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light engine for racing boat 7,5 tones displacement + LiFePo system


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Can a Volvo Penta D1-30 (max 28.4 HP at crankshaft) with an 130S saildrive (max 26 HP propeller shaft power) be used on a racing boat with a 7500 kg displacement, that will also have attached an Mastervolt alternator alfa 12/130 for charging Mastervolt LiFePo batteries  MLI 12/5500?

The alternator seems to use also about 3-4 HP (130Ax14.25V = 1,85kW = 2,5 HP)

Max 26 HP at propeller would be at 3200 rpm, but in normal conditions at 2200 rpm would be 8 HP at propeller.

Is that such a rule of thumb is that race boats should have 1 HP per thousand pounds of displacement?

So for 7500 kg is about 16500 pounds so based on the above "rule" would be 16 HP, which is enough according to the above "rule".

So can the Volvo Penta D1-30 be used in such a setup?

Any considerations?

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Kind of depends on the design of the ‘racing’ yacht. Many older Imoca 60s weigh around 7.5 tonnes and they have 30hp engines but that will only really get them on and off the dock. But motoring into a headwind just isn’t going to work. On the flip side a Rustler 36 also displaces 7.5 tonnes and as standard it comes with a 29hp engine which is probably good for 7-8kts of speed

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4 hours ago, JL92S said:

Kind of depends on the design of the ‘racing’ yacht. Many older Imoca 60s weigh around 7.5 tonnes and they have 30hp engines but that will only really get them on and off the dock. But motoring into a headwind just isn’t going to work. On the flip side a Rustler 36 also displaces 7.5 tonnes and as standard it comes with a 29hp engine which is probably good for 7-8kts of speed

So charging ‘resistance’ + wave making (s/l?) + wetted surface + windage?  And then the type of prop, and, and, and..... as usual with boats it gets complex, esp with some things going up by the cube and other things the square.  Does anything go up linearly?

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I cruised a 36 ft boat at around 8 t. Had a 22 hp diesel and fixed 2-blade. Was plenty. Did the Baja Bash many times. An Express 37 race-only boat here, 4.5 t, has a 12 hp diesel with folding prop. Shakes the boat to a blur but is way more than "on and off the dock". Good enough for tooth-loosening overnight offshore deliveries.

I doubt the alternator will output 1.8 kW for more than a few minutes before it reaches its thermal limit. So temper your expectations. However it will make a good system.

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I really appreciate the feedback.

The problem is somehow related to the fact that the choice of the engines is quite limited. By looking on the internet O understand that the cause is due to environmental directives in E and EPA regulation in the USA, so some engines that were available till few years ago, are not possible to installed on a new boat by the constructor due to this regulations. For an unknown reason, probably it can be changed, there are only two alternatives provided: Volvo Penta and Yanmar. Probably only some models of the engines can be fitted to the boat.

So I made a table with these engines

 
Manufacturer Model Weight Power cyl Notes
1 Yanmar 3YM30AE+SD20 157 kg 29 HP 3  
2 Volvo Penta D1-30+130S 158 kg 28.4 HP 3  
3 Volvo Penta D2-40+130S 189 kg 40 HP 4 Recalled due to pollution
4 Yanmar 3JH5E+SD60 216 kg 38.5 HP 3 EU:RCD2 BSO2 EMC
5 Yanmar 3JH40+SD60 236 kg 40 HP 3  
6 Yanmar 4JH5E+SD60 245 kg 53 HP 4  
7 Yanmar 4JH4-TE+SD60 251 kg 75 HP 4  
8 Volvo Penta D2-50+130S 253 kg 50 HP 4  
9 Yanmar 4JH45+SD60 258 kg 45 HP 4 New model
10 Volvo Penta D2-60+150S 264 kg 60 HP 4  
11 Volvo Penta D2-75+150S 264 kg 75 HP 4  

Seems that there is hard to find a 40 HP engine, as I suppose that this will suit the purpose, as I see such engines installed on similar boats (i.e. Swan 42)

The Volvo Penta D2-40 is not anymore installed on new boats and i found information that it was recalled.

Seems that the only options offered to be installed are those in green, but there are 100 kg between a 30 HP engine and a 50-75 HP engine.

