Sometimes it seems like a curse and not a coincidence, that when sailing downwind, the apparent wind angle so often becomes around 150 degrees. Which will make the genoa ineffective on many sailboats, even when using a barber hauler. One good solution is to bear off course some degrees. When sailing on the Scandinavian coast however, the track is often dictated by terrain and the archipelago. Zigzagging downwind will also mean jibes, thus having to reset the sails often. Including preventers and barber haulers.
Previously I believed that the wide beam of a catamaran was enough to avoid using such a spreader pole that I saw some monohulls using. But I noted that the monohulls sometimes, with the help of a pole, could keep the genoa steady while I could not. That was a bit embarrassing, so I decided that I needed to try a pole. The drawback of the poles that I could observe on board the monohulls is that they are bulky, some are heavy, and they are a bit difficult to stow. I see many placed up in front of the mast. That is not ideal for the airflow over the leading edge of the mainsail.
So what to do then? I decided I would make a lightweight prototype. For use as a spreader only, not a spinnaker pole. In my garage were a couple of windsurfer masts stored, and the longest of them was the basis for the project. I would have preferred a carbon pole, but did not want to buy one as I did not know if the project would be a success or a failure. But carbon is lighter and stronger.
The outer end contains a dyneema rope loop that can move a snapshackle outwards by pulling or winching the attached rope inwards. The best practical reason for the loop is that the shackle can be connected to the genoa more easily when the genoa is not stretched outwards.
There is a small simple Spinlock jammer that holds the rope tight and the shackle out towards the pole end. That specific jammer is not the best solution, it tends to lose the grip if the line is jerked frequently. At least it must be pressed hard down to grip the rope properly. The low friction ring is there so the line can be angled off to a winch.
The snapshackle is attached to a Dyneema loop in the genoa clew. The length of this loop, the snapshackle and the snapshackle attachment to the pole loop all together give some length capacity loss for the whole system. After the first trial season an extension of about 30 cm (one foot) was put in because I wanted some more capacity. This gave a total length of 4 meters (approx 12 feet).
The pole has worked very well for us, we use it a lot. I also put in an attachment point for it at the base of the inner forestay so that it can be used with a spinnaker too. That also works well, but as the wind shifts forward and the spinnaker approaches reaching, we have to be ready to remove it. The force on the pole rapidly increases and the pole can bend and break. That has actually happened. But that was at the point where the one foot extension was put in. I did that fiberglassing job too hastily, and the joint was too weak.
A long windsurfing mast is required for such a project. The tip will be quite thin and flexible. I did cut off some of it, also because the outer sheave needs a hole to be cut for it. In addition to that there is the hole for the sheave axle. If the mast section is too thin, this point will be weak. That said, that specific area must be reinforced anyway. Our catamaran does not have the widest of beams, 6.5m. For larger boats, this concept may be too weak. But as a spreader pole ours has worked with no sign of overload. (Actually, I believe the force required to push the genoa out and stabilize it is not huge. Most of us have sometimes been standing at the boat side, holding the sheet out manually with our arms for a short amount of time to keep the sail filled.) For larger catamarans I believe parts of more than one windsurfer mast glassed together can work.
The spreader pole attaches to the mast by a shackle. A carbon fiber reinforcement ring at the connecting point for the end fitting can be seen.
This spreader pole stores easily attached to the stanchions by welcro tape. It even bends to follow the curve.
Some follow-up info regarding use with a spinnaker:
Sailing with the wind from behind, slightly in from starboard. Assymetrical spinnaker. Our simple setup is, I presume, like most other cruising multihulls for spinnakers. One guy and one sheet at each corner. We sometimes use only one guy and one sheet on the assymetrical, if the wind is expected to be stable.
Our mainsail is quite large, again like on most cruising catamarans, and will block a lot of wind for the spinnaker if the spinnaker is allowed to be pushed sideways downwind into wind shadow. This will happen if only using the beam of the boat for upwind support as is most commonly done. The spinnaker will be more unstable and less effective. Note the guy on the picture, pressed outwards and out of the main's wind shadow, instead of the opposite way. It can easily amount to 3-4 feet, and this can make a difference in sail efficiency. I think it really does help to get the spinnaker into free air and also at a better angle.
The non active sheet is used to pull the clew outwards and backwards. At fairly low wind speeds, the force on the spreader pole is not at all large as long as the wind is mainly from behind.
For spinnaker purposes, I found support for the spreader pole at the lower inner forestay bracket. Just drilled a hole for a shackle. And used some synthetic washers to stop any rattling. But I found that a stainless steel anti-chafe plate was nice to have in place to avoid ugly marks from the pole end fitting.
Again, this is a setup for fairly light conditions, not racing. But on the other hand, most people use spinnakers for light conditions.
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