I hope not to be too late since you guys are so fast !!
Here a sketch about possible solutions for deck mounting. Any one could adopt his own method.
…
With the ‘option one’ it may be necessari to use more or several (every 20cm) deck beams in order to maintain the deck line curvature. Generally this problem do not exist when a female mould is used. With ‘option two’ beams are also needed in lesser number profiting of the self support of the integrated bevel.
About the deck line border, the type of wood I prefer is the Samba, for me Pine is too stiff - see section marked in the drawing.!
On my opinion this hull detail causes a lot of construction problems. I suggest to avoid this detail, making a normal 90° angle between hull and deck up to the stem.
The complex painting of ETNZ, hides very well this difference (see the Alessandro boat images). Of course if you want a more realistic model, you can spend time working on this detail, but that will increase a little bit the boat weight ed probably that will decrease the hull resistance in case of craches with other boats.
As I’m going with option two, would CF 25 mm (175 gsm) wide strip be sufficient for deck support, was thinking of laying wet-on-wet with FBG would this be ok ?
Interesting day today making my first lead bulb, never tried this before :bouncy: you don’t need much equipment: a gas stove, aluminium pan and a ladle.
Aluminium has a higher melting point than lead, so the pan won’t melt. Made up a ladle to transfer the molten lead from the pan to the mould from an old tin can, formed a spout in the lip of the can and bend a piece back to make a
handle. Need pliers or multigrips handy as the ladle filled with molten lead will get hot!
As exposure to lead fumes can be toxic need to do it in a well-ventilated area, I used the BBQ in the backyard. Melting lead should not create lead fumes as melts at 321 Celsius and boils at 1750 C. there is no reason to ever heat lead up to the boiling point.
Two kilograms of lead took about 15 minutes to melt. Once melted, took impurities out with a spoon so there is just the clean molten lead, the pure lead is bright, shiny silver the used the ladle to carefully transfer from the pan.
The lead poured & settled nicely into the mould without problems and then just as I had finished the mould cracked !!! … Failure :lol: too much heat for the mould & maybe should of pre-heated it or the mould was too thin… oh well a lesson for the beginner … back to the drawing board on that one :dunce:
You have been advised about plaster mould ! and luky you that din’t splashed.
By the way have you calculated the bulb dimensions as function of your lead specific weight ?
For Matthias,
this is why I replied to ALAN with two options.
Personally a support the intention of Alan to try option 2 and the 5 or 10g more wood does not matter. at this stage and in accordance with the Budget presented.
Alan has already proven how precise is in his work, obviously not all can do this type of engineering work.
There is time to change method if necessary.
Of course the bevel pretend the cutting also of the Hull upper sides
Thanks for your concerns Claudio, but I just have to try making lead bulbs, just part of making your own boat if you know what I mean & believe me I take all possible precautions including wearing motorbike leathers on hot 39 C sunny day.
In regard to calculating bulb dimensions as function of weight … I stood on my chair reading that one, but was still too high above my head for me to understand ?
What I did, using the appendages plan, made bulb shape that was slightly larger (1-2mm) than what was on plan, considering would need to find C.G of bulb with longer fin slot to move fore & aft to find right position.
Can you explain to us how to calculate dimension as function of weight ?
Having said that, let go back to what it is needed as bulb weight.
The AC120 Rules call up for a maximum of 3000g, Fin included.
The difference with the Fin will represent thus the weight of the bulb.
Little remark : is much easier to remove weight simply drilling holes then to add weight.
The teory suggest that the lead has a specific weight of 11340g/dm3 or 11.34kg/dm3
therefore a bulb of 2850g (if the fin is 150g), will have a volume of 252cm3 - (11.34g/cm3 x 252cm3 = 2857g)
very nice ,but this is just theory because in practice the lead specific weight is generally lower and can be also as low as 7.8kg/dm3 due to the alloys used. See hunting and fishing application as well the car wheels balance masses or the carpenter lead film coverages.
Assuming the lowest I knows of 7.8kg/dm3, the bulb volume will be 365cm3, that is more then 100cm3 from the theoretical calculation.
At this point, the dimensions being close parents of the volumes, the bulb dimensions shall be tailored with your lead specif weight.
The Bulb Calculator will give the dimensions as fonction of the selected real lead weight, forms and profiles choosen.
I let you to experiment the Bulb Calculator, being ready to all your questions.
Cheers
Claudio
PS:
Scrolling the above link, you will see this window in which can be selected the “material density” this is KEY parameter !
Claudio that is great stuff :graduate: will study this info further and get back to when I ready to go with my next attempt, I’m thinking of doing a sand cast for the next moulding… for 1 peice bulb (no gluing)
Late yesterday FBG arrived for the deck, thanks Rouven and was keen to lay-up the deck mould, light was poor in my workshop and ultimately lead to a few problems which I only saw when I popped the mould today. Used 2 layers of unidirectional (shaping) 105 gsm for the first time, which has some interesting characteristics.
Further, I laid two 25 mm strips of CF on the foredeck to replace the beams, proved to be good idea as the deck is very strong in this area now. The cockpit and stern turned out perfect with a clean profile, however, my FBG skills need to improve using undirectional FBG, on corners had air bubbles which I did not see (poor lighting) and the corners in the cockpit are … well less than desired lets say, hence this deck goes IN THE RUBBISH BIN.
