Thread: Distance between mast and centerboard

No, I understood the premise of the post, but was attempting, obviously poorly, that it's a complex and often convoluted subject. Simply put, lead can be almost irrelevant in small craft (to a point). If the designer uses common sense and has a modest amount of experience, then it'll be close enough so that the cB can be adjusted accordingly. Now, this cB isn't the same as CB. It's not Center of Buoyancy or center of Balance. It's center of Butt, which is wholly different.

As a young lad I was kind of cocky, as young lads tend to be. I was commenting on the Opti instructor's sailing skills, suggesting I could beat him. I'd never been in an Opti, but did have some small keel boat sailing experience. He took the challenge when I was snitched on by some of the Opti trainees. I hopped in one and we headed out to the seemingly very small course, where he trounced me easily on the first couple of laps. I knew which strings to pull and had good sail set, but didn't notice he'd move around on different points of sail, while I remained fixed in one basic location. On the third lap, I noticed his cB location on an upwind leg and I mimicked it. Suddenly, I wasn't losing ground any more and he circled back to make fun of how much distance he'd gotten on me. I said "lets do a few more laps", where I stayed on his hip the whole time, having this new found understanding of cB.

In small craft, you can adjust the boat literally with half a cheek. This can take a neutral helm to weather, so you can do better on a windward tack or solve a feel issue in really light air. The same is true with a boat that might have a minor flaw in it's lead location, making it all but imposable to truly define a perfect lead percentage on a cB adjustable type of boat. Unless matched against other boats of the same type and configuration, this isn't noticeable. It is the thing that separates the men from the boys in dinghy racing (finely honed cheeks), assuming the boat is sailed well and tactics are mistake free.

It's in larger craft, where the cB isn't as important as the fixed CLP, that nailing down a reasonable lead becomes important. So, much so, that reciprocating saws are often used to fix things. As a rule, you can ignore the rudder used in most small, shoal craft, as they are usually spades, in regard to lateral area calculations. Bard door rudders and skeg or keel hung rudders should have some portion attributed to lateral area, but how much can be arbitrary to a degree, especially in small craft. Bolger fooled around with this quite bit in several designs, placing a fairly high percentage of lateral area in a typically unique rudder approach. Personally, I don't bother in small craft, unless some other factors are involved, such as rig and appendage aspect ratio or even hull form. I generally place the CE over the leading edge of the main appendage and hope for the best in small craft. I haven't had to adjust this much over the years, except on odd arrangements of hull and/or rig. I think Mik does something similar, so we'd both have a lead within a few inches of each other on similar designs, with cB being able to cover the rest.