Your design is very intriguing. Very light weight. It may have some very interesting characteristics. The volume of the fat keel may supply so much flotation that the hull barely touches the water (or maybe sits an inch above the water). This could perhaps elminate a lot of hull drag. Or it could cause some control problems. My first thought was that it might turn upside down, but you have some weight at the bottom, which should prevent that. You can also add weight as needed. But after you play with it a while, it may turn out to have some very beneficial characteristics. Have you put it in the bathtub? Please keep us posted. It may turn out that the hull is irrelevant, you only need the keel.
The “Law of Unintended Consequences” strikes again
The volume of the keel, with batteries installed and the addition of the 42 gm solder weight attached to the bottem, floated. So the boat basically Floated on its side. I cast a much larger bulb, which seems adequate to provide sufficient righting moment, but the all-up weight of the complete Footy is now 500 gms. (Which quite defeats the ‘object of the exercize’!!!) I will still try to race it tomorrow at Windsor.
The volume of the keel must be reduced. I will dispense with the battery holder and will solder all the connections instead tosave not weight but volume. I will make a wooden rodof a size to contain the batteries within its volume, of appropriatre hydrodynamic shape, surround it with clear stiff plastic sheet, and then glass it to retain its shape and structure. The wood will be removed. This will produce a keel of the smallest possible dimension, although some additional weight may still be required.
You can also reduce effective volume by letting the fairing admit water. Remove the foam fairing. Make the inner section water tight, but add the fairing afterward. Use a thin aluminum or plastic sheet, and leave openings at the top and bottom. This will let the air out, and let the water in. Then the volume enclosed by the fairing will not add flotation. But you might still need to make some other changes.
As feared, the boat did not control well enough to move far enough offshore to get into a steady wind. So, back to the drawing board, to design and make a smaller keel. I intend to fill the triangular trailing edge of the keel with left-over lead shot, and perhaps no supplementary bulb.
and p.s. no Footy race transpired, although four Footys were on the water at the same time.
perhaps you could try making a longer, shallower keel, that would allow for a proper airfoil shape to exist, while still stowing your batteries. I believe the weight of the batteries alone will not be enough, so you will prolly have to supplement with lead shot. I’m working on a design now where I used pennies in the keel as ballast. I figure even if it turns out to be a POS it will still be worth at least 50 cents or so! :lol:
And after all that it appears that there will not be room for 2ubes in my Litefoot design at all.
Thinks - how much do I have to chill the AA cells to reduce their volume enough to fit in? Does anyone know the thermaal coefficient of expansion of alkaline cells?
Can I lie down in a darkened room, please
I have completed the new keel for “Da’s Foot” and am ready to try again tomorrow, weather permitting. The keel has room enough for the batteries in a two by two vertical column, and a small amount of lead shot in the trailing edge compartment. All up -355 gms fully rigged.
Sailed on my local pond on Saturday. Cold! Da’s Boot was almost contollable but the keel leaked and was a little too light yet. Needs a bit more fore-sail, or the jib moving forwards. The wind was too light and fitfull for any definitive conclusions. I enclose photo.