Upward Force

I have a new question for all you Mothies out there. How much force does it take to hold the daggerboard down while sailing? I’d think that there must be quite a bit of force upward on the daggerboard while sailing between the weight of the boat crew and acceleration forces. The reason I’m asking this is because I need to re-design my daggerboard box to work with my ride height adjuster. The daggerboard box on Mothball 1 is a 1”x 8” rectangular reinforced box that has a tight insert that bolts into the daggerboard box at the top to kept the foil from raising above the deck level. Then I had a pin that mostly kept the daggerboard from falling out while sailing. However, I need to change some of these parts to make the ride-height adjuster work and that includes cutting off parts of the daggerboard box insert and many of the areas that bolt the insert to the boat. Clearly I need a major re-design here. So the questions remains, what’s the best way to hold the daggerboard down? The two best options I see are to simply beef up where the pin goes through the daggerboard and assume that it will hold up. But my other idea is a bit different and seems like it would be much stronger. The other ideas is to bolt a removable flare onto the daggerboard at the bottom of the hull, so instead of holding the daggerboard down from the top with a pin, the flare would push up on the bottom of the daggerboard box in an inset receiver and prevent the foil from moving, then I’d just pin it on the top again to keep it from falling out. I kind of like the flare idea because I could make the foil/hull interface much stronger and stiffer utilizing the beefy rectangular daggerboard box originally designed in the boat. How do other boats deal with this?

Boat-Work Season

It’s still a bit cold to begin sailing in Montana, but ski season is officially over so let boat-work season begin! Thankfully most of my projects this year will be easy, I want to re-finish pretty much everything and make a few mods/improvements, but nothing too drastic. One of my projects for this year will be to construct a new rudder gantry. I must say that the original gantry that I fabricated out of solid oak was probably the strongest thing on the entire boat. After two years of useit never had a single failure, but that’s probably because it weighs a ton. Going to a carbon gantry will save me a lot of weight. So now I’m trying to figure out what diameter and wall thickness I need in a carbon tube to give me good weight savings but still be reliable. Is there a standard recommended size for gantry tubes?