat to the 35' performance cruising catamaran Banshee. We have also built all the dinghies, the Strike 15 and 18 and the Skoota 20 and 28 powercats. We have built boats in sheet ply, foam sandwich, strip cedar as well as several catamarans built using grp moulds (that have also been built by us). Most have been built in our garden, and all with very limited tools and boatbuilding skills. I usually build a prototype design each year. These boats have been built in ply, strip plank and foam sandwich, always at home using basic DIY tools and even more basic boatbuilding skills. Once launched I then go out testing, trying things, changing things, reverting to my original idea. It goes on and on. That way the design can be 100% right. So that the end result is a better boat for you. Just drawing a set of plans means the boat is only 95% perfect. So we know at first hand the problems that home boatbuilders face. The resulting boats have been used as full size test bed for new ideas, while, of course, building the boats ourselves helps ensure that the plans are fully detailed and that backyard builders can build them. If you do not want to build yourself and are interested in having a catamaran built for you then a number of yards round the world build either grp production boats or catamarans on a one off basis. Please contact me for more details

July / August Issue No. 299  Preview Now

woods designs catamaran

Janus sailing catamaran

Janus is a 4 berth trailable sailing catamaran built in sheet plywood. However, don’t be deceived by Janus’ simple dory shaped hulls (which make it a very easy boat to build). It has a lot of internal room for its length and a surprisingly good performance. It is a safe, seaworthy boat, several have made English Channel and North Sea crossings (over 100 miles non stop).Trailering and assembly are easy as the flat bottomed hulls remain upright unsupported. Janus is the best choice for the less experienced builder or sailor and for those who prefer simplicity.An owners comment: “After we’d reach the bridge we were broad reaching and went very fast indeed. We realised that Richard Woods designs great boats. For what is more fun than leaving with two monohulls of the same size and a few miles further on all you can see are a couple of dots behind?”We also have a number of other trailable sailing catamarans from 20 - 25ft, see www.sailingcatamarans.com for more details.

Design Specifications

Richard Woods of Woods Designs Foss Quay, Millbrook, Torpoint, Cornwall, PL101EN, UK [email protected]

Janus sailing catamaran

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Richard Woods design plan difficulty?

Discussion in ' Boat Design ' started by SnappyB , Sep 29, 2019 .

  • richard woods

SnappyB

SnappyB New Member

After quite a few months of reading/research I've decided that I want to build a smallish cruising catamaran. It seems like it would be the best way for me to acquire the kind of boat that I would like to have. I originally liked the idea of the Wharram designed tiki 30, but I think that the Richard Woods Gypsy 8.5m has better accommodations in a slightly smaller package. Plus (almost) standing headroom!! My question to anyone with experience in Woods Boats would be, how difficult are the plans to understand for someone with little knowledge in woodworking/boat building? I understand some of the basics of woodworking from high school shop and have read and watched a few videos on plywood stitch and glue, but those can only be so useful. The Wharram plans seem to be extremely easy to understand for first time builders, some places even described them as "as good as a boat building coarse". My father is a life long carpenter and would be able to help me through the odd snag or difficulty but I don't want to rely on him to heavily. Thanks for any input  

fallguy

fallguy Senior Member

Richard tends to be pretty high level, but very thorough. But he usually sends you build pics. And I recommend you consider joining bateau.com or a builder's forum. Bateau is a s&g site mainly. I post often on my build blog and answer other builder's questions on my foam Wood's build. And I would be happy to be a resource. Many things in a foam build are similar to s&g. Richard is also pretty decent with responding to emails; although that can get to be too much. His boats are special. I encourage you to go for it. He also has a builder forum with a handful of guys that can respond.  

bajansailor

bajansailor Marine Surveyor

I am sure that the plan's for Richard's Gypsy should be easily understandable. I wanted to do the same as you, about 15 years ago - I bought a set of study plans for Gypsy but then other things happened / got in the way, and this project never got off the ground. In many areas on Richard's website www.sailingcatamarans.com he posts random selections of construction plans for his boats - they appear to be very clear and concise to me, but you should have a good look through all the free study plans on offer on the site so that you can form your own opinion. Here is a link to the 'new' forum mentioned by Fallguy - woodsdesigns https://www.tapatalk.com/groups/woodsdesigns/index.php  

