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S&S Swan Maintenance - Potential engine replacement for a Swan 41
26 April 2010 - 13:37
#1
Join Date: 27 August 2009
Posts: 44

Potential engine replacement for a Swan 41

As part of an up-grading programm and as many other old S&S Swan owners I am considering changing the 4.108 Perkins, which is leaking oil.

I am being offered to replace it with a Nanni 60HP as it sounds to be the engine that requires the least modifications to the existing surroundings.

Does this sound right to people familiar with the matter?

What feedback could be provided to me on Nanni engines. Are they reliable? Efficient? Is it easy to find spare parts in The Atlantic and in the Mediterranean sea? Are there less noisy than the 4.108 Perkins?

Is there any usefull tips I should be aware of before making any decision?

Any input would be greatly appreciated.

Many thanks in advance. 

26 April 2010 - 15:37
#2
Join Date: 02 March 2007
Posts: 83

Dear Christophe,

  I started looking at a replacement engine for my "41" , but as yet hav'nt gone ahead with it. I thought it was important to use an in line gearbox, in order to keep the height low, and as I have recently fitted a reconditioned Borg Warner, decided to keep the gearbox. I got a quote from Betamarine, who do a Kubota BV1505 marinisation. I have attached the quote. I thought this was quite expensive for an engine without gearbox.

 

regards Cosmo Little

Dear Mr Little.

 

Thank you for your e-mail.

 

The price of our Beta 38 (BV1505) delivered to Falmouth is £5127.00 including VAT and delivery.

 

Beta 38, heat exchanger cooled.

No gearbox but with adaptor, drive member and oil cooler for a Velvet drive gearbox.

Panel with tachometer and 3m loom

Flexible mounts

Sump drain pump.

Wet or dry exhaust outlet

Special feet, see drawing SK087096 that must be completed, with as many dimensions as possible.

65 amp alternator

Calorifier connections

Tri Wall packing

Delivery to Falmouth

 

I hope this helps, if you need a full written quotation please let me have your postal address.

 

Best Regards

 

Andrew

Beta Marine Ltd

27 April 2010 - 04:27
#3
Join Date: 02 June 2007
Posts: 4

Christophe,
i replaced my Perkins 4-108 with a Beta 50 HP 2 years ago (I kept the original Borg-Warner transmission - which I had rebuilt). The price was about the same as a Yanmar, but my mechanic recommended the Beta so highly I went with it. It is quieter than the Perkins ( though the 1/2" of sound insulation I added certainly helps!). I can't speak to replacement parts in the the Med or Atlantic - I'm on US pacific coast, and was assured parts in Central & South America and So Pacific are readily available.
I have been happy with the engine and the installation was pretty painless....
Good luck!
Richard King
SURPRISE
431/018

29 April 2010 - 09:40
#4
Join Date: 19 June 2007
Posts: 23

Dear Christophe, I honestly think that a 60hp engine is way too big what your boat’s needs. You probably will not be able to swing the right prop for that size engine because the prop aperture on your hull is not that big. I did all the calculations to get the right size replacement engine on my boat (S/40) and the result was between 33 and 35 hp, including an extra 5hp for adverse conditions and a high output alternator. I ended up installing a Kubota based 37hp which I now think is bigger that what I need. With the original aperture I could not swing a prop bigger than 13.5 inches, so basically I could not use my new engine to its full potential. So I had to open the aperture to the max I could in order to have a larger prop. My boat now reaches hull speed but it squats (at top end) to the point that I get water in the cockpit through the scuppers, my fuel consumption increased while my fuel tank remained the same so obviously my range under power is less. Bigger is definitely not better in this case. I dealt with the whole subject so much that I became a rep for Phasor engines (Kubota based). Beta marine, Universal and Nani marinize that same Kubota engines each in their own way.

29 April 2010 - 14:45
#5
Join Date: 27 August 2009
Posts: 44

Thank you to all for your input.

As relates to comment on 60hp, although 60hp may sound large, I was wondering if part of the explanation was not coming from the fact that the S&S 40 and S&S 41 don't share the same weight. The 40 weights 8.600KG and the 41 10.800KG, which makes a difference! On the same line, the initial engines installed on the 40 were Volvo Penta MD2B giving 25HP at 2.500rpm whereas for the 41 it was a Perkins 4.108 giving 37HP at 3.000rpm.

Since I have posted my thread I also had a phone conversation with the owner of Kallinira (Swan 41) who has installed a Nanni 60 in 2007 and has confirmed to me that the engine was giving him full satisfaction. Kallinira has since than crossed the Atlantic back and forth so it is a highly valuable feedback for me.

