Fractional to Masthead rig?

[Roach1948]

A friend has offerd me his almost new cruising chute from a Stella. He worngly sized it and it is too small for the Stella but it really is slightly too big for Roach. The Luff is 24' where as my working jib luff on a 3/4 fractional is 20'6". Looking at the sail plan, this chute would get tangled in the diamonds. So, I was thinking, maybe I can set it flying from the masthead? There will be considerable load, but was thinking that maybe I could use running backstays on tackle to ensure the load is supported. Maybe, as the chute is set flying, the sail bend alone would take up the extra 3' 6" and I could fly it from the normal 3/4 string point. I have a solid douglas fir mast, recently re-glued. What do people think?

 

[tillergirl]

When using the crusing chute, the luff gets tightened the closer to the wind that you go. Given that you can't use the chute for dead downwind sailing like a spinnaker, you need to beware of reducing its window of use (I think) if you fly it just above the forestay. I think otherwise, it will have a narrow window. So that's argument for masthead rather than just over the forestay. Yes I think you will need some running backstays.

I think I can upload some photos to give you an idea of how tight the luff gets 'on the wind'.

 

[tillergirl]

This is with wind on the beam. I think the luff could have been tighter to point up a little more but I don't think you could lose 3.5ft

This is a composite photo with the main pulled in to allow a picture of the chute. Again, I don't think you could lose 3.5ft on 24ft. This is 32ft; my I is 33.13ft and I certainly could have put another foot on my luff.

Does any of this help? I reckon you should try it. I guess it might be small flown from the masthead? Even that though can give you some good extra speed.

 

[Roach1948]

Yes it does help. Thanks for the pcitures. My mast is 29ft from Deck to truck and the problem with making a strong point between the 3/4 point and the masthead is that this area of the mast is completely unsupported. So hence my preference for the masthead so that I can attach running backstays without the need for major mast surgery.

 

[tillergirl]

Yes, I guess your masthead is quite slender?

I suppose altering the sail would be quite expensive?

 

[tillergirl]

Your other post on uphauls etc is all scrambled. You'll need to re-post that.

 

[Roach1948]

Yes the mast head is very slender - maybe 2 1/2 inches in diameter. As I have a wooden mast, it is one of tehse cases where mast fittings etc, will be cheaper to alter/add than altering the sail. With mast work I can atleast do that myself.

Re: Other Post - thanks for alerting me; most odd, when I open it I just get a whole load of other people's unrelated posts..

 

[Roach1948]

After a second think, I think its best not to go from the masthead after all. The need for running backstays will be a pain, and at the normal spinnaker strong point, the rig is already strengthened by an extra set of rear shrouds. So I reckon I could get away with this sail if, by my calculations, I have a temporary 2ft bowsprit - it might ease gybing too?

 

[tillergirl]

You are probably right. Now if you knew the angle between the temp bowsprit and the forestay, we could work out the distance from the end of bowsprit to top of forestay? if it was 135 degrees, it would be 21.96 feet. If its 160 degrees, it would be 22.39 feet but if it was 120 degrees, it would be 21.57 feet.

You're goving to need a longer bowspit! 4ft at 135 degrees will give you 23.50ft,
4.65ft of bowsprit will give you 24.01 ft of luff.

 

[Roach1948]

Before I was measuring off my working jib luff , but ofcourse I should measure up to the spinnaker halyard swivel above the forestay which is 22'6' from the stemhead.

 

[grumpydog]

Beware, Tudor. If you are significantly increasing the size of your headsail, it's not just the mast you need to be thinking about. It's the winches for the headsail sheets as well (assuming you have winches). I recently covered the restoration of a 1950s Holman which went from fractional jib to masthead genoa in the mid-60s, and it pretty much destroyed the yacht! The excess strain on the jib sheet winch mounts caused cracking, rain water got in and the whole cockpit was rotted out in the end. So you will probably need some hefty extra stiffening in way of the winch mounts?

 

[Roach1948]

Re: Fractional Chute?

Yup, got winches.

I don't think the winches will be problem as they are mounted on the deck, and being a flush-decked sloop the stresses are taken to the sides anyway (where hanging knees have been added). If I had a coachroof or the winches mounted on the cockpit sides I would be concerned. So hence my primary concern is the mast, but I think I can beef the fittings up. Being solid I think it can take the pusnishment - it is not an immense sail and only marginally bigger than the genoa. Now that I have decided to fly it as a Marconi genny, I will not require running backstays. I will get mast insurance next year anyway!

 

[Boatmik]

Change the whole boat to use one sail ... begs the question - runners, deck gear.

I'd say it would be warranted with a light wind running spinnaker because the backstay would support it and it would never introduce the lateral loads you are rightfully worried about and it would overcome a weak point of the boat's performance nicely with a minimum of gear.

But for the cruising spi it is a lot of trouble to brace the mast for the lateral loads that the chute will produce when reaching in medium to strong winds. Also adjusting runners through gybes while handling the mainsheet - there is no real problem but are you ready for it all?

A cheap sail that requires these sorts of changes sounds like a false economy.

If the boat has aft swept diamonds or jumpers going from the top of the mast you won't need the runners - but you would need to speak to a rigger who deals with raceboats AND cruising boats. I still think this is still too much complication. A smart person is one who takes gear OFF a boat rather than adds it.

Adding gear can be OK but it should be for some big advantage - but not a sail that will be useful only a small part of the time you spend sailing. The cruising staysails are not very effective compared to a spinnaker running or broad reaching and because the boat has not been properly set up for it (though it might be after a conversation with a good rigger) you won't be able to use it for reaching either when the wind is up at all.

Best wishes
Michael Storer

 

[Roach1948]

One of the reasons I want a chute is because I think I WILL use it quite a bit. I do much River sailing in light winds, and a chute will certainly help me in these conditions. I have to admit I am a budget sailor; the £200 or so I am saving on this sail can easily cover the changes to the boat - that is the joy of wood. It allows the amatuer to make such changes relatively cost effectively. Now, if I was dealing with changes to an aluminium rig, that would be another story.

 

[Boatmik]

Howdy,

Sounds like it will be a fun project for you - so who am I to argue I still think that for every time you have it set and drawing fine there will be three or four where it is not quite working properly.

More details on aft swept uppers...

The aft swept uppers I suggested may make more sense than runners. They don't require any handling and are the standard way of getting the same result on race boats with a fractional rig but a masthead kite. The struts themselves need to be slightly above the existing hounds.

The downside is that you won't be able to ease the mainsail out quite as far - but this is generally accepted in raceboats because of the added spinnaker area.

The top of the wire should go to near the top of the mast - within a foot or so, and the lower end needs to go around the same distance below the strut as the top goes above.

You might want to check with a rigger about the right angle of sweep - I would be expecting about 20 to 25 degrees aft of thwartships.

Put a working sail weight stickyback sail patch where the mainsail is in line with the strut end when the sail is eased.

Don't overtension the wire a slight static tension when the mainsail is properly trimmed in medium wind is enough - too much tension and it will pull the masthead back and flatten the top of the sail excessively.

Hope this helps.

Best wishes
Michael Storer