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Old 12-13-2022, 06:04 PM   #641
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Wow, that's quite the list of upgrades.


By the way, what's the status of LH65?
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Old 12-14-2022, 06:02 AM   #642
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All the drawings (2d and 3d) are ready. Shipyard is ready to start building. Looking to find a first customer, as we ourselves are currently preoccupied with family affairs that take up a lot of time & energy.

Regards, Edwin.
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Old 12-14-2022, 09:29 AM   #643
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Salty are you planning on starting construing your prototype or do you need to wait until the first customer contracts with you?
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Old 12-14-2022, 09:38 AM   #644
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Ideally we'd start it ourselves, but currently - given our family circumstances - that is not an opportunity. Maybe in a year things will be different, but health has changed goals, unfortunately.

Regards, Edwin.
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Old 01-11-2023, 05:58 AM   #645
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S/L- and D/L-ratio's and more ...

With our current motorboat "Moonshine" at the shipyard and the LM65h project on hold for now, I did some calculations on S/L and D/L ratio's for both ships. See the picture attached.

Moonshine has a D/L-ratio of 246. I'd say that makes her an average weight boat, not a heavy or light weight one. The LM65h will be build out of aluminium instead of steal. Weight is pretty close to Moonshine's, but her LOW is much longer, resulting in a D/L-ratio of 111-ish. Now, that's definately light weight category.

Moonshine has a S/L-ratio of just 1.0 when we sail her at a cruising speed of 7 knots. The uses 9 liters per hour, or about 2.2 gallon per hour at that speed. Engine turns 1,500 rpm out of a maximum of 2,500.

On longer passages over sea, I'd like to go a bit quicker. Preferably 7.5 to 8 knots, instead of only 7. That would bring the S/L-ratio to 1.1 to 1.15. Fuel consumption does go up significantly though to 13 to 14 liters per hour. That's 3.2 to 3.5 gallons per hour, compromising total range, since she carries 2250 liters of diesel (550 gallons) total.

We are considering changing the current fixed prop to a Brunton's Autoprop for more efficiency at half load / cruising speeds. Should allow for a faster cruise without compromising on range.

Regards, Edwin.
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Old 01-11-2023, 06:59 AM   #646
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We are considering changing the current fixed prop to a Brunton's Autoprop for more efficiency at half load / cruising speeds. Should allow for a faster cruise without compromising on range.

Regards, Edwin.

Presumably the goal is to shift engine operation to a different rpm/torque combination that has better bsfc (fuel burn per hp or kw of power developed)? What engine(s) do you have, and do you have access to a reliable fuel burn map? They seem very elusive for many manufacturers.
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Old 01-11-2023, 07:10 AM   #647
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Fixed props are designed to operate at one explicite speed/rpm. Optimized for any boat, that's usually top speed, because: 1. That's where power is needed; 2. If you optimize for lower cruising speeds, if you go faster you over rev the prop, damaging it prematurely.

Now, a normal motorboat would have a 60% efficiency at that top speed, with the prop performing optimally, but if you look at "hp in the water charts", it is easy to establish that at anything lower than top speed, efficiency easily halfs, resulting in 30 to 40% efficiency only.

Since we run Moonshine at cruising speeds, and I want to both increase the cruising speed and the range, here's what the autoprop does: it automatically - based on rpm, water pressure, and torque - adapts pitch and diameter. It thus optimizes (with careful selection of the right autoprop) efficiency at any speed. Gain at top speed is neglegable, but at lower cruising speeds a 30 to 40% gain should be obtainable. Even at 1500 rpm and a 9 liter per hour fuel burn, the efficiency will now be closer to 60% instead of the 35-40%-ish, that we get now. This efficiency gain can be used for higher cruising speeds and/or longer range.

Here's an evaluation from some years ago:

http://mayrik.com/images/ArticleAutopropPM.pdf

Moonshine has a 6.1 liter Vetus Deutz 6 cylinder. M3/4-rating. Turbocharged. 170 hp at 2500 rpm.

Regards, Edwin.
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Old 01-11-2023, 07:39 AM   #648
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Originally Posted by Salty Pelican View Post
Fixed props are designed to operate at one explicite speed/rpm. Optimized for any boat, that's usually top speed, because: 1. That's where power is needed; 2. If you optimize for lower cruising speeds, if you go faster you over rev the prop, damaging it prematurely.

Now, a normal motorboat would have a 60% efficiency at that top speed, with the prop performing optimally, but if you look at "hp in the water charts", it is easy to establish that at anything lower than top speed, efficiency easily halfs, resulting in 30 to 40% efficiency only.

