Largo
Fuel Efficient Power Boating For a New Economy
I’ve been getting a significant number of inquiries for the power version of my Gato Especial sailing cat. I let it slip out, some time back, that there would be an engine driven version coming along, but time got away from me and so, the project sat idling on the design table.
I’m kind of drawn to cars and boats that can solve a host of utility needs, as well as provide a comfortable, transportation experience. I’m about to sell my venerable Toyota Landcruiser and get myself into something that makes a lot more sense when it comes to utility and fuel efficiency. As a result, I began to think of a motorized version of the Gato platform as a Crossover/SUV type of vehicle with a big interior volume aft of the helm station and truly fuel-efficient engines to complete the picture.
The new boat would have a stand-up position for the driver with a sliding, deck-mounted seat that would allow the skipper to sit while steering. There would be a huge deck surface behind the helm for all sorts of seating and/or gear carrying options. The new boat would have a tailgate/liftgate setup for ease of loading. The new design would have a big storage space forward of the helm for the odds and ends that always end-up on a boat. Power for the initial design would be from a pair of four stroke outboard engines for redundancy, as well as beneficial weight distribution.
On a personal level, I am attracted to design concepts that deliver a responsible set of solutions for this new economic reality in which we all live. I like the term, Crossover, which is openly lifted from the automotive industry, as it touches on the realities we will all face in the coming years. We are headed to a time in which our vehicles will need to do more than just give us a sedan in which to cruise around, or a truck to do our dirty jobs.
In the world of cars, the Crossover approach has created vehicles that live in the niche right between the heavier, clunkier, SUV’s and the typical, everyday passenger car. Similarly, with this new design, I was looking to take the slot right between the generously proportioned sport cruisers you see at marinas all over the world and something like a cleanly drawn work boat. I wanted some of the people driven touches of scale and fit/finish, while being able to morph from one working task to another as a truly useful, all-around watercraft.
The result would be my take on what a boat should look like which is much more fuel-efficient and less expensive to build and transport. It would provide a very high degree of utility and of course, it would need to be wrapped in an aesthetically pleasing package.
The aesthetic, design component is pretty much a subjective thing, but the fuel-efficient aspects are a design process that combines easily driven lightweight hulls, drive systems with high economy for delivered horsepower and a significantly reduced aero drag signature allowing the boat to just slip through the air.
I’m of the opinion that I have reached all the basic design criteria with this new design, The Largo.
Yeah, sure there’s a distinct connection to the Bond films, Thunderball and Never Say Never Again, with the bad guys both being named Largo. Beyond that, Largo is also a direct take on the ‘48 Film Noir thriller with Bogey, Bacall and Edward G. Robinson. It is also, the well-known island in the Florida Keys where boating adventures await in every direction.
Largo Specifications
LOA 21′
BOA (trailer legal) 8′ 6″
Height 6′ 5″
Displacement 2000 lbs.
Suggested engine package Twin 9.9 hp four stroke outboards
The aft cabin space of the trimmed-down version will have the potential for a huge, manual, slide-back sunroof for a full open-air effect in the main cabin volume, as well as large side openings for breeze and visibility. The side openings can be fitted with removable, semi-structural soft windows for better streamlining and also for inclement weather.
Way back at the aft end, the boat has a floor level, drop-down tailgate, as well as a glassed, liftgate. I see this as a utility benefit when the boat is beached, bow out, in a marina slip. The tailgate will allow easy loading of gear and anything else that might be shoved in the back of this boat while it is still on the trailer. It will also give a chance to sit on the tailgate and hang out. The entire hardtop can also be removed for a full-on waterborne convertible. Or, if you like, a pick-up truck for the waterfront that can haul a whole bunch of oddly shaped objects, should you have a need for that kind of utility with friends while enjoying a sandwich or cold beverage.
The suggested engine package is based on need. If the owner wants to cruise with high efficiency and still be able to bang out 11-12 knots when he likes, then a pair of Yamaha Hi-Thrust 9.9 hp engines will do the trick. The engine setup can be equipped with remote starting, steering and power engine tilt. They both have pretty healthy alternators to keep any onboard electrics going, so lighting, navigation and radio systems can be easily powered-up.
Cutting edge enthusiasts will ditch the outboards and equip the boat with a bank of batteries under the deck in each hull and a pair of powerful electric motors that drive matched, counter-rotating props. As an alternative to the twin outboards, this boat so equipped, will silently cruise with a pretty decent range and be able to go to full power instantly whenever the owner wants the buzz of the electric drive potential.
