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The Buzzards Bay Cats Blog
04/11/2010 - 4:28pm
Welcome to The Buzzards Bay Blog. The purpose of this blog is to discuss the technical aspects of a Buzzards Bay and how they benefit you, the boater. We will break down the catamaran myths. It is our ultimate goal for more boaters to understand the benefits of this truly remarkable hull form, the catamaran. Editors from Power and Motor Yacht, Yachting, Boating, Motorboating, Multihulls Quarterly, and Power Multihulls have all tested our boats and they are all saying the same thing, "Wow"! The Buzzards Bay 34 power catamaran is at the head of her class in every category. When it comes to interior comfort, storage space, ride quality, noise levels, stability, low draft, fuel efficiency, cruise speed, quality of construction, Buzzards Bay does it all. This is the greatest attribute of a good catamaran; you can have your cake and eat it too. Physics simply does not allow traditional mono-hull designs to excel in all areas. This is not marketing hype, this is fact. And thats what this blog is about. Facts. Straight talk. We hope you will find this blog informative and another means to get to know us and our boats. Please e-mail us comments, suggestions, and your questions. Like our boats, we would like to continually improve this blog, with your help.
Russell Hunt, President
Buzzards Bay Cats
20/11/2010 - 10:31am
For a while we‘ve been telling folks about the ride comfort advantages our Buzzards Bay 34 enjoys. Within this blog, we wanted to share the technical features that produce these advantages. After all, there is nothing magical about naval architecture. It is something that can be understood, compared, and judged
So how does a 34 foot, 12,000 lb vessel offer the ride comfort of 40+ foot, 30,000 lb deep vee’s? The answer is straight forward physics. Force is equal to Pressure x Area (F=PA). Water has a given pressure at 30 MPH and the more hull area that is impacting the water, the greater the force produced. As a result, naval architects are constantly campaigning for narrower mono-hulls in order to present less surface area to the waves, decreasing slamming forces. However, important considerations such as stability and cabin space require a minimum amount of beam, working in direct opposition to these slimming efforts. Mono-hulls can only be so skinny before they become un-livable and unstable. This practically limits mono-hulls to a length to beam ratio of 3.5 to 1, but normally are around 2.75: 1. In comparison, the Buzzards Bay 34’s hulls are each over 9:1. A catamaran’s architecture combines very narrow hulls that slice through seas instead of pounding their way through, with wide overall beam that affords the kind of space that boaters love. Just as important, the wide spacing of the hulls from the vessel centerline greatly increases stability, for a drastic reduction in roll compared to a mono-hull. Consider the advantages presented thus far. Even if a catamaran did not have a softer ride than a mono-hull, the stability advantages would be merit enough. To combine a softer ride with much greater stability is simply yacht design nirvana, and is something that physics just won’t let mono-hulls do.
With a mono’s broad hull, you’ve got but one choice if you don’t want to be limited to hull speed. Hull speed (in knot’s) is equal to √(1.34 multiplied by the vessels water line length). Beyond this speed, the mono-hull is pushing so much water that the drag goes up exponentially, practically limiting speed. For the average 34 foot mono-hull, this hull speed limit is around 6 knot’s. To go faster than this with any degree of efficiency, a mono-hull must climb over its bow wave and travel on top of the water, much as an airplane transitions from runway travel to flight. There is allot of energy used in the process of climbing onto plane, but once there, drag is reduced, and the hull is much happier. Just as an airplane has lift producing surfaces (i.e. wings), the planing mono-hull must also have lift producing surfaces. The hull bottom itself is the lifting surface, with the amount of lift dependant on deadrise angle and surface area. Designers create lift with relatively flat and broad hull sections and wide chine flats. Again, compromise limits what mono-hulls can achieve, because the more surface area and flatter sections there are, the greater the lifting force produced, which is good for efficiency and speed (and stability for that matter), but bad for ride comfort. Those broad and flat planing surfaces really bang in a sea-way, making you pay for every percent of efficiency gained.