Richard Woods

Richard Woods Woods Designs

Thank you for your interest in my Gypsy design. A large number have been built over the years. It is a simple boat to build, nearly all flat panel. Either using foam sandwich or ply hulls. You can also build round bilge hulls but that's only recommended if you like boat building. I built the first Gypsy for my own use so know the boat well. That was nearly 25 years ago, under a new owner it sailed to Morocco last year. Several others have made ocean crossings. So the design is well proven and will last a lifetime. The Gypsy plans comprise 7 large (ie A1 or A2) sheets plus 60 A3 (legal) sheets of more detail drawings and photos. One the left menu of my website is a link to some free plan sheets which will give you an idea. A studyplan costs GBP13 and you can also buy partial plans at a greatly reduced rate. These include all the building plans except the lines plans and offsets. So you cannot build the hulls but can see how to build the boat. And in the case of Gypsy you can actually build the central cuddy, beams and cockpit before buying the upgrade to full plans I hope that helps. Incidentally Dan Fall is building the prototype of a modified design, so his plans are not as developed as the Gypsy plans We will be in the Neuse River/Oriental area in early December if you want to meet up Richard Woods of Woods Designs www.sailingcatamarans.com  
I do apologize. I had planned to edit my post and remind the fellow I am building the first demountable Skoota. It is not a simple boat to build, but Richard accomodated my needs since I want to get the boat to the west coast at 17' beam. This is not the same as a boat built many times like Gypsy. Richard has been incredibly gratious and kind and patient with me and my build is going well. I reiterate. If you are able to build a Gypsy; it will be a great thing. Building a boat is an incredible experience. Building a Wood's design even better, because Richard loves sailing enough to really design great sailboats and those are proven designs. The ply Gypsy would be much easier to build and cheaper by far than foam.  
Thank you all for your responses, I'll definitely check out the other builders forums. A few days before posting I purchased the study plans, however my computer was to small to see them well. I opened them on a friends larger screened desktop last night and they seemed very clear. I've decided it's definitely the boat I would like to build. Hopefully within the next few weeks I'll be able to purchase the plans and start sourcing materials.  
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SnappyB said: ↑ Thank you all for your responses, I'll definitely check out the other builders forums. A few days before posting I purchased the study plans, however my computer was to small to see them well. I opened them on a friends larger screened desktop last night and they seemed very clear. I've decided it's definitely the boat I would like to build. Hopefully within the next few weeks I'll be able to purchase the plans and start sourcing materials. Click to expand...

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Woodson dual cathedral 18

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Acorn by Woods Designs

Simple 2 berth trailable catamaran with hard chine hulls.

Length overall
Waterline length
Beam
Draft
Draft (cb up)
Berths2
Headroom
Weight
Displacement
Sail area
Main area
Jib area
Hull construction Stich-n-glue

URL: http://sailingcatamarans.com/index.php/designs/2-catamarans-under-25ft/167-acorn

Description:

The Acorn is a 21ft lightweight plywood minimum fast cruiser that has been kicking around for nearly 20 years but only recently have plans been drawn. Some parts, eg boards, rudders, spars, can come from large beach cats (ie Hobie 18 or larger).

The rig shown is the optional racing rig which is only suitable for experienced sailors in lightwind areas. Smaller rigs are available, see the study plan.

Acorn

Catamarans about same size as Acorn

 
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Questions? Suggestions? Contact us at: [email protected]

woods designs catamaran

MIKE WALLER 

Yacht design.

slideshow_w1480b.jpg

WE SPECIALIZE IN BOAT PLANS FOR AMATEUR BUILDERS

We provide stock boat plans for both monohull and multihull sailing vessels, including sailing skiffs and sharpies. Our designs mainly feature timber construction, in plywood or cedar strip plank composite construction, using the W.E.S.T. system (wood epoxy saturation technique). Our designs are intended mainly as cruising boats, although several have done well in racing. All designs are suitable for amateur boat builders.

Monohull designs by Mike Waller Yacht Design.png

 MONOHULLS

 multihulls  , photos from our builders.

Waller TS 540 by Mike Waller Yacht Design -  under sail

Photo galleries are provided on each design page where available

woods designs catamaran

Son of the late inventor of the modern catamaran follows in his father’s legacy

H ONOLULU (HawaiiNewsNow) - Woody Brown Jr. is the keeper of a family legacy. The treasure in his chest is a twin-hulled sailing craft commonly called a catamaran.

“You see catamarans all around the world, but a lot of people don’t know it was created right here in Hawaii,” he said. “I want to make sure we keep that going for as long as we can.”

He says that because the modern-day catamaran was created by his father, Woody Brown Sr., a legend to many who know about his history and his love of the sea.

