Multi Marine

After a lifetime of being involved with Marine Science, education, boat – building, repair, service, and selling ( see below ), it’s time to morph my business once again.

35 years of teaching oceanography at various Universities and running a marine business where I sold epoxy, paint, fiberglass, and multihull sailboats and 40 years of building multihulls ( 19 sail and power boats – size range 14 to 40 ft. )……’s time to spend some time assisting other people with their projects and education.

I still intend to be a sailboat broker but will also include education and consultation as a main hallmark of my business.

Toward those ends there will be a “used boats” listing area, a re-cap of many of my various projects, designs, and lessons learned as well as a sections about general oceanography.

Michael Leneman has been racing, building, and voyaging on multihulls of all types and sizes since he was in his teens. He has gone through the entire evolution of catamarans and trimarans over the past 35 years.

He was Director of Sailing at the University of California at Los Angeles in the 1970’s, and is the organizer and founder of the largest offshore multihull event on the West Coast, the Indian Summer Splash. Mike is also championship racer; a four time winner of the Newport to Ensenada Race and holder of the best multihull racing record of any sailor in Southern California.

In the early seventies Mike raced Hobie Cats and worked for Hobie Cat of France for a summer (winning the French National Championships), but soon gravitated to offshore cruising/racing and has seen his share of offshore mishaps. In the 1980’s, on the Transpac race to Hawaii, for example, he was on a custom catamaran that broke apart at night. He was saved in a dramatic nighttime rescue.

Like the other pioneers of multihull construction, Mike learned his lessons along the way. In the early 80’s, while working with multihull designer and legend Craig Ashby, he built a 40 foot offshore racing cat, Minette. For many years Minette held the Santa Barbara to King Harbor race record and has won the Ensenada Race four times. He has also designed and built: two 32’ trailerable powercats, a 23’ trailerable powercat, a 20’ sailing/peddling catamaran, the L-7 trimarans (23 ft.), and various other small boats.

Always a go fast freak, he got involved with Corsair trimarans in 1990 at the request of the owner, John Walton, and became a dealer. In the mid-90’s he remodeled the F-31 to make it the fastest F-31 on the west coast. This proto-type then became the basis for the Corsair F-31R. He even designed the aluminum mast and rig for the production Corsair 31, as well as kayaks for local companies.

Presently, he is working on an 18 ft., 65 lb., car-toppable, fin drive, sailing trimaran with sliding akas.

Talk to Mike: (310) 821-6762


  • B.S. Geology from U.C.L.A.
  • M.S. Marine Geology from U.S.C.
  • N.A.U.I. Scuba Instructor


  • 33 years of teaching Oceanography and Marine Geology at various Universities and Colleges in the L.A. area.
  • Sailing Instructor at U.C.L.A.
  • Teaches “Oceanography for Boaters ” course presently


  • Director of U.C.L.A. sailing club in the 70’s
  • Builder/Designer of various multihulls – sailing and power, from 14 to 40 ft.
  • Organizer and founder of the largest offshore multihull event on the West Coast, the Indian Summer Splash.
  • Four times winner of the Newport to Ensenada Race……on different multihulled sailboats.
  • The best racing record of any multihull sailor in So.Cal.
  • Cruised and raced on multihulls in the Pacific, Caribbean, Med., and North Sea.


  • Owner/founder of Multi Marine (founded 1980), which over the years has been a seller/distributor of marine supplies, epoxy, and paint. Also, a past Corsair Marine, Fountaine-Pajot, and Switch dealer.
Sailor, boat designer & owner of Multi Marine, which offers plans for the L7 and Beach Tri 22 models, and is also the N. A. dealer/importer for the Multi 23 small trimaran

This chapter is based upon my interview with Michael Leneman: sailor, multihull designer and owner of Multi Marine in Venice, California. In this interview, Mike discusses how he came to develop the L7 and Beach Tri 22 small trimaran models, which he consults individuals on how to build themselves, and also talks about the Multi 23 – a French production model Multi Marine sells directly to customers.

I’ve been a college professor of marine biology for over 33 years, and have sailed since I was 13. I’d bought catamarans and trimarans, and even worked for Hobie Cat of France at one time. But eventually, I couldn’t find what I wanted in a boat out there in the market.