The hulls of the Largo are exactly the same as those of the Gato Especial sailing cat. They are 10-1 in Length to Beam ratio at the waterline and will be very easily driven while still providing a respectable displacement payload. The is a spray chine on the inside and outside of each hull to direct wave action away from the boat while underway, as well as reduce drag on the hull. At cruising speed, a small amount of hull lift is also a side benefit of the spray chines.
The aft end of the hull bottoms is relieved with a slot to allow engine placement forward of the typical transom mounting and to allow the power tilt capability to raise the props well clear of the hull bottom for beaching and trailer loading/unloading. Moving the engines forward adjusts the balance point of the boat forward and helps with handling and pitching moments. It also puts the engines inside of sound deadening boxes, so the overall noise level is reduced while underway. Cruise the harbor on a warm summer evening with soft music playing on the surround sound system and you can really hear the soft music.
Bridgedeck clearance between the hulls is a generous 17″, so wave slap under the main deck will be kept to a minimum. This raises the overall comfort level of the boat, which is especially nice on a longer trip.
The large deck space inside the boat will make for a spacious camping environment, gear hauling space, or just about anything else you can think of doing with a boat that is this versatile. The tailgate opens to a generous 49″ width, allowing the owner to load full sheets of plywood right through the back of the boat without leaning them up on edge.
The hull volumes below the main deck can also be used for the storage of fuel, batteries, water tanks, anchor, rode, etc. It’s always a good thing to keep the heaviest items on a boat as low as possible to enhance stability and improve ride. The space in front of the main forward bulkhead can be accessed via a large hatch. This is an excellent location for lighter weight storage needs such a sleeping bags, tents, clothing, etc.
Clearly, the Largo is a boat with a generous latitude of use potential, it draws design cues from a pretty diverse group of sources and sets a new standard for homebuilt power boats with a decided edge towards fuel economy and responsible boating.
Chris Ostlind
Lunada Design
Posted: March 5th, 2009 under Power Boats, Power Cats.
Comments: 16
Comments
Comment from Dan
Time: March 6, 2009, 7:02 am
I love the removable hardtop concept there. Having a Jeepster style ragtop would be cool as well–nautical meets road I suppose. Would there be standing headroom if standing on the floor of a cat hull? I also like the tailgate element. That will be a cool feature. In some respects this reminds me of a more fully enclosed Gougemaran that Mead and Jan put together for S. Florida. I think they used some d class style hulls as I recall. This more compact iteration should be the hardtop answer to a lot of boaters needs. I could even see a commercial version with a more utility feel. Getting enough payload to astisfy those guys might be tough, but the economy of running twin 9.9’s might make up for it.
Dan
Submitted on 2009/03/06 at 7:04am
I forgot to add that it might be tough to get to the bow as drawn. A runabout style split windscreen might do the trick or perhaps a slightly wider sidedeck. Looks great to my eye!
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The bow thing… yes, I’ve heard some similar positive comments from different sources. There’s a fix in the works for that issue, along with a few others that I feel will really enhance the basic design.
I am looking at a ragtop scenario for the boat with a folding Bimini setup that has removable side panels. This will allow the boat to be used fully enclosed in crappy weather, as well as a transition process to a full-on open sports convertible when it’s nice outside.
Chris O
Comment from David
Time: March 6, 2009, 9:42 am
I’ll second Dan’s comments on the bow access issues — you’ll want an opening in the windshield to get to the foredeck. You may also want an opening in the forward pulpit/rail for beach access and possible anchor point access.
On the bridgedeck waveslap issue, have you considered a slight V-bottom to reduce this? And won’t use of large battery banks for electric power dramatically change the weight and waterline of the boat?
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Thanks, David
I found your comments to be powerful and will morph them into the design for what, I am sure, will wind up as a better boat.
It’s interesting, the vee shaped form under the bridgedeck is a part of the Gato Especial design, only it principally works as a longitudinal beam to help spread the compression loads of the mast. Your suggestion will be incorporated.
The switch over to the use of electric motors, should the builder decide to go that way, will cut out some of the total load potential of the boat compared to the use of gas engines. The Largo has 2000 lbs.+ of displacement, so the extra drive system weight should not be too big a problem. Electrifying the drive system does allow me to put the biggest weight right in the middle of the boat and quite low as well. This should give the electric option a real boost in that it will reduce pitching quite a lot and actually enhance the handling… and it’s really quiet, too.