Since we run Moonshine at cruising speeds, and I want to both increase the cruising speed and the range, here's what the autoprop does: it automatically - based on rpm, water pressure, and torque - adapts pitch and diameter. It thus optimizes (with careful selection of the right autoprop) efficiency at any speed. Gain at top speed is neglegable, but at lower cruising speeds a 30 to 40% gain should be obtainable. Even at 1500 rpm and a 9 liter per hour fuel burn, the efficiency will now be closer to 60% instead of the 35-40%-ish, that we get now. This efficiency gain can be used for higher cruising speeds and/or longer range.

Moonshine has a 6.1 liter Vetus Deutz 6 cylinder. M3/4-rating. Turbocharged. 170 hp at 2500 rpm.

Regards, Edwin.


Thanks. So you are talking strictly about the efficiency of the prop itself? I guess a ratio of shaft HP to thrust? I would have expected prop efficiency to drop at higher revs, not increase, so this is quite interesting to me.
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Old 01-11-2023, 07:41 AM   #649
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It is! No, boats are more efficient at lower speeds, but the engine (or better: fuel burn translated into actual hp in the water) becomes much less efficient and looses up to 50% of its hp (delivered in the water) at cruising speeds. That's why the autoprop is such a great option for longer range cruisers: at the lower speeds we cruise at friction etc. are pretty low, now if we can almost double the prop efficiency ... that's like cutting fuel burn in half ...



Edwin.
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Old 01-11-2023, 09:29 AM   #650
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If I understand it correctly, a Variable Pitch Prop allows you to run higher pitch at lower rpmís to allow the prop curve to get closer to the HP curve allowing more speed (prop rpm)at the same rpm or same speed at lower rpm (but more actual HP input). Allows the engine to operate more efficiently. At WOT the pitch reduces to what would on a fixed pitch prop be the closest to max rpm and HP/prop curves meet. Itís all about loading the engine more efficiently through its operating range.

James
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Old 01-11-2023, 09:35 AM   #651
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Any thoughts on how this translates to parallel hybrid propulsion? Understand how the Autoprop is an advance over a fixed prop but accept a true CPP gives yet another gain in efficiency. So the question is although there’s a clear benefit with either a Autoprop or CPP for internal combustion is there any benefit for electric motors?
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Old 01-11-2023, 12:50 PM   #652
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I think your description is adequate, James. And the better load at lower rpm does not only result in a faster cruising speed and/or lower fuel burn, but - indeed - also loads the engine at lower rpm. Better for the engine and no need to do a 20 minute per 24h full throttle to burn the engine clean.

Hypo, I'd say the engine does not matter. Electric engines also have a power range and rpm and thus a prop that's tailored to the upper end.

I'd add to that that it - the autoprop - might even be more beneficial if the electric engine - as a hybrid - drives the main shaft. Usually in a "electric/hybrid/back-up"-situation, the electrical engine is much smaller in power / torque output than the main diesel. For that small back-up to push that big prop with big pitch through the water is less than optimal. Given the wide "spread" of the autoprop, it could be of tremendous help here.

On CCP's: the consensus seems to be that is an even better system, but it needs a lot of constant tweaking and is pretty darn expensive. Personally, I like the "auto" bit of the autoprop solution.

As an update, we just visited the shipyard. We decided to go for two 16 inch plotters instead of the two 12 inchers originally planned. Looks amazing, I won't have to use my reading glasses, and the dashboard is made for it.

The through-holes for the generator (10 kW) are put in place, as is most of the tubing. Generator itself comes end of February.

The Diesel Dipper is installed. It syphons water and sh*t from the very bottom of the tank, and - via a labyrinth - separates it from the diesel, thus preventing filter and/or engine contamination.

AIS is installed, as is the radar reflector. The Raymarine Doppler radar is also installed.

Two small dents in the underwater-ship have been pushed out and repaired. New (bigger!) batteries for bow and stern thrusters are in. The original traction house battery bank will be replaced by a 23 kW LiIon package.

The airconditioning unit is in, but still needs to be installed. The Dockmate (remote control for anchor, bow and stern thruster and main engine, for single-handed docking) is almost fully installed.

We are still considering an electric or other solution to help lower the mast. Might be something we do next year (if at all).

On the autoprop: it fits in the propellor window, so that's the good news. The less good news is that the prop window needs to be enlarged at the cost of a little bit of keel and rudder, that would need to be removed. Makes the operation a bit more costly than expected, especially since the autoprop is not cheap.

Next step is an upgraded calculation of the true gains we will achieve with the autoprop, so we can offset it with the investment. Hope that makes sense.

Plans? In May we'll leave for a few months of cruising in Scandinavia. From Holland to the top of Denmark, then starboard to Sweden. Return trip via the Danish archipelago and the Kieler Canal in Germany. End of August and beginning of September we'll join a flotilla that'll sail over the North Sea and Channel via Belgium to France (the Seine mouth, to be precise), and back.

Regards, Edwin & Veronika
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Old 01-11-2023, 02:03 PM   #653
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I've heard of maintenance challenges with the autoprops with relatively minor issues leading to significant vibrations. This is with smaller, saildrive mounted units but I was not impressed.
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Old 01-11-2023, 03:07 PM   #654
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Thanks for sharing. There is more maintenance involved, for sure. It needs greasing once a year and a re-assembly every 2,000 hours.