I decided to build one for myself. This led me to develop some of my own designs. At first, I was just modifying things that were already out there. And then it went to starting from scratch, and designing a whole new boat from the bottom up.

Originally, I started working with catamarans and experimenting with performance, cruisibility and transportability. So I started early on in the “trailerable” boat concept. I can honestly say that in the 80s I probably built the largest demountable, transportable catamaran ever done in this country. It was a 40-foot catamaran that could be demounted by a few hands and then trailered.

A few friends and myself even built the trailer, and then transported this boat 3000 miles across country from Los Angeles to Florida. When we got to Florida, we reassembled the boat and launched it. Then we sailed around the Bahamas, came back to Florida, and disassembled the cat to take it back home. This was not a “small” catamaran either. It’s a big 40-foot catamaran. This particular boat is featured on the MultiMarine website. It’s called the Minette.

On another occasion, we took the Minette apart and drove it to Baja, California to launch it. This boat is a full, standing-headroom-in-the-hulls 40-footer, with a 55-foot mast. We assembled it on the beach in Baja with no marina, and no launch ramp. Then we waited for high tide, and simply pushed the boat into the water. Then we sailed the Sea of Cortez before coming back and disassembling it on the beach again for the drive back home.

But doing something like that is quite an undertaking. It requires many hands to help, so being able to do it relied upon the assumption that we’d be able to attract enough attention in order to be able to solicit the physical help of bystanders to move things around, and actually launch the boat.

If people hadn’t come by and asked us what we were doing then we wouldn’t have been able to get the help necessary to accomplish what we did. Eventually, I decided to go smaller so we didn’t need an entourage.

As you can see, the trailerability aspect of boating has been my focus for a long time. I grew up sailing in southern California, and I did so much sailing around here I wanted to go other places. I realized that almost nobody I knew actually took their boats to faraway places. They claimed they wanted to do that. They said they were going to do that. But it’s pretty onerous in both sailing ability and time to go very far.

I’ve worked my whole life so I didn’t have time to take off for 2 years and cruise around the world. The idea of a trailerable boat made a lot of sense because in one day I can drive to the Sea of Cortez and be sailing. And it only takes about 4 days to drive across the country and be in Florida to go sailing. Those are time periods that I could do. So that is why I got in to trailering.

I went from about the largest thing I could trailer (the 40-foot cat), to smaller boats. I’ve always been a multihull guy, and they’re perfect for this kind of thing. The concept of monohulls never really appealed to me. And the beautiful thing about multihulls is that you can go very fast with a small boat. That doesn’t work for monohulls. To go fast in a monohull you have to have a big boat. You’ve got to have a long boat. But that doesn’t work for trailering.

Birth of the L7

I got into sailing the folding trimarans designed by Ian Farrier, and eventually became a Corsair dealer because the guy who started Corsair Marine was a friend. In fact, because of the Minette, and its ability to disassemble and go across the country, we used to race against each other all the time when he first came out with the F-27.

He approached me after a race one day, and told me Corsair was going to have dealers. He invited me to become one. I already had a marine business fixing boats, and selling paint, epoxy, fiberglass and other products. But that invitation is what got me interested in selling multihulls.

After about 14 years selling those particular folding trimarans, I wanted to do something a bit different. I’d been associated with guys who built boats for years because I’d sold materials in this market.

For example, we were one of the first West Coast dealers for the Goughon Brothers’ epoxy products. So I knew a lot of “building people” and I kept hearing them tell me they’d like to build a Farrier-type boat, but they wanted simple plans. After talking to customers about design plans on the market for trimarans, many did seem very complicated for homebuilders to attempt to build themselves.

I like to build boats, and I like to keep things “simple” whenever it’s possible. Even after building the 40-foot catamaran from scratch, I don’t know that even I would attempt to build certain boats out there because they take a long time, and the plans are complicated. So I thought there might be a simpler boat that could be built, while still offering a whole lot of fun.

I’m not a guy who likes to sit in the office. I need to be out in my shop building something. So I came up with an idea for a small trimaran, along with a simple system for folding it up. The result was a sliding system, like a “drawer slide,” so a float can just be slid in and out.

I knew this would limit the size of the boat because you need to stay under 8′ 6″ in width to go down the road in a trailer. That meant I could build a boat somewhere between 23 and 24 feet in length. This led me to design the L7.