The Buzzards Bay 34 takes a different approach to mono-hulls, and even most catamarans, because our hulls have a displacement hull shape. A Buzzards Bay does not need to climb up on top of the waters surface in order to travel faster than hull speed, because our very slim hulls produce so little drag, the hull just glides right through this barrier. So here again, physics allows the catamaran to avoid the compromise that mono-hulls are stuck in. Chris White, the designer of the Buzzards Bay 34, was free to design a hull shape that is soley focused on producing as little drag as possible traveling through the water, with rounded sections, free of the broad expanses of flat areas that would slam into waves. The same attributes in displacement catamaran design that make for smoother slicing through waves also make for lower drag and higher efficiency. The net affect is a much smoother ride in waves, while still being able to cruise over 30 mph. Though not optimized for top speeds, the Buzzards Bay’s are still fast enough. Recently, Doubletake has been clocked at 43 mph by Boating Magazine. Perhaps more importantly, the Buzzards Bay 34, even with base power, can run 20 mph on one engine!
Catamarans do have an Achilles heel, and that is the tunnel roof, or bridge deck. This broad panel can, when slammed into waves, create a great amount of force, resulting in pounding. The trick then, is to avoid the waves by keeping it high and gently sloped, especially forward. Chris White, when asked “what is the right amount of tunnel clearance” will say he’s never met a catamaran that had too much tunnel clearance. And I think he’s probably right. There are practical limitations of course, but in general, you want a lot of clearance. The Buzzards Bay 34 has about 20 inches of clearance minimum at rest. I’ve kayaked underneath one, using a sit on top kayak to boot. This amount of tunnel clearance is often two to three times what is normally seen in power cats in this size range. The Buzzards Bay 34 has this design for a reason and the results speak for themselves.
In general, these are the biggest contributors to the Buzzards Bay 34 exceptional performance. It’s hard to beat a well done displacement hulled power cat when it comes to all around performance and comfort. In fact, I’m not sure you can.
If you have any questions about these issues and wish to discuss them, please contact me any time. Thanks for reading.
Blog No 3 will be dealing with interior space, how the catamaran hull shape affects this, and the cruising aspects of the Buzzards Bay 34's interior design.
Russell Hunt, President
Buzzards Bay Cats
21/01/2011 - 10:59am
Buzzards Bay Blog No 3: Interior Design
-Buzzards Bay 34 Versus the Establishment -
Throughout my experiences conducting sea-trials, tests for boating journalists, and just all around acquainting
people with the Buzzards Bay 34, I’ve heard some assumptions being made about power catamarans.
One such assumption is that catamarans do not have as much interior space as their similar size, mono- hull
cousins. The cause of this assumption is simply that the catamaran has a tunnel running down the middle of the hull
and a mono-hull does not. Therefore, among vessels of similar length and beam, a mono-hull is assumed to have
a greater capacity for interior space, storage, and all around more comforts.
Sounds like a good technical subject to explore. Here, we will compare the Buzzards Bay 34’s interior with
other mid-sized coastal cruisers. In an attempt to compare apples to apples, the comparison is between boats
equipped with pilot houses because a pure express cruiser (a.k.a. Sea Ray Sundancer) would offer up too
different of a layout to compare. Besides, we have learned from our internal marketing information that our
boats are not typically cross shopped with this style of vessel.
So here are the comparison boats:
Tiara Sovran 35
Buzzards Bay 34
The first major difference to be noted is the rectangular fore deck shape of the Buzzards Bay 34 compared to the mono hulls.
This rectangular shape is common to all catamarans, and is the reason why among similar sized vessels,
the Buzzards Bay 34 has so much more on deck space. The Buzzards Bay 34 is a very big 34 footer, and feels like it.
The second characteristic I ask you to notice is the way the mono hulls proportion their space between pilot house space
and below deck space. The mono hulls all have a greater focus on their below deck cabins, and the Buzzards Bay 34’s
interior space has been clearly focused in the pilot house. There are three reasons why we gave the majority of space
in our layout to the pilot house at the expense of below deck space, and the reasons are important.
1) The pilot house is the area you spend the most time in whether underway or at rest, so we wanted to make this space
as large as possible.
2) A catamaran’s tunnel places unique restrictions to the below deck layout that can be successfully achieved.
Since a catamaran is not a mono-hull, a designer should not try to achieve a traditional mono hull layout in a catamaran.
3) Generally speaking, the farther aft you are positioned in a boat traveling at speed, the less up and down motion
you will experience. For this reason, most power boats are restricted in how far forward they can position their helm.
The Buzzards Bay 34, which has a ride that is far superior to most mono hulls, is free to have the helm positioned
farther forward, without a negative impact on passenger comfort. This is one reason why our pilot house is
much larger, it simply extends a lot farther forward than any mono-hull designs dare.
Here are the four boat's pilot house sizes, as measured in square feet.
