Reliability and simplicity in the 40-55ft range?

Well there is NO
Reliability and simplicity
In this.

Boats are a like girlfriends. The experience depends on how well you treat her. And sometimes it doesn't.

I like that.
,rc

Ralph, never knew Volvo made outboards...Duh??

Pretty nice lil ones up to 50 hp tillered.. Not sold in the states but they came over. My better Volvo shop ordered any part needed.
In the rest of the world, tiller control is common to mid hp outboards. If you can hang on,,,,,,

I never knew about Volvo outboards either. When we bought a center console, we bought triple Yamaha 300's instead of 350's simply because we'd heard better things about reliability. It's not worth sacrificing reliability for a slight increase in speed. We did not consider Seven's.

Sorry for the delayed response, been travelling and thinking about this. I've been an automotive engineer for decades, hang with people who like to discuss the latest anti-lock technology, the newest machining center, suspensions and engines. I assume everyone talks about that stuff, but realize not everyone does or cares.

Gasoline engines went through a revolution decades ago when they had to become OBDII compliant, loaded with sensors and computer modulated. Since then they've gone through a series of revolutionary changes with a combination of technological changes. Sensors and injectors and casting and machining changed dramatically, and engines were redesigned to take advantage of them. Individual coil packs individually controlled, along with individual injector control, and the faster sensors to control them, brought more improvements. Variable valve timing and lift are bringing huge improvements in torque and efficiency, and it really isn't a complicated addition, it is old technology from airplane props.

The ability to computer model flame fronts and pressure waves in cylinders and intakes brought subtle but significant changes to combustion chambers, intakes, turbochargers, etc. That kind of computer modelling is still improving rapidly, and engine designers are still trying to incorporate all the new discoveries into their newest engines. The engines we are producing today are already obsolete, we just can't change our tooling and designs fast enough to keep up with the new discoveries.

New gas engines are smoother, more efficient, better machined and better sealed, they are a world away from the carbureted V8s most of us knew and hated. Even things like computer modelling of internal engine temperatures has not only greatly improved thermal efficiency, but greatly reduced thermal stresses on the structures of engines and heads. As an old fart, I'm jealous of the young guys who are designing with all this new knowledge and tools, making huge improvements that will be enjoyed by most of the people on earth.

I'm far from qualified to explain everything that is changing in production engines today, but I can tell you things are changing at bewildering speed. Scientists can't even keep up with all the tools for discovering new ways to analyze and improve engines, and it is hard to know where engineers should start with the changes we need to make on new engines.

I can't help feel a bit nostalgic when I drop into my engine room with two 13-yr-old, computer controlled big-blocks. It isn't like I'm working on a six-pack hemi 'Cuda, but darn near as primitive compared to current offerings. However, they do put out impressive low-end torque with almost no delay from idle, for smooth low-speed maneuvering. They don't mind a lot of time at 1,000 RPM lightly loaded, and they are so smooth and cool from idle to max RPM, they aren't rattling and twisting their bearings and seals into failure like older engines did. These same attributes that are allowing truck owners to see 300,000 miles+ without a rebuild, should give me 3,000 hours+ of reliability in a boat.

I don't think gas engines are better than diesel in big boats, and for smaller boats in specific applications, but gas engines have become a much better option in small cruisers. I understand the safety concerns, they are real dangers, especially on older boats. On newer boats, technology again has made significant improvements in reducing those dangers to near or below the levels of many other dangers of boating we all live with.

Nice highlight of engine technology, remember that most of the this technology transfers to today's modern diesels too.
"Gas engines have become a much better option in small cruisers" Usually comes down to cost. A short season , 50 hour per year boater would be the sales target, but for more robust boating, diesels are the preferred set-up.
I ran a Sea Ray 340 Sundance with gas big blocks and Yanmar 315hp diesels and much preferred the Yanmar set-up for the long haul. But most of those sales are gassers to keep the purchase price down.