Believe it or not, the majority of the L7’s design was fleshed out on a road trip from L.A. to Florida. I was towing a pre-fab house designed as a beach home to put on a lot down in the Bahamas. I brought a friend along for that trip, and he is a product engineer from Stanford. He helped me put together the boat’s design while we drove for 5 days across the country. I drove, and he sat and did sketches, and then worked on the computer.

After we got back to California, I started building this thing. We used Nacra floats that someone had given me as the basis for the L7’s amas. We chopped off their decks and raised the freeboard. I found fiberglass ibeams that could be used, and then built the main hull. Someone even donated a “Super Cat 20” mast, and I knocked out the first prototype boat.

The prototype ended up being very close to the design my friend and I fleshed out on that road trip. This prototype boat is still sailing. It’s a little faster than the later boats, but it’s pretty close to what we have now.

I’ve always believed in bigger buoyancy and better-shaped floats. This seems to be the trend today if you look at boats such as the Arma 60, or the America’s Cup 90-footers. You’ll see the look of more buoyancy in floats … like a Nacra catamaran shaped float.

The advantage to this type of design is that the boat doesn’t depress as much when you’re driving it harder. With more buoyancy in the floats, there is less likelihood the boat will bury a float and cause a pitch-pole. This float shape also allows a boat to go faster. The less rocker you build into the floats the more you’re capable of driving the boat using the floats’ buoyancy, which allows for more speed.

Bigger floats will not add much weight to a boat this size because we know how to build lightweight floats. It’s been demonstrated around the world that it’s a matter of whether you want to trade off light wind performance for a little bit of heavier wind performance.

Lighter floats with smaller buoyancy will certainly give you a little bit better speed when the wind is under 10 knots. But as soon as the breeze picks up, and you need the floats for buoyancy and stability, then any advantage of lighter floats goes away because their weight is less critical, and buoyancy becomes more critical.

With bigger floats you have the ability to apply more power, or more driving force to the boat, and the floats aren’t a limiting factor. I’d rather have better top-end speed by using floats with more buoyancy than try to gain better low-end speed by using smaller floats. There are other ways to save weight on a small boat like this.

For example, take a 23 or 24-foot sized boat, such as the L7. The difference in weight between what would be considered a “small float,” as compared to a “big float,” might be 30 pounds per float. So if you add the 2 together, you come up with an added boat weight of 60 pounds for the 2 amas. This is irrelevant on a boat the size of the L7, which is designed to weigh 1300 pounds. With crew, the boat’s weight goes up to over 2,000 pounds. So how much influence would saving 60 pounds be to a boat like this? Zero.

“The Proof of the Pudding”

How much more benefit is there with added buoyancy in bigger amas? Well, the proof is in the pudding. On our very first race, we took an L7 on a 36-mile race to Catalina. I was stunned by this boat’s performance.

My original goal had been to be faster than a standard boat in our industry, such as an F-24. There are hundreds of these that have been built. These Farriers are fast boats. They’re vacuum bagged, high-tech built boats that can cost nearly $50,000 to build in some cases. I thought, “Gee, if we can do a back-yard boat that is faster than an F24 then we’ll be happy.”

When we started this race, I noticed early on that the F-24s were way behind us. But then we noticed that the F-25Cs and F-27s were behind us as well. We found ourselves sailing right in the middle of the F-31s. In fact, we finished 4th in that race, and ended up beating more than half of the F-31s in the field. And the F-31s are boats that can run upwards of $160,000 to build. Honesty, I was stunned.

I thought the L7 was going to be fast … but nobody, including me, expected the boat to be that fast. Our conclusion was the bigger floats really made a huge difference.

In ideal conditions, the L7’s top speed is probably in the 18 to 20-knot range. Average speed in the open ocean, such as what we experienced that day racing to Catalina, is in the 9 to 10- knot area. Top speed is really an irrelevant number when you consider GPS readings can be inaccurate. The relevant thing you need to talk about is how far you went, and how long it took you to get there.

