Twin forestays

graham

graham

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Our boat used to have two forestays side by side ,one with a roller genoa on the other for hank on storm jib and extra large genoa.Apparently the stays were attatched to metal plates top and bottom to seperate them.

I would like to reinstate this system but dont have the original plates. Anyone know how far apart they need to be? Its not just the diameter of the reefing drum to consider but also the sideways deflection of the stay when under load from whichever jib was in use.

I am guessing about 6 inches seperation between the stays should do it. Boat is 25 ft forestay about 32 ft.
 
Probably the reason they were removed is because they can be problematic. They pre-date roller reefing and the idea was that you could hank on your alternate sail to reduce the changeover time. Also possible to fly two sails downwind. Problem was getting forestay tension even (at least on the boat I sailed with them). Likely to be even worse if you set them far enough apart to use roller reefing on one. Went out of fashion when roller reefing came in.

Better set up to use a storm jib is a detachable inner forestay. An extra light weather genoa can be set flying, or more likely replaced with a cruising chute.
 
Entirely agree! Twin forestays are a rotten sysytem IMHO. I did a Pond circuit on a boat with them, using twin headsails in the Trades. The blasted things kept clashing with, and over, each other resulting in the hanks being opened or damaged repeatedly, because we couldn't get the the stays anywhere near tight enough without risking damage to the backstay or boat.

One morning I came on watch (after a tired SWMBO) to find that one of the headsails was only held on by 6 hanks!

As mentioned above, getting sufficient tension is virtually impossible, which is of course, what causes the problem I note above.

An engineer may well have a better explanation, but it seems to me that if, for example, you tension the backstay to 2000lbs, each of the forestays (assuming equal load) can only reach 1000lbs.
 
I've heard that too. With twin forestays you may struggle to get sufficient tension. When closehauled the stay can sag to leeward, so you won't be able to point as high. To fix the problem you may need to change the backstay or make it adjustable to get enough tension on the forestay. If the mast is stepped to the coachroof then the extra compression loads can affect the roof (but I'm only guessing at that last point, I'm certainly no expert, and a compression post would fix the problem).
 
Sounds like a detatchable inner forestay will be a better idea then. Thanks for the replies , saved me a lot of wasted time and money.
 
Two forestays = half the tension in each = much sagging. Having fitted these 25 yrs ago, one passage decided removal. Detachable inner forestay must be the most sensible answer for reducing sail area and moving C/E aft.
 
On our 30 foot cutter, which is firmly in the MAB cruiser category with hanked on sails, the twin forestays are set about 4 inches apart. Forestay tension is acheived by using thinner wire for the forestays than the backstay, but even so forestay tension is not brilliant but it's not really an issue on our boat as it's a heavy cruiser, not a racer. We haven't esperienced any problems with the twin headsails getting caught up with each other.

I would say that the system works very well on our boat. It means that we never need to use the main or a spinnaker/cruising chute for running and being able to change the headsail without having to unhank it is a real benefit, especially in the med where you tend to be changing sails rather a lot.
 
One reason your system works may be that your sailmaker has been told to expect sag and cut your jib(s) without the excess cloth at the luff. If this is done, there is no reason why you should not get a good set, as has been done for centuries on traditional Dutch craft.
 
You should also consider that a dual forestay arrangement will never let you put adequate tension on the rigging, so you will always lose forestay performance. This may not matter to you, but you should not excpect the same tension with a doubled forestay as a single, the geometry doesn't permit it.

PWG
 
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