Advantages to a 21hp engine over 13hp in a Nonsuch 26C

[Ken Murphy]

I am the proud owner of an 1982 26C with the original Westerbeke W13 engine.  I find cruising in heavy waves & currents I often struggle to obtain more than 2 knots. I calm sees at @2000 rpms I can cruise along at 5 knots.  I have gotten hold of a same year, fully working 21hp Westerbeke engine, compatible with my current setup (transmission, MaxProp prop etc) but am wondering if there really is an advantage to 21hp engine over the 13hp. Running the two engines at the same RPMs will the boat not travel at the same speed?  As I would be using the same transmission 2:1 ratio what is the advantage of the greater horsepower per RPM?  Clearly there is something I am not understanding as the W21 became the standard engine in the 26C shortly after mine was built.  

Any input is much appreciated.

Cheers

Ken Murphy

Sir Will

NS26C

Vancouver Island

[Joe Weinbrecht]

My W21 uses a RH 15x12 prop.

What size prop does the 13 use?

That may be the performance difference.

Joe 

1985 NS26C #156

--
You received this message because you are subscribed to the Google Groups "INA Nonsuch Discussion Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to INA-Nonsuch-Discussi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/INA-Nonsuch-Discussion-Group/f956e5f2-9f88-4d98-8233-966ffaa8260dn%40googlegroups.com.

[Ken Murphy]

Hi Joe

I have a Max Prop RH 14x10 2 blade feathering.

I wonder if the extra hp is needed to drive the larger prop?

Cheers

Ken

[Fred Rachwitz]

Ken

You likely already have what will be able to make a difference, and that is the MaxProp. I also have a MaxProp on my 30U and learned that the prop is adjustable for pitch. First, yours may be adjusted incorrectly now which may cause your problem, but I’m guessing that you will only solve it by going to the 21hp engine and then finding the proper adjustment. The distributor for MaxProp, PYI (I think I have that correct) was great to work with when I bought my boat and wanted information about the prop. They will tell you the necessary pitch to set the prop at based on you boat and engine. I would think that they would know when you first call whether a good result is even possible with the 13hp. But I certainly think they will know how to set the prop for the 21hp.  The proper setting will give the maximum power just as you engine gets to the recommended maximum RPM. Cruising RPM will be I think recommended at 80% of that. I also had them overhaul my prop and they set the pitch as I remember but you can do it yourself. All of it was easy for me in Michigan during the winter in a heated storage building. If you are in the water you have more to do. But, since you are considering an engine swap you do want to find the right pitch either way. Hope this helps and others chime in. 

Fred Rachwitz

Concerto

Nonsuch 30 U #445

Harbor Springs, Michigan

Northern Lake Michigan

Sent from Fred’s iPad Air 3

Fred 

Sent from Fred’s iPad Air 3

On May 20, 2021, at 12:25 AM, 'Ken Murphy' via INA Nonsuch Discussion Group <INA-Nonsuch-Di...@googlegroups.com> wrote:

I am the proud owner of an 1982 26C with the original Westerbeke W13 engine.  I find cruising in heavy waves & currents I often struggle to obtain more than 2 knots. I calm sees at @2000 rpms I can cruise along at 5 knots.  I have gotten hold of a same year, fully working 21hp Westerbeke engine, compatible with my current setup (transmission, MaxProp prop etc) but am wondering if there really is an advantage to 21hp engine over the 13hp. Running the two engines at the same RPMs will the boat not travel at the same speed?  As I would be using the same transmission 2:1 ratio what is the advantage of the greater horsepower per RPM?  Clearly there is something I am not understanding as the W21 became the standard engine in the 26C shortly after mine was built.  

--

[Ken Murphy]

Hi Fred.

Thanks for your input.

I have changed the pitch on the prop as suggested by PYI (who as you say are very helpful) and it appears to have improved the performance of the existing 13hp a fair bit.  Going to the 21hp, staying with the same prop I would actually be able to increase the pitch again. I guess the question I am trying to come to terms with is, is that the extent of the improved performance of going to the more powerful engine. It basically lets me increase the pitch slightly on my current prop, or change to a larger 15" prop, which willl obviously provide more grunt to get through the water.