“He was a glider pilot, a surfer, and a sailor,” Woody Jr. said.

His catamaran, the Manu Kai, started the family business that’s been a fixture on the Waikiki Beach shoreline for decades.

Woody Sr. had his son very late in life. Woody Jr. didn’t fully grasp what his dad had done until he was older.

“Hearing all the stories from all the old-timers and realizing how much of an impact he gave to all these people, that’s when I started realizing, ‘Dang! I’m really lucky and blessed to be a part of this family and legacy,’” he said.

That’s why he has been living in Washington State for the past two years. He built a new catamaran for the family’s company, seeing it through design, construction, and trials at sea. It’s named Hawea after his daughter.

“The boat sails amazing!” he said. “It’s a pretty quick book. Very smooth, quick, slick. Beautiful boat. It’s a little more modern than the original style that was built.”

Now, he and his crew are sailing the boat from the mainland West Coast to the shores of Waikiki, a trip he hopes will take a couple of weeks. It’s his first trans-Pacific crossing.

“It’s not crazy out there in the Pacific Ocean with the exception of hurricane season. They call it the Golden Month where in July you get the nice consistent trades that take you right to Hawaii,” he said.

After it’s docked at Ala Wai harbor, Woody Jr. will file the paperwork to put Hawea to work for the Brown family’s Waikiki Sailing Company. It replaces his brother’s boat, which has been working off Waikiki Beach for about 50 years.

This is how Woody Jr. is paying tribute to his father, who passed away in 2008.

“I think he would be very proud of me. He built his own. My brother built his own. So I felt I needed to do this myself and be a part of the whole build process from state to finish,” he said.

To follow Hawea’s journey across the Pacific and to see video updates of the crew and catamaran at sea, go to this link here .

Son of late inventor of the modern catamaran follows in his father’s legacy

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Catamaran Hull Design

  • Post author By Rick
  • Post date June 29, 2010
  • 2 Comments on Catamaran Hull Design

woods designs catamaran

Part 1: Notes from Richard Woods

Since the America’s Cup experimented with going multihull, there’s been a lot of interest in catamaran performance and the catamaran hull designs that define performance. Many guys are investigating whether to buy a catamaran or design and build their dream boat. Let it be said here that building a large catamaran is not for the faint of heart. People begin building 100s of boats a year, yet few are ever completed, as life always seems to have a way of interfering with a good boat build. 

Never the less, since the rest of this website is about selecting and buying a boat , it only seems fair to have at least one webpage that covers catamaran design. This page contains notes on boat hull design goals and an accompanying page from Terho Halme has mathematical formulas used in actual catamaran hull design. It has become a popular research stop and an important reference to the catamaran design community.

The content of this page was reproduced from the maestro of Catamaran designs, renown British naval architect, Richard Woods, who not only designs catamarans, he sails them across oceans…. repeatedly. He has a lot to say on the subject of catamaran hull design.

“…When it’ all said and done, the performance of a sailing catamaran is dependent on three primary specs: length, sail area and weight. If the boat is longer it generally means it’ a faster boat. If she has more sail area, it means she’ a faster boat and if she’ light it means she’ a faster boat.  Of course, there are limits: Too much sail area capsizes the boat in brisk winds. If the boat is designed too light, she will not take any kind of punishment. Too slim a hull design and the boat becomes a large Hobie Cat capable of only carrying your lunch. Of course, too long and large and you’d have to be Bill Gates to afford one. Then there are lot of additional and very important factors like underwater hull shape, aspect ratios of boards and sails, wet deck clearance, rotating or fixed rigging and so on….” Richard Woods

All Catamarans are not equal, but all sailboats have two things in common: They travel on water and they’re wind powered, so the Catamaran design equations in the 2nd part should apply to every catamaran from a heavy cruising Cat to a true ocean racer.

Richard Wood’s comments on catamaran design:

We all know that multihulls can be made faster by making them longer or lighter or by adding more sail. Those factors are the most important and why they are used as the basis of most rating rules. However using just those figures is a bit like determining a cars performance just by its hp and curbside weight. It would also imply that a Tornado would sail as fast forwards as backwards (OK, I know I just wrote that a Catalac went faster backwards than forwards)

So what next?? Weight and length can be combined into the Slenderness Ratio (SLR). But since most multihulls have similar Depth/WL beam ratios you can pretty much say the SLR equates to the LWL/BWL ratio. Typically this will be 8-10:1 for a slow cruising catamaran (or the main hull of most trimarans), 12-14:1 for a performance cruiser and 20:1 for an extreme racer.

