Would be nice if it was in feet. I don't like yards or parts of yards meters or metres.<br /><br />Basically I have a 5.3 yard(meter) vessel and can be happy with a .8 yard(meter) wave height. <br /><br />To me it is easier to say the boat is 17 feet and the wave height of 2.6 ft is max before there are any real issues ie: water over the deck and reduced speed.There's a really good explanation of boat size versus wave height at this web address
Volumes of info there......... and probalby very good info. One striking statement is the size of the swell and how far apart they are rolling.....truly a bench mark we all need to pay attention to.<br /><br />Give me a 40 foot crest and 100 feet apart, it would be great for 10 min's then boring.Originally posted by Boatist:<br /> I do not know your boat or experience but I can tell you about my 21 foot closed bow boat.<br /><br />It about more than wave height. First a closed bow boat and self bailing boats are safer than open bow boats.<br /><br />My 21 foot closed bow boat we do not launch if the seas are over 8 feet or less than 8 seconds. Instead we do something else that day. We have been out in building seas that were 9 feet every 7 seconds and had a dry safe ride back in but it was no fun comming in I had one person just watching for big breaker astern. Had the sea on the port quarter and was no problem.<br /><br />I belive you could go out is 12 foot seas if swells were 20 seconds apart. This would only happen witha storm way out to sea and calm condintion near shore.<br /><br />Another very important factor is water you must cross getting back into port. If you have to cross shallow water the swells will peek up and then break. Also with a incomming sea and wind and a outgoing current waves will get steeper and more dangerous.<br /><br />One condition I really do not like is a confused sea where the swells are moving one way and the wind waves are going a different directon.<br /><br />Lucky for us here in the USA most Coast Areas have wave rider buoys. One I use here in Northern California Is 11 miles outside of Bodega Bay. There is another out side of San Francisco. These give you all the information you could want. I will include a link and capture current condition. <br /><br />They will give you the Swell height and time apart, direction. Also the wave height. The steepness of the swell. Lots of other info. <br /><br />Bottom line start out in good low swell conditions and make notes. Over a short time you will know what your boat and Crew can do. I personaly suggest two power sources with enough power to steer the boat in the worst condition. Also a big sea anchor just in case all power fails and you have to ride out a storm. Also a good regular anchor with lots of line to keep you off the rocks is drifting to shore and no power.