Personally, I am not anxious of damaging the prop, as our ship has a "enclosed" propellor window: the keel continues under the prop, the rudder is held in place from the top and from the bottom.

Regards, Edwin.
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Old 01-11-2023, 03:32 PM   #655
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If I understand it correctly, a Variable Pitch Prop allows you to run higher pitch at lower rpmís to allow the prop curve to get closer to the HP curve allowing more speed (prop rpm)at the same rpm or same speed at lower rpm (but more actual HP input). Allows the engine to operate more efficiently. At WOT the pitch reduces to what would on a fixed pitch prop be the closest to max rpm and HP/prop curves meet. Itís all about loading the engine more efficiently through its operating range.

James

Well said, and a bscf "map" will show this plotted for rpm vs torque across the engine's operating range.


The theory is that you are moving operation from one point on the fuel map to a more efficient point on the fuel map. But that's theory, and the actual fuel map for the engine is reality. I'm wondering if this is being done with a fuel map in hand knowing what results to expect. In my experience, these fuel maps are very hard to come buy, so it's nearly impossible to quantify the expected gains - something I'd personally want to do before spending a bunch of money to change propping. Scania published the bsfc numbers for my engine, but it's only along the prop load curve. The bscf is nearly flat across the whole normal operating range, suggesting there isn't much to gain by moving around on the map. But it's map a full map, so still leaves you guessing.
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Old 01-11-2023, 03:43 PM   #656
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Thanks for sharing. There is more maintenance involved, for sure. It needs greasing once a year and a re-assembly every 2,000 hours.

Personally, I am not anxious of damaging the prop, as our ship has a "enclosed" propellor window: the keel continues under the prop, the rudder is held in place from the top and from the bottom.

Regards, Edwin.
It wasn't an issue from being struck, it was just low tolerance to factors of wear or growth. What I heard of as problematic was the blades becoming loose on their individual shafts, either due to bearing wear or improper tension (assembly) and this in turn causing a vibration. The other issue was barnacle growth making a much more significant challenge to balancing due to their self pitching nature, if the foil shapes of each blade are no longer matched, the prop will vibrate significantly.
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Old 01-25-2023, 05:58 PM   #657
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More info, numbers, and calculations on the autoprop

First calculations on the autoprop are in. Fresh from Brunton's HQ. That's for our current motor yacht "Moonshine", a 50 feet steel water displacer with CE-A certification, build by Jetten in the North of the Netherlands. With a Vetus Deutz 170 hp inline six diesel.

At 7 knots, we might be able to save 37.5% in fuel, resulting in, well, 37,5% more range. That's pretty impressive. At 8 knots the calculations estimate savings above 40%, relative to our current use case. A cruising rpm of 1,500, that we often use, results in an increased speed of 7.75 knots vs. the current 7 knots.

I am having all the numbers re-evaluated as we speak, by the way. I know the calculations are no guaranty, but I want to understand the info behind it (fuel map, prop info, ship's weight, LOW, average draft of canoe body, practical info, etc.). If we can get the current fixed prop calculations as close to where they are in practicality, that'll result in a better prediction model.

So far, the first indications show a range increase of 3000 to slightly above 4000 kilometers. Fuel burn at 7 knots - for longer crossings - would become an estimated 2 Nm per gallon.

MVTanglewood: yes, we have the actual fuel maps. I feel they are essential to make predictions that actually make sense and that can be expected to translate into real life gains.

More technical info on how the autoprop works its magic:



Regards, Edwin.
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Old 01-26-2023, 12:13 AM   #658
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The Autoprop sounds intriguing, although the marketing mostly appears to be targeting sailboats. From a realistic perspective however, cost is usually a big factor with boat owners. I see online that a 22" model costs about $6500. However, for most "trawlers" we'd be looking for something in the 36" to 48" diameter range. So if the cost is (guessing) about $20k to $25k, then that is a important thing to consider. Twenty grand does buy alot of fuel, or even a variable pitch prop, which is a well-known and proven option.

Appreciate if you could share some actual numbers for your new build. Thanks
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Old 01-26-2023, 06:11 AM   #659
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Hemisphere Dancer, a powerboat that cruised South-America, has changed to autoprops and is very happy with the results and outcomes. Here's the read of their experiences & learnings:

http://mayrik.com/images/ArticleAutopropPM.pdf

Hi Mako, I agree that it is a hefty investment that needs to be offset with how much fuel it will save. But that's just one of the metrics. The other one, which is quite important to us, is the added range. This allows us more use-cases for our boat.

Anyhow, the autoprop we need costs EUR 8.000,- ex taxes. That'll be around 10k including taxes in North-America.

Regards, Edwin.
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