Thanks guys for your kind words. I did put this and more into an article for Model Boats magazine to be followed up with the gaff cutter conversion of Bella. I am afraid it was rejected as being too wordy and I suspect a lack of understanding.

Even in the model boat communituy regard us rag and stick fans as a minority. But glad someone appreciated it.

The clubs I belong to, both primarily model engineering, think an old yacht hull just needs a couple of old hankies and a bit of bamboo mast to sail like an Americas Cup yacht.

I converted the Bella about 4 years ago and apart from going to Black Park it has never ventured far so perhaps there is another conversion some where.

I have used the method on about six yachts and they all sail very well hands off on a tack to windward or a beam reach.
regards
Roy

Thank you Roy for giving such a comprehensive explanation of C of E and CLR. Once you have these points established, it's not difficult to design a rig, any rig, around them.

Nerys
.

I do like your 'Bella' rigged as a gaff cutter. One of the first boats I built was a 'Bella' and even as I was building her, I wondered how she would sail with a gaff rig. Had I been a bit more experienced at the time I might have experimented. I remember seeing a gaff rigged 'Bella' at one of the shows, Blackpool or Haydock a year or two ago, could that have been yours?

Cheers, Nerys

Hi Roy,
Excellent explanation of a simple way to find the balance point on a model.
Correct me if I am wrong but, with the two headsails, is your Pelican rigged as a gaff cutter?

Hi to illustrate, this is my yacht called Pelican. She was meant to be a Bermuda rig and is the Aeronaut kit Bella.

I decided I wanted a gaff rig yacht more old fashioned and in keeping with the wood hull. The sail area is greater, but the C of E is lower. Also I wanted an extra jib and decided to lengthen the 'sailing hull' by adding a bowsprit.
Make your mind up which you prefer.
Roy

Hi how nice to read casual use of CLR and C of E!

If you want to start again with this hull then try this. You will need a good size bath of water, or similar.

Load the hull down to a waterline I suspect all up weight of this hull is 25 lbs. You need side access to the floating hull. Using a finger push the hull effectively sideways and away from you.

The hull will slide to one side or the other. Move your finger along until the hull moves sideways and away from you evenly and not drifting to one side or the other. Mark this point. This is the Centre of Lateral Resistance.

You can work out the sail area group centre and this point should be 4% ahead of the already marked CLR.

When the sails are set up as above then the yacht will sail steadily on all courses. It works for the scale type hulls, you may want to set up differently if you run a class racing yacht,

I have set up hulls with no other information as to origins and they sail very well.

Clearly you may have to play with sail areas and where masts are positioned but the masts can be fixed points and the sails the variable part.

As a hint on sail area a 20 mph wind puts a pressure of 1 pound per square foot on a flat surface. The effect of the keel weight is measured from its estimated centre to the centre of bouyancy of the hull, (or the waterline if in doubt). There are several variables to juggle but it is fun to work it all out and of course there is more than one solution!
Make sure the yacht looks right, compa.re photos of full size
This does skate over a few points but you get the basics.

Regards
Roy

Bear in mind that the boat would have been designed as a ketch and the balance beteen the CLE (centre of lateral effort) of the sails and the CLR (centre of lateral resistence) of the keel would have been a much needed part of that design on the full size vessel. This gives a yacht its 'balance' when sailing and any deviation gives you the effects of 'lee helm' and 'weather helm'. Normally full size yachts are designed to have slight 'weather helm', where the boat tends to point up into the wind and 'lee helm' is most undesirable. Any deviation, even in a model yacht, could make it difficult to sail.
Don't let me put you off, after all it's your model, just wanted to point out any possible problems.
Good luck with your build.👍

will be taking your advice and go for a Yawl i can overcome the squire thing that is aft

David

Yes Derek,
Having looked at the photos again and realising what those square things are on the deck, she looks as if she is intended to be rigged as a ketch, although, as a yawl you could have a bigger and more efficient mainsail, which would give you better windward performance. The mizzen of a ketch often backwinds the mainsail and the mizzen of a yawl is usually too small to do likewise. This has been a divisive subject for years and we could argue the pros and cons for weeks.