Chris O
Comment from Gene Buchholz
Time: March 6, 2009, 11:18 am
Nice looking boat Chris. It would be great for the Pacific Northwest, where I live now, and for Southeast Alaska, where I lived for almost 30 years. I can see myself standing down in one of the hulls setting and pulling crab pots or fishing for salmon or halibut. On nice days one could sit comfortably on the tailgate with fishing rod in hand.
Pulling a big halibut up over the tailgate would be easier than over the side decks. Your engine placement would reduce chances of a fish fouling a line on a prop. Tilting the engines up would be even better in that placement.
I agree with Dan about a split windscreen for easier and safer passage to the foredeck for anchoring, etc. That would enable one to eliminate the side decks or make them very narrow only for structural reinforcement. A flat area perhaps 18″ wide all the way across the boat at the bows would make for secure footing for anchor and line handling.
I like the speed potential (11-12 knots), reliability and maneuverability of the twin 9.9 high thrust Yamaha outboards. I’m very pleased with the one I have now on my sailing cat.
Fair Winds,
Gene
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Gene,
Thanks for the kind words on the Largo design study. I’ve been getting a pretty good response to the boat over the last week and a half and there have been some very good suggestions as to how to make the design even better.
Right now, I’m modifying the original design to reflect the changes and will be showing the boat again as soon as I can pull it all together with some new renderings.
Chris
Comment from Tom Lathrop
Time: March 6, 2009, 5:02 pm
This is a good concept and a nice looking rendition. I do have some questions and comments.
Echoing Dan’s comment on getting to the bow, it needs a split windshield.
The whole issue of moving around, other than in the cockpit looks difficult. The only way around that might be to eliminate the necessity of going outside. Most docks are only for parallel tie-up and it looks like access for that is also difficult on other than the open version.
Even if tied stern to, the lift gate interferes with entrance – exit without head banging. This is made even more difficult without standing headroom. Perhaps the most sensible solution is to make the aft upper cover out of canvas which could be zipped completely out of the way.
I wonder if there is room to turn the outboards for adequate steering. The covers look too narrow for that now.
My few trips on power cats have been not as satisfying as I expected due to too low decks that banged in more than a very small chop.
Still, I really like the novel concept and don’t mean to sound negative.
Tom
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The Largo study is undergoing a series of modifications right now and the really great comments, such as your own, have provided a powerful source of input for the eventual design solution.
There will be a split windshield, room to maneuver on the foredeck and possibly a fold-down bow ramp for easy access when beached bow first.
The hull sides will see a removable, or swinging, doorway for dockside loading and the hull volumes aft are being increased for air circulation, as well as full, lock-to-lock engine movement per Yamaha specs.
Chris
Comment from John Bagshaw
Time: March 7, 2009, 7:53 am
Dear Mr. Ostlind,
I can say that this is a home run! This is exactly what I have been looking for in my next project. I need something to cruise and fish the Gulf and Tampa Bay waters with my family. I do have one question about steering: Does this boat have a rudder system or are the motors cleared enough to steer? They look tight and quite frankly I don’t mind. I like rudders. When can I sign up for the opportunity to build this wonderful boat? Best regards to you and yours. JCB.
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Hi John,
Thanks, so much.
The Largo is undergoing a set of modifications which will enhance the boat’s utility. This has been based on the really great input from enthusiasts such as yourself.
One of the items being modified are the aft hull volumes to allow for full engine movement as per Yamaha specs. There will be no rudders, though I enjoy them like you.
Plans will be coming soon after I finalize all the new modifications.
Chris
Comment from Paul Fitzgerald
Time: March 10, 2009, 2:58 am
Great idea, especially for a utility boat for island living.
Could be a problem loading and unloading from a beach or ramp, the motors are vulnerable even if tilted.
Maybe there could be a way to load it from the bow? Would be much easier for beach work.
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Thanks so much, Paul. Your take on the design use is right on with how I hoped the boat would be used. I see the Largo right at home in protected waters, estuaries, lakes and larger rivers with limited offshore use in calm conditions.
Due to the powerful responses I have gotten from boaters like yourself, the Largo is undergoing a set of modifications to enhance the potential of the boat. There will be hinged or removable openings on each hull side, the windshiled will get a fold-open panel for bow access and there could even be a folding bow ramp for beaching.
Chris
Comment from Martyn
Time: March 12, 2009, 5:46 pm
Hi Chris, i love this design, its a great idea.
For bow access, how about having a windscreen with a vertical split down the center and one or two gull wing style doors that open to give access. This would also give side access too. They do not have to open with the same angle as a car door either – if you imagine a hinge running from top of the vertical split in the windscreen to the starboard side just behind the driver, then opening the door upwards would give access in both directions. A vertical split might look ugly though.
