Dudley Dix Interview on Catamaran Design

Below is our interview with Dudley Dix about his DH550 catamaran, 43 and 47 foot sisterships, and a future 38 foot version. He talks about catamaran design, why he is popular in Russia, the problems with reverse bows, and why, for most people, the ideal catamaran length is 38 to 40 feet. World renown for his beautiful and surprisingly fast designs, it was a great pleasure hearing directly from this naval architect.

It’s bad to design a boat that looks fast and isn’t, but it’s great to design one that looks slow and is actually fast.

Dudley Dix on yacht design

Please contact Dudley for information about his plans or to purchase one of his build kits. His website is www.DixDesign.com

Tell us a little bit about yourself.

Okay I am South African born in Cape Town. My dad was a provincial champion in Flying Dutchman. We lived on the side of the lake and so I grew up with boats. I spent a lot of time surfing as well as sailing. I’ve done four transatlantic voyages on boats that I’ve designed, a lot of coastal racing, and coastal cruising experience around the coasts of Cape Town, Cape of Storms which so many cruising world cruising sailors dread.

Spent a lot of time on the water.

Do you mind telling us about your DH 550 design and her smaller 43 and 47 foot catamaran sisters?

The way that the DH 550 actually originated is I designed a boat which I had raced. It’s a plywood boat called the Didi 38 which is radius chine. So it looks like it’s a round hull boat, but it’s actually built with sheet plywood.

Didi 38 Radius Chine Construction

Phil Harvey had known me for years and seen the boats that I’ve designed and built. He loved the concept, but he was a catamaran sailor. He contacted me and said he was wanting a boat for cruising with his family. He was a boat builder. He built catamarans professionally, but he wanted a plywood boat for his own boat and liked that construction concept.

So he contacted me and said, “Can you design it using that construction method?” I didn’t have enough time available, so we agreed that we would do it between us. I would do the basic design, and he would do some of the detailing.

DH550 Layout Drawing

So that’s the origin of it as a boat.

Turned out it’s a surprisingly fast cruiser. It’s not a racing boat. It’s intended as a cruiser, but it’s a fast cruiser. Phil launched his boat I think now about 14 or maybe 15 years ago and cruised with his family.

That boat has now been sold twice. It’s now based in Florida.

Dix DH550

All of the owners have been extremely happy with those boats.

Then the 47 originated with a company in UK Exocetus Marine. They wanted to build something similar but a bit smaller and to develop a CNC kit for it.

Dix 470 Under Construction

We contracted the 55 to 47 keeping the same hull beam but shortening the length of the house and reducing the width of the bridge deck. Then the Exocetus Marine commissioned the 43 foot sister to it.

I didn’t want to do it on the same basis as I’d done the 47 because the hulls would have been getting too fat, so I kept the underbody slim and introduced a step in the topside to keep accommodation width while keeping the drag down.

Dix 430 Line Drawing

Then the 38 is still a concept in my head. That will be based on the 43. That’s the same basis that the 47 is based on the 55, and I expect to be starting on that one probably within about five or six months.

Can you share with us some of the main differences when designing a catamaran versus a monohull?

They’re very different of course in terms of structure because the structural loading on a monohull is very different from the structural loading on the catamaran. The catamaran hull is designed to operate upright. It’s vertical most of the time whereas with the monohull the hull is heeled over most of the time unless you’re going directly downwind.

The boat is operating at an angle through the water, but the big difference is in thestructure and of course in the accommodations. You can get so much more into a catamaran of the same length as a monohull.

It’s a totally different thing. You can’t go into a catamaran design thinking monohulls. You’ve got to think catamaran when you’re designing catamaran and vice versa.

Although the DH550 hull is actually my Didi 26, a trailer sailor, which I expanded and pushed and pulled in CAD to get it to the proportions that I wanted for the 55. So the hulls have got a common basis but other than that they feel very different.

Didi 26

Now for your new 38 foot design, what is the main design goal you’re looking to achieve?

Wanting a boat that is going to be economical for a family, give them a space for a family of two adults and two to four kids.

So we’re looking at pretty much the same number of births as we’ve got in the bigger boats but contracted into a much smaller space because a 55-foot boat is a big boat for somebody to finance.

You building that big boat logistically it’s a problem. Getting it into the water is a problem. You need to build it near to the water to be able to launch it.

The cost of building a boat like that is expensive and then also operating it. You can sail it single handed, but you really need to have the experience to sail that big of a boat single-handed.

The 38-footer is a much easier boat for a young family to handle. In monohulls for a family of four, I would normally say to people you need to be looking 43 to 45 maybe even 48 feet to have the space that you need.

In the cat you can get it at 38 to 40 feet, that sort of range.

So do you think the 38 to 40 foot range is the ideal size for a family that’s looking to go cruising on a catamaran?

Yes I do although we started with a 55 because that’s what Phil wanted. We have been working down towards the most popular size range, and that popular size range is 38 to 43 feet.

What’s the most important design feature you’re considering when you’re designing a catamaran?

I’m designing primarily for families. I designed both primarily for amateur builders to build themselves.

