> I'm building a CLC Patuxent and the suggestion is that the fillets should
> be wide enough to cover the copper wire (which I intend to leave in). Is
> this really necessary, since a less wide fillet should be strong enough
> and the epoxied tape over the fillet should cover the wire. It just seems
> to me that 3 times 17.5 feet of wide fillet might add considerably to
> weight without necessarily improving strength. But then again, I don't
> want the boat falling apart under me. Comments welcomed.

PL,

The principle for the practice of covering the wire is that it's far easier to bridge the wire and run a smooth consistent fillet without going bump-bump-bump over each stitch, fairing out the bumps, and running a finish fillet. You are correct about adding considerably to the weight of the fillet itself. The approx. weight of epoxy is 9.7 lbs per gallon, 231 cu. in. per gallon, or .042 lbs per cu. in.

Increasing the width of the fillet to cover the wire will increase the weight by approx 225% for each doubling of the distance from the joint on a 90 deg. corner. The increase ratio changes a bit by a decreasing angle, but since you have to further increase the distance from the joint to build sufficient height over the joint, the ratio of weight gain is very similar.

To save weight by using a smaller fillet and yet not increase the difficulty of running it, you'll have to:

1. stitch closer to the joint -and/or-

2. use lighter gauge wire (more stitches may be needed here) -and/or-

3. angle the pre-drilled holes so that less loop is exposed.

My own rule of thumb for fillet size is: Distance from the joint is increased with the decrease of the thickness of the smallest cross section being joined. It is likewise increased by the decrease of the joint angle.

Using a 1" cross section and 1/2" fillet spread from the joint, and a 90 deg. angle, as a reference point, I increase the spread by 20% for each 50% reduction of cross section. So if the minimum cross section is 1/8" and the angle is 90 deg., my fillet spread in both directions from the joint would be .864" rounded to 7/8". (1x.5x1.20=.6x.5x1.2=.72x.5x1.2=.864=6.912/8 rounded to 7/8")

Next, for every 50% reduction of angle I add 20% spread. So 1/8" c.s., (7/8" @ 90*)

a 45* angle = .875"x1.20=1.05" rounded to 1"

a 22* angle = 1.05"x1.20=1.26" rounded to 1 1/4"

a 11* angle = 1.26x1.20=1.512" rounded to 1 1/2"

Is my R-O-T scientific or have any basis in physics?? I don't know, perhaps, but it's always worked for me and no joints have failed under normal conditions.

Regards,

Patrick