Surfhunter 33: 59 ft2
Tiara Sovran 35: 50.5 ft2
MJM 34: 67 ft2
Buzzards Bay 34: 109 ft2
The pilot house on the Buzzards Bay 34 is 115% larger than the Tiara 35, 84% larger than the Surfhunter 33,
and 62% larger than the MJM 34. In fact, the Buzzards Bay 34 pilot house is 51% larger than that of an East Bay 39
As a result of this space, and with the desire to work within the confines of the catamaran configuration, not against them,
we gave the Buzzards Bay 34 a “great room” style pilot house. Like the great room in a shore side home,
the pilot house of the Buzzards Bay combines the galley and lounge area in one shared space, up on deck.
Traditional sailors might bemoan this decision, but our customers all tell us they much prefer to be cooking
and lounging up in the bright and airy pilot house, instead of down below. There are many benefits of this design.
The galley is never more than a few steps away, whether your reaching in from the cockpit for a cold one,
or your running at 20 knots and can safely (as co-pilot) reach the galley without having to negotiate a set of stairs underway.
Having the helm, cockpit, galley and lounge - spaces you frequent most on a boat - all on the same level greatly reduces
the climbing of stairs making for a safer layout. After all, we may not be as limber as we use to be, and this is something to think about.
I remember a few years back when PDQ Catamarans, a builder of the then successful PDQ 34 came out
with a larger vessel, the PDQ 41. The significant and unique feature of this design was the on deck master stateroom,
located in the back half of the pilot house. This feature dominated the whole design. PDQ marketed this concept based on,
among other things, that it would lessen the amount of times you had to use the stairs. I never understood this.
The stateroom is the least frequented space on a boat. And the boat had a galley down design. The lower helm was
not great, but the flying bridge was very roomy and well laid out. It was obvious that it was intended to be the primary helm,
so there’s more stairs. If you really want to reduce the need to use the stairs, put the head up on deck.
If it would not compromise pilot house visibility and privacy so much, we would love to put a really nice head up on deck in the pilot house.
That would be something, wouldn’t it?
To keep this comparison fair and balanced (I’m an avid Bill O’Reilly viewer) we should discuss what we have lost below decks.
As already mentioned, we don’t have a galley down, and the others do. For those who prefer a galley down,
obviously this is a loss, no way around that. What about the effectiveness and size of the galleys?
Let’s compare based on counter space, available storage, and standard appliances.
Counter Space Surface Area
Buzzards Bay 34: 10 ft2
MJM 34z: 9.5 ft2
Surfhunter 33: 8 ft2
Tiara Sovran 35: 12 ft2
This is an estimate only, as it is difficult to measure via scale drawings and pictures
exactly how much storage space is contained in the galley unit of the comparison boats.
Buzzards Bay 34: 26 ft3
MJM 34z: 13 ft3
Surfhunter 33: 17.5 ft3
Tiara Sovran 35: 20ft3
Buzzards Bay 34: separate fridge and freezer, 2 burner stove, microwave
MJM 34z: appliances optional
Surfhunter 33: combination fridge / freezer, 1 burner stove, microwave
Tiara Sovran 35: combination fridge / freezer, 2 burner stove, microwave
From this comparison, you can clearly see the galley up design of the Buzzards Bay 34
does not suffer in any way. In practice, our galley design is one of the most effective in this size range.
Another obvious difference between our pilot house centric design and the more traditional layouts of the comparison boats
is our lack of a lounge below decks. Again, for us it’s a matter of working with the catamaran configuration, not against it.
Our customers like having their living room up in the pilot house, where there is plenty of light and air.
Our customers do not go boating to be inside, and they tell us our bright and airy pilot house design makes them
feel like they are outside, participating with the environment, even when they are just lounging around.
For this design, what do you give up? Well, for one thing, the comparison boats are forced to have two lounges,
one below decks, and one in the pilot house, for even on these boats with their more traditional layout, the majority
of time spent is still in the pilot house. We have already shown how much larger our pilot house is than the comparison boats,
62% larger than the next biggest pilot house. So we have one very big living room, versus two smaller ones.
Not quite a question of which is better, but certainly a personal decision, as no amount of calculation is
going to decide this. We highly believe in a pilot house centric approach when it comes to cruising.
Now, let’s talk staterooms. Surely this is an easy win for the mono-hulls, considering the Buzzards Bay 34 has the tunnel protruding
into the living space.
The following is a stateroom comparison of all 4 vessels based on three important criteria: comfort, privacy, and storage.