Safety of course is the most important criterion. And also, working with amateur builders, you’re not working with people who’ve got the same building skills as a professional builders.

So I try to build in more safety factor into the detailing of the boat, into the structure of the boat, so that there’s less chance of the builder messing up and ending up with a weak build.

I don’t like to overpower the boat, so these boats on the sail plans we actually state this is a cruising boat. Don’t try to fly a hull with it. I designed the rigs so that if you’re going to fly a hull you are at risk of breaking the rig because we would rather the mast falls down then they turned the boat over.

Have you seen catamaran designs change over the years?

The main difference that I see is that 20 to 25 years ago catamarans were designed for crossing oceans and then those boats were used for charter.

Most of the cats we see now are designed for charter and most of them are really not good ocean crossing boats, so that’s the big difference that I see.

Who is generally building your designs and where in the world usually is that located?

My boats are built all over the world. I’ve had my boats built in 90 countries. We get orders from all sorts of strange places. I got a call last week from a sail maker in Saint Petersburg, Russia and he said to me that I am one of the most popular designers in Russia. He makes more sails for my boats than other designs.

In fact I pulled out the database the other day and had a look and nearly 400 of my boats have been built in Russia. In fact we’ve got an order today for a trailer sailor from Vladivostok. I have boats built literally all over the world all the way to Vietnam and Indonesia.

Any thoughts on why you think you’re so popular in Russia in particular?

I think primarily because my background is amateur boat building and the detailing that I do is aimed at amateur boat builders. Most people in Russia cannot afford to buy a boat.

So most boats that are launched in Russia are built by the owners and also I have a very good reputation for being approachable by the builders. If they have a question I’d rather they ask me then ask somebody across the board from them or in the yacht club.

So I invite questions. We very seldom get questions but also the drawings are very clearly detailed, so most people will buy the plans.

I might get an odd photograph from them while they’re building and then they’ll send me possibly a photo when they launch the boat.

So that is a big part of it. You’ve got to be approachable for the amateur builders if needed.

Where do you see catamaran design going over the next 10 years? What’s your best forecast of what that looks like?

I see go fast features coming into the boats, and I don’t like that personally.

I think that some of the features that are going into boats are not really healthy for the boats particularly the reverse bows.

Reverse Raked Bows

There are fashions that come into boat design, and fashion is a very bad reason for putting anything into a boat.

It’s all very well for the really experienced skipper to be sailing a boat that’s got a heavily reverse rake for wave penetration if he’s going to be sailing close to shore for racing and so on, but I really don’t like as a concept for ocean crossing.

I prefer to see more moderate boats for ocean crossings and most of the boats that I’m designing are for ocean crossings rather than for coastal use.

Do you foresee new designers potentially entering the market?

There seems to be a fairly static number, but it sort of goes through rotation.

The older designers sort of run out through the end of the lifespan. I’m heading that way myself.

Younger guys come in at the bottom. We’re going to see many more. It’s healthy that you start seeing new designers. Input from different designers creates different styles and gives people more options.

Do you work with anyone else?

I work better by myself. I learned long ago. At one time I had three staff working for me, and I found that it was sometimes a battle to get them to draw exactly what I wanted because they see themselves as creative people. But sometimes what they’ve got in mind is not what I want, and in the end, I decided I work better by myself.

I’m just that kind of person. I’m basically an introvert, and introverts are more creative working by themselves. You put an introvert into a committee and the loudest person in the committee is the one that carries. The introvert might have better ideas, but they get lost in the noise.

I find if I’m working by myself it’s my own ideas. I tend to be a lateral thinker and I go through cycles. I might do three or four concepts on a boat. I draw something that I don’t quite like, so I draw another version of it until I get what I want. I can do that if I’m working by myself.

So the business is just my wife and myself. She does all the bookkeeping and the orders and that sort of thing, and I do the designing and the web work. She does all the printing also, and it works very well that way for us.

I’ve got a tremendous number of designs, and I’ve got a very broad range of designs. I draw the boat that the client wants or the client needs. Sometimes the client really wants something that they don’t need.

I like a boat to be pretty. I don’t like to see ugly boats, and so I work hard to make the boat look very pretty. But at the same time, it must sail very well.

As a result a lot of my designs, people look at them say “oh that’s a pretty boat,” but it’s not going to sail well. And then it’ll sail past them, and that’s the best thing.

It’s bad to design a boat that looks fast and isn’t, but it’s great to design one that looks slow and is actually fast.

For those watching this video if they’re interested in learning more about your designs or how they could purchase build plans from you, how do they contact you?

I’m approachable by phone or or email or through my website is the best. The website is www.DixDesign.com. They can contact me by email from the website. Email is my preference. It gives me time if they’ve got questions. It gives me time to put down really comprehensive answers rather than answering telephone questions.

Thank you Dudley so much for joining us today. It’s been a pleasure getting to hear a little bit more about you and your designs. And thank you all for joining today on catamaran site.

Thank you.

By Richard

Vagabond and webmaster # 2 of CatamaranSite.com

Leave a Reply

Your email address will not be published. Required fields are marked *