Fitting the Keels

Sunday 17th October 2010

Have fitted the two fins (Keels) today, one being made up of three layers of balsa and shaped to profile, and the other from a broken model helicopter blade, scrounged from a friend.

Helicopter blades have exactly the right profile for a fin and rudder - if you have a friend who flies RC helicopters, they will have a broken blade or two lying around - trust me!

Once again they were tacked in place with cyno and then when secure, set in place with epoxy.

Both rudders have been cut out and the intention is to again, layer them up from three pieces of balsa, but to set the pivot into the middle of the lay-up.  This will be done in conjunction with setting up the rudder pivot tube to get the correct height and placement to enable the servos to be mounted in the hull.

Making the Rig:

Thursday 14th October 2010

Whilst this was drying off, I then set about sketching up the rig.

I decided to follows the Plans for the Rig, and on a large flat piece of cardboard, accurately sketched out the proportions of the rig from the thumbnail sketch given on the plans. 

The mast position was included to help with getting the balance of the rig  so that excessive weather or lee helm was not present when setting the whole lot up the first time.

The roach of the sail was drawn in free-hand and looks about right!

The Centre of Effort of the sail was then drawn out and established by finding the centre point of each side of the sail and then drawing a line to bisect the opposite side. 

Where the three lines crossed (in practice, a cocked hat) this was the C of E of the sail.  This was found to be 3.5mm behind the mast position.

The fin will be offered up to the hull, which will be laid on its side beneath and in line with the rig to see how the C of E of the sail sits with respect to the Centre of Lateral Resistance of the fin. (C of LR)  In theory, the C of E should lead the C of LR by aprox 5-10% of the hull length – we’ll have to wait and see…………

Wednesday 13th October 2010

I had adjusted the original design of one of the hulls by narrowing the after sections to give a more slippery hull through the water, but this necessitated  having a much wider stem fillet that will require some additional shaping that may put it out of class – but hey, who cares……..this was achieved by fitting the two side panels the “wrong way round” to create the desired shaping – looks good!

A small fillet of ply was epoxied to the inside of the hull to act as a mast step on which will be positioned the mast support tube.

 Tuesday 12t October 2010

Following the advice in the notes on the plans, It was decided to pre-bend the side panels before attempting to attach them to the hull panels.  My son in HK had put his in a streamer until they were soft and then taped them round a suitable object until dry.

I opted for soaking them in a bowel of water for about 30 mins and then supporting the edges between two tins of tuna with the centre held down by a jar of coffee to get approximately the right curvature.  The second set of panels had to make do with two pudding bowels and a glass jug!

After struggling unsuccessfully to tape the side panels into position and again glue them, I gave up and used the stitch and tack method again, working my way down each panel and being very careful to ensure that the side panel was at right angles to the hull bottom panels.

Eventually I had two hulls with all the bits tacked together but looking completely out of shape!  The introduction of a spacer equal to the maximum width of the deck temporarily inserted sprung the sides out and brought everything into shape, more or less.

This then enabled me to shape up and insert the stem and stern fillets.

The building of two identical (?) Footys

Monday  11th October 2010

A Footy is a 12 inch long (aprox) Radio Controlled, two channel sailing yacht, generally home built, with any type of rig, that conforms to its class rules which basically say that the hull and fin must fit in a box 12”x12”x6”.  Look at the class website for the exact rules, have a look at the photos and explore the links to get a feel for this unique little sailing boat that can be built for literally only a couple of pounds, plus the cost of a cheap two channel RC unit. 

So, why build two Footys?

I am spending some time in Spain in a property that has a 10m x 5m swimming pool, both my wife and I sail, as do all our friends, so building two seemed a good idea at the time.  At least we can have a race with two boats. 

My son, who is in Hong Kong and also sails, decided to build a Footy as well, and so we came to the conclusion that from the several sets of plans available for free download, we would build a “Razor 3” and swop notes as we went along and perhaps learn from each others’ experience………….

The plans were eventually downloaded after some fun and games with two printers jamming up, not being happy with sheets of paper taped together to try and achieve a 14” long sheet of paper as demanded by the plans, but eventually we found some water colour art paper that was cut down to size and the printer persuaded to accept it. 

By checking with the scale guide given on the plans, I was able to confirm that the plans were to the correct scale when printed.

I purchased three sheets of standard 1/16” ply and managed to get all the components of the two boats cut out and bagged up before I took off for Spain.  I also visited a local model shop and acquired some suitable tubing for the rudder pivot and some quality glue!

 

Bruce, my son in HK had started his build before me and had made a slight error in the purchase of the wood and ended up with 1/16” bass wood, slightly stronger than balsa but more difficult to bend.  He started his Footy by building it upside down to try and get the correct shape, and ended up with a lot of epoxy on the outside of the hull which is difficult to sand down!

Learning from that, I attempted to tape mine together, using masking tape to bring it into shape, with the idea of tacking it together on a temporary basis with Cyno (Superglue) and then filleting it in with epoxy. 

The first attempt was not good, the whole structure twisting out of shape and fingers glued together……….

This was then dissected into its component panels and I started again by tacking the two hull bottom panels together with cyno, trying to replicate the stitch and glue method of construction that is used on Mirror Dinghies and similar.  This was much more successful, with the bottom two panels pulling up into shape as I went along.

I use cyno from a model shop and also use a “kicker” to get an instant grab with the joint – it literally joins in four or five seconds!