How many engines is ideal?

[mvweebles]

Wing engines have a bad rep , mostly because there not used enough to be reliable.

The EZ cure for that would be for the get home to also perform as your gen set.

FF -Interesting point. Early Willard 40's had a massive electric get-home driving the main shaft. Power was a very large 3-phase generator that was expensive to replace, and difficult to load-up; and of course relied on main prop shaft (vs redundant system). I would think a better installation would be a short secondary propshaft driven by a hydraulic motor via PTO on generator. This would be compact and relatively economical to design/install into a new-build North Pacific, DD, or similar.

Peter

 

[Mako]

Using a generator as a get-home is not usually practical, especially for bluewater (heavy) boats. A 20 hp genset with a hydraulic drive might be lucky to transmit half that to the prop shaft. But your 15kW genset will never get loaded up properly to maintain its health.


A large boat might require 40-80hp at the shaft. Is it practical to keep a 100kW genset onboard???


If you are coastal cruising, which most people are, then forget about a wing or get-home and pay $150 for a TowBoatUS membership. And take care of your engine and fuel system, like Charles Lindbergh and tens of thousands of commercial fishermen.



If a small boat then how about a sail backup, which is true redundancy. Even a kiteboard sail will pull you along at a knot or two.

 

[Art]

I think Charles Lindbergh's approach makes good sense. If you're risk of failure (with catastrophic results) is extremely small either by time or percentage, there is reliability in simplicity of a single engine. As time or percentage increase, the law of probability catch up with you.

For coastal cruising, I rationalized that single engine failure would likely be life threatening <1% of the time. As such, the odds were decidedly in my favor. If I were traveling to remote locations without a reasonable expectation of help in 24 hours, or crossing oceans where weather could compound the problem, the risk factor warranted a second form of propulsion. Eventually I came to the conclusion that 2 identical drive trains made more sense than a single and a wing engine.

Ted

Cautious, pronounced safety, Rule of Thumb: Prepare for the worst, hope for the best.

Conclusion [for power pleasure boats]:

- Boating offshore or transiting across the ocean there is planning backed by hope that there will not be a sudden storm of ferocity.

- Boating offshore or transiting across the ocean there is planning backed by hope that there will not be a sudden, non-repairable engine breakdown.

- Boating offshore or transiting across the ocean just might have those two plannings thrown out the window with those circumstances occurring; either separately or [God forbid] simultaneously.

Therefore: Although the chances are slim that either one or both listed items above should occur... you know Murphy's Law. Which basically intones - "When You Least Expect It, Expect it"!

Soooo... To best as possible avert a Murphy's Law upset from happening; I opt for twins or a darn good setup for a get-home motor in power boats.

 

[rslifkin]

I'm with Ted on the idea that two of the same makes more logical sense than single + wing. Keeps all the spares and such the same for both, plus you get the maneuvering benefits of twins. Only downside is possibly hull design factors and being harder to protect the props. If done right, the fuel burn penalty should be minimal compared to the single + wing config.

 

[mvweebles]

Using a generator as a get-home is not usually practical, especially for bluewater (heavy) boats. A 20 hp genset with a hydraulic drive might be lucky to transmit half that to the prop shaft. But your 15kW genset will never get loaded up properly to maintain its health.

If a small boat then how about a sail backup, which is true redundancy. Even a kiteboard sail will pull you along at a knot or two.

The Willard 40's had 12kw generators to spin their 5hp 3-phase electric motors. Would drive the boat at about 4.5 kts. Would think hydraulic would be more efficient, though swinging a separate shaft and folding prop would lose a lot of efficiency.

In 1987, a Willard 36 went from San Diego to Hawaii - about 2300nms. I believe the boat had a decent sail plan at the time - she burned about 330 gallons of diesel, or around 0.9 gph at 6 kts, which is about 15% better fuel economy than I would have guessed, so I'd guess the sail plan gave some extra push. There's a lot to be said for a decent sail plan on a long distance trawler of modest proportions.

Peter

 

[Art]

I'm with Ted on the idea that two of the same makes more logical sense than single + wing. Keeps all the spares and such the same for both, plus you get the maneuvering benefits of twins. Only downside is possibly hull design factors and being harder to protect the props. If done right, the fuel burn penalty should be minimal compared to the single + wing config.

Regarding: "...being harder to protect the props.

I've often mentally pictured and have actually seen photos of twin screw props stemming from separate keels to either side of center... complete with skegs that extend under separate rudders.

I imagine that for D or SD hulls the draft in this twin keel design could be minimized in comparison to a centered keel for single shaft/prop/rudder.