Comfort: Among the four boats, only the Buzzards Bay and Tiara have normal beds, the others have V-berths that convert to beds.
A one piece mattress is simply more comfortable than a v-berth made up of many cushions with all their seams.
The V-berths require a custom foam pad be laid down in order to experience any real comfort. Just one more thing you have to do
when you make the bed and put it away. Both the Buzzards Bay and Tiara are listed as having queen berths, but the Buzzards Bay
has a rectangle design, with the width consistent from shoulder to feet. The Tiara has what is called a “coffin” style mattress,
where the foot of the mattress is significantly tapered, reducing room. This may not be an issue if you are small, but I'm 6' / 225 lbs,
and for me its an issue.
Privacy: This is an easy one. The Buzzards Bay 34 is the only one of this comparison group to have a private stateroom.
All the others have either the stateroom as part of the below decks space (Surfhunter and Tiara) or the bed is the lounge and
must be converted before sleeping (MJM).
Storage: Again, this calculation is not done with a great deal of accuracy. Here is our best estimation.
The amount that the v-hull shape cuts into the available storage could be significant.
Buzzards Bay 34: 34 ft3
MJM 34z: 38 ft3
Surfhunter 33: 35 ft3
Tiara Sovran 35: 59 ft3
The Tiara seems to be the clear cut winner here, with 59 ft3 to our 34 ft3, the MJM’s 38 ft3, and the Surfhunter’s 35 ft3.
As far as stateroom design, I think we edge out the number two Tiara as a result of our more home like mattress design
and greater privacy. The Tiara does offer greater storage in the berth area, but it is still just an extension of their living room area.
Only the Buzzards Bay 34 actually has a separate, private cabin for the master. On a cruising boat, this is pretty significant.
Do you really want to go cruising on a yacht without a bedroom? Or how about having a quiet place to nap on a busy summer afternoon,
away from the rest of the party. Grand children anyone?
The other two lag far behind, and it is obvious the stateroom just wasn’t high on the list of design priorities.
I think the stateroom on the Buzzards Bay 34 surprises many people. For all of the focus on the space above decks,
there are certainly no tradeoffs being made in the stateroom. Folks who believe a catamaran just can’t offer a
comfortable stateroom should really have a look at what we were able to do with the Buzzards Bay 34.
One of our marketing guys’s said, “this stateroom will make you want to downsize”.
No comparison of yacht interiors can be conducted without looking at the heads.
Here’s how they stack up.
Buzzards Bay34: 7’L x 3’W
MJM 34z: 4’L x 4’W
Surfhunter 33: 4’L x 3.8’W
Tiara Sovran 35: 5.5’L x 4’W
The Buzzards Bay 34 and Tiara 35 both have a similar volume of head space, and both have separate shower stalls.
Neither the Surfhunter nor the MJM have separate shower stalls.
I would have to call it a tie between the Buzzards Bay and Tiara for head supremacy.
Both are big for this size range, and having a separate shower stall is really significant for the cruiser I think.
One last area to discuss is additional storage. We gave the Buzzards Bay 34 lots of interior storage, in addition to the areas
previously analyzed. Among the largest storage areas is found under the lounge in the pilot house.
Instead of the normal “settee shuffel”, of clearing off the table so you can put the cushions there, so you can lift the storage lids,
so you can access the storage, we designed a one piece hatch that rises on gas charged cylinders with cushions in place,
giving you unrestricted access to your stored goods. There is about 30 cubic feet of storage inside.
More storage is to be found in the port and starboard companionways (stair wells). Taking the dead space under the side decks,
this conveniently located storage areas works great as a pantry (port side just ahead of the galley), and library (starboard side,
just ahead of the lounge). Total storage volume here is about 18 cubic feet. The final “bonus” storage area is pretty significant.
Lift the starboard companionway stairs on a Buzzards Bay 34 and get ready for a surprise. The hull is a wide open space,
about 5 feet long, nearly 3 feet wide, and about 2.5 feet tall, for a total of 37.5 cubic feet of storage. Perfect for golf clubs, tools, spares,
even hard side luggage.
To continue our fair and balanced reporting, we should look at the comparison vessels to see what bonus areas exist.
The only standout item for the comparison boats has to be Tiara’s “media room”. It’s a bit like an open aft cabin,
set up with couches that can convert to a bed. I thought Tiara did a good job with this space, as a dedicated aft cabin is
not used very much, this set-up being more versatile.
Up above in the comparison vessel’s pilot house spaces only the Surfhunter and MJM have additional storage under their settees.
I would approximate the additional storage to be about 48 cubic feet on the MJM, and 35 cubic feet in the Surfhunter.
I hope you have found this comparison illuminating. When it comes to interior accommodations,
a power catamaran can compare very well when analyzed along same size mono-hulls. In nearly every comparison,
the Buzzards Bay 34 was at or near the top of this group. When you take into account that it is also among the most fuel efficient,
has the highest stability, and offers the softest ride, while being able to float in less than 2 feet of water.....well what isn't there to like?
In a well done catamaran you can have your cake and eat it too. This is what we mean when we say Buzzards Bay is “Beyond Ordinary Limits”.
I hope you have enjoyed this edition of our Buzzards Bay Blog. Please call or e-mail me with any comments or questions.
Russell Hunt, President
Buzzards Bay Cats and
Multihull Development, Inc.
Our mailing address is:
Buzzards Bay Cats
PO Box 583
Buzzards Bay, MA 02532
Copyright (C) Buzzards Bay Cats 2010 All rights reserved.
30/03/2011 - 5:19pm
We build fast cruising boats. The Buzzards Bay 34, when optioned with a pair of 300 HP outboards (our maximum horsepower option for this hull) has been clocked at 43.35 MPH by Boating Magazine, test No 2575. This is considered fast by cruising boat standards, but high top speeds are not something we focus on or really care about. They are more of a fringe benefit. What we care a great deal about, what we stay up late at night tinkering and thinking about, is maximizing comfort and efficiency at cruising speeds between 15 and 30 knot’s. Why this speed range? Why not 7 to 15 knot’s like that of semi-displacement mono-hulls? Our simple answer is it’s too slow. For all of you trawler and sail boater’s out there with white knuckles already starting to show, release your grip on the mouse and let me explain.
Operating a Buzzards Bay is kind of a unique experience. Imagine walking into a fully enclosable pilot house with all of the visibility and ventilation you could ever want. You will start the engines and often find yourself looking at the gauges just to know they are running because the engines are so quiet. Imagine a helm station that has excellent ergonomics, with adjustable seating that lets you stand at the helm, or sit while affording an easy reach to all the controls and electronics. Now lets cast off and get underway. As your speed picks up past 7 knot’s, to 10-11- then 12 knots, the trim angle remains virtually unchanged. No bow in the sky and no high resistance, just a steady direct speed increase at every throttle setting. Now you’re traveling at 18 knot’s and your visibility is the same as it was at the dock. There is no wind noise, barely any water noise, and the four-stroke outboards are humming along a distant murmur. The fine catamaran bows are simply ignoring the 1 to 2’ chop that’s out there, and if you weren’t glancing at the GPS speed on the chart plotter affirming 18 knot’s (20+ mph), you would swear you were going 8 maybe 10 knots. That’s right, 20 mph in a Buzzards Bay 34 feels slow. It’s a comfortable pace you could easily keep up for 10 or 12 hours. Still, you bring the throttles even higher, finally settling on 25 knot’s (29 mph), not out of any discomfort, but simply balancing fuel efficiency with your desire to get to your destination quickly. It’s quite hard to fully grasp unless you’ve sea-trialed a Buzzards Bay 34 with us, but the capability for cruising comfort even offers a relaxed 30 knots.
A fast cruising boat can be a real asset. To us, the most obvious advantage is that you can cover much more ground in a shorter time at 20+ knots than typical trawler speeds.
Side Note: It has been our experience to acknowledge that most owners of a semi-displacement craft will find themselves operating in displacement mode most of the time. These boats that have a top speed of around 15- 16 knots, end up cruising between 7 and 10 knot’s simply because they pay the penalty of high fuel burn. To a lesser degree, the comparably greater noise and trim levels at higher speeds are uncomfortable in these boats. It is interesting to note that the Buzzards Bay 34 traveling typically achieves the same fuel efficiency level at 15 to 18 knots as she does at 7 to 8 knots.
At the top is a chart covering SE Florida and Bahamas. The blue rings show the capable cruising ground available when traveling at 18 knots for 2 hours (inner ring), as well as 6 hours respectively (outer ring). The red rings show the cruising ground available when traveling at 8 knots for 2 hours (inner ring), as well as 6 hours respectively (outer ring). Home port is shown as Port Everglades.
Quite a difference isn’t it? If a Buzzards Bay 34 traveling at 18 knot’s and a typical trawler traveling at 8 knots both departed Port Everglades at 0700 hours, the Buzzards bay 34 would arrive at Grand Bahamas Isle a little before 1130 hours, just in time for lunch. At this time the trawler is not even half way to Grand Bahamas Isle, not arriving until 1430 hours (That’s a 4.25 hour trip versus 9.5 hour trip).
“Why are we all in such a hurry these days?” is a question you may be asking yourself, “I boat to relax”. Good point. And we think you would agree with us that it’s more relaxing on a Buzzards Bay 34 traveling at 18 knots, smooth and quiet, compared to a trawler going 8 knot’s for several reasons…
First and most importantly is safety: At 18 knot’s you only need a 4.25 hour weather window to cross to the Bahamas. At 8 knot trawler speed you need 9.5 hours. Let’s not forget that if needed, the Buzzards Bay 34 can shrink that required weather window to about 2.5 hours by simply speeding up to 30 knots. When you’re out in the open ocean, it’s nice to have options. In a trawler traveling along at 8 knots you are committed to whatever Mother Nature throws at you during that 9.5 hour crossing. If the weather turns nasty, there is not much for you to do other than prepare for the worst and hope for the best.
Speed can help you relax as well. 18 knot speed allows you to sleep in an extra 2 hours, make your departure at 0900 and arrive at the Bahamas by 1:30 pm, still a full 3 hours ahead of the 8 knot trawler that left 2 hours before you. How’s that for relaxation?
Speed isn’t just an asset on longer cruises. Can you imagine what kind of impact 20 + knot cruise speeds can have on your boating weekend if you were previously limited to sail boat or trawler speeds? The entire Chesapeake is roughly 160nm from top to bottom. At 20 knots, a Buzzards Bay can navigate all of Chesapeake Bay in about 8 hours. Leaving after sun up, getting back to the dock before sun down. All of a sudden, the entire Chesapeake is made available to you…in a weekend.
There are a lot of fast boats out there. There are also a lot of comfortable boats out there. What the Buzzards Bay 34 does so nicely, so uniquely, is to combine a high level of cruising comfort with relaxed and fast cruise speeds. To achieve all this, along with great fuel efficiency and a shallow draft is simply unavailable anywhere else. This is what we mean when we say Buzzards Bay Cats are Beyond Ordinary Limits.
Russell Hunt, President
Buzzards Bay Cats
09/05/2011 - 9:38am
Buzzards Bay Blog No 5: Fuel Efficiency
By what measure is a boat considered fuel efficient? Is 0.5 MPG efficient? Well, it is if that boat’s a 70 foot sportfish traveling at 25 knots. Is 5 mpg efficient? It is not if it’s an 18 foot light tackle boat. Fuel efficiency is of course a relative statement. We must first look at the intended use. Do I want to cruise offshore in potentially rough conditions, or will I cruise the coast via the ICW, always staying in protected waters? To be able to handle rough water comfortably may require a heavier boat with a deeper v-hull to maintain comfort in a seaway, at the expense of fuel efficiency. Do you prefer to cruise at slow speeds, or do you want to run fast? Perhaps you would like the ability to cruise at a relaxed pace efficiently, and at times, run fast in order to outrun bad weather or just for time constraints. In the traditional mono-hull world, all of these choices demand that serious compromises be made. No boat will not do it all…with a few exceptions. It has been our position at Buzzards Bay Catamarans that a well designed, carefully built catamaran, utilizing advanced composite construction for light weight, and a high speed displacement hull shape for low drag, can in fact do it all with very little compromise. Our Buzzards Bay 34 delivers best in class interior, significantly higher levels of ride comfort, fast cruise speeds, and outstanding fuel efficiency. If you’ve been following these blogs, you understand our advantages when it comes to sea-keeping ability, interior space, and have a good understanding of our speed performance. For the Buzzards Bay Blog No 5, we would like to evaluate our fuel efficiency advantages against competitive boats over a wide speed spectrum.
To accomplish this, we’ve assembled a broad mix of similar mission / size boats and we’ve broken them down into two groups, outboards and diesels. To make the results as meaningful as possible, we gathered single engine, twin engine, and pod drive competitors, so as to leave no questions unanswered.