Good luck!
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Geez, Martyn… thanks for the truly kind words about the Largo design.
After all the really wonderful suggestions I have been getting about this design, the Largo concept re-entered the design study barn here at the studio compound, destined to be revealed again as a much more useful craft.
Largo will be back soon with a host of changes to include: hull side openings for entry/exit, a split wind screen for bow access, a fold down bow ramp for painless loading when the boat is beached and wider aft hull volumes for full engine movement as per Yamaha specs.
Chris
Comment from mark shaw
Time: March 14, 2009, 5:05 am
Looks cool! Do you have plans for sale yet.? Im looking to get started on a boat that we can use this summer.
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Mark, I don’t have plans for the Largo yet. The design is getting a series of modifications and when those are done and I like the whole package, then I can sit down and crank out the plan sheets.
Chris
Comment from paul salkaln
Time: March 14, 2009, 12:17 pm
Great concept. I like the hard top/pickuo concept as it enhances trailerability for storage and camping. Not being able to lock up and a rag top flopping around on the interstate on extended outings would just add anxiety. Sixty-five, retired, heading down the highway looking for adventure. Sign me up.
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Paul,
Thanks for your insight. The Largo is getting a set of mods right now to make it a better boat for the typical boater. There will be a new article here with some new renderings as soon as the reworked design is done.
Chris
Comment from Dan
Time: March 29, 2009, 4:06 am
Get real!The exhaust from any boat will come in over the transom and get into the cabin but especially if you slow down the escape of exhaust gasses by enclosing the motors. The same thing happens on cars. Look at the back window of any hatchback design car. Negative pressure area at the rear of the car.
If that wasn’t bad enough you have trapped the engine noise inside the hull. Low frequency noise is hard to kill. I built a cabin on a boat with a friend (Alaska-Yukon River) You would have sworn that the boat was quieter when you closed the door on the cabin but a db meter indicated that it was actually 10 db louder under way due to trapping the low frequency sound and the added influence of wave pounding on the hull. The cabin cut the highs but had no affect on the lows. You can wear adequate hearing protection for up to 110 db high frequencies but the lows can’t be adequately stopped. This boat design is gong to get you in at least two ways. Think carbon monoxide poisoning and permanent tinnitus. (No dear that isn’t your phone ringing)
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Hi Dan,
I appreciate your comments on the Largo design study and will take them into consideration as I complete the final design work on the boat.
The exhaust issue has been considered for quite some time with this boat. One of the important issues with regards to the exhaust of these smallish outboards is that when underway, the exhaust exits through the propeller
underwater and does not get to the surface until the boat has moved along some distance. The only time that the exhaust does not exit through the prop is when the boat is not in gear.
The second issue I considered, was that the engine cavity will need to have a supply of fresh air so that the idle engine will not be breathing its own exhaust. Each side of the boat will get an air scoop of sufficient size to provide air flow into, and through, the compartment. The engine compartments could also see a pair of small, electrically operated fans that kick-in when the engine is out of gear to facilitate flow and remove exhaust gases.
Every boat of this size will have similar issues of vortex generated exhaust swirling back into the passenger area. The trick is to minimize the effect as best as possible. I have been looking at the solutions being used in the
automotive industry to prevent exhaust from recirculating and some of them hold real promise.
About the potential noise problems… The engine compartments will have sound absorbing material on all sides, save for the very lowest sections of the hull. Engine vibration is going to be present no matter what you do to
isolate the engine itself from the structure of the boat. Some vibration can be reduced through the use of isolastic mounts, but they are not especially feasible for the typical outboard engine. This means that virtually all boats with outboards will face the same problems of low frequency
transmission through the structure. I do not see this as a really big problem for this type of boat, as the engines are only 9.9 hp units and they will be operating most of the time at partial throttle settings.
I have specified Yamaha four strokes, because they are very well balanced engines, have low external noise signatures and due to their smallish size, will not be generating as much low frequency rumble.
If one wishes to reduce, substantially, the amount of transmitted noise as it is produced by the average outboard, then they might look strongly at going electric.
Electric motors can be equipped with vibration isolation mounts that are very effective. Electric motors are already quite a bit less noisy than are internal combustion engines and they represent some real design opportunities for placement of the weight centers for best boat
handling characteristics.