For hard chine, relatively flat bottom P hulls the boat's draft may be slightly increased. Also, on a P hull I do not know what the added "drag" coefficient of two relatively large keels would produce for speed debilitation... nor for nmpg reduction. Both items could result prohibitive to fast speeds. For sure, the faster the boat was pushed the higher the drag coefficient would become.

I actually fantasized taking the bottom of our Tolly and designing a dual keel, full skeg, dual rudder addition. Then I thought better of it - as I never seem to have ample time for all the other items in my life!

Photo is Tolly 34' bottom. Would not take rocket science design to add structurally sound keels, skegs etc onto this profile. Would take some time and capital as well as sea tests to determine the outcome!

 

[rslifkin]

Your bottom profile is similar to mine, but it looks like you have a little more deadrise and a slightly rounder V in the center. And I've got more exposed shaft with a bit shallower angle. On either your boat or mine, I wonder what the drag would be to convert the struts into skegs or short keels that protect the prop (I don't personally see the need to tie into the rudder as the skeg and prop will be deeper than the rudder). And maybe chop down the center keel a bit to make up some of the drag there.

 

[Art]

Your bottom profile is similar to mine, but it looks like you have a little more deadrise and a slightly rounder V in the center. And I've got more exposed shaft with a bit shallower angle. On either your boat or mine, I wonder what the drag would be to convert the struts into skegs or short keels that protect the prop (I don't personally see the need to tie into the rudder as the skeg and prop will be deeper than the rudder). And maybe chop down the center keel a bit to make up some of the drag there.

Good thoughts on dual keel design!

Yup...

Back in the day of high powered, hulky, fast, full planning Twin-"Screwers" [LOL], when fuels were still in the cents per gallon cost category, the top boat manufacturers all had fairly similar bottom designs.

Only reason I can see having the dual keel design would be for prop protection... and rudder stability/protection if skegs were fully extended. Dual keels would probably make the boat track better too and may place additional damper on the roll charistics.

That said: I've always been super duper careful to not go aground as well as to keep keen eye out for flotsam while on fly bridge 99% of the time under power.

So... the effort and cost of installing the keels as well as the potential for reduced speed and increased fuel usage just don't make sense in comparison to simply being super duper careful. One thing is for sure. Even if the dual keel design became a reality on our Tolly - I'd still be super duper careful regarding grounding and flotsam. Additionally, the $$$ cost of correctly installing dual keels would probably way exceed the cost of prop, shaft, rudder repair if a mistake were to happen

We leave in a couple hours for weekend aboard our boat! 2020 has not enabled us to be aboard very often. As time progresses I plan to try and not recall this year with Covid-19 pandemic as well as economic shut down and our areas of Norcal so much in flames that it produced over 40 days of so much smoke in air that most stayed home with all doors and windows closed tight! Yesterday was the first clear day here in 30 days [some times 100 yard visibility was the best all day]. I hear that smoke in air may return in this area [from other ongoing west coast fires] beginning of next week. We were lucky that our heavily forested area has so far not become just another fire statistic!

 

[smitty477]

Good thoughts on dual keel design!

Yup...

Back in the day of high powered, hulky, fast, full planning Twin-"Screwers" [LOL], when fuels were still in the cents per gallon cost category, the top boat manufacturers all had fairly similar bottom designs.

Only reason I can see having the dual keel design would be for prop protection... and rudder stability/protection if skegs were fully extended. Dual keels would probably make the boat track better too and may place additional damper on the roll charistics.

That said: I've always been super duper careful to not go aground as well as to keep keen eye out for flotsam while on fly bridge 99% of the time under power.

So... the effort and cost of installing the keels as well as the potential for reduced speed and increased fuel usage just don't make sense in comparison to simply being super duper careful. One thing is for sure. Even if the dual keel design became a reality on our Tolly - I'd still be super duper careful regarding grounding and flotsam. Additionally, the $$$ cost of correctly installing dual keels would probably way exceed the cost of prop, shaft, rudder repair if a mistake were to happen

We leave in a couple hours for weekend aboard our boat! 2020 has not enabled us to be aboard very often. As time progresses I plan to try and not recall this year with Covid-19 pandemic as well as economic shut down and our areas of Norcal so much in flames that it produced over 40 days of so much smoke in air that most stayed home with all doors and windows closed tight! Yesterday was the first clear day here in 30 days [some times 100 yard visibility was the best all day]. I hear that smoke in air may return in this area [from other ongoing west coast fires] beginning of next week. We were lucky that our heavily forested area has so far not become just another fire statistic!