I cant understand why the builder is not happy to install  a Yanmar 3JH5E, as i see that it has

Environmental compliance RCD2 (rcd2 = recreational craft directive 2013)

https://www.yanmar.com/marine/wp-content/uploads/2020/05/Yanmar-Datasheet_3JH5E.pdf

From here it derives also the question if the Volvo Penta D1-30 could be an option as the constructor can install it and the next option seems to be 50 HP at 100 kg more.

Is there any point to stress the constructor to install the Yanmar 3JH5E, or did they have a reason why this is not an option for them (boat produced in EU)?

Should I try to figure if the the Volvo Penta D1-30 can be still used in a 44 feet 7.5 tones weight in safe conditions or just to exit/enter the harbor during race days.

Or should I just give up and install a 50-75 HP engine, 100 kilograms more?

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Your alt will take away HP from shaft - but how much will depend on the batt state of charge. Once batt bank is charged, alt HP draw will decrease close to zero. So depending on size of batt bank & depth of discharge you can have full output getting to shaft. Also, check out the programming specs on the alt regulator - some smart regs can restrict output to reduce alt HP draws.

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11 hours ago, iurie said:

Is that such a rule of thumb is that race boats should have 1 HP per thousand pounds of displacement?

That is a very old rule of thumb for sailboat auxiliaries, not just race boats - 2HP per ton of disp.

It worked well for decades until people started treating all boats like they were  motorsailers which is when the horsepower wars started.

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Why do you think that Volvo should be operated at only 2200 RPM? I have a 30 HP Volvo MD 2030 in a 15,500# (empty) performance cruising sloop of 39'3" LOA and the owner and engine manual call for fast cruise at 300-500 RPM under full throttle performance or 80%. At full throttle my engine can make 3650 RPM on my tach. At a touch over 3,000 RPM I can maintain a little over six knots against a 15-20 kt wind and sea state with a 70 amp Balmar alternator and sail drive with Gori folder and I've done it for multiple hours. That's with the boat loaded for a long coastal delivery. An old 40 HP Perkins 4108 or Westerbeke equivalent would probably run at 2200-2400 RPM with the same performance.

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Modern diesel engines (Yanmar etc...) are very much more efficient, and cleaner too, when running near or at designed optimum speed.  Output goes up faster than consumption.  Think about a generator engine running at 2800-3000 for hours on end.

A long time ago we were planning an eventually un-built ULDB maxi for the 89/90 Whitbread.  75 feet, and just 12 tons. We decided to take the IOR rating hit and put in a retracting propeller.  This cost us, I think two feet of rating.  

OK, it was a bit heavier than a standard shaft, P-bracket and folding or feathering prop, but it meant we could do a highly efficient 5-blade fixed propeller on the retractor leg, matched to a tiny engine, as we didn't need the IOR engine weight.  I think we settled on a 29hp 3-pot Yanmar, as it was all that was required to get us up to rule hull speed.  We lost a mountain of weight, and fuel tankage too.  Spring starter too, to save on starting battery, alternator and starter motor.

A retracting propeller (if rule legal) would really help a modern boat, not just at 20 knots plus, where prop drag can become significant, but in very light air where you drift along nicely with just your clean foils in the water. 

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9 hours ago, iurie said:

I

3 Volvo Penta D2-40+130S 189 kg 40 HP 4 Recalled due to pollution
             

The Volvo Penta D2-40 is not anymore installed on new boats and i found information that it was recalled.

 

Any other info on the recall? A friend of mine has one in his boat and was curious.

I believe they make a D2-50 now which is the same engine block.

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6 hours ago, woodpecker said:

Any other info on the recall? A friend of mine has one in his boat and was curious.

I believe they make a D2-50 now which is the same engine block.

