Simbo Rig


Simbo safe downwind sailing offshore

Although developed for short handed ocean sailing, The Simbo Rig (Simple Bow Rig) could prove useful to coastal cruising sailors and those who are not inclined to handle flying spinnakers on a heaving foredeck in open seas. What is required is a twin grooved jib furler on which to hoist two identical traditional working jibs on a single halyard. These sails have their own set of sheets which lead through the fairleads and on to the cockpit winches in the usual way. For this purpose it is useful although not essential, for the jib track to carry two fairlead cars (one for each sheet) to avoid the downwind leeward lazy sheet becoming trapped under the sheeve of the dominant upwind leeward sheet.

On the wind and also when reaching, one trims the upwind jib to the wind to which you then tighten the downwind lazy jib. Although it is convenient to have four cockpit sheet winches, it is not essential as the downwind leeward sheet carries no load and can be made up by hand. It is worth mentioning that the two sails can usefully interact with each other to enable you to re-run the sheets from outside to inside the cap shroud when hardening up on the wind. You merely release the upwind sheet to rest the sail on the downwind jib whilst re-routing the sheet inside the cap shroud. After hardening up, re-route the blanketed downwind jib sheet. The converse exercise applies when easing off on to a reach. Similarly, by resting the upwind jib on the downwind sail you can relieve the pressure on the sheet to adjust the jib car and following tightening up, then adjust the downwind blanketed jib/car. Visa versa when reverting back to the original car settings. The interaction between the two sails is also useful when adjusting the sheets under load. First ease the blanketed downwind jib/sheet to the required setting following which the loaded upwind sheet can be released without risk of straining a wrist, in the knowledge that the sail will be captured by its downwind twin.

When bearing away to a run with the wind 35 degrees or less off the stern, you hoist two whisker poles on separate boom lifts against fore and aft guys made off around the fore and amidships cleats. If these are made off to measured marks, you can hoist the whisker poles on their individual topping lifts until tight against the guys in the knowledge that the poles will be at right angles to the mast and level with the horizon.

twin downwind sails flown on a Simbo rig

At this stage the downwind running sheets together with the upwind reaching sheets are led under the whisker poles retractable end bolts which then continue through the fairlead cars and on up to the cockpit winches. For this exercise move the cars to the aft most extremity of their track. To avoid having to deal with flogging jib sheets, furl the two sails away before running the sheets under the retractable bolts and then pull them out to their respective whisker poles. If one is on an extended passage however as in trans-Atlantic,  I would advise running the sheets through a double block attached to the whisker pole and back to a banjo turning block on the cap rail afore the pushpit and returned to the cockpit winches. This will likely protect the sheets from excessive wear.

An alternative option is to rig the weather whisker pole as outlined above, whilst still on a reach. On bearing off to a run, ease the mainsheet and haul the upwind jib to weather via the whisker pole to redirect the wind into its separated leeward twin that doesn’t require a whisker pole to set. Subsequently, the leeward jib sheet load can be temporarily transferred to its opposing reaching sheet in order to rig the whisker pole and run the slackened running sheet under its retractable bolt. The reaching sheet can then be eased to return the load to the running sheet in preparation for taking up weather jib duties following a gybe.

Going on to a run from a broad reach when the sheets have previously been led under the whisker pole bolts or through double blocks, you pull the upwind leeward jib to weather and separate the jibs to leave the lazy reaching sheets laying idle. During this manoeuvre let the following wind fill the sail when half way across to take the jib clear of the mast and in particular the radome. If you power the sail across with the winch the leech will likely hook under the radome.

Once set, the wind captured in the weather jib is redirected into the leeward jib to keep it fully powered when otherwise it would be blanketed by the mainsail. The mainsail boom is eased to no more than 45 degrees off the centre line so that the wind in the mainsail can be redirected into the weather jib to then also flow into the leeward jib.

A further reason for restricting the main boom's angle is to avoid it directly opposing the pressure exerted on the mast at right angles by the weather whisker pole. The leeward whisker pole exerts no pressure which all translates into minimum boat roll.. The only reason for the leeward whisker pole is to take over weather sail duties after gybing. All that is required to gybe is to haul the mainsheet. The whisker poles, guys and jib sheets remain untouched. The whisker poles are always set at right angles to the mast.