Our 30-mile trip over the open ocean to Catalina took just 3 hours that day. And that is a stunning average speed for a boat the size of the L7. When asking about “top end” sailing speeds, you need to be clear about what reality is. A lot of perspective buyers don’t have a lot of actual sailing experience. If they read somewhere that a boat is capable of doing 18 knots then they reason a trip to Catalina should only take a couple of hours because it’s just 30 miles away. When somebody says this I say, “If you can get to Catalina in just a couple of hours then you’re going to have one of the fastest sailboats in all of southern California.”

The best time I’ve ever made it to Catalina was in my turbo F-31, which is a very light boat with a masthead rig. It may be the fastest F-31 west of the Rockies. And the fastest time I ever sailed to Catalina in that boat was in about 2 hours and 20 minutes. Our crew probably averaged about 13-14 knots of speed — and that was in perfect, ideal conditions.

Taking Away the Hard Part of Building

As far as boat building goes, I tried to take away the hardest part about building most hulls. That was really a goal here.

At first, I tried diagonal planking, and that was a nightmare. That took a lot of time. Since we already had existing catamaran hulls for floats we saved some time there. We also used off-the-shelf fiberglass ibeams for the L7’s crossarms.

The challenge with a main hull is the underwater shape. When you look at the center hull of most multihulls, they’re very flat sided above the waterline. But they need to have rocker and a lot of rounded shape below the waterline. And it’s very hard to make a very rounded, changing shape. You need bulkheads and a lot of furring to do this shaping.

If you’re going to try and use foam on top of these challenges in order to create your hulls, then you might try strip-planking foam, or using heat to form the foam to get the shape you want. But we approached this challenge a bit differently.

We decided to make a mold of just the underwater waterline part of the boat. We could then offer a “bottom fiberglass pan,” as we call it, to prospective builders. We ended up designing pans that are specifically just for the hull portions of the L7. All a builder now has to do is take a pan and build the topside, or above waterline portion of each hull.

In addition, we designed the L7 to have totally flat decks. There is nothing easier to build than a totally flat boat deck. Then we designed totally dimensional curved sides, which means you can take plywood, glass it, and then bend it to make the sides of the hull.

Just working part-time, it’s possible to make an L7 ama float in less than a week. You cannot make a stripped-plank or diagonal-planked float in a week. So far, this is the fastest way I know of to build the ideal kind of float for a homebuilder. There are simpler methods of tortured plywood, or bend-up kiss principle, but you don’t know what kind of shape you’re truly going to end up with using such methods.

The interior frames of each hull built that have to be built for the L7 are actually trapezoidal. They’re easy to make, like picture frames. The frames you actually build the plywood around are straight-sided. There isn’t really anything to cut out. You take 4 strips of wood, lap glue them together, and then you have your frames. You could build all the frames for the entire boat in an afternoon.

There is no frame that goes into the pan. That would require you to cut the curvature of the inside of the pan. You can do this for the main hull bulkheads, but we provide full-sized patterns for those. The rest of the frames are just straight sided.

In my opinion, the biggest drawback to this sailboat is its aesthetics. This is because we made it so simple to build. It’s got hard sides. The cabin top is designed with exactly one length of a sheet of plywood. This eliminates the need for anyone to have to scarf plywood. The deck is exactly the length of 1 sheet of plywood. So again, we tried to design around available materials in an easy way.

Because plywood was used to develop the cabin top, it has hard sides to its shape. Flat decks are not as aesthetic either. The crossbars, which are off-the-shelf ibeams, are not as pretty as a faired beam. But the advantages of designing things this way is that instead of taking months to build crossbeams, like you’d have to do for some other trimarans, you get can acquire things very quickly and put together an L7.

Buying the 3 pre-formed pans we created for the L7 saves a homebuilder an incredible amount of money, time and effort. For about $4,400, a boat builder gets complete fiberglassed bottoms for all 3 hulls. So even though our boat may not be as pretty as some others out there, it’s probably a lot faster to build, in addition to being a faster sailing boat than most others its size.

The biggest question people tend to have is whether or not they can build this boat. If you have boat building skills, then answer is, “Yes.” Can a guy who can’t drive a nail into a piece of wood do it? Probably not.

Multi Marine doesn’t even sell plans for this boat per se. We sell the fiberglass pans used in the hulls, and then offer builders consulting instead. We’ve published plans by letting some of the builders post them on their Internet sites. If you can build the bottoms yourself then you could, in theory, even build the whole boat without talking to me at all. This part of my business isn’t a big moneymaker. I make money selling boats, not kits or designs.

