Adding a Spinnaker to a Farr 3.7

After a year of sailing my 3.7 I had got tired of getting to the top mark with the other boats I would sail against (420s and Cherubs) and then watching them sail away from me downwind. I wanted a spinnaker. This is what I did.

I did not take many photos, I hope you can work out things from these pics.

The pole is a windsurfer mast tip. I got a carbon tube made up for the pole to slide in. A hole was drilled through the bow and the pole tube passes through the first bulkhead and buts up against the front of the support for the mast step.

Here's a view taken through the hole I cut in the main bulkhead for the spinnaker tube to exit. Looking forward you can see the hole I drilled in the bow, and the bits I cut out of the bulkheads and girder for the pole tube.. Light is also shining in from the hole in the deck for the entry to the spinnaker tube.

I made a polystyrene plug for the entry to the spinnaker tube, covered it with packaging tape and then glassed it. Afterwards the polystyrene and packaging tape was dug out and the overall shape cleaned out and painted

The main tube was made by wrapping glass around a large PVC tube which had been wrapped in plastic sheeting to allow separation. I think I did 3 wraps of 6oz cloth to lay up the tube with some reinforcement at the end that exits into the cockpit. Getting it off the PVC tube was quite a drama. Here is the tube and entry moulding completed. Don't glue them together yet...

A view of everything being dry fitted prior to gluing everything up. The vertical height from the cockpit floor to the top of the main bulkhead is a bit limited. I cut the exit hole for the spinnaker tube in a slight oval so that it was wider than high so that things would fit. The fibreglass tube was easily squeezed to the oval shape when fitted.

Another view of the dry fitting. The PVC tube used to mould the main tube is on the floor to the right.

Sanded back ready for gluing and glassing.

A view looking in from the hole cut in the main bulkhead. The mast step is directly above us to the right. The pole tube buts up against the girder under the mast step. Some carefully shaped pieces of wood plug into the end of the tube and locate it on each side of the girder. Looking forward where the pole tube passes through the front bulkhead and girder I have glued in pieces of plywood to block it into position on the remaining bits of the front bulkhead.

The front of the pole tube with a carbon tab attached to take the forestay.

The final result!

The spinnaker ended up being about 8 m^2. It should have been something like 10 m^2. The size was a bit constrained by my decision to limit the length of the pole so that it did not remain extended out too far when completely retracted. I also kept the hoist of the spinnaker just above the hounds. I was worried that having it higher would risk the mast inverting and breaking. If the rig used spreaders rather than just lowers one would be able to use a higher hoist with safety.

What's it like? It's great! It's surpisingly easy too. Hoist the kite, pull in the mainsheet, then pull it in a bit more because it will be backwinded by the kite. Cleat the main, yes cleat it and leave the mainsheet on the cockpit floor! Get out on the wire, work the kite sheet and steer to stay up.

Enjoy!