<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi,<div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 04 Jul 2015, at 11:23, Rick Walsh <<a href="mailto:rickmwalsh@gmail.com" class="">rickmwalsh@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">I multiplied 7500 fsw by 0.304 (feet to metres) divided by 10 (metres salt water to ata) and multipled by 1.01325 (ata to bar).<span class="Apple-converted-space"> </span><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">7500 * 0.304 / 10 * 1.01353 = 231.021 bar<br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class="">It's close, but I think my conversion was very slightly out, and assumes a certain density of salt water, which varies slightly around the world. If I recall correctly, fsw is a "special" American unit of pressure rather than depth. I think it is actually defined as 33 fsw = 1 ata. In which case, to convert to bar should be:<br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">7500 / 33 * 1.01325 = 230.284 bar<br class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">We should use that number if we take 7500 fsw as the correct value. 2301.021 vs 230.284 makes no perceivable difference to the calculated plan. But ~230 vs 250 does. I have updated the patches anyway.<br class=""></div></div></blockquote></div><br class=""></div><div class="">speaking of units: For total clearity, we could use types indicating units as those defined in dive.h for all kinds of things (although for these calculations we might invent new ones to handle doubles).</div><div class=""><br class=""></div><div class="">Best</div><div class="">Robert</div></body></html>