So by and large faster boats have finer hulls. But the wetted surface area (WSA) increases proportionately as fineness increases (for a given displacement the half orange shape gives the least WSA) so fine hulls tend to be slower in low wind speeds.

The most important catamaran design hull shape factor, is the Prismatic Coefficient (Cp). This is a measure of the fullness of the ends of the hull. Instinctively you might think that fine ends would be faster as they would “cut through the water better”. But in fact you want a high Cp for high speeds. However everything is interrelated. If you have fine hulls you can use a lower Cp. Most monohulls have a Cp of 0.55- 0.57. And that is about right for displacement speeds.

However the key to Catamaran design is you need a higher Cp if you want to sail fast. So a multihull should be at least 0.61 and a heavy displacement multihull a bit higher still. It is difficult to get much over 0.67 without a very distorted hull shape or one with excessive WSA. So all multihulls should have a Cp between 0.61 and 0.65. None of this is very special or new. It has been well known by naval architects for at least 50 years.

There are various ways of achieving a high Cp. You could fit bulb bows (as Lock Crowther did). Note this bow is a bit different from those seen on ships (which work at very specific hull speeds – which are very low for their LOA). But one problem with them is that these tend to slam in a seaway. 

Another way is to have a very wide planing aft section. But that can increase WSA and leads to other problems I’ll mention in a minute. Finally you can flatten out the hull rocker (the keel shape seen from the side) and add a bustle aft. That is the approach I use, in part because that adds displacement aft, just where it is most needed.

I agree that a high Cp increases drag at low speeds. But at speeds over hull speed drag decreases dramatically on a high Cp boat relative to one with a low Cp. With the correct Cp drag can be reduced by over 10%. In other words you will go 10% faster (and that is a lot!) in the same wind and with the same sails as a boat with a unfavorable Cp. In light winds it is easy to overcome the extra drag because you have lots of stability and so can fly extra light weather sails.

The time you really need a high Cp boat is when beating to windward in a big sea. Then you don’t have the stability and really want to get to your destination fast. At least I do, I don’t mind slowly drifting along in a calm. But I hate “windward bashing”

But when you sail to windward the boat pitches. The sea isn’t like a test tank or a computer program. And here I agree with Evan. Immersed transoms will slow you down (that is why I use a narrower transom than most designers).

I also agree with Evan (and why not, he knows more about Volvo 60 design than nearly anyone else on the planet) in that I don’t think you should compare a catamaran hull to a monohull, even a racing one. Why chose a Volvo 60/Vendee boat with an immersed transom? Why not chose a 60ft Americas Cup boat with a narrow out of the water transom?? 

To be honest I haven’t use Michelet so cannot really comment. But I have tested model catamarans in a big test tank and I know how inaccurate tank test results can be. I cannot believe that a computer program will be better.

It would be easy to prove one way or the other though. A catamaran hull is much like a frigate hull (similar SLR, L/B ratios and Froude numbers) and there is plenty of data available for those. There is also a lot of data for the round bilge narrow non planing motorboats popular in the 1930’-50’s which again are similar to a single multihull hull.

One of the key findings I discovered with my tank test work was just how great the drag was due to wave interference between the hulls. Even a catamaran with a modern wide hull spacing had a drag increase of up to 20 % when compared to hulls at infinite spacing. One reason why just flying a hull is fast (the Cp increases when you do as well, which also helps). So you cannot just double the drag of a single hull and expect to get accurate results. And any speed prediction formula must include a windage factor if it is to give meaningful results.About 25 years ago we sailed two identical 24ft Striders next to each other. They were the same speed. Then we moved the crew of one boat to the bow. That boat IMMEDIATELY went ½ knot faster. That is why I now arrange the deck layout of my racing boats so that the crew can stay in front of the mast at all times, even when tacking or using the spinnaker.

I once raced against a bridge deck cabin catamaran whose skipper kept the 5 crew on the forward netting beam the whole race. He won.

Richard Woods of Woods Designs www.sailingcatamarans.com

  • Tags Buying Advice , Catamaran Designers

Rick

Owner of a Catalac 8M and Catamaransite webmaster.

2 replies on “Catamaran Hull Design”

I totally agree with what you say. But Uli only talk sailing catamarans.

If only solar power. You need the very best. As limited watts. Hp.

The closer to 1-20 the better.

Closing the hulls to fit in cheaper marina berth. ?

You say not too close. But is that for sailing only.

Any comment is greatly appreciated

Kind regards Jeppe

Superb article

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