Right, gassers do keep the purchase and maintenance costs down. The difference in fuel costs has to be compared to those cost increases for diesels. If you are going to do a lot of long-haul, diesels are going to win in small cruisers. If you are going to do what most recreational boaters do with small cruisers, maybe not. That line has just shifted a little. I'm a recreational boater on my own boat, mostly doing a lot of puttering around with a boat full of family and friends, anchoring at the beach, short day trips and occasional weekend overnights. We will run to Mackinac Island, over 500 miles round trip, diesels would be nice for that run, and I just love the smell and sound of diesels.

I'm the kind of guy who hates to start my engine to move my truck into the garage, as I know how bad that is for the engine and exhaust. I'd be cringing every time I take my boat out for short, slow trips to the beach with the kids, if I had diesels. A lot of diesels offered in small cruisers are not small enough to be happy running at displacement speeds, and not big enough to push the boat at a good planning speed. But makers offer them and owners buy them, abuse them, don't spend the money to maintain them, and then wonder why they slowly lose top-end over the years and need a rebuild. It isn't so much that diesels aren't great at what they do, they are being used for things they aren't great at by people who don't understand, and that is impacting what they end up costing the owner.

I'm surprised diesels aren't changing as much as gas engines, but there really isn't a lot of demand driving money and research and retooling to take advantage of new discoveries. Like most things, it is probably a money thing. Diesels are being squeezed by the EPA and marketing, to put out more power and less emissions. It was easy to tighten up diesel engine tolerances and add turbos and coolers to give marketing and the EPA what they asked for. Dealers were happy to sell these engines with better numbers. Low-sulfer fuel and tighter tolerances are starting to show up in less longevity, even for commercial operators who use and maintain their diesels well.

Diesels vibrate, the more power they put out the more they vibrate, it is the nature of diesels. Tightening and lightening and turbo-charging small diesels is simply not going to help longevity. Using all the technology available to reduce vibration would help a lot, maybe that is coming, but in the diesel world they have always lived with it and compensated with mass, because diesels are supposed to be heavy. It will require a change in attitude more than technology.

I'm hoping catalytic converters will allow engine makers to really open up their engines to perform to their abilities. A lot of people are dreading it, but it could actually be a good thing.

I can see your gas preference and anti-diesel bias coming through .
The on-highway diesel market has driven great technology leaps in small diesels, the maintenance intervals are increased and you can get 1,000,000 miles today routinely.

You have oversimplified the emissions/EPA chase for diesels and have failed to note the new common rail technology, sequential turbochargers, and complex fuel mapping that have reduced emissions considerably. Not to mention advancements in metallurgy and the entire combustion process. Everything is cnc'd just like gassers as well.

New diesels are more capable of low load operation than the old 2 cycles, thanks to computer controlled fuel monitoring, some have cylinder cut-outs as well. As far as matching performance, what model are you considering when you feel they can not perform at adequate planing speeds? What boat?

Not a fan of extreme temp cats on a gas vessel, can't get the same air cooling as a car and see it as a reliability and maintenance cost for a gasser.

I am biased, and I try not to let my preference for diesels cloud my decisions.

When I searched for small flybridge diesel boats, I found a most had received expensive engine work. Looking at the data for my boat, I found a post from a factory rep comparing the 315hp diesel to the 370hp gas, showing the gasser were cheaper to own. I had read plenty of complaints from owners of other diesel boats, that they wished they'd gotten bigger engines. Their mechanics felt they had pushed their diesels to early failure because they were undersized.

I'd like to sit down with whoever keeps thinking gas-electric hybrids are a good idea, but I fear it would be a marketing person and not an engineer. I partially blame my brother. He was an exec at Toyota/Lexus many years ago, and like all my brothers he lusted for a diesel Jetta, to replace his high-performance Jetta. And like all of us he had to do a lengthy analysis, but he had all the resources of Toyota to do a formal study. The study specifically compared the diesel and gas Jettas, and the total cost to an owner. In the study, maintenance costs exceeded fuel savings about the time belts and alternators and other typical failure items needed to be replaced. A typical owner did not save money with the diesel Jetta. The main reason was more expensive parts and maintenance, which is even more true on boats. Yes, you can compare automotive and marine applications when there are similarities.