I have not yet made my final decision as we are still discussing around pricing issues and timetable. I am currently being offered circa €20.000 for a full engine replacement and installation.

Any more feedback appreciated.

Fair winds.

Christophe

 

29 April 2010 - 22:04
#6
Join Date: 01 February 2007
Posts: 234

Christophe, just to confuse you more I replaced my Perkins 4108 with a Perkins MD 65 which is the same size as the 4108. It produces 65 HP at 2300 revs. I had a Borg Warner 72CR reverse reduction gearbx fitted with 2.1 reduction. 70 Amp alterntor fitted

I took the opportunity to replace shaft and exhaust at the sametime. Semed silly not too.  

No turbo, just a lot of HP at low revs which means low full comsumption and simple maintenance.  We can get 3.5 litres per hour at 1800 revs at 6 knts.

30 April 2010 - 19:47
#7
Join Date: 02 January 2008
Posts: 1547

Dear Christophe

When choosing an engine there are several aspects to consider, amongst them the marketing and the technical aspects.

The marketing aspect says that the more power the better, this thinking comes from the automobile industry.

The technical aspect says that things are not that simple for yachts, and that the end results depend on several factors.

As a representative for the technical side of things I would like to propose some thoughts for your consideration.

Although the procedure usually is that the engine is chosen first, and then the gear ratio and propeller as an afterthought, this is not necessarily the proper way, particularly for S&S Swans which tend to have restricted space for the propeller.

With the powerful engines put in today the propeller often becomes too small for the engine, and can not absorb all the power available. The maximum capacity of the propeller is related to its blade area and speed of rotation. Swan 41 has a 17" propeller, and with two blades it can absorb less than 30 hp, with three blades about 40 hp efficiently. Over that increasing loss of propeller thrust begins to restrict the advantages of additional power. There are, however, considerable differences between propeller brands in reference to efficiency when highly loaded.

For cruising speed in calm weather very modest power is needed, at six knots some 15 hp is sufficient . This is by the way confirmed by John's statement above, according to the M65 performance sheet the propeller absorbs the mentioned power at 1800 rpm. The stated fuel consumption 3.5 litres per hour is a little high, normally less can be expected.

The propeller size and speed of rotation influences the fuel consumption, and it is important to check which gear ratios are available, and select the proper one. The lowest shaft rpm normally gives the best performance for sailing yachts, but if the propeller diameter is restricted a higher rpm may give better results. This requires comparative calculations, and the engine suppliers do not always provide such services, they tend to be influenced more by the marketing aspects.

Some thougth should also be given to the relation between planned cruising power and maximum power: The engine manufacturer's recommendation is that at least 25% of the maximum power should be used for extended cruising, otherwise the engine will suffer. The maximum fuel consumption is stated on the engine performance sheet, take 25% of this and work out for how many hours the fuel tank capacity will last.

Also, it should be noted that 25% of maximum power is achieved at about 63% of maximum rpm, and not at 25% rpm.

Pls feel free to ask if some points need clarification

Kind regards

Lars

01 May 2010 - 21:12
#8
Join Date: 30 January 2007
Posts: 15

I have the original engine and gearbox in my boat (swan41/41). I like the Perkins which seems fine but the gearbox is grumbling. I would like to recondition the gearbox and replace the engine with a re-manufactured Perkins 108. Is this crazy? If not does anyone know of a source of re-manfactured engines (I live in the UK)?

Rob

02 May 2010 - 10:57
#9
Join Date: 27 August 2009
Posts: 44

Professor,
Many thanks for your highly valuable comments.
Would a 4 blade vari-prop be installable? What figures would you need to confirm?
Many thanks in advance.
Christophe

02 May 2010 - 15:08
#10
Join Date: 27 August 2009
Posts: 44

Professor,

I was trying to send you some further details on the engine as found on the internet site: www.nannidiesel.com but it seems that I can't easily do it with the 4,0 Mb constraint. May be you could take a look at the site under Nanni N4. 60 - Kubota base and you will see in the attached leaflet that technical details are being provided for this specific engine.

Talking about engine power / consumption, if my understanding is correct, maximum power is 60HP at 2,800rpm. Should I apply your 63% ratio, I find 1,764rpm. This in turn leads me to a circa 4 liters per hour consumption leaving me with circa 25 hours range for a 100 liters tank. Taking a different angle, 25% of the maximum consumption of the engine leads to 3.5 liters which would leave me with 28hours of autonomy + or -. Is my understanding correct?

Turning back to the propeller side of things, how should I decide which propeller is the most appropriate? Looking at Matteo's Only You, it seems that he has installed a 4 blades Vari prop. Hence my previous thread.

