We got our 311 in April and we sail/race her in Arklow Sailing Club in the South East of Ireland but we need some help about race trimming.

1. Use the self tacking jib or not?  We found it was too small off wind and have put on a furling genoa off another yacht and it seems to be better but we are not sure.

2. The 2-blade Saildrive Prop is fixed so when we are sailing should we have it in neutral or reverse? 

And what gain should we expect if we invest in a folding prop?

3. Any other comments about trimming the main?  We have been used to a mast head rig and the larger main is new to us.

Thanks

Alan & Gerry 

About the fixed/folding prop;

The fixed propeller makes less resistance if it is allowed to rotate. But it might be harmful to some engines to rotate without proper lubrication. I don't know how the Yanmar is in this respect.

In the Swedish handicap system (LYS) the difference between fixed and folding prop is 1% in average boat speed. I think that the difference could be larger in many conditions.

/Magnus

Alan & Gerry,

At all but the slowest speeds speed a two blade fixed prop will produce less drag when locked in astern, especially if you can arrange for it to stop in the vertical position. i.e. with one blade in the 'shadow' of the strut. (When you learn how to do this please let me know ;-)

Franko,

is your statement based on scientific grounds, or is is it just common knowledge (i.e. rumour)?

I read the results from a test performed by Volvo Penta which said that the drag redecued to 1/4 when the prop was allowed to rotate (which also seems reasonable). Unfortunately I'm not able to find the evidence at the moment...

/Magnus

And here is the evidence...

The diagram is from Volvo Penta, measured on their sail boat drive.
Y-axis i drag in N, X-axis is boat speed in knots.
Curves from top to bottom
3 blade fixed, locked
2 blade fixed, locked
3 blade fixed, rotating
3 blade folding
2 blade folding

Quite clear that rumour isn't always truth...

/Magnus

Magnus,

That is great. First time I have seen any proof of the relative resistances. I am going to eat my hat now.

Where is the curve for the 2 Blade fixed, Rotating?

What about the merits of feathering versus folding?

Can you let us have the link to the graph?

Skål         &n bsp;

Thanks for all the replies so far.  Peter Thomas has recommended the Kiwi feathering prop which certainly looks interesting.

No comments yet on the self-tacking jib?

Hello,

I have 140 gen plus 2 blade folding.

As stated to other message I have drop keel and this efects performance and I suspect fold prop was not my best buy.

The prop makes little difference except under power when we go .5 knot slower, I tell my self that I  am going faster when sailing with prop as it cost alump.

http://www.brunton-propellers.com - www.brunton-propellers.com have some interesting figures.

If you want a deal I would be happy so sell prop on and revert to original it cost £ 580 and is on yanma sail drive.

spec was 15x11 varifold and has only had 6 months use

simon

Thanks for that.

As a matter of interest did you find any difference in performance over the 140 jib and the self-tacker jib?

I know on my 311 when I got rid of my fixed prop and put on a folding prop I had 3/10th of a knot better speed. 

And I get good speed out of the self tending jib so I stay with it.  Now, I sail in a very windy area so I have no real need for a large head-sail.

Franko,
sorry for not answering until now, I've been out sailing...

I don't have a link to the graph. It was published in the Swedish magazine På Kryss 2004 #7 (som du kanske har..). The fethering prop was not mentioned in the article.

If I had the option today, I would definitely be interested in a three blade fethering prop (depending on price diff, of course).

/Magnus