A million miles on an over-the-road commercial truck diesel was common in the '80s. There have been great improvements in efficiency and emissions, but nobody felt longevity was an issue to put money into. More likely, longevity was something they were willing to sacrifice for better numbers up front.

I hear you on the cost factor, you can certainly make a case for a gasser, especially with short seasons and low annual hours per year. It can be the cheaper route in those cases under 40. On a low cost, low use under 40' basis, it will be the low cost option and get more people into boating, who typically chose diesels for their next bigger boat purchase.

Cummins has a 370hp engine and your point of reference may be skewed by the manufacturer trying to hit a price point and going cheap with the 315hp Yanmar, which I happen to like very much in a 340 SR. Production builders do not always make the best engine match, as they try to hit price points instead of performance. You can get that same Cummins in a rating to 480hp, which really shows off its power and size and weight advantage.

If I recall correctly, the DD Series 60 was the first real million mile production diesel for the on-highway market, it did not hit the marine scene around the year 2000, was released in the late 80s for on-highway but really hit its stride in the the 90s and later with the second and third generation.

Automotive engines do not account for the marinization package, which vary in quality from builder to builder, and the fact the the marine application is more severe than on-highway. It is much less taxing on an engine to roll wheels at set highway speeds than move an object through the resistance of sea or fresh water.

This string has taken some turns, and some interesting view points on gas vs diesel. There is plenty on the web on this subject, and strong opinions.

Overall, I think PAC has made some valid points, and backed it up with his data as an Auto Engineer. That is why I have always enjoyed interacting with engineers. They generally stay with the facts, and avoid embellishment. Another reason I like this site in general...low drama.

Like many others on here, I also worked on car engines when I was younger and always wanted diesels for the boat when we could afford them. That happened 3 years ago, and I love my oil burners. We spend about 100 nights per year on the boat, so the safety aspect alone justifies it for me.

With that said, I also believe the newer gas engines are fine for the typical rec boater up to 40 ft. Heck, I initially said "50 hours". Most people I know with gassers are much less than that.

It's all good if you are on the water whether it's a bath tub or a fancy yacht. For that matter, I know people who have more fun on their 25 ft boat than folks on 85 footers.

Absolutely agree, it is about sharing (professional) perspective and continuous learning.
I can truly appreciate the point of view from a dedicated boater, especially one who can manage 100 nights onboard a year, that I really admire.
The Great Lakes are a haven for the gassers we are talking about, along with various pockets in the country like the Texas/Oklahoma lake system, the Tennessee waterways, etc. It is a somewhat struggling market at times, but one that can not be ignored by boat manufacturers. A lot of their input is dealer driven.
My own background as a Naval Architect and Marine Engineer, and I get to work with a number of knowledgeable engineers of all types, many who come from the automotive side, and they bring a lot of technical know how and good processes from the more formal auto engineering side.

All lakes and rivers are havens for gas. I boated the first 29 years or so of my boat ownership, first 42 years of my life, with gas inboard outboards and none of them ever left me stranded. Still on the type coastal and ocean boating I do now, I'd only have diesel, if having an inboard. There are far more gas boat engines sold than diesel in total. However, they are still less than ideal for certain uses. I think it's not just the type cruising but I think salt water vs fresh is a bit of an issue as well.

Still, for some people it comes down to gas boating or no boating and I'd always choose gas out of those two options.

Another approach to increase the likelihood of a successful trip is to have a boat that you would use frequently. For that reason, I would argue that a boat that is small enough to be suitable for day boating to nearby places is more dependable for the "day of the trip".

For example, I have a 36' boat and use it locally to reach boat up restaurants and bars or to anchor and swim. This frequent use may be the reason that I never faced an issue during longer trips to Bahamas and the southern Keys. I am in the process of upgrading to a 41' boat, as I want to increase the comfort for two couples overnight trips, the boat I chose, a Bavaria R40, is still suitable for daily trips.

There isn't much difference in taking a boat out whether it s 36 or 60 or 80'. Pretty much the same number of engines to start up, generator, power cord (bigger cords make no difference ) and same number of lines although bigger

There's a bit of difference in some of the places you might go and I think psychologically you're more likely to take a 36' out for a lunch trip than an 80'.