"Back in the day of high powered, hulky, fast, full planning Twin-"Screwers" [LOL], when fuels were still in the cents per gallon cost category"


I have never understood the folks that say .."fuel prices were cheaper in the past" discussions as fuel adjusted for inflation is not really a factor at all.

 

[Art]

"Back in the day of high powered, hulky, fast, full planning Twin-"Screwers" [LOL], when fuels were still in the cents per gallon cost category"


I have never understood the folks that say .."fuel prices were cheaper in the past" discussions as fuel adjusted for inflation is not really a factor at all.

Well - That is sorta true. However, when marine gasoline back east was in the $0.29 to $0.35 cent category and diesel was going for $0.19 cents a gallon - which in a 38' single diesel boat that got 3 nmpg = $0.06.33 cents per mile was damn CHEAP!!

1000 mile, four week pleasure boat vacation only cost $63.00 in fuel - Now that IS cheap, cheap, cheap!!! No matter how you equivilize it to today's fuel costs...

 

[smitty477]

Well - That is sorta true. However, when marine gasoline back east was in the $0.29 to $0.35 cent category and diesel was going for $0.19 cents a gallon - which in a 38' single diesel boat that got 3 nmpg = $0.06.33 cents per mile was damn CHEAP!!

1000 mile, four week pleasure boat vacation only cost $63.00 in fuel - Now that IS cheap, cheap, cheap!!! No matter how you equivilize it to today's fuel costs...

Fuel costs adjusted for inflation:
https://inflationdata.com/articles/inflation-adjusted-prices/inflation-adjusted-gasoline-prices/

It was also great when you could purchase a new 45' fiberglass twin diesel boat under $100K but without adjusting for inlfation the comparisons have little value.

 

[BandB]

Well - That is sorta true. However, when marine gasoline back east was in the $0.29 to $0.35 cent category and diesel was going for $0.19 cents a gallon - which in a 38' single diesel boat that got 3 nmpg = $0.06.33 cents per mile was damn CHEAP!!

1000 mile, four week pleasure boat vacation only cost $63.00 in fuel - Now that IS cheap, cheap, cheap!!! No matter how you equivilize it to today's fuel costs...

Wifey B: No, in ancient days, $63 was a lot of money. Not cheap. Cost of gas in 1950 was 30 cents so guess that's about when you're talking about. That's the equivalent of $2.64 today. Your $63 in 1950 by inflation would be $679.45 (thanks to hubby for finding). If you consider $679.45 cheap then $63 was cheap.

 

[Art]

Wifey B: No, in ancient days, $63 was a lot of money. Not cheap. Cost of gas in 1950 was 30 cents so guess that's about when you're talking about. That's the equivalent of $2.64 today. Your $63 in 1950 by inflation would be $679.45 (thanks to hubby for finding). If you consider $679.45 cheap then $63 was cheap.

Conceptual Semantics! - LOL

 

[smitty477]

Conceptual Semantics! - LOL

Actaully if you look at the chart gas was cheaper after inflation in the late 90's then when it was at or near 29 cents a gallon in the 50's.
Just a fact - no tricks , smoke or mirrors.

 

[Hippocampus]

Fascinating discussion. Would note when the first Artnautica was built it was single screw. It was built in NZ then went off to cross the Pacific east to west. The Artnautica built in Europe are available as double screw but fully protected by keels. The Nordhavns we’re looking at are single screw with the get home fully exposed. Just shaft, strut and prop hanging out there. Buying used this time. My experience is I’m more likely to have trouble with saragasso then anything else. I fully intend to run the get home before leaving and before entering a harbor as this seems to be de rigor for these boats. Think this is the best we can realistically do. Comments?

 

[mvweebles]

Fascinating discussion. Would note when the first Artnautica was built it was single screw. It was built in NZ then went off to cross the Pacific east to west. The Artnautica built in Europe are available as double screw but fully protected by keels. The Nordhavns we’re looking at are single screw with the get home fully exposed. Just shaft, strut and prop hanging out there. Buying used this time. My experience is I’m more likely to have trouble with saragasso then anything else. I fully intend to run the get home before leaving and before entering a harbor as this seems to be de rigor for these boats. Think this is the best we can realistically do. Comments?

I'd never heard of the Artnautica before Hippo mentioned it a while back. Surprisingly, it took me this long to Google it (HERE). Looks like a slow version of the Dashew FPB.