  Note the true wind shown by the ensign compared with the apparent wind from the mainsail, displayed by the courtesy flag. This generated apparent wind greatly increases the pressure into the twin jibs to enable them to fly without whisker poles

It is possible to fly the Simbo Rig dead downwind without poling out the twin jibs which can be useful at times. To expedite this you need to run the sheet cars forward and sheet the jib clews down which tightens the leach and cups the sails; the pressure around the mast from the mainsail together with the wind captured directly astern by the weather jib is sufficient to keep the twin jibs fully powered. Of course, without the poled out headsails the amount of pressure in the jibs is lessoned but with a strong following wind this will not necessarily be the major consideration to the short handed sailor. You will be required however, to keep the apparent wind 170-180 degrees off the bow.

When reverting to a reach, one allows the backed weather jib to fly across to leeward when it then becomes the dominant upwind reaching sail. The sheets can continue to run under the whisker pole bolt or through the double blocks, until hardening up on the wind when you release the sheets by retracting the bolt and stow the poles down the side of the mast. Of course, if one is using double blocks then the sheets will have to be re-run through the sheet cars in which case it is probably simpler to furl the headsails first. For ease of identification in the cockpit, it is better to have the running sheets marked with a different coloured fleck to the reaching sheets.

If your boat has swept back spreaders which enable you to dispense with forward lowers, you can attach the two whisker poles to a single forward mounted mast track on separate cars This allows the poles to set like wings and later conveniently stow to forward mounted deck fittings. However, this is not possible for boats with forward lowers. In this case, you will need two attachment points, one forward for stowing with a corresponding forward deck fitting and the other on the side of the mast for flying the whisker poles between the cap shrouds and forward lowers. I attach the inboard end of the whisker pole to the mast with a standard spinnaker pole protrusion. When stowing the whisker poles, I turn them upside down to use the retractable bolt to clip on to a bar on the front of the mast.

Carbon whisker poles are considerably more suitable, particularly if you have to manually set up the poles between the cap shrouds and forward lowers.

Apart from the flying and stowing of the whisker poles there is no foredeck work required as the sails are totally controlled from the cockpit. When striking the sails from a run, you bring the boat on to a broad reach which allows the weather jib to fly to leeward. This then enables you to furl the sails together in the normal way. There is no noticeable additional wear on the twin sails when flown together on a reach although I would advise strengthening the sliding furler-car shackle as the twin jibs when running, could work a weaker shackle to metal fatigue. In fact, I have removed the snapshackle on the sliding car in preference for attaching the head of the sails to a stout screwed shackle on the car with a 6mm spectre line.

Easy to control and furl, Simbo twin downwind sails for safe ocean and coastal cruising.

The Simbo Rig allows the ordinary cruising person to handle all points of sailing with the one suit of sails with minimum foredeck work. The split jibs provide a downwind sail area of around two thirds the area of an asymmetric spinnaker. However unlike the Simbo Rig, an asymmetric spinnaker can not be flown dead down wind in conjunction with a full mainsail. In addition, if the Simbo Rig is complemented with an in-mast furling mainsail then the control of the yacht can confidently be handled by one person from the safety of the cockpit.

On a run, the Simbo Rig gives good performance in all winds from 10 knots through to full gale. With such control the Simbo Rig remains set regardless of night or day, fair or foul weather which is why I have carried the rig onto my Najad 570.

A final word on the Simbo Rig is that all the power is contained within close proximity of the boat. The length of the whisker poles should not exceed 50% of the J measurement and as the main boom is no more than 45 degrees off the centre line it provides a compact, powerful, easily handled rig giving peace of mind in all conditions. It is worth emphasizing, that unlike coloured sails, the twin jibs can be reefed to suit strong and even heavy downwind conditions from the safety of the cockpit. A reef can be put in on the run by furling the sails down from their respective whisker poles. You can also dump half the sail area by allowing the weather jib to fly to leeward on a broad reach. This can prove a useful option if caught out by a severe line squall.

Videos of Simbo Rig being deployed: