Merci Claudio pour tes reponses. Je vois que tu es de Nice. Moi je suis d’un peut plus haut, de bretagne pour etre plus precis, mais je vis a Dublin en Irlande depuis des annees. I revert back to English as it is the forum language, I am pretty sure we use the same here - I think they call it flashing which is used around chimneys. Not sure of the thickness they use but now I can enquire about it.
I was asking about the software because I have a project in mind but I need a 2m long hull to do it and i was wondering if and how I could “extend” your drawings to that length and the impact on the bulb weight I would need and any other parts that would be affected. please don’t read me wrong if I can pull this together I intend to give credit where credit is due to all supporting parties.
I was looking at the VOR70 design but i’m not sure a wide boat makes sense in VRC where it makes senses in full size to help with righting moment with the ballast, swing keel and crew and gears whereas your design should pierce through the waves and keep it momentum and speed better then a wider hull. just my views anyway and because it is to sail on the sea the sea condition will be key to the boat speed.
if you like to extend to 2 meters the actual 123 design, the bulb weight will be multiplied by the scale cube as per :
200 / 123 = 1.62
1.62 x 1.62 x 1.62 = 4.26
4.26 x 2.95 kg (actual bulb weight) = 12.56kg
Similarly the displacement will be :
4.1 kg x 4.26 = 17.46 kg (bulb included)
While the sail areas shall be multiplied by the X² : 76dm² x 1.62 x 1.62 = 199 dm²
Staying with black, cutting of unidirectional carbon panels tissue for fin & rudders. 1 layer at +45° - 1 layer at -45° - 1 layer at 0°.
Depending on the rigidity and weight, it may be possible to adds additional layers.
oh that is brilliant, merci bien. I knew it was not just a matter of using the 1.62 ratio for the mass and the area. now that makes sense. And for the line drawings however is it just a matter of increasing the size by that 1.62 ratio ? I suspect the mast position and keel position are also located in the same relative place for the 200cm ?
Linear dimensions like length and width and height are multiplied by 1.62 only, therefore mast and fin positions are proportionally sitting at the same place.
Cheers
ClaudioD
For drilling the lead I recall that K1W120 advocates using a masonry drill bit at low speed, however I’ve found that normal bits are quite adequate so long as they’re regularly dipped in white spirit (or turpentine substitute) - it prevents the lead from loading up the flutes of the drill giving a much cleaner hole.
With the bulb now being black, is that a paint finish used as a tracer for final filling & fairing? Also, will the bulb be encapsulated in a layer of fibre glass or carbon when finished?
Hi Row,
Drilling carried out slowly and step by step to remove lead chips from the cutting bit.
The bulb is already finished, the black paint will be doubled and covered with epoxy resin, I’m not sure if I will adds fiberglass !
Cheers
Claudio
Hi Todd,
For patterns I use the Bulb Calculator as mentioned some posts ago and recalled by Don.
For the drilling, same as Row mentioned in post 170. Operation shall be made very slowly and time to time clean the bit from lead incrustations.
Coreldraw 5 do not calculate surfaces, probably most recent version may do. My ‘antique’ method for calculations is explained some post ago
16 hour later I couldn’t resist and I opened the press to see what happen.
The weight is just a little above then expected since I was targeting 150g !
There is still need for reshaping and wet sanding and check finally the flexibility, but for that it is necessary to wait for the complete polymerization process lasting at least a week or so.
ClaudioD
PS:
I spent some time sanding the fin and the weight drop easily to 147g.
I think will be necessary to add additional layer of normal carbon tissue of 160g/m² and probably an extra layer of glass to support the final sanding.
The expected weight will be close to 170g.
Cd
Back to the rudders …
btw :
the slim one has thickness of 11% of the chord
the shorter one has a thickness of 12% of the chord
Some more wet sanding needed to finish them.
The weight are not far away from the expected ones, respectively 35g and 40g
ClaudioD
I have decided to cover the deck master with packing tape. Not easy task. I do fear that wax only will be not sufficient. Too many corners !
I regret now to have combined the deck with the hatch.
The tape irregularities will be corrected on the female mold, will be easier working on a surface offered by the gel coat with the use of wet paper.
At the end of this project I will recommend to keep the option of adding the hatch after completion of the deck
Claudio
PS :
Application of Gel Coat and glass lamination starting with 2 layers of 105 g/m² twill, followed by 3 layers of 162g/m² twill and finished with 2 layers of 300g/m² twill.
Will be sufficient ? I do not knows, wait for tomorrow !!
and because it is to sail on the sea the sea condition will be key to the boat speed.