The only good news today is that the raw whole deck weighed in at 115 gsm, 5 gsm under target weight
Today we have high humidity from lots of rain so wait until it gets better ambient conditions before I start the next deck. Any tips on laying undirectional FBG will be muchly appreciated :help: I cannot get hold of the usual directional FBG cloth in 100 gsm.
Cheers K1
P.S Claudio we have another build about to start here in Germany with friend Rouven who’s keen sailor and big boat AC follower also … GO IAAC 120 !!! :icon_tong our numbers are growing !!!
Hi Alan
congratulation for the build anyhow, pity to trow it away, probably a good mastic and paint would had arranged all.
According to my experience, I do not think usefull to use specific unidirectional clots beacause the loads in one direction are not so high to justify that use.
The corner is always a problem but fortunately some one has made a good guide.
I’ m always pleased to knows that some others are interested in this model construction, therefore my best wishes to Rouven.
Cheers
Claudio
PS : from this picture http://www.rcsailing.net/forum1/attachment.php?attachmentid=3806&d=1250850621 it appears that the end of the bevel is finished as a sharp corner at 90°. In reality this bevel is reduced progressively to zero as a triangle. I invite to see the NZL92 picture inserted some messages ago - Message 321 enlarged photo ;
K1W1, with regard to the air bubbles on the corners; these are probably because the corner is tighter than the glass cloth will conform to without some assistance and you might find it occurs again. Ideally this assistance would be with vac bagging but you might find that some strips of wood wrapped in parcel tape (to act as a release agent) clamped into the corner will do the trick. You might also consider thickening some epoxy and forming a fillet in the corner before the lay-up.
FG cloth, or any woven cloth for that matter, does not like to go around sharp corners, inside or outside. For inside corners that you want to have a sharp edge, thicken up some epoxy and make a fillet in the corner. When you are cutting the glass to lay on the mold, try to turn the cloth at a 45* bias so that the threads are going around the filleted corner at angles instead of half going parallel to the corner, and half at 90*. Use lots of thickened epoxy where three panels meet!
For outside corners that need to be sharp, the 45* bias cloth will help, but pressure is needed to prevent the glass from lifting and allowing air underneath. Vacuum bagging is a fairly simple way of putting pressure on the layup, but you have to plan for that when you are making the molds, so that the entire thing can be put into a bag without crushing it, or puncturing the bag with sharp corners.
I have also had good luck with strips of clear mylar. Lay one strip on one panel, past the edge, and squeegee the air from underneath. then another strip on the panel meeting up to the first, as close as you can get to the first mylar. Squeegee the bubbles from underneath it. If the glass wants to lift from the corner, the mylar will prevent air from getting through the cloth. Without this air being allowed to get through the cloth, there is a “vacuum” under the cloth, and the air pressure will keep the two sides from lifting up. That’s my theory anyway. It does seem to work!
Claudio those links are very good info, thank you Ray and Hew great tips that I will try today, thanks guys !
After looking closely at the fitting of the deck to the hull I will make few minor adjustments 1) the bevel is little to wide so will narrow it down a little more and 2) I will take out the 90 degree finish near the shrouds and try to reduce the bevel to progressive zero at the shrouds.
Lets see how it works out tomorrow when I pop the next moulding.
Couldn’t wait until the morning to see how 2nd attempt at the deck went :shake: so popped it off this evening … whew ! no problems this time, this practice is beginning to pay-off ! thanks for all the tips guys, everything really helped
Weight mangement is getting better with target of 120 grams, this baby came in at 102 grams !! :bouncy:
Will lay the second deck tomorrow and will just about ready to start fitting everything together early next week … getting excited
Second deck done (110 grams). This week I need to hunt down fittings & rigging etc. unfortunately need to drive half the country to get everthing :mad:
I have decided with the weight savings made so far there is no need to go with the CF masts so I wish to use aluminium airfoils, two sizes are available 19 mm & 16mm (chord length) which one do you recommend ?
16mm I suppose is oval ? otherwise is too big.
The CF tube are normally of 10mm and 12mm or the one sold by TD Model Estruded CF oval.
Matthias has the correct answer.
Cheers
Claudio
Today dry fitting the fin boxes to make sure they fit perfectly and then cutting keel fin slot in the hulls, planning on wet-on-wet gluing in fin box with CF 200 gsm underneath (hull support for fin box) and at same time will be aligning keel fin.
Claudio apart from the additional CF support for rudder is there any other areas I should apply CF support to the hull ?
Taking one weeks break before putting everything together and get some time on the water with some big boat sailing …:jump2:
Yes Alan, is the area close to the deck beam use to anchor the Forestay. See Hull sides.
In addition, personally I would adds a litthe chain, wire or cord between the hull bottom and the forestay beam mounted on deck. The Forestay exerce a pulling force to the deck area rather important expecially when the Backstay is also pulled.
See also AC33 arrangements
Cheers
Claudio
Thanks for that Claudio, I will use same forestay deck anchor design you have done on your AC 33.
Have been playing around with graphics and come up with two designs (1 for each boat) hope you don’t mind that I have modified your original graphic file Claudio.
Design 1 is the orginal AC 32 - NZL 92 with only varition being using white instead of the grey/silver for hull curves.
Design 2 is as South Pacific series held in NZ in Jan/Feb this year with fern on the stern, once again with white instead of grey/silver.
Both boats will have predominately white cockpit decks.
and was keen to lay-up the deck mould, light was poor in my workshop and ultimately lead to a few problems which I only saw when I popped the mould today. Used 2 layers of unidirectional (shaping) 105 gsm for the first time, which has some interesting characteristics.