Bavaria 44 Fixed propeller size

[Winga]

Hi all,

(even as I am avare of this post; http://bavariayacht.org/forum/index.php/topic,508.msg2609.html#msg2609  - I would like to ask the community if anyone got a Bavaria 44, OR a Bavaria 46 (I've heard they are more or less the same hull?), produced around 2002 (as mine) to tell me their propeller size and pitch.

My Bavaria 44 2002 is equipped with an Volvo Penta D2-55 (53hp), MS25S saildrive and a Volvo Penta 2002 17x16 three blade FIXED propeller. That propeller is broken, due to a defect boss.

I suspect the 17x16-propeller is a too steep pitch, max RPM with this propeller is about 2400, but the solid vibrations caused by the defect boss might also effect the RPM. At 2000 rpm the boat makes about 7,5/8 knots.

I've also tested a VP threeblade fixed 17x12 propeller, and with this pitch the boat only makes 5 knots at 2000 rpm, so I consider the 17x12 propeller to have too little pitch.


suggestions?

Winga

[Symphony]

Welcome to the forum.

Unlikely you will find another 44 fitted with the same engine/drive combination. Originally the boat would have been fitted with an MD22 but a previous owner has replaced it with a later D2 55 but retained the original drive instead of fitting the later 130 drive.

You do not say what maximum rpm you achieved with the 17*12, but I would guess that you would have easily achieved maximum, which is I think 3200. A rule of thumb is that 1" of pitch changes engine revs by between 250-300, so the difference of 4" pitch between the two propellers would lead to a difference in maximum engine revs of over 1000.

Therefore fitting a 17*15 would increase revs to 2700 which is still a bit on the low side - you should aim for at least 3000. However, rather than experimenting (expensive with Volvo props where the pitch cannot be adjusted) I suggest you determine exactly which reduction ratio your drive has and feed your boat details into the sizing programme on www.Vicprop.com which will give you a good indication of an appropriate size propeller. Before you buy, though it is best to provide the information to a propeller specialist and buy their recommendation. Be aware that if you are buying a folding or feathering propeller that the recommended size may not be the same as for a fixed propeller.

Hope this helps

[Winga]

Thanks Symphony!

I have tried to ask my local dealer of Volvo Penta, but they can only calculate to folding propellers - wich are sold to 5 times the price..

Had a look at the calculator on the site you suggested, and the best result I could get was 17.6 x 11.4 (for a 3 blade).

As I already know that the 17x12 is to low-pitched for my boat, I am a bit unsure of what I should do next. Do you think my input data is correct?

This dataset is my best guess - but it tells me 3 Blade   18.0   X   11.1
Waterline length in feet:   37.50 feet
Beam at the waterline in feet:   13.90 feet
Hull draft in feet (excluding keel):   3 feet
Vessel weight in pounds:   23369 lbs
Engine Horsepower:   55 HP
Number of engines:   1
Total Engine Horsepower:   55 HP
 
Engine R.P.M. (max):   3200 RPM
Gear Ratio:   2.23:1
Shaft R.P.M. (max):   1435 RPM
 
Number of shaft bearings (per shaft):   0 (according to the manual of D2-55 ( https://pubs.volvopenta.com/publications/47709056 ), the propeller shaft power is 53 hp.
Desired speed in Knots:   9 knots

[Symphony]

Have done a bit more checking and Volvo quote the engine rev range as 2700-3000rpm. This means it is governed to 3000 and should be propped to achieve a minimum of 2700. The reduction ratio of the MS25 drive is 2.19 according to the Volvo chart I have. Your boat measurements are OK except for the waterline beam which is probably 3' less than maximum beam which is measured at the deck (not sure that makes too much difference though).

I have put these revised figures into Vicprop and it comes out as 18.4*11.9. You can't actually buy that size - the only 18" are 15 or 16" pitch. So a 17" is the only practical diameter. Trade off between diameter and pitch is 1.5-2" pitch for 1" diameter, so going down 1.4" would be the same as upping the pitch between 2.1 and 2.8". That gives you a 17*14 or 17*14.8.

Going back to rule of thumb I mentioned earlier a 17*15 will raise the revs to just under 2700rpm and a 17*14 to just under 3000rpm compared with your 17*16.

I would be inclined to go for the 17*14" as the power curve shows hp still rising after 2700rpm. You have a heavy boat and could use all the power you can get. This will still enable you to cruise comfortably at between 2-2200rpm at 6knots+.

[acheronvelero]

I have a B44 2002, same motor and propeller.
I recommend you to change it for a foldable propeller. The right one is a 18x15, but is also right to choose a 18x14 or a 18x16..it depends if you wish more speed or more force. We prefer an intermediate decision
I attach picture

[Winga]

I have a B44 2002, same motor and propeller.
I recommend you to change it for a foldable propeller. The right one is a 18x15, but is also right to choose a 18x14 or a 18x16..it depends if you wish more speed or more force. We prefer an intermediate decision
I attach picture

Thanks for your reply!

If I understand you correctly, you got a VP D2-55, MS25S saildrive, and a 3 blade fixed propeller 17x16?

I am definetly considering a foldable propeller - however, currently the focus on cost weighs heavier than the speed of sailing

[Winga]

Have done a bit more checking and Volvo quote the engine rev range as 2700-3000rpm. This means it is governed to 3000 and should be propped to achieve a minimum of 2700. The reduction ratio of the MS25 drive is 2.19 according to the Volvo chart I have. Your boat measurements are OK except for the waterline beam which is probably 3' less than maximum beam which is measured at the deck (not sure that makes too much difference though).

I have put these revised figures into Vicprop and it comes out as 18.4*11.9. You can't actually buy that size - the only 18" are 15 or 16" pitch. So a 17" is the only practical diameter. Trade off between diameter and pitch is 1.5-2" pitch for 1" diameter, so going down 1.4" would be the same as upping the pitch between 2.1 and 2.8". That gives you a 17*14 or 17*14.8.

Going back to rule of thumb I mentioned earlier a 17*15 will raise the revs to just under 2700rpm and a 17*14 to just under 3000rpm compared with your 17*16.

I would be inclined to go for the 17*14" as the power curve shows hp still rising after 2700rpm. You have a heavy boat and could use all the power you can get. This will still enable you to cruise comfortably at between 2-2200rpm at 6knots+.

Thanks for your detailed help!

I had a test run a coulpe of days ago, with the 17x12 propeller, and I got 7,7 knots and 2750 rpm. I suspect that both the boat could need a clean under the waterline, and that max on the throttle might not be max on the motor.

[Brian]

I have a Bavaria 44 with identical mechanicals.  I am quite pleased with the standard prop. At 1800 rpm I can cruise at 7knts all day using about 3 Lts of fuel and hour. A Bavaria is not by any means a fast sailing boat and the addition of a folding prop would doing little to improve its performance under sail or power.