In the future, there will be a propulsion choice for Largo builders, as I will be specifying a battery/electric motor combo that will give a whole different take on the boat. Electric drive is not for everyone who may wish to own a boat, but for those who have a use
application which matches the capabilities of an electric drive, they will be able to enjoy the advantages.
The Largo is meant to be a step in the right direction for utility, boat balance, low fuel consumption and ease of trailering… all in a lower profile, more aerodynamic package when compared to the average outboard boat with a full cabin. It is not designed to plane, uses much smaller, and quieter engines which weigh considerably less and the weights are positioned forward towards the center of buoyancy of the boat providing a less pitchy ride.
No boat is going to be a perfect solution to all that a boater may wish to see in a personal craft. If the design meets your utility needs and satisfies your aesthetic sense of design, then it might be a really good solution for you.
I do appreciate that you have taken the time to post your opinions and will keep your comments active as I finish the design of the Largo, prior to offering plans.
Chris O
Comment from mark shaw
Time: April 5, 2009, 3:54 pm
Hi Chris,
still intested in plans. I noticed you mentioned largo had same hulls as Gato.
Can I buy a partial set to get started like the guys in greece?
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Hi Mark,
I have sent you an email regarding the plans for the Largo.
(snip)
My email to you bounced for some reason. Could you write me directly at Chris@wedgesail.com , so that I can resend the info on the Largo?
Chris
Comment from Jim Pope
Time: April 28, 2009, 1:37 pm
A neat boat.
An attribute that I didn’t see commented on is the utility of the vessel for people in wheelchairs. It looks to me that a simple small boarding ramp might make that possible. And if so you may really have a winner.
How do you imagine she might be in a fairly rough sea with a lot of wind?
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Hi Jim,
A bow ramp is one of the modifications that the Largo will be getting, along with a split windshield and at least, one side opening (hinged door?) for loading when side tied at a dock.
The bow ramp will allow the Largo to be driven onto a shore (mud, dirt, sand, gravel) where the ramp can be lowered for exit and entry. This will keep the engines in the water for reversing off the beach.
In a seaway, as you describe it, I imagine that the Largo will be a bit out of her element but should be able to handle short periods like that with a skilled skipper. There are better boats for those conditions.
Chris
Comment from RODNEY DREDGE
Time: June 5, 2009, 6:42 pm
Hi Chris,
Stumbled across your web page and I am very happy I did.
Can you advise the cost of the plans for the Gato 21 and 24
As well as the Largo model shown. We would like 2.500m Beam if possible.
Keen to talk with you in regard to Australian outlet for these hulls.
Judging from the feed back and your comments they are set for a winner.
Note take care when you add a door as it weakens the panel quite a lot.
Cheers Rodney
Comment from Don Schultz
Time: July 6, 2009, 8:12 am
Couple of thoughts. Mount the center, or forward 1/3rd of the hard top to slides so it can be slid aft for docking to the side of the boat. The sliding portion would need to be removed separately from the aft section.
I would build it with a slot in the aft section (astern the slider) hardtop for standing room, and ventilation, with a snap down cover for weather.
Of course it may be considered to slide the whole top aft, which may also be part of the removal process.
Yep, these along with the bow access and the boat becomes very friendly from a handling standpoint, and a recreation standpoint without losing utility.
Comment from bruce
Time: August 28, 2009, 6:27 pm
Chris, First, I am not a designer nor do I ever intend to be- I have seen your comments on boat design forum only. I am a semi-experienced small boat builder, I used to be a sailboat dealer and did extensive repair on glass and wood boats. I “need” a small power boat for lake and inland coastal waters, and have been considering a small power cat. Slightly larger than the converted hobie 16-18 cats but in the same concept- 18-20 feet, maybe foot wells in the hulls, and a flat bridge deck, sort of a “fishing” platform for two people. I don’t know where to start for the hull form. I prefer the efficency of a single center mounted engine, 15-25hp and would LIKE! to have 18- 25mph. I prefer building in ply, but sometimes foam/glass is the best choice. Can it be done, and do you have any ideas? Bruce
Comment from Kristine B
Time: December 7, 2009, 4:56 am
I do like the idea of your craft and one only needs to look at the price of fuel to understand where this craft has it’s usefulness. For myself this craft in about 24 to 28 feet would work well for weekending with the kids here in Puget Sound or running up the Inside Passage to SE Alaska, for a summer time getaway from the lower 48.
I look at some of the changes that are being asked for and I worry about the added weight they are going to add, over how useful they would really be. You do the same thing when you design a homebuilt aircraft… It all comes down to trade-offs. I would really like to see this little beast when you get the design done.
Kristine
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