Large Genoa

[Mr Cassandra]

Hello all .
I have just bought a new full battened mainsail and am very pleased .I am also considering a new genoa. With the one that i have the sail area /dis, is 16.92. If I go up to a 160% i can get a SA/D of 18.02 The total sail area being 886sq ft on a displacment of 22,000lbs .Loa 44ft Lwl 38ft10 in. Is 18.02 a bit to high for a cruiser.? We do get lots of times in the Aegean, when the winds are very light, but also quite high in F6/f7 range.Are there any down sides to having such a large head sail?.. cheers bob t

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[johnsomerhausen]

I sail on Long Island Sound which also has more than its share of light winds and I got a 150 % furling genoa (SA/D ratio with 100 % foretriangle is 16). I think I would have been better off with a 135 % one plus a 180 % drifter or gennaker, set flying (no hanks). The problem with too big a genoa iss that once you furl it for F 5 or 6, it looks about 10 months pregant....
john

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[Strathglass]

Sa/displacement. I always thought that sail area in that instance is usually calculated from the 100% fore triangle plus the mainsail area. Changing the overlap does not increase the SA/D ratio.

I would think that a 140% genoa with a foam luff and a much lighter and larger sail for lighter condotions would be the optimum for yourself ( If you were purchasing two sails )

If you only want to buy one sail and you sailed mainly in light conditions then I would opt for a 160% genoa again with a foam luff.

I have foils but have sailed with roller reefing often.

My normal no 1 genoa is 160% and has a slab reef reducing it from 450 sq ft to 350 sq ft, made from 6.4oz cloth.

The light no 1 is also 160% but the cloth is 2.9 oz only usable up to 8 knots.

I have other white foresails for heavier weather.

A bit old fashioned perhaps but!

Iain



<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by iainsimpson on 07/09/2003 11:09 (server time).</FONT></P>

 

[Mr Cassandra]

Thanks for the answer .Can you tell me why ,if you increase the sail area, you don`t alter the sail area / disp. ratio?
When I said light winds its usually a min of f3/4 in fact under 12 kts we only move at about 4.2kts that why I was looking at a160% head sail.
cheers bob t

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[Strathglass]

It's one of those silly boating things. The SA/D is a ratio which is quoted on each yacht type and is a figure used to compare different yachts.
Something which varied depending on which sails were fitted could not be used for comparison purposes, thus, the fore triangle area is always used to calculate this factor.

Of course the actual sail area will increase as you up the overlap thus the ratio of the sail area to the displacement will increase. But the actual factor as quoted by the manufacturers will not change.

Does this explain things?

Cheers

Iain

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[charles_reed]

A 160% genoa is large and limited in scope. I fear you'll find very little difference in light air performance and you might find you get a lot of lightweather lee helm.

Most sailmakers would recommend a 140% as a good general purpose roller genoa - you should not forget that the sail can only be effective when rolled to more than 60% of its full area, and that's with a very good foam luff.

For light reaching a genniker is a far better bet (sometimes called an asymmetric).
Med winds are either inadequate or too much for comfort, in my experience. I found adding about 18% to the main by having a fully-battened aggressive roach gave me far better light air performance than adding to the foretriangle. The main does now overlap the backstay by about 400mm, over 3 of the 5 battens but its not proved a problem when tacking and fitting single-line reefing has made the set-up very serviceable.

However my boat is about 35% of your weight, 75% of the lwl and with 100% foretriangle 520ft2.

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[Mr Cassandra]

Hi, that is what I have done with my Full battened main, had it made with a very big roach, mine also overlaps the back stay,the thing was that I only had it delivered to the boat 3days before I came home ,and guess what ,no wind for those days. cheers bob t

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[Mr Cassandra]

Yes ,thanks for taking the time to explain. cheers bobt

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[Jacket]

Its one of those things that didn't matter in the days when all yachts carried overlapping sails, as the relative ratios stayed more or less the same whether you used 100% foretriangle or actual area of the genoa. In calculating the sail area, you used to assume that the main was triangular, and ignore the roach area.

Now that many more boats have non-overlapping jibs (and too wide a shroud base to fly a genoa) and heavily roached mains, more people seem to be quoting SA/displacement ratio's based on actual sail areas, which is much more useful.

If you want to guage the effect enlarging your genoa will have, you have to use SA/disp ratio's based on actual sail areas.

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[quaelgeist2]

Unless you are prepared to carry a second sail for BF 5 and up, it is too large to be reefed sufficiently.

I am sailing a (second hand) 160% genoa just to test it this season and I am very pleased with the results in both racing and cruising. With 31ft and 5t weight I need not bother sailing with a standard 135-140% genoa in a BF 2-3. With the 160% of a lighter fabric I can sail happily as long as it is beam reach or closer.

Have had to reef down in changing weather to fit a BF 5, but also generally from BF 4 I go down to a 100% foresail, as they pull with similar power, then. Even with a foam strip they get baggy when you reduce them by more than one third of their size.

In my case the second downside is the genoa track which is about a foot too short and does not allow to flatten the sail sufficiently for a really close-haul (i.e. less than 35 deg too apparent wind)

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[Mr Cassandra]

Hi Realy all I want is to be able to go faster in light winds ,Without using Spin ./Cru Chute As it only wife and I and two young children .
cheers bob t

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