Here you'll see the retriever in more detail.



It is important to notice that on the right the diameter between two disks is larger than the between the other disks. The far left is used to coil up the halyard. The two drums on the right hand side as used for the tensioning system.



A small diameter bungee is run from the middle drum to the far right drum when the halyard is pulled out = retrieving the spinnaker. Because the diameters of the two drums on the right hand side is different, the bungee cord will be stretch with more or less a constant length per rotation of the drums. This, in combination with again the different diameters of the drums will result in a more or less constant torgue on the whole setup of drums. The torgue doesn't increase with pulling out more halyard line as would be the case with just a spring.



Notice that the bungee cord wants to be in the non stretched state and therefor on the drum with the smaller diameter. In order to go there the Halyard needs to be allowed to be retrieved to it's own drum hence a the bungee cord put a continious fore on the halyard trying to retrieve it.



Now when the spinnaker is set, the Halyard is pulled through the cleat near the mast and the excess of line on the trampoline is immediatley retrieved by the drums for this allows the bungeer cord to return to it's favoured state or drum.



Now the tension on the line is determined by the diameter of the drums and the stretching constant of the bungee cord.



Naturally the winding and unwinding of the drum may change diameters of the drums a bit too. So the dimension of the setup must take this into account.



I estimate that for a trampoline bag launched spi you'll have 10 mtr. (33 ft) or less halyard to retrieve. A drum of a diameter of 0,1 mtr. (1/3 ft) could retrieve a 5 mm = 1/5 inch halyard on 6 cm ( 2 inches) wide drum in two layers. This would only offset the force on the halyard by 10 % (10 cm diamter going to 11 cm diameter).



I expect a bungee cord of 2-3 mm ( 1/12 to 1/8 inch) to be enough for the tensioning. The bungee drums could than be about 2 to 3 cm wide (4/5 and 6/5 inch).



The whole setup would be less than 5 inches wide.



Assuming a max. CONSTANT stretching of 0,3 mtr. per 1 mtr = 30 % the diameter of the bungee drum would become.



Small drum = 0,1 mtr = 10 cm = 3,96 inches = say 3 inches

Big drum = 0,134 mtr. = 13,4 cm = 5,3 inches = 5 inches



The whole setup would be less than 0,15 mtr high = 6 inches.



And it would retrieve 10 mtr. halyard at a constant (give or take 10 % fluctuation) force. With a little experimentation the right diameter of the bungee drums or bungee stretch constant would be found.



I'm expecting this setup to greatly help my manual retrieval of the spin when I sail solo. I'm a little bit hesitant about using a snuffer because of the windage and I noticed that snuffer drops take quite a bit of fiddling and time to get that thing to go into the snuffer properly. If I do opt for a snuffer system then I will copy the trampoline launched system of teh Stealth.



This system has the extra advantage that it allows the jib to be sheeted of the trampoline just behind the mast which is the best place to make full use of the slot effect of the jib.



I would run the bag diagonal across my trampoline on the top side and make it so that I can run it on the other diagonal to optimize the platform for both port and starboard races and to align to centreline of the bag to the expected line of setting and retrieving of the spi.



But for now I will go for the manual system with bag o the trampoline. The Hobie bag ofcourse (see next post with attached photo) That bag works really well and I found that I can launch it immediately from the bag after pulling the loop and opening the bag.



Bob are you reading this too ? Use any of these idea on your custom F16 !!



Wouter