One last question on easiness to handle the boat. Are 4 blades propeller easier to deal with when motoring backwards? I find the 2 blades propeller quite challenging in some crowdy situations in some ports where you get at the same time current and wind.

Thanks again for your input.

Best regards.

Christophe

02 May 2010 - 15:15
#11
Join Date: 29 January 2007
Posts: 913

Dear Christophe,

I changed the 4 blades VariProp, I was not happy with it, even if the mechanism to set the pitch was OK, it was quote noisy and as the drag increases when you increase the number of blades...

I have now a 15" three blades Max Prop which is quite small so I have less noise and vibration, but with increased pitch (as per Lars 's suggestion) I can easily get 6,5 knots at 2.800 RPM

Fair winds

Matteo (38/067 Only You)

p.s. you can upload JPG files and not PDF, sorry, it's the Forum's software, not me!

03 May 2010 - 10:08
#12
Join Date: 02 January 2008
Posts: 1547

Christophe

Thank you for the information.

The engine specs can very well be viewed on the website.

60 hp is the crankshaft hp, for technical purposes the propeller shaft hp is required. It appears this is not stated, can be assumed to be about 55 hp.

Pls note that this is a turbo charged engine, and the exhaust hose therefore has 76 mm diameter.

Referring to fuel consumption it can be assumed that the stated 4 ltr/h refers until confirmed by measurements.

Would suggest that you choose the optional two pole electrical system, the original engine has it.

Referring to the choice of propeller it is necessary to ask what your main priority is? Maximum top speed, keeping up speed in a strong headwind, minimum fuel consumption at cruising speeds, or something else? Propellers are peculiar insofar that they can be optimised for one condition only, usually the choice is a compromise.

Assume you have a 2-blade folding propeller now, depending on the brand the power in reverse may be rather low. The problem with most sailing yachts having skeg rudders is that they are difficult to control in reverse. The stern is pulled to one side, and the rudder can not prevent this.

The recommendation is to not use much power, but to start going astern slowly, with the rudder on the centerline, then when some speed has been gained the rudder will work. This requires that there is some room for this manoeuver.

It is not the propeller itself causing the stern to move to the side, but the slipstream hitting the hull in reverse is the reason, and V-shaped hulls suffer more.

It is good to remember that the direction of the propeller side thrust is as it was rolling on the sea bed, use this to your advantage when approaching the dock. If you have the original installation the propeller is left handed, and you should have the dock to starboard, then reversing will bring in the stern towards the dock.

Best regards

Lars

03 May 2010 - 11:39
#13
Join Date: 02 March 2007
Posts: 83

Dear Rob,

  When I bought my 41/31, I thought that the borg warner gearbox was very noisy. This was a whine rather than a rumble, however I decided that I could not live with it. I removed the gearbox and took it to Mermaid Marine who are the agents. They took it to pieces on the spot but could not see anything wrong. Aparently noisy gearboxes are very hard to diagnose as to the exact cause. They offered me a reconditioned borg warner of the same type which I reluctantly purchased.

  When I refitted the gearbox, I replaced the solid coupling with a Vetus flexible coupling. This meant a new shaft as well!

The good news was that the transmission is now very quiet, with just a slight vibration from the 2 bladed Maxprop.

The improvement could have been the new gearbox, on the other hand it could have been the new flexible coupling, there is no way of knowing.

regards Cosmo Little

03 May 2010 - 12:10
#14
Join Date: 27 August 2009
Posts: 44

Thank you for your feedback.

As assumed by the Professor, 41/11 currently has a 2 blades propeller. I believe it is a maxprop although I am not 100% sure (I have attached the best pictures I could find in my photo library so experts may recognise...).

By changing the Perkins I will get more power. Assuming I would like good power against strong headwinds, a reasonable cruising speed and consumption, would a 3 blades max prop work better for me?

If I were to change propeller, would I have any other piece to change as well?

My questions may sound candid to experts but I used to sail a racing sailing boat without any engine so I am discovering the issues linked to modernism...

Fair winds.

Christophe

 

 

03 May 2010 - 12:38
#15
Join Date: 02 January 2008
Posts: 1547

Christophe

It appears to be a Max-Prop, and the performance in reverse should be the same as in forward. Is this your experience?

Before entering into the big task of replacing the engine, I would appreciate to hear what the present performance under power is.

Max speed and rpm, cruising speed and rpm?

Lars

 

03 May 2010 - 13:22
#16
Join Date: 27 August 2009
Posts: 44

Lars,

The reason why I am considering changing the engine is that (i) it is leaking a lot of oil and (ii) the power is short.