The issues I've heard with wing engines are 100% related to non-use. Well----there's also the slow speed item, but given the alternative (no propulsion), hard to look a gift horse in the mouth. Folding prop gets hard growth and fouled. The Yanmar's in the N40's are reportedly decent engines. I would think standard maintenance would be all that's needed - sort of like checking the air in your spare tire from time to time. Nothing worse than having a flat spare when pressed into action.

Hippo: I'll press a bit - sounds like you agree that a twin-engine setup is where you're headed. Why a main + wing vs a twin?

Peter

 

[Hippocampus]

Mostly because in the size we’re looking at and in our budget the twin installations engine rooms look like more boat yoga than I want to deal with. You previously mentioned you can get crazy with redundancy. I agree with you. But also have had things malfunction although well maintained and being checked out before departure. I’ve replaced all standing rigging sailboats every 8 years as that’s what recommended for voyaging boats. For other uses you commonly see 20+ years. Attitude depends on usage. We like remote quiet places. Think for key systems you need a fallback. Propulsion is a key system. So you have a key system but it rarely fails. Redundancy with twins means much more expense, weight and maintenance. Although a wing has cost, weight and maintenance it’s service intervals by calendar time (not engine hours) with be much longer. Weight is much less. Cost is much less. And there’s much less boat yoga.

 

[Nomad Willy]

Did nobody see;

“Fuel costs adjusted for inflation:
https://inflationdata.com/articles/i...soline-prices“

That smitty477 posted?

Americans are buying huge pickups like crazy but very few small to very small sedans. The sedan being most efficient would be a big dog in sales if fuel prices were high. They are not.

And hippocampus twins are not heavier if power is the same.

 

[Hippocampus]

Petit spray cans with lanolin over it or propspeed. In the Caribbean hard growth meant a pliable plastic scrapper and a wooden spatula when we’d jump in the water. Done at least weekly. Had a feathering Maxprop. With the new lifestyle guess a wetsuit and a hookah is in our future. Any thoughts on what’s the best prop to use for a wing? What’s the coating to prevent growth?

 

[Hippocampus]

Engines may be close. But you need two of everything else and would think transmissions, exhaust systems, shafts, props, hoses, gauges, alternators etc. would need to be duplicated. So to get the same shaft HP there would be a gain in weight.
Used to get on a old woody with a 3+3 Gardner. Although really just two blocks stuck together just one drive train. Don’t see twins making sense in this application

 

[rslifkin]

Space to work on twins varies widely even in the same size boat. Some have great engine rooms (Defever), others are crawl in, but have enough room to move and access everything (like my boat), and some are pretty much top-down access from hatches only with not much room to really get in there with the engines.

 

[Hippocampus]

Have put defevers on the list. Thanks

 

[Fletcher500]

This gets discussed a lot and there is nothing new I can add that hasn’t already been discussed. Our previous two boats had twins. We switched to a single 2.5 years ago. There are no guarantees in life, but I can say I have become very comfortable with our single engine and that includes going to some out of the way locations and periods of time when I am solo. But, we are coastal cruisers and stay within 50Nm from shore. If we were going farther ashore I would probably want a wing or twins. But then again, two of my ex college class mates paddled across the Pacific Ocean in a row boat, so it’s all relative.

 

[PNW Drifter]

One.

Same as your car, truck, motorcycle.

 

[IslandTractor]

....

So my ideal boat would be 1 main + 1 inverter bank + tons solar. But that's without aircon.

Yep, here in New England that is pretty much ideal for a cruising boat.

 

[fletch]

Two...

Ever since I forgot the seacock that time

 

[trawlercap]

Drove 123' trawler 28 years, Bering Sea. Single main engine, 3 aux. all Cats. No thrusters. I towed boats in, but never needed a tow.

 

[Fletcher500]

Impressive vessel Trawlercap.

The only thing I know about the Bering Sea is what I have watched on the Deadliest Catch TV series. I have googled their boats in the past and it seems most of the crab boats are twins, except for the Wizard which is an older converted WW2 boat. I realize that's just TV world, but are most of the crab boats twins and the draggers single?

 

[markpierce]

My father was flying a 4-engine plane at 27,000 feet when engine number 3 was lost. He bailed despite having three working engines because the fire was out of control.

 

[rslifkin]

Impressive vessel Trawlercap.

The only thing I know about the Bering Sea is what I have watched on the Deadliest Catch TV series. I have googled their boats in the past and it seems most of the crab boats are twins, except for the Wizard which is an older converted WW2 boat. I realize that's just TV world, but are most of the crab boats twins and the draggers single?

I know at least a few of the Deadliest Catch boats are singles. I'm 99% sure the Northwestern is a single.