Here it is the info from 2017:

https://www.cruisersforum.com/forums/f136/volvo-penta-d1-30-and-d2-40-engine-recall-188024.html

Here is information for the new D2-40 being EPA tier 3 compliant (sold 2017-2018 - http://verdemotors.ro/fisiere/RepoweringCampaign.pdf)

https://www.navaboats.com/pdf/D2-40_EPATier3.pdf

However this engine is not anymore found on Volvo Penta website, where its start from D2-50.

https://www.volvopenta.com/marine/products/saildrive/saildrive-engine-range/d2/

 

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10 hours ago, kinardly said:

Why do you think that Volvo should be operated at only 2200 RPM? I have a 30 HP Volvo MD 2030 in a 15,500# (empty) performance cruising sloop of 39'3" LOA and the owner and engine manual call for fast cruise at 300-500 RPM under full throttle performance or 80%. At full throttle my engine can make 3650 RPM on my tach. At a touch over 3,000 RPM I can maintain a little over six knots against a 15-20 kt wind and sea state with a 70 amp Balmar alternator and sail drive with Gori folder and I've done it for multiple hours. That's with the boat loaded for a long coastal delivery. An old 40 HP Perkins 4108 or Westerbeke equivalent would probably run at 2200-2400 RPM with the same performance.

I did not said that it should be operated at 2200 RPM, but I said that if the batteries will be charging, then the alternator will consume something around 4-5 HP (which I understand is not fully correct and can be regulated trough  alfa pro III  regulator). I just assume that if the batteries are discharged (80%) than they should be charged and if they will be charged normally than it will be a drop of 4-5HP. This means that if the engine will be running at 3000 rpm, then the power will be 27-4=23 HP, that correspond to the engine running at 2200 rpm, for which the power at propeller will be 9 HP.

This is actually indicating that when charging the batteries at full charging speed, the engine cant be really used for boat propulsion during storm. But if the batteries are charged, or if decided not to charge them even if they are discharged, then the engine could be used for boat propulsion during  a storm?

My question is in relation to safety, not to transform a sailing boat into a motor boat.

Thank you for indicating MD2030 Volvo Penta. Seems that can run at higher rpm than D1-30 at it has the same weight. But is this engine still sold bu Volvo Penta, or it has the same problem of not being anymore compliant with environmental regulations?

Here is the full list:

https://www.volvopenta.com/marine/products/inboard-shaft/inboard-shaft-engine-range/#/all

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I computed with Gori propeller calculator and there are warnings

Of course I am not expecting to achieve hull speed by motoring, but this is computed by the software, I have no choice to change it:

https://gori-propeller.com/en/calculate-propeller/

Waterline Length (feet):    44
Beam:    14
Draft:    9.1
Displacement (tons):    7.5
Displacement w/full tanks (tons):    7,55
Estimated Hull Speed:    8,89
Suggested Minimum Engine Horsepower:    30
Number of Engines:    1
 
Engine Details
Manufacturer:    Volvo Penta
Engine:    D1-30
Max. Horsepower:    28,4
Max. R.P.M.:    3200
Reduction in Gearbox:    2,19:1 130S(R)
 
Calculated Propeller
Racing Blade:    425 x 300 LHS/RHS

The calculated propeller is the suggested propeller for your sailboat and engine installation. Our suggestions are based on propeller calculations using up to date computer software combined with our long time experience suggesting propellers for sailboats. Though every attempt has been made to guarantee the accuracy of the information and propeller calculation, we refuse to accept any responsibility for errors or omissions. The only way to ensure a correct propeller match for your sailboat and engine is to make a seatrial. On very rare occasions, if we have suggested a propeller that does not match the boat and engine information provided, then we will exchange or modify the propeller, but we don't cover any other costs involved, except for our own parts.

Warning
The available HP is smaller than the usual required HP to achieve hullspeed on a boat like yours. Please contact us before ordering.

Warning
There is an unusual big difference between the estimated hullspeed of your boat, your previous topspeed under power and the expected speed. The propeller sizing you get here might need modification, please contact us before ordering.
 

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There is something a bit odd with your numbers, a class 40 which is just a bit shorter displace 4.5 metric tons. What kind of tons are you using? 

IME bigger racing boats (40ft) tend to have a 3 cylinder engine which is plenty enough for how these engines are used. Also if you plan to use the engine to recharge batteries at sea (quite typical!), you probably don't want it to be too powerful so that the alternator can add a big enough load compared to the engine size. Apparently it is bad for the engine to be used unloaded...

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4 hours ago, iurie said:

I did not said that it should be operated at 2200 RPM, but I said that if the batteries will be charging, then the alternator will consume something around 4-5 HP (which I understand is not fully correct and can be regulated trough  alfa pro III  regulator). I just assume that if the batteries are discharged (80%) than they should be charged and if they will be charged normally than it will be a drop of 4-5HP. This means that if the engine will be running at 3000 rpm, then the power will be 27-4=23 HP, that correspond to the engine running at 2200 rpm, for which the power at propeller will be 9 HP.

This calculation isn't quite right - power absorbed by the prop is directly related to rpm, but drops non-linearly with rpm. So at 3000 rpm your engine could produce 27hp (on a test dyno, that's the top curve), but with the standard prop will only be producing the 23hp absorbed by the prop (the engine governor will only add enough fuel to maintain rpm). This is because the prop is sized so that it absorbs full engine power at full rpm. So from that chart you could actually run at 3000 rpm and have enough power to deliver 23hp to the prop, plus have 4hp to the alternator. But this is a bit of an "overpropped" situation, since with the alternator load you can now no longer reach full rated rpm with the standard prop. But with the adjustable alternator that may not be a problem.

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If one is motoring in a storm, or foul weather on the nose, such pain normally continues for many hours. Full rate battery charging is then not required because there is plenty of run time required anyway.

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6 hours ago, Panoramix said:

There is something a bit odd with your numbers, a class 40 which is just a bit shorter displace 4.5 metric tons. What kind of tons are you using? 

IME bigger racing boats (40ft) tend to have a 3 cylinder engine which is plenty enough for how these engines are used. Also if you plan to use the engine to recharge batteries at sea (quite typical!), you probably don't want it to be too powerful so that the alternator can add a big enough load compared to the engine size. Apparently it is bad for the engine to be used unloaded...

I agree that 40 feet boat could be at 4.5 tons. However there is a big difference between 40 and 44 boats.As someone already mentioned on this thread the difference it with cubic factor, not just linear.So it is not just 10%. As an example Swan 42 that is competing at ORC has approx 7 tones. So a 44 fiber glass boat at 7.5 tones will be actually not heavy at all.

Probably I forgot to mention that the boat is fiber glass, not carbon.

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2 hours ago, andykane said:

This calculation isn't quite right - power absorbed by the prop is directly related to rpm, but drops non-linearly with rpm. So at 3000 rpm your engine could produce 27hp (on a test dyno, that's the top curve), but with the standard prop will only be producing the 23hp absorbed by the prop (the engine governor will only add enough fuel to maintain rpm). This is because the prop is sized so that it absorbs full engine power at full rpm. So from that chart you could actually run at 3000 rpm and have enough power to deliver 23hp to the prop, plus have 4hp to the alternator. But this is a bit of an "overpropped" situation, since with the alternator load you can now no longer reach full rated rpm with the standard prop. But with the adjustable alternator that may not be a problem.

So I just understand that is is just a meter of more fuel consumption actually and the alternator will charge the batteries on a longer time. Sorry for these questions but I am not familiar with LiFePo batteries systems, so I am on the learning curve.

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2 hours ago, El Boracho said:

If one is motoring in a storm, or foul weather on the nose, such pain normally continues for many hours. Full rate battery charging is then not required because there is plenty of run time required anyway.

That's a good point. Thank you for clarification. It means that actually the electrical system should be monitored before and during storm.

I am thinking in acquiring:

Category

Brand

Item

p/n

Details

Main battery

Mastervolt

MLI 12/5500

66012750

2 batteries x 27kg

Protection

BlueSea

Remote battery switch

7700B-BSS

0.9 kg

Inverter

Mastervolt

mass sine 12/1200

24011200

6 kg

Charger

Mastervolt

chargemaster 23/50-3

44010500

4 kg

Charger

Mastervolt

macplus 12/12-50

81205100

2 kg

Distribution

Mastervolt

dc distribution 500

77020200

1.2 Kg

Alternator

Mastervolt

alfa 12/130

48612130

10 kg

Regulator

Mastervolt

alfa pro III

45513000

0.4 kg

Shore power

Mastervolt

ss2+PE 16A/230V

121160000

 

Protection

Mastervolt

shorefix 16A/30mA

124001000

0.7 kg

Conexions

Mastervolt

Combination Output Interface (COI)

80-911-0119-00

1.9 kg

Alarm

Mastervolt

Digital DC 10x10A

77020400

0.7 kg

Display

Mastervolt

CZone Touch 7

80-911-0200-00

0.7 kg (1.56Wh stand by)

Meter interface

Mastervolt

Meter Interface (MI)

80-911-0005-00

 

Fuse

Mastervolt

MasterShunt 500 CZone

77020115

0.7 kg

Fuse

Mastervolt

MasterShunt fuse

77049000

 

Engine start battery

Optima

Optima Blue Top SLI

Or

Optima Red Top 34

BT-SLI-4.2

Or

9002-002

17.4Kg - 1000 CCA or 800CCA

Battery switch

BlueSea

Battery switch

11001

0.6 kg

 

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You're using the prop / engine curve wrong. Operate at 2800 RPM and the gap between what the engine can produce and the demand (prop demand + alternator load) is such you won't overload the engine. 

We had a 7.5 T catamaran with a single 27 Hp Yanmar. Not very fast motoring into a headwind (lots of air drag with a cat) but certainly enough power to motor at 5 knots at 2600 RPM /6.5 knots at full power

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8 hours ago, Panoramix said:

Also if you plan to use the engine to recharge batteries at sea (quite typical!), you probably don't want it to be too powerful so that the alternator can add a big enough load compared to the engine size. Apparently it is bad for the engine to be used unloaded...

Good point. Thank you.

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Running at fast idle for extended periods is indeed bad for the engine, but adding in run periods at full continuous RPM will cancel those effects. On a delivery from Oahu back to SoCal, it will take 14 -21 days of low RPM batt charging to keep boat running. Any motoring across the high is also done in low/med RPM to conserve fuel. When on final approach, having a definite arrival time, I run engine at full RPM for 45 - 60 minutes. At the start of this run, exhaust will be showing quite a bit of blue smoke. At the end of the run, as engine has come up to full temps, smoke and discharge water will be clear

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11 hours ago, Zonker said:

You're using the prop / engine curve wrong. Operate at 2800 RPM and the gap between what the engine can produce and the demand (prop demand + alternator load) is such you won't overload the engine. 

We had a 7.5 T catamaran with a single 27 Hp Yanmar. Not very fast motoring into a headwind (lots of air drag with a cat) but certainly enough power to motor at 5 knots at 2600 RPM /6.5 knots at full power

That's why I asked. Thank you for clarification. However is still not clear how to use the prop & engine curves by adding also the the alternator, but is good to know that even a 7500 kg catamaran could have an engine of 27 HP. Engine is not for speed, but I want to be sure that is safe enough during storm and that also the batteries can be charged (faster or slower, it is not important)

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Some smart regulators will allow you to manually control the output of the alternator. My Swede 55 had a 22hp diesel and a big 165amp alternator. I had two switches- one reduced alternator output by 50%, and the other stopped load altogether. These were “oh shit” switches, when you needed full engine power dedicated to moving the boat.

I never needed them, but they were there just in case.

 

 

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On 11/14/2020 at 2:26 AM, iurie said:

Volvo Penta D1-30

Look at it this way. At a given RPM the engine can produce X HP. That HP has to be greater than the combined demand of alternator load + prop load. If it cannot, the engine will slow down until the prop + alternator load matches available HP. 

For example at 2800 RPM there is enough power available to provide 18 HP to the prop, 4 HP to the alternator, and have 4 in reserve. Ooops typo in my write up on the engine graph. The engine is only putting out 26 HP at 2800 RPM. But still has 4 HP in reserve.

image.thumb.png.5acaead44ab2d9aa22eeb487b3f27185.png

This is mostly because the shape of a prop demand curve doesn't match the available power from an engine very well, if you are using a fixed pitch prop.

It is only at maximum RPM, where the propeller can absorb all the power of the engine, that there is no reserve power left for  the alternator.

An alternator disconnect switch might not be a bad idea for your application. Just make sure it stops the field current first before stopping the output. Technical details are left to the more electrically inclidned.

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@Zonker I think that in between the two curves is the power that is spent in the saildrive 130S due to friction and the efficiency of transformation between rotation of the propeller and the movement of the boat. Higher the RPM -> higher the efficiency. But maybe I'm wrong.

I compare with a car. If a car has a small engine I can travel with 150 km/h maximum speed. But if I turn on the Air conditioning I am able to travel with a maximum of 130 km/h.

However if the car has a big engine, I can travel with 200 km/h with or without air conditioning as it does not count at all. I am never able to reach 220 km/h due to safety reasons even if most probably the car is able.

