Genoa sheeting

A genoa foresail can be used on the Nottingham 48, Nottingham 60 and the International Dragon is designed for the genoa from outset. The 48 creates more of an engineering challenge because of the reduced space under the deck but the bigger the model, the easier it becomes! Note that my objective is not to create a more efficient rig but to create a model which is a smaller version of the full sized yacht and delivers a sailing experience closer to that of the full sized yacht.

The genoa can be used in conjunction with a bermuda or gaff sail configuration and there is no reason why the same sheeting system couldn't be utilised for multiple overlapping foresails but I haven't tried this yet! I have a plan to create a replica of Velsheda (see projects) and she will fly twin overlapping foresails.

The system is expensive on pulleys which I use to reduce friction and some cost savings could be made using other ways of changing the direction of the cord but my view is that engineering the system takes time and the small additional expense should make the system more reliable.

genoa sheeting principals.pdf

Winches Fixed Pulleys Control Pulleys

W1 Main winch 1 Tacking fixed loop 9 Main sheet pulley

W2 Tacking winch 2 Main fixed loop 10 Starboard tacking pulley

3 Port/Starboard sheet splitter 11 Port tacking pulley

4 Starboard sheet guide Fixed Points

5 Starboard sheet to deck 12 Main sheet to servo deck

6 Port sheet guide 13 Main sheeting post

7 Port sheet guide 14 Genoa sheeting to servo deck (or pulley)

8 Mainsail sheet guide 15 Genoa sheeting to fixed loop

The two fixed loops are shown in yellow. Movement is controlled by the winches W1 and W2 which are operated individually from the transmitter. The control pulleys 9,10, and 11 are attached directly to the fixed loops.

The mainsail is controlled by the cord in blue. The cord is attached to the servo deck at 12 using a bowsie for fine adjustment. The cord travels to the control pulley 9 to adjust the length of the cord to open and close the mainsail before travelling via pulley 8 to the mainsail sheet post. The diagram shows the mainsail "sheeted in".

The Genoa sheets are controlled by the cords in green (starboard) and red (port). There are two ways of starting these sheets. The first is to attach them (using bowsies for fine adjustment) to the main fixed loop at 15, this will create travel in both sheets equally at 50% of the mainsail sheet and in this case 14 will become a pulley. The second is to use 14 as a fixed point on the servo deck and attach the ends of the cords, using bowsies for fine adjustment. In this case the operation of the main winch will have no effect on the genoa.

The genoa sheeting travels aft to the splitter pulley 3 and then to their respective sides of the hull via the sheet guide pulleys, 4 and 6, to the control pulleys 10 and 11, then up to the through deck pulleys (not shown) on the deck via pulleys 5 and 7. As the control pulleys 10 and 11 move in opposite directions the sheeting to the clew is shortened/lengthened to move the clew to the chosen position. I.e., as 10 moves forward shortening the starboard sheet, 11 will move aft lengthening the port sheet.

On the deck the sheeting is taken forward from the through deck pulleys to the travellers each side of the deck. The travellers allow for adjustment in the angle that the sheeting rises to the clew. When adjusted aft the effect is to put more tension into the foot and less into the leech, when adjusted forward there will be more tension in the leech and the foot will have more camber.

At the time of writing for the Dragon I've retained the options of attaching the genoa sheeting to either the fixed loop or a fixed point on the servo deck but my experience from the genoa 48 and the larger model is that both sheets should move no more than 50% of the mainsail sheet otherwise the shape and control of the genoa will be lost.