Cheers

Ken

[Tom Schoenhofer 26C#28 North Star Penetanguishene]

My original prop 

RH14x10 Martec folder on the W13. This prop had very poor reverse, loud clunk when shifting into gear, and I thought it was the cause of vibration.

In a calm:

RPM    kts   

1000   2.4

1500   3.7

2000   4.6

2250   5.2 

2500   5.5 transom squatting so exhaust is just below waterline

2750   5.8 some grey smoke near the exhaust, some smell, a grey day so I could not really tell if there was any black smoke.

2950   6.2 full throttle, grey smoke apparent, big bow wave, transom exhaust well below water, strong exhaust smell in cockpit. Grey smoke may be water vapour.

Speed into waves and headwind was poor. But engine is used on and off anchor and dock and in a calm so this isn't really an issue in Georgian Bay.

Temporary new prop. Plastic 13x10 fixed. Excellent reverse, no noise, very light weight compared to the Martec.

2200 rpm 4.4 kts my usual speed, no strain, least vibration.

3000 rpm 5.?kts, large bow wave

Very poor performance into wind and waves but it will still go just slowly. I would sail in these conditions anyway. This prop is very gentle on the motor and transmission.

New prop, modern efficient 2 blade design, 14x10 fixed. Marina splashed the boat in before I had a chance to put it on this year.

Hope this helps.

Tom

26C #28

Penetang

[Mark Powers La Reina 26C Vancouver, B.C.]

Ken here is a link to a Westerbeke brochure contains information on the W13 and W21. wtbk_small_aux_13_to_33.pdf

The torque figures are difficult to see. The 21 is rated at a continuous 35 ft pounds and about 41 maximum foot pounds. The 13 is rated 21 and 25 respectively.

As you can see from the chart the 21 will weigh about 64 pounds more than the 13. This is not a huge difference and may help level the cockpit seats. Fuel consumption will be very similar.

The 21 is a 3 cylinder and will be quieter and smoother than the 13. The 21 takes up a fair amount of space and the location of the impeller makes service a royal pain. Some owners with the W21 in the 26 Classic install an access port in the side of the port quarter berth to make changing the impeller easier. 

The 13 has enough power to push the 26 along in flat seas with no head wind but as you have found it does not have the power to push into waves and head winds. 

If you kept the transmission, prop and prop settings the same you would get the same boat speed for the same engine rpm. The extra hp would not make much difference going into waves because your prop would  only put so much power into the water. The 21 will allow more pitch and or a bigger prop. This would allow more power to reach the water which would help beating into waves and wind. One thing you need to watch is that you don't over prop/pitch so that the engine is overloaded. Generally you want the engine hitting max rpm when the boat hits hull speed.  You can go a bit bigger than that and it will allow you to reach cruising speed at a lower (quieter) engine speed. Too much and the engine will have to work too hard and can overheat when you are pouring the power on to beat into the waves. 

I went from a W13 (2:1 trans ratio) to a Beta 20 hp engine. It is better going into waves than the W13 but I don't have enough experience with it to give you hard numbers.  The Beta is rated at 3600 rpm and has a maximum torque rating of 45 ft pounds. When I first installed it I set the pitch on the 14" two blade Max prop at 20 degrees. With the W13 it was set at 22 degrees pitch. In that configuration the Beta would hit 3600 rpm but the cruising  rpm for the same boat speed was higher. The next year I switch to the 22 degree pitch. The engine would only hit 3300 rpm but cruising was more pleasant. Both the engine vendor and the PYI said at that setting it was not over proper too much. If you went with the W21, same transmission and kept the Max prop I would suggest you talk to PYI to see what setting they think you should use.

Do not try changing the setting on the Max Prop Classic while it is in the water. With the  Max Prop Easy  you can change the pitch in the water.   Maxprop gives the pitch in degrees not inches. I was told by the guys at PYI that for the 2 blade 14" prop 20 degrees is about 9.6 inches, 22 degrees is about 10.9 inches and 24 is about 11.8 inches of pitch.  For the W13 22 degrees seemed just right. With a clean bottom and flat seas it would pull 3000 rpm at just over 6 knots. At 3000 RPM it was really noisy. 

Mark Powers

[Mariner's Cat V 26C Brentwood Bay BC]

IMHO the 13 is too small for a 10,000 boat.  Day sailing you'd be ok, but any kind of cruising exposes you to wind and wave conditions that could be problematic. As well you lose 1 -2 hp off the alternator, that is 10% off the 13 vs 5% off the 21....

I get 5.6 K @75% rated rpm using a Gori 15x12 two blade folding prop.  Fuel burn is .4 gph.   I have a 120 amp alternator de-rated to 90 amps.

T

[Tom Schoenhofer 26C#28 North Star Penetanguishene]

Mark says "The 21 is a 3 cylinder and will be quieter and smoother than the 13."   Right there is a good reason to toss the 13 if you have a 3 or 4 cylinder to replace it with.

Tom

[Mark Powers La Reina 26C Vancouver, B.C.]

Thor is pretty smart but he hates to motor and probably only has 10 hours on the engine so he does not have a lot of experience to speak from. I do think he is right in this case.

Mark Powers

[Ken Murphy]

Thanks everyone. It seems that upgrading to the 21hp will have lots of benefits, with the main one being getting more out of my existing prop or upgrading to a new 3 blade.  

Cheers

Ken

[Fred Rachwitz]

Ken, give the two blade a good chance. My MaxProp which I mentioned in an earlier post is just a 2 blade. It is a 16 inch, (I don’t know the other number(s)) but mine is pushing a 30 footer. It definitely does the job. Would I like a three blade? I guess if I was able to trade for one or was first purchasing one and knew what I know now that I would go with the three blade, but, at least for my sailing in my area there is certainly no need. 

My engine is a Westerbeke 27A, I think 30 hp or maybe 27, I can’t remember. Full throttle gives me 6 1/2 to 7 knots in calm water @ 3,000 RMP. Cruise at 23-2400 at 6 knots. 

What does the second number designate?  Eg 14 X ?? 2 blade

Fred Rachwitz

Concerto

Nonsuch 30 U #445

Harbor Springs, Michigan

Northern Lake Michigan

Sent from Fred’s iPad Air 3

On May 21, 2021, at 12:20 AM, 'Ken Murphy' via INA Nonsuch Discussion Group <INA-Nonsuch-Di...@googlegroups.com> wrote:

Thanks everyone. It seems that upgrading to the 21hp will have lots of benefits, with the main one being getting more out of my existing prop or upgrading to a new 3 blade.  

--

You received this message because you are subscribed to the Google Groups "INA Nonsuch Discussion Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to INA-Nonsuch-Discussi...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/INA-Nonsuch-Discussion-Group/da22f02e-8913-4fd2-8bae-7e9ccd0b76f2n%40googlegroups.com.

[Ken Murphy]

The second number is the props pitch, in inches.  

Cheers

[Mariner's Cat V 26C Brentwood Bay BC]

And for 9 of those hours I was lost...

On Thursday, May 20, 2021 at 12:47:19 PM UTC-7 Mark Powers La Reina 26C Vancouver, B.C. wrote:

[newelljc9]

Mascouche was equipped with a 16 hp Universal that peaked at 2,800 rpm. The original prop was a small Flex-o -Fold 2 blade designed for a high revving gas engine which George H had in stock. As a consequence the engine never reached operating temperature and she could never hit 4 knots without the wind behind her.  I switched to a stainless steel Slipstream 3 blade folder by Seahawk from Australia. They tailored the prop to the Universal and managed to produce a perfect fit. The engine reached 2,800 rpm and Mascouche could cruise at 5 knots at 2,200 rpm while hitting the desired operating temperature. In 2006 the Canadian exchange rate made it prohibitive to consider a bigger Flex-O-Fold, but I saw subsequently a joint study by Sail Magazine and Yachting Monthly that the 2 blade F-O-F performed among the best and outperformed its 3 bladed mate, much to the surprise of the testers. Nevertheless, I never regret my purchasing of the Slipstream from Ben Hawke who knew his stuff .

.

John Newell

Mascouche 26C 1

Toronto 

.