My intention here was to give homebuilders a realistic option, as opposed to building an expensive trimaran. Building any type of boat can be very challenging for some people. For example, I’ve seen statistics that say only about 1 in 10 boats that get started ever get finished. If that figure is true, then the completion rate for homebuilt boats is pretty bad.

What we’re trying to do with our building model here is help homebuilders overcome the challenge of an extremely long project. There is often 10 times more interest in building a boat than actually doing it.

The L7 started out by people telling me what they wanted. Most people don’t want to build a boat most of the time; they want to own a boat. We built a couple of boats for people and realized there is little money in building small trimarans unless the boat price is extremely high, or the boat-building operation is moved to Asia, where labor costs are very cheap. And that is not something I was interested in doing. So we now offer the pans and consulting to anyone who wants to build one of our designs for themselves at home.

The L7 Builder

What kind of person will build an L7? It’ll be someone who likes building as a process, but who also wants a project that can get finished and done without taking a long time. It might be a software engineer with a wife and a couple of kids, or a dentist who likes working with his hands, or anyone else who has building skills and wants a fast small trimaran.

There is a certain satisfaction in building things. Those of us who are builders can’t help it. If we’re not building a boat then we’re building something else.

If you can’t build a boat and you want one then get a second job, after hours, and save up enough to pay for the boat you want. It can be difficult, however, to buy the small trimaran you want in the marketplace. Many small trimarans are like toys, and are meant to be sailed in protected waters or lakes. That’s okay, but it’s not the functionality I’d want in a trimaran.

In my mind, you sometimes have to go to extremes, such as building a boat like the L7, to get the boat you want. If you’re not going to get a boat that is light enough to be cartop-able, then go for a boat that is fast, and can be easily trailered, such as the L7.

A lot of people truly can’t afford a boat like a F-24 or Corsair Sprint 750. They’re cool boats, for sure. The L7 is very similar to those, just a whole lot less expensive.

We even provide a sailing rig for the L7. I had a mast designed and extruded just for this boat. I have these masts here at Multi Marine, and builders can buy them from me at a very good price. In fact, when some of the guys who are building F-22s go looking for a mast, I think they may end up on my doorstep because this mast would be a good fit for an F-22. It would even be an appropriate mast for anyone building Ray Kendrick’s Scarab 22 design model.
The Beach Tri 22

Another set of small trimaran plans we’re planning to offer here at Multi Marine is for a sailboat called the Beach Tri 22. This boat will be even simpler to build, and less expensive, than the L7.

The concept for this boat came about because a lot of people are looking for a small trimaran that’s a simple, affordable, day sailer. Again, the goal is to help them save time and money. And like the L7, everything won’t have to be built from scratch.

All that will have to be done is build a main hull, which is designed with an open cockpit, and then use catamaran floats for the amas. This is sort of an updated concept comparable to Dick Newick’s Tremolino design.

Even with the L7’s simpler small trimaran design for a homebuilder, I knew that many people were not going to build their own small trimaran. Nor did they want to camp out in the boat, or go for extended cruising. I thought the Nacra beach cat floats are more ideal in shape than older Hobie’s, which the Tremolino design incorporated.

This boat, which we call the Beach Tri 22, has been designed, but there are none sailing yet because our focus lately has been on selling the Multi 23 small trimaran. But the Beach Tri 22 will be a budget boat.

If you can find a used beach cat that’s an ideal match for the main hull then you’re going to have the sails, rigging and ama floats ready to go for a Beach Tri 22. All you have to do is build the main hull using one of our pre-fabricated pans. A sailor could be into this boat for under $8,000 if they built it themselves.

The Beach Tri 22 will easily fit 4 people on the boat. It’ll have good speed, and be a really fun boat to sail. And another benefit to building this boat will be that you have rigging options.

If you wanted a self-tacking jib, then you could put one on this boat and it would be easier to sail than a beach cat. With beach cats, you have to change sides when tacking. Hiking out is crucial to the stability of the boat. It’s a standard part of beach cat sailing. But as we all get a bit older, we tend not to want to constantly hike out onto the trampolines. So of course, with a trimaran like this, you’ll have a lot more stability than you’d have with a catamaran.

