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S&S Swan General - Fix propeller for Swan 40
19 November 2021 - 08:27
Join Date: 09 November 2021
Posts: 43

Fix propeller for Swan 40

Hi, This is my first post on this forum and I am glad to have a place to put my questions.

Very rencently I bought a swan40 and I had to sent the propeller Maxprop to refit.

I need to put the boat in the water as soon as possible and I am considering buying a fix propeller to do the passage to Portugal where I will houlout and will use have then the oportunity to installed my serviced Maxprop propeller. Also to have a fix propellor is handy and something nice to have as a spare.

My problem is to find the right pitch as I could not find from the Maxprop.

Anyone can help me in calculating the right one? I am considering a 3 blade.

This is my boat data:

Engine: Yanmar 3JH3E (righ hand)

Max power for 1 hour 40hp at 3800rpm 

Sustained power 36HP at 3650rpm

(I guess normal crusing engine speed would be 2800rpm)

Gear box ratio: 2.61:1

Propellor size 15" (16" I think is to big, no?)

Some photos to help:


Shaft dimension

Shaft dimension

Shaft dimension

20 November 2021 - 09:16
Join Date: 02 January 2008
Posts: 1547

Dear D
The dimensions for a 3-blade would be 15 x 14", for a 2-blade 15 x 16".
3 blades give an advantage only near the maximum rpms.
The high pitch values indicate that 16" diameter would be advantageous, but it is
likely that you then have to cut away a little of the hull laminate for creating a

This is not a problem, you can add laminate on the inside to compensate.

Kind regards


21 November 2021 - 11:26
Join Date: 09 November 2021
Posts: 43

Dear Lars,
I have read so many anwsers from you with advices and technical information that I feel I know you so much, although it is the first time you write to me.
Thank you so much. I feel fortunate to belong to an association like this with the ability to learn so much specially from you. Thank you so much for your reply.
I also have read a lot about propellers in this forum, and I read a few swans 40 are using propellers of 16" and even 17” of diameter. Very strange to me as I have read somewhere that, as a rule of thumb, the clearance between the shaft and the hull must be around 12% of the diameter of the propeller. So in the swan 40, with a 15” propeller as nearly 12% diameter of clereance
Do you know the what is the max beam at water level?
I also have a big issue with the mast step as I do not have any drawings for that, but I will do another post.
Dear Lars, it is a really pleasure to meet you here. I hope you are well.
Best and warm regards,
Duarte Champaliamaud 
Star Swan (47/51)

21 November 2021 - 13:57
Join Date: 29 January 2007
Posts: 1018

Dear Duarte,

for an unknown reason Oscar Ibanez from Nautor Global Service Badalona, and absolutely out of the blu, a few weeks ago gave order to his employees not to share any construction drawings with the Association, and of course mast step is among them.

We luckily have in our files a lot of drawings and probably even more drawings that Nautor still have in their files, but unfortunately we are missing that specific about the mast step of S40.

If someone has this drawing and would like to share it with the Association, the Association will be very grateful.

All best,

matteo (47/069 Vanessa)

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