Now see what you have done Claudio, hordes of old blokes invading haberdashery shops driving sales assistants mad. Who said Radio sailing was boring!!!.
Yeah - and some of those sales assistants aren’t so bad looking either. When I tell them I’m shopping for fabric for my “sailing yacht” they follow me all over the store !
:devil3:
Sorry Claudio, for hijacking your thread - just a silly mood today !
LOL !!!
Dick , you don’t need to tell that is for an RC Sailing, just that you are learning to become a famous fashion stylist !!! probably will worst !!!
Today I present something unusual, I took the hull, I manage to tilt her at 30° and I filled with 3.65 liters of water (actual hull displacement without appendages) to observe the form of the Water Plan.
A useful tool ! I remove it from the “level ruler”
[img]http://img23.imageshack.us/img23/9809/c57e.jpg[/img
This explain why I din’t cut the stern yet !
A useful tool ! I remove it from the “level ruler”
Claudio
claudio,
how have you taken into account the change in fore aft trim when a boat of such shape heels :vconf:
rob
rfyacht
I’m sorry , I’v not understood your question, could you rephrased it again ? Thanks
Claudio
Is time for the appendages openings !
Claudio
Rudder Trunk installation
Claudio
Hull deck corners supports
corner lamination
Claudio
sorry about the claudio i’ll try again,
when a yacht heels the bow will also sink a little due the change in shape of the hull. The transom is wider than the bow so it will lift the aft end of the hull as it heels. this should be more noticeable with your delta hull shape with more volume and beam further aft.
the effect of this is that the transom will be higher out of the water when heeled.
i was just wondering if you had calculated this for your heeled water line test and if you had how you had calculated it.
i hope this makes sense this time?
Rob
Got it rfyacht,
I have not made yet any verification of the volumes with the Curbe of Areas at 30°. Since I do not use dedicated software, I have to do it manually.
In order to anticipate the issue, I decided to fill up with water the hull and look as the water plan shape could come out.
It appears that the volumes and the shape have a uniform distribution and at the transom I do not see excess of volume compared to the bow as such to produce unbalance.
The only thing I made was to advance the rocker point under the frame 4 with the intent to obtain some volumes forward but I do not knows yet if this will help once tilted. According to the pictures presented above seems to produce some effects.
To answer to your question, actually I do not know, but if you have any suggestions I will be interested to learn from you.
This design is an experimental trial and I will appreciate any suggestions
Thank you for the remark.
Cheers
Claudio
Fin Box
I changed my mind !
Having decided to obtain an adjustable height for the Fin/Bulb, the Fin Box will have a rectangualr section and not a profiled opening as shown above. The rectangular section will offer a better sliding and retaining caracteristics. The lifting rod will protrude by 30mm from the deck once the fin is fully retracted, therefore the wang will be positioned above the boom to avoid conflicts.
In the sketch can be notice that the Servo Arm will be positioned in front of the mast. Because of the arm swing, I decided to make a bridge capable to support the mast . The mast could be adjusted using a perforated alluminium plate.
Claudio
The question of rfyacht let me thinking how to check the assumptions made.
Not having any dedicated software, I decided to fill-up againg the hull with water and checking the max water level for each frame.
I, then, transferred this information to trace the lwl on each tilted frame. Easy from there to calculate the frame’s wetted surfaces and retracethe New Curve of Areas.
The drawing shows the two C.of A. and it is visible, as the overall volumes shift (3.3cm) to the bow direction producing a better lift.
Therefore I can conclude that the boat, with his form, once tilted, will not produce any down effect. Obviously all boats have tendency to lower the bow under wind pressure and this can be compensate with the classic tuning.
The design idea to put the rocker deept under the frame 4 was a good idea.
The picture is offering another view about the regular form of the Water Plan suggesting also an unexpected good symmetry and not a ‘banana’ shape.
Claudio
General setting view
May be a crazy idea but to increase the jib efficiency it is generally necessary to close it near as possible to the deck plan.
The boom and in particular the swivel do not allow such setting, therefore I have decided to recess the rack position creating a little box under the deck level. The deept will be dictaded by the swivel lenght as such to allow also the free swinging of the boom
Claudio
sounds entirely sensible to me claudio.
in theory you can achieve a similar effect on the main sail by fitting a wide boom that will act like the wing on a keel. this may add weight and drag that could counteract any gains.
rob
A drain might be needed.
i cant imagine that it would hold more than a few grams of water, and with the slot shown in the drawings most of it would drain out as the boat heels. it would be similar to the IOMs with their swivel going down to the hull in a tube.
As you said, the weight will be in the worst case in the order of 6/7g, a drain construction may be heavier !
Once constructed I will think about.
For the increased volume toward the bow I 'm happy as came out, one could think to increase the jib surface.
Actually is fixed to 49% fo main, but it is not escluded to go to 55%.
The jib has, in general and if not mistaking, a component lifting force going upward, orthogonal to the forestay, probably helping to sustain the bow from sinking.
Just an idea !
I will repeat the measurements to verify also the effects of simulating a bow down and tilting the hull for about 3° and verify the shift of the CB.
Claudio
I have repeated the complete control of the volumes displacements with exactly the same amount of water (3750cm3), including the tilting of 30° and also by adding a 3° longitudinal inclination (bow down) to simulate potential “nose down” and checking the CB shift.
The surprise come by the fact that between the two healed conditions, the CB shift is only of 13mm. Practically non changes !
3750 cm3 of water in the hull
One of the various steps to reach the final calculation
Claudio
FIN and RUDDER CONSTRUCTION
I have changed the fin width from 10cm to 9cm aiming to reduce the Wet Area
Waiting polimerisation of epoxy
Claudio
The rudder
The carbon rod is glued in - this is made to avoid squeezing of the tube when the arm is mounted.
Claudio