We’ve included some larger (by length) vessels, the MJM 40z, Grady White 36, Pursuit 375, and Back Cove 37 because these vessel match up to our Buzzards Bay 34 in actual size and space on board. However, to be fair, we did include their smaller brothers (Grady White 33, Pursuit 345, MJM 34z) so there were no boats we were trying to “duck” in this comparison.
For a little fun (and more than a little perspective) we also included a vessel that represents an extreme attempt at achieving fuel efficiency; the Greenline 33 Hybrid, which is a fully enclosed pilot house cruiser featuring a layout similar to the Buzzards Bay 34. It is powered by an inboard diesel engine that is fitted with an integral generator / motor. The operator has the ability to operate on battery power alone, diesel and battery, or just diesel, all with integral solar charging. Its system is too complex to adequately describe here, but in nut shell, it is an attempt to bring automotive style plug in hybrid technology to boats. Will the same fuel efficiency advantages that hybrid cars enjoy carry over to express cruisers? We’ll see.
Let’s have a look at the outboard powered boats first.
(To see the graphs, see attachments below. )
Looking at the outboard fuel efficiency graph, you can see that the Buzzards Bay 34 enjoys a substantial fuel efficiency advantage over every other vessel here.
At 15 MPH, the Buzzards Bay 34 is achieves 1.95MPG, which is 70% more fuel efficient than the next highest boat, the Glacier Bay 34 (1.15MPG). Last is the Grady White 36 Express at .71 MPH, a full 174% less fuel efficient.
At 20 MPH, the Buzzards Bay 34 is running 2.05 MPG, 85% more fuel efficient than the second highest vessel, Grady White 33 ( 1.11 MPH).
Finally, at 30 MPH, the Buzzards Bay 34 is returning 1.38 MPG, with the next highest Grady White 33 at 1.23 MPG, a difference of 12%. The Pursuit 345 is 22% less efficient at 30, and the others are all over 55% less efficient.
At 30 MPH, you can see the deep-vee hull of the Grady 33 becoming a little happier, a little more efficient. It has shed some of its wetted surface (lower drag), dropped its trim angle a little and is now in the groove. The Buzzards Bay 34’s hull, being a displacement cat, does not receive the advantage of reduced wetted surface drag as speed continues. In return, you get a hull that operates over a much wider range of speeds very efficiently compared to a planning mono-hull.
Now let’s look at how different levels of fuel efficiency affect bottom line costs to operate. (see outboard compare cost graph)
For this chart we calculated each vessels relative fuel cost per gallon, adjusted for their average fuel efficiency at the measured speeds (15, 20, 25, and 30 MPH). This gives you a very true sense of the relationship between fuel efficiency and operating costs. We set the Buzzards Bay 34 operating cost at current prices for a baseline ($4 per gallon, we’ll see what summer brings). The next most efficient vessel on average is the Grady White 33, whose owner is paying $6.28 per gallon of gas in relation to the Buzzards Bay 34. That’s 57% more expensive. The most expensive boat to operate is the Pursuit 375, with a relative fuel cost of $7.84 per gallon. That’s a whopping 96% more expensive. Rising fuel costs and uncertainty about the future seem to be something we’re all going to be living with for some time. Wouldn’t you like to be paying $2, $3, and compared to some boats almost $4 less per gallon for gas? When you’re running a Buzzards Bay 34, that’s just what you’re doing.
Of course, fuel efficiency has an impact on range too. The higher the fuel efficiency, the farther you can travel, or the less fuel you need to cover the same distance. With the Buzzards Bay 34, we chose to use our fuel efficiency advantages to achieve a very competitive range while carrying far less fuel. Less fuel means less weight to push, which means less horsepower is needed. All but the Glacier Bay in the above comparison needed heavy Yamaha V8 350HP outboards to push them well, while the Buzzards Bay 34 is a real jack rabbit with lighter weight 6 cylinder outboards.
Range at best cruise speed has the Grady White with a 387 mile range, ahead of the Buzzards Bay 34 and virtually identical Pursuit 345 (350 miles and 346 miles respectively) by 10%. The rest of the boats have around a 300 mile range. The interesting thing here is actual fuel capacity; how much fuel it took to achieve that range. The Buzzards Bay 34 has a total fuel capacity of 190 gallons while the Grady carries 350 gallons of gas, a full 84% more than our Buzzards Bay to travel just 37 more miles.