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3 hours ago, Slowboat said:

Some smart regulators will allow you to manually control the output of the alternator. My Swede 55 had a 22hp diesel and a big 165amp alternator. I had two switches- one reduced alternator output by 50%, and the other stopped load altogether. These were “oh shit” switches, when you needed full engine power dedicated to moving the boat.

I never needed them, but they were there just in case.

That's a good hint. Would be nice to put an ”oh sheet 50%” and ”oh big sheet” label on top of the two switches :D.

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The loss in 2x 90 degree bevel gears is about 5%. It's there but it's not that significant.

You lose a similar amount between a conventional stuffing box & cutless bearing in a propeller strut.

In other words ~1 HP or so.

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On 11/14/2020 at 7:36 AM, Amati said:

So charging ‘resistance’ + wave making (s/l?) + wetted surface + windage?  And then the type of prop, and, and, and..... as usual with boats it gets complex, esp with some things going up by the cube and other things the square.  Does anything go up linearly?

Cost of dinner when adding the kid's friends. Well, come to think of it, they are hungry little buggers, maybe it goes up by 1.34 * the number of extra mouths?

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On 11/15/2020 at 3:37 AM, Panoramix said:

Also if you plan to use the engine to recharge batteries at sea (quite typical!), you probably don't want it to be too powerful so that the alternator can add a big enough load compared to the engine size. Apparently it is bad for the engine to be used unloaded...

Amen to this! A bigger load from a high speed alternator is mandatory if you use your engine at anchor to charge your batteries. Otherwise, the engine doesn't get up to proper temperature and you get glazing of the cylinder walls with loss of compression. At that point you have to tear down the engine and either re-sleeve or at least hone the cylinders.

Ask me how I know. :wacko:

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1 hour ago, kinardly said:

Amen to this! A bigger load from a high speed alternator is mandatory if you use your engine at anchor to charge your batteries. Otherwise, the engine doesn't get up to proper temperature and you get glazing of the cylinder walls with loss of compression. At that point you have to tear down the engine and either re-sleeve or at least hone the cylinders.

Ask me how I know. :wacko:

I do not expect the batteries to be charged at anchor at all, but either during boat transfer (decrease in boat speed is expected) or during long regatta (day and night) when the batteries need to be charged without using propeller. Otherwise batteries are charged at shore.

Proposed engine Volvo Penta D1-30 with 130S sail drive

Proposed alternator: Mastervolt  alfa 12/130 (48612130)

Batteries to be charged 2 or 3 Mastervolt MLI 12/2750

Any considerations?

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12 hours ago, Zonker said:

An alternator disconnect switch might not be a bad idea for your application. Just make sure it stops the field current first before stopping the output. Technical details are left to the more electrically inclidned.

Opening the field circuit of an alternator stops the output and engine load. No need to put a switch in the output wire. So just a small switch to disconnect the field will do. It may cause the ALT lamp, alarm and tach failure on the engine panel, though, so some more design may be required. 

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My Swede had an Ample Power smart regulator and the regulator controls alternator output (just like it would for charging batteries effectively) with different modes and charging curves. They had built in the controls for limiting output and stopping charging all together, so it was all done via the external regulator- not an actual disconnect of the field or output wires. It also had something like a 30 second or one minute delay on ramping charging amps after you started the engine, which was very smart.

 

 

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1 hour ago, El Boracho said:

Opening the field circuit of an alternator stops the output and engine load. No need to put a switch in the output wire. So just a small switch to disconnect the field will do. It may cause the ALT lamp, alarm and tach failure on the engine panel, though, so some more design may be required. 

Yeah, totally agree. Just wanted to ensure that was the approach; not just disconnecting the output.

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8 hours ago, kinardly said:

Amen to this! A bigger load from a high speed alternator is mandatory if you use your engine at anchor to charge your batteries. Otherwise, the engine doesn't get up to proper temperature and you get glazing of the cylinder walls with loss of compression. At that point you have to tear down the engine and either re-sleeve or at least hone the cylinders.

Ask me how I know. :wacko:

Yes this is well documented.

ISTR that on Figaros they have a big alternator fitted to minimise this and also the time necessary to recharge the batteries. Figaro 1 were definitely single cylinder engine, may be on the 2s and the 3s they have a dual cylinder.

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