Nerys

No expert but the keel looks fsr to shallow mine also carries the lead ballast?

Hi Roy sorry for the delay the Hull is 52'' long. 12'' 3/4'' wide and 11 '' deep that is to the bottom of the keel

David

thank you Derek i would agree with your observation about the after mast is ahead of the Rudder Head and think that you are right in suggesting wooden supports etc below the deck👍

Hi not sure if I missed something but how long is this hull?
Roy

Would hate to dispute what other members have said but I think your model should be rigged as a bermudan ketch and NOT a yawl. Modern full size yachts are rarely rigged as a yawl. The definitions are that a yawl has its mizzen mast mounted aft of the rudder head and a ketch forward (forrard) of it. Note that this position is determined by the rudder head and not the tiller. From your photos it looks as though there are 2 square moulded sections giving the position of the main and mizzen masts and the after one looks as though it will be definitely ahead of the rudder head. I would try to step the masts on the deck with wooden supports below the deck extending to a shaped semi-bulkhead moulded to the bottom the hull. You will find it better to keep the hull watertight and also to rig and de-rig the model. As has already been mentioned, don't forget a fairly large deck opening to be able to access your radio gear, etc. One final point - have you considered using lead shot sealed with epoxy for your internal ballast? Enjoy your build - if she sails as well as she looks you will have many happy sailing days.😎

on photo 5 there is a section that has been marked out in pencil it's the big squire section on the cabin roof that is the section that i will cut out and make cover so yes i am going to fit RC and in photos 2 and 3 there is a deep hollow keel section that has a hole i was going to make a plaster mould of that section and cast in lead so i can drop that in and on the bottom outside of the keel make a lead section with a bolt that go up trough the fiberglass trough the inner lead in the hull and fit a fixing point so the keel will be a bit deeper the keel will not have that cut off look hope it makes sense

the 5 photo along shows 2 small squire sections on the deck section that will be cut out so the mast will go into the hull will make a support section in the bottom section of the hull. will make the mask so that i can pull them out if need be

Another thought.. if the mast is not deck fitted you would need extra support to step the mast onto the Hull.

Just a thought, are you going to fit RC in it? Also you may well need some ballast in her so internal access will be required. It would be advisable to cut out suitable access in the deck molding.

Hi Roy the deck has a raised lip all the way round and there is a thin piece of wood 2mm x 5mm that has been glued to the top inner edge of the hull so as you push the deck section down onto the hull the inner lip of the deck touches the wood strip so i would think the deck would seal itself

David

Hi let me give you a contraversial answer! Does the deck seal itself or 'self position' itself to the hull when placed in position? If so then use bathroom sealant. This does work! Make sure that all shrouds and tensions from ropes etc go through to the hull and it will work fine.

It means if you ever need to get inside it can be peeled off and the sealant will automatically stop water from getting in.

I would look on-line for full size yacht photos of 25 years ago and see what you prefer. The mast position is probably designated but sail proportions can be calculated.

I submitted an article to the magazine on how to guarantee results for sail calculations, it was even advertised to appear, but never has. Several of my yachts use my method and they have sailed very well hands off, nicely balanced.

good luck
Roy

The hull lends itself to rigging as a Bermudan yawl, ideal rig for her.

Nerys

thank you Trev Have found a plan of a Bermuda Yawl in a magazine Marine modeling the rudder layout looks the same as the fiberglass deck has two hole sections to be cut out

You Would attach the deck to the hull with polyester resin.
That would be permanent.
Not sure why you need ribs inside the hull if it as stiff as you say.
From the look of the deck it might be tricky applying wood decking.
Good Luck!
Trev