Now on to diesel powered boats. This gets interesting, because in this we group we have some boats that, from a design and build standpoint, really focused on fuel efficiency as their number one priority. (See diesel fuel efficiency chart)
At 15MPH, the Buzzards Bay 34 is about 30% more efficient than the second highest MJM 34z. The least efficient is Tiara’s Sovran 35, a full 158% difference. This vessel, having pod drives, is lacking the downward angle thrust that is helpful to planing at slower speeds. Pods are good for efficiency at higher speeds, but not always at slower speeds. According to the test, the Tiara reaches a trim angle of 7 degrees at 17 MPH. At this speed, the hull should be solidly on plane and leveled out to 3: 4 degrees. This boat would not be too fun on the ICW where there is allot of slow to medium speed running, continually powering up on plane and slowing back down. The lack of visibility would be potentially dangerous.
At 20 MPH thru 30 MPH, there is not much difference in efficiency between the Buzzards Bay and MJM’s 34z, with both vessels far and away the most efficient among this group. The MJM 34 is designed and built with an almost single minded mission to achieve maximum fuel efficiency. Her narrow beam, minimal super structure, shallow v-bottom hull, and light weight construction compromise interior space, stability, and ride comfort in favor of getting the lowest fuel burn. The fact that our significantly larger Buzzards Bay 34 can match her efficiency, and in some cases exceed it, while providing superior levels of interior space, ride comfort, and stability is significant.
Now have a look at the diesel compare costs graph. This chart has the relative fuel cost per gallon of each vessel, adjusted for their average fuel efficiency at the measured speeds (15, 20, 25, and 30 MPH). We set the Buzzards Bay 34 operating cost at current prices ($3.50 per gallon of diesel, we can dream, right?).
The MJM 34 is about 13% more expensive to operate than the Buzzards Bay 34, with its owner paying a relative fuel cost penalty of $0.44 per gallon over the Buzzards Bay 34, followed by the MJM 40z ( $5.22 per gallon), Back Cove 37 ($5.85 per gallon), Sabre 34 ($6.55 per gallon), and lastly, the Tiara 34 at a pricey $7.71 per gallon, a 120% operating cost increase over the Buzzards Bay 34.
The MJM 40 has the most range at 554 miles, with the Buzzards Bay in second at 513 miles (on roughly half the fuel), followed by the Back Cove 37 with 454 miles, Sabre 34 (356 miles), MJM 34 (320 miles) and lastly the Tiara with 281 miles.
Among purpose built vessels aimed squarely at fuel efficiency, pod powered, single and twin engine installations, the Buzzards Bay 34 is at or near the head of the class in every comparison. With an optional fuel capacity increase of 30 gallons, there isn’t a category she would come second in.
How does the diesel powered Buzzards Bay 34 compare to the most extreme vessel here, the Greenline 33 Hyrbid? At 15 mph, the Buzzards Bay is 40% more fuel efficient than the Hybrid. Unfortunately, the Hybrid is not able to achieve speeds to 20 mph, according to the test. This performance may seem a little disappointing. Still, it has the ability to operate very quietly on electric power alone, and for some, the onboard serenity that low noise levels produce is alluring enough on its own merit. To these folks I say consider an outboard powered Buzzards Bay. At 15 mph, the efficiency nearly matches that of the Hyrbid (2.05 vs 2.11) and at any speed above 7 mph, our Mercury Verado outboard powered Buzzards Bay is actually quieter because the Hybrid has to run its diesel. In full electric mode the Hybrid is limited to a range of 20 miles at 6 mph. I think there’s allot of compromise here for very little performance. It’s neat and different, but are there real benefits to the owner?
There you have it. Whether diesel or outboard powered the Buzzards Bay 34’s fuel efficiency is outstanding. Factoring in her class leading size, ride comfort, and stability, and her dominating performance is even more impressive. This is what a good catamaran can deliver. No gimmicks, no unproven technology, no compromises. Just good catamaran design work (courtesy Chris White Designs) and light weight advanced composite construction techniques with quality craftsmanship.
I hope you enjoyed this edition of the Buzzards Bay Blog. To tell you the truth, we were a little surprised at how efficient the Buzzards Bay 34 is compared to the rest of the market. Once we started to see all of the data compiled on so many vessels in one place, well…..we were pretty excited about the results. If there are any questions regarding the data used or other vessel comparisons you would personally like to see, please let us know.
Next months Buzzards Bay Blog No 6 will be covering shallow water operational design considerations. Not as sexy a subject as fuel efficiency, but still very important.
-Thanks for reading.
Russell Hunt, President
Buzzards Bay Catamarans and
Multihull Development, Inc.