The Multi 23

Before finishing our design for the Beach Tri 22, I had a customer call me and tell about a sailboat they’d seen at a boat show in Paris. After some investigating, I discovered this boat was a beautiful, 23-foot take-apart trimaran that weighs only 700 pounds. It’s called the Multi 23.

It has vacuum-bagged resin infusion, carbon crossarms, and a rotating rig. It’s a fun, fast, beautifully designed boat. And it probably has the best French design team in the world behind it.

I couldn’t believe they were offering this boat to be sold by dealers for under $30,000. It comes fully equipped, and is all ready for sailing and racing. As a result, we’re now the North American importers/dealers for the Multi 23 small trimaran.

There is no way even I could build this boat for what they let me sell it for. The only drawback this boat has right now is that it doesn’t fold. If I could make one design change, it would be to create a folding system for the amas.

The Multi 23 design team made the boat without folding crossbeams because they add weight to the boat, and they don’t look as nice as the ones on the boat now. The Multi 23’s current crossarms are one piece. And they only weigh 62 pounds. Both of the Multi 23’s crossarms weigh only 1/2 of what the crossarms weigh for the L7.

As far as trailerability goes, you can trailer the Multi 23, but you have to take the crossbeams apart to do it. And a single person can’t do it. It also takes about an hour to put them back together. Taking apart and putting together a Multi 23 isn’t hard. But prospective buyers need to understand right away that they won’t be able to do it by themselves. It takes 2 people.

The way I look at this is that every boat has its pros and cons. In this case, we decided the Multi 23 is such a light, fast, and fun boat that it’s truly a great boat despite not having folding amas. Before I’d even imported one boat, we sold over a dozen Multi 23s just by showing its picture to customers.

Now that we have Multi 23s in stock, the boat appears to be much bigger to prospective buyers than what they imagined just from its pictures. We tell potential customers that they’re going to want to store the boat in a place where it can stay fully assembled. Or, a customer may want to take it to where they’re going to sail the boat over a period of a week or so, then disassemble it for trailering back home.

The Multi 23 isn’t a boat that you’d want to take somewhere for a day sail, set up, go sailing, and then disassemble it at the end of the day. You can do this, but you probably won’t end up doing it very often because it just takes too much time.

The person who wants this boat doesn’t want to build his or her own boat. They’re looking for a fast, great looking boat, and they’re willing to spend $30,000 for it. A lot of people just aren’t builders. As a matter of fact, more aren’t builders than are. I recognize that. And so this small trimaran is a better way to go for them.

We’re going to have just one strict design class for the Multi 23. And you have to buy the sails from us. So everyone will have identical boats.

This is very appealing to many sailors because this situation doesn’t exist in the slightly bigger multihull world. It did exist in the beach cat world, and sailors liked it a lot. Corsair tried it with their F-28R model, but it never took off. We already have a one-design class here in Los Angeles and everyone is happy with it. This will spread around the country.

You can go cruising on the Multi 23, but you’d have to be on the tougher side for that. You can’t sleep inside the peak of the hull. You can store your sails in there … or even a porta-pottie … but you couldn’t use the porta-pottie while it’s in there. You can camp on the trampolines with a tent. We’ve already done that over on Catalina Island.

The Multi 23 is a fast boat. It’s little faster than the L7. And it’s about as fast as an average F-31, although in light airs it’s faster because it’s a smaller, lighter boat.

The Multi 23 is one of the easiest multihulls I’ve ever sailed because it has a self-tacking jib. The crew has to do almost nothing. You can single-hand sail it, and it’s even easier to single-hand than the L7 because of that self-tacking jib. And the Multi 23 can sail with up to 6 people, but 4 are more preferable when it comes to the weigh limit in my opinion.

The Multi 23 isn’t a wet boat either. As a matter of fact, we just went to Catalina and the Multi 23 sailors were dryer than those in the Corsair boats, even though the Multi 23 has an open cockpit. This is because when you smack a wave, its crossarms allow the water to fly by without blowing into the cockpit area. It’s a much dryer boat than most sailors imagine.


The Multi Marine website offers more information on the L7, Beach Tri 22 and Multi 23 small trimarans featured in this chapter. To see pictures, get quotes or inquire about any of these boats visit