Again me with some exotic ideas.
I would like to here from you who tried to scale down real boats to footy size.Maybe to add them as a subsection of the class. Lets say a semi scale boat that fix in the box (with this I mean a bare hull, without rudder/s or bowsprits)
The rudders and rig must be as on the original.
It’s m opinion that it would be a worthy chalenge.
Of course these boats would not be as competitive as racing footys (or maybe I am wrong), but from my experience, sometime it is much more satisfying to just steer a scale hull than achieving some “great” speeds with newly designed racing hull.
Would you think in terms of purely linear scaling, or would you take ^1, ^2 and ^3 relationships into account to some extent?
my first generation “OPEN FOOTY” was lke that. then i decided to stop messin with something that might work, to a design that will work. but that’s just me. it’s now on my mantle where it belongs…as a memory of the spirit build.
the main thing was, as you put it, a challenge. got to keep building and muckin, or i’ll go insane.
i still want to build an exact scale replica, of the “OCD” open 60, in one meter size. when, who knows.
Angus, you’ll have to excuse for my poore english, but if you could explain those relations. I thouht of linear scaling.
Scale linearly or in some sense by volume and/or area? Don’t apologise:your English is infinitely better than my Croat!)
I think what Angus was pointing out is the “scaling effect”. This means that as the boat is scaled down proportionately according to the linear dimensions, the measures of area (sail size, wetted surface etc) and volume (displacement, buoyancy, mass of keel etc) will no longer be proportional to the full size boat by the same ratios. These properties scale down exponentially to the 2nd & 3rd power respectively. This is why a directly scaled version of a full sized boat won’t sail all that well until these factors are taken into consideration, which often results in modifications to sail area and/or keel volume & depth.
is there something with the water molecule size as well?
i’ve been told that to get similar results with a wee boat, it would have to be tested in alcohol, or acetone.
is this true?
Thank for your explanation. I am well aware of facts that displacement changes to 3rd power, and area to 2nd. Only the way it was written was not so clear to me. And that is exactly what makes building a scale boat so challenging. Especially with boat as small as footy.As I posted at start of this thread, it would not be exact scale, but in the end, boat should look pretty much like the original. What I mean to say is that you can’t put deep fin keel on a boat with full lenght keel, or lets say use a bermuda sail if original had lateen one. But if you make a hull a bit chubbier in order to achieve more displacement, that would be ok.
Hello Crashimir… nice idea which I like alot.
My first footy was a ‘scalelike’ model called the ‘Pintail12’. Not based on anything in particular, just a generic short fat cruiser type. Funnily enough it does fit withing the rules box quite easliy and with it’s lug sail has a fair turn of speed.
I think if you look to the small fat cruisers for the prototypes then quite close to scale is quite feasible… look to Bolger, Michalak et al. Has anyone looked at ‘Spray’ in this light? The big ocean types will of course fall foul of Angus’ inferences. Scale rigs would be practical I am sure but a scale rudder would probably prove to be a problem. What happens underwater is maybe best left to what works rather than what is scale, the practical fin bulb will not be scale after all.
I can attest to the fun of travelling and just cruising a footy. You get to meet some very interested people this way. I should mention that our Bob’s ‘Kitty’ was my inspiration to come into footys in the first place.
One of the projects I haven’t gotten to yet (there are so many!) is a close-to-scale catboat. The hulls were nice and beamy, so I think it’s workable. I’d go with a very non-scale fin and bulb as a practical matter, but hull and rig should translate pretty well to Footy size.
Someone mention Kitty? I gave her away as a Christmas present this year! Miss her already, but she has gone to a good home. Hopefully we will see some pictures of her sailing on the Central Park pond in NYC. The boat I am currently working on his semi-scale too.