I have to feed the engine with a full bottle of oil every 10 hours or so. Technicians at Kervilor claim thay can't cure the issue.

When cruising with my engine I can bearily reach 6 knots in a calm sea. The cruising speed is closer to 5 knots as vibrations are significant above 5 / 5.5 knots. I can't properly check the rpm as the indicator doesn't work properly although I have asked for it to be fixed.

Finally when 41/11 was shipped back from the US and sailed by a crew from Southampton (where she was delivered by cargo) to Brittany, engine broke and was repaired (apparent reason was breakage of screws fixing the piece between engine and shaft, probably due to poor quality of screws and significant vibrations).

As Antares is going through a renovation and while she is grounded I was of the opinion that changing engine would give her a new youth and provide increased security to her owner...

Kind regards.

Christophe 

03 May 2010 - 17:38
#17
Join Date: 30 January 2007
Posts: 15

Dear Rob,

  When I bought my 41/31, I thought that the borg warner gearbox was very noisy. This was a whine rather than a rumble, however I decided that I could not live with it. I removed the gearbox and took it to Mermaid Marine who are the agents. They took it to pieces on the spot but could not see anything wrong. Aparently noisy gearboxes are very hard to diagnose as to the exact cause. They offered me a reconditioned borg warner of the same type which I reluctantly purchased.

  When I refitted the gearbox, I replaced the solid coupling with a Vetus flexible coupling. This meant a new shaft as well!

The good news was that the transmission is now very quiet, with just a slight vibration from the 2 bladed Maxprop.

The improvement could have been the new gearbox, on the other hand it could have been the new flexible coupling, there is no way of knowing.

regards Cosmo Little

Hi Cosmo,

Thanks for your response. My gearbox definitely rumbles, but only when the gear is initially engaged. It's fine above a few hundred RPM. I will leave it alone until more definitive signs of failure, but this thread provoked me into thinking about the engine. Although very much an auxiliary the 4108 is adequate and simple. I had assumed replacing it with a re-manufactured engine would be the easiest route.
Cheers
Rob

03 May 2010 - 22:57
#18
Join Date: 19 July 2007
Posts: 65

Rob.

Like yourself I was initially thinking of keeping the 4108 in our 411.

However the spares situation in the UK now seems poor for this engine. Perkins were not able to supply a new set of injectors,and it took most of the winter to get the existing set reconditioned properly. Other parts have been difficult to procure. It looks like Perkins have decided not to support, what to them must be a very old product.The spares situation seems much better in the USA,

When compared with more modern engines the 4108 is noisy, heavy, not very economical and awkward to maintain.I am watching this thread with interest, as I cannot decide which engine is most appropriate as a replacement. I agree with other contributers, that it is unnecesssary to go for a unit with much more power, than that originally installed. It is likely that the original engines we are still using are producing less power than their rating and that a modern engine of simlar power, with a suitable prop, will give much better performance, particularly fuel consumption.

Regards

Paul   411,042

 

 

04 May 2010 - 08:09
#19
Join Date: 02 January 2008
Posts: 1547

Paul

The engine output can be determined from the full throttle speed and rpm, and the reduction and propeller characteristics. The accuracy depends on the accuracy of this information.

I can do a calculation for you provided you supply the above info.

Kind regards

Lars

 

04 May 2010 - 21:09
#20
Join Date: 01 February 2007
Posts: 234

All,

Spare parts for old Perkins engine in the Uk can be purchased via;

Charlie Childs

tele 017338 44362

Also worth looking at www.bruntons-propellers.com  the "auto-prop" is capable of changing pitch as the revs increase and from tests is supposed to give max distance. Also no prop walk! 

 

 

05 May 2010 - 07:37
#21
Join Date: 30 January 2007
Posts: 15

Rob.

Like yourself I was initially thinking of keeping the 4108 in our 411.

However the spares situation in the UK now seems poor for this engine. Perkins were not able to supply a new set of injectors,and it took most of the winter to get the existing set reconditioned properly. Other parts have been difficult to procure. It looks like Perkins have decided not to support, what to them must be a very old product.The spares situation seems much better in the USA,

When compared with more modern engines the 4108 is noisy, heavy, not very economical and awkward to maintain.I am watching this thread with interest, as I cannot decide which engine is most appropriate as a replacement. I agree with other contributers, that it is unnecesssary to go for a unit with much more power, than that originally installed. It is likely that the original engines we are still using are producing less power than their rating and that a modern engine of simlar power, with a suitable prop, will give much better performance, particularly fuel consumption.

Regards

Paul   411,042

 

 

Hi Paul,

A problem with spares would be decisive. I will investigate. Thanks for pointing this out.

Rob 41/41 (Jaka)

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