[quote=Edchris177][quote]We also need an engineer to step up and tell us the math on how much more righting weight is required for every once put into the end of a mast, for a given mast length and for say an ounce of water or material.
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Very simple, it's a teeter-totter problem. Unfortunately,our Americam friends still hold onto that archaic British system of measurement.
Think of a simple balance beam weigh scale. Next, we need to understand grade 10 physics, & units of measurement.
One cc(cubic centimetre) of water weighs 1 gram, therefore 1000 cc is 1 litre, & weighs 1kg,(kilogram-2.2lb).
My nacre 5.7 has a 30' mast. So, 1/2 litre(500 cc) of water in the end weighs 500 grams, (appx 1.1lb). 1.1lb x 30'=33 lb holding the mast down. To get it back up, you need 33ft lb more on your righting line. You can accomplish that by having 33 lb at a distance of 1' from the pivot point, 16.5 at 2', or 11lb at 3'.
You see, very simple.
I have ignored a small bit of physics,(statics & mechanics), in that when on its side, the mast is below horizontal, therefore requiring slightly less than the examples. As the mast comes out of the water, to horizontal, that is when the greatest righting force is required, hence the propensity to get it about 3' off the water, then no more. Once the mast moves above horizontal, the required force decreases. You know this, the further your mast comes up, the less the force required.
The example is static conditions, no wind. If you have the mast into the wind, you benefit. Wind pushes on the tramp, but the boat is dragged in the water,creating what we call a "couple" (arm x force), helping to right you. This righting moment pivots around the dragging hull. Obviously, the stronger the wind, the greater the couple assisting you, & the less mass you require to hike out.
I can solo right my 5.7 in a 20mph wind,less than that I need to use the righting bag. In dead calm,I need the Colorado Big Bag full.
Going back to your post, & using those horrible British units of measurement, for every ounce in the mast head, you need to balance it by your righting moment. An ounce at 30' requires a 2 ounce at 15', or 10 ounce at 3'.
Do your kids & grandkids a huge favour, petition your Gov't to join the 21 Century & adopt the Worldwide system of measurement, no one else uses that anymore, & it greatly complicated teaching & retention of physics.
Ie, I "weigh" appx 85kg, do you know how many "stone" you weigh?
No, lbs is not a value of mass, it equates to force, & these mis representations of units are the basis for much misunderstanding of fairly smile problems.
Ok, that's the end of my rant.<!-- editby --><em>Edited by Edchris177 on Aug 16, 2016 - 04:24 PM.</em><!-- end editby --> [/quote]