<br /><br /><br /> http://www.ndbc.noaa.gov/station_page.php?station=46013 <br /><br /><br />--------------------------------------------------------------------------------<br />Conditions at 46013 as of<br />(9:50 pm PDT on 05/24/2006)<br />0450 GMT on 05/25/2006: Unit of Measure: EnglishMetric Time Zone: Station Local TimeGreenwich Mean Time [GMT]British Summer Time [GMT+1]Eastern Greenland [GMT-1]Azores [GMT-2]Western Greenland [GMT-3]Atlantic Standard [GMT-4]US/Eastern StandardUS/Central StandardUS/Mountain StandardUS/Pacific StandardAlaska Standard [GMT-9]Hawaii-Aleutian Standard [GMT-10]Samoa Standard [GMT-11]International Date Line West [GMT-12]Western European [GMT+0]Central European [GMT+1]Eastern European [GMT+2]Moscow [GMT+3]USSR Zone 3 [GMT+4]USSR Zone 4 [GMT+5]USSR Zone 5 [GMT+6]USSR Zone 6 [GMT+7]China Coast [GMT+8]Japan Standard [GMT+9]Guam Standard [GMT+10]GMT+11International Date Line East [GMT+12] <br />Click on the graph icon in the table below to see a time series plot of the last five days of that observation.<br /> <br /> Wind Direction (WDIR): NW ( 320 deg true ) <br /> Wind Speed (WSPD): 15.5 kts <br /> Wind Gust (GST): 19.4 kts <br /> Wave Height (WVHT): 7.5 ft <br /> Dominant Wave Period (DPD): 12 sec <br /> Average Period (APD): 7.8 sec <br /> Atmospheric Pressure (PRES): 30.16 in <br /> Pressure Tendency (PTDY): -0.03 in ( Falling ) <br /> Air Temperature (ATMP): 54.5 °F <br /> Water Temperature (WTMP): 55.2 °F <br /> Combined plot of Wind Speed, Gust, and Air Pressure <br />Continuous Winds TIME<br />(PDT) WDIR WSPD <br />9:50 pm NW ( 316 deg ) 15.3 kts <br />9:40 pm NW ( 310 deg ) 14.0 kts <br />9:30 pm NW ( 308 deg ) 12.2 kts <br />9:20 pm NW ( 306 deg ) 12.6 kts <br />9:10 pm NW ( 307 deg ) 13.2 kts <br />9:00 pm WNW ( 297 deg ) 14.0 kts <br /> <br />Previous observations MM DD TIME<br />(PDT) WDIR WSPD<br />kts GST<br />kts WVHT<br />ft DPD<br />sec APD<br />sec MWD PRES<br />in PTDY<br />in ATMP<br />°F WTMP<br />°F DEWP<br />°F SAL VIS<br />mi TIDE<br />ft <br />05 24 8:50 pm WNW 15.5 17.5 7.2 13 7.8 - 30.16 -0.05 53.8 55.6 - - - - <br />05 24 7:50 pm WNW 11.7 13.6 6.9 12 7.9 - 30.17 -0.04 54.3 55.8 - - - - <br />05 24 6:50 pm NW 9.7 13.6 7.5 13 8.6 - 30.19 -0.03 55.6 56.5 - - - - <br />05 24 5:50 pm WNW 7.8 11.7 8.5 10 8.8 - 30.21 -0.03 56.5 56.5 - - - - <br />05 24 4:50 pm W 5.8 7.8 7.5 13 8.5 - 30.21 -0.03 56.5 56.8 - - - - <br />05 24 3:50 pm WSW 5.8 7.8 8.2 13 8.7 - 30.23 -0.02 57.0 56.7 - - - - <br />05 24 2:50 pm WSW 5.8 5.8 7.9 14 8.9 - 30.24 -0.01 57.2 57.2 - - - - <br />05 24 1:50 pm SW 3.9 5.8 8.2 13 8.9 - 30.24 +0.00 56.7 56.1 - - - - <br />05 24 12:50 pm SSW 3.9 5.8 6.9 14 8.3 - 30.24 +0.01 57.2 55.8 - - - - <br />05 24 11:50 am S 1.9 3.9 7.5 13 8.6 - 30.25 +0.03 56.5 55.6 - - - - <br />05 24 10:50 am S 1.9 3.9 8.9 13 8.9 - 30.24 +0.03 56.5 54.9 - - - - <br />05 24 9:50 am E 1.9 5.8 9.8 13 9.5 - 30.24 +0.04 55.6 54.5 - - - - <br />05 24 8:50 am S 1.9 5.8 9.5 13 9.5 - 30.22 +0.04 55.0 54.1 - - - - <br />05 24 7:50 am NE 1.9 3.9 7.9 12 8.7 - 30.22 +0.04 54.7 54.0 - - - - <br />05 24 6:50 am ENE 1.9 1.9 7.5 12 8.4 - 30.19 +0.03 54.7 53.8 - - - - <br />05 24 5:50 am SW 3.9 3.9 8.5 12 9.1 - 30.18 +0.02 55.0 53.8 - - - - <br />05 24 4:50 am SW 3.9 5.8 7.5 13 8.5 - 30.17 +0.02 55.0 53.8 - - - - <br />05 24 3:50 am SW 3.9 5.8 7.2 13 8.2 - 30.17 +0.01 55.2 53.8 - - - - <br />05 24 2:50 am S 3.9 5.8 7.9 13 8.1 - 30.16 +0.00 55.4 54.0 - - - - <br />05 24 1:50 am S 7.8 7.8 8.2 13 8.5 - 30.15 +0.00 55.4 54.0 - - - - <br />05 24 12:50 am SSE 7.8 9.7 7.2 13 7.7 - 30.15 +0.00 55.8 54.0 - - - - <br />05 23 11:50 pm SSE 7.8 11.7 7.9 14 7.7 - 30.15 +0.01 55.8 54.0 - - - - <br />05 23 10:50 pm SE 9.7 11.7 7.2 14 7.3 - 30.16 +0.01 55.9 54.0 - - - - <br />05 23 9:50 pm SE 7.8 9.7 7.5 13 7.1 - 30.15 +0.01 55.6 54.0 - - - - <br /><br />--------------------------------------------------------------------------------<br />Detailed Wave Summary <br />for 46013 as of <br />(10:00 pm PDT on 05/24/2006)<br />0500 GMT on 05/25/2006: These wave data are displayed in rounded times.<br /><br /> Unit of Measure: EnglishMetric Time Zone: Station Local TimeGreenwich Mean Time [GMT]British Summer Time [GMT+1]Eastern Greenland [GMT-1]Azores [GMT-2]Western Greenland [GMT-3]Atlantic Standard [GMT-4]US/Eastern StandardUS/Central StandardUS/Mountain StandardUS/Pacific StandardAlaska Standard [GMT-9]Hawaii-Aleutian Standard [GMT-10]Samoa Standard [GMT-11]International Date Line West [GMT-12]Western European [GMT+0]Central European [GMT+1]Eastern European [GMT+2]Moscow [GMT+3]USSR Zone 3 [GMT+4]USSR Zone 4 [GMT+5]USSR Zone 5 [GMT+6]USSR Zone 6 [GMT+7]China Coast [GMT+8]Japan Standard [GMT+9]Guam Standard [GMT+10]GMT+11International Date Line East [GMT+12] <br />Click on the graph icon in the table below to see a time series plot of the last five days of that observation.<br /> <br /> Significant Wave Height (H0): 7.5 ft <br /> Swell Height (SwH): 7.2 ft <br /> Swell Period (SwP): 12.1 sec <br /> Wind Wave Height (WWH): 2.3 ft <br /> Wind Wave Period (WWP): 2.9 sec <br /> Wave Steepness (STEEPNESS): SWELL <br /> Average Wave Period (AVP): 7.8 sec <br />Previous observations MM DD TIME<br />(PDT) H0<br />ft SwH<br />ft SwP<br />sec SwD WWH<br />ft WWP<br />sec WWD STEEPNESS AVP<br />sec <br />05 24 9:00 pm 7.2 6.9 12.9 N/A 2.6 6.2 N/A SWELL 7.8 <br />05 24 8:00 pm 6.9 6.6 12.1 N/A 2.0 5.6 N/A SWELL 7.9 <br />05 24 7:00 pm 7.5 7.2 12.9 N/A 1.6 4.2 N/A SWELL 8.6 <br />05 24 6:00 pm 8.5 8.5 10.0 N/A 1.0 4.0 N/A AVERAGE 8.8 <br />05 24 5:00 pm 7.5 7.5 12.9 N/A 1.0 3.8 N/A SWELL 8.5 <br />05 24 4:00 pm 8.2 8.2 12.9 N/A 1.0 3.8 N/A SWELL 8.7 <br />05 24 3:00 pm 7.9 7.9 13.8 N/A 1.0 3.0 N/A SWELL 8.9 <br />05 24 2:00 pm 8.2 8.2 12.9 N/A 1.0 3.8 N/A SWELL 8.9 <br />05 24 1:00 pm 6.9 6.9 13.8 N/A 1.3 4.0 N/A SWELL 8.3 <br />05 24 12:00 pm 7.5 7.2 12.9 N/A 1.3 3.6 N/A SWELL 8.6 <br />05 24 11:00 am 8.9 8.5 12.9 N/A 1.3 3.7 N/A SWELL 8.9 <br />05 24 10:00 am 9.8 9.8 12.9 N/A 1.3 3.8 N/A SWELL 9.5 <br />05 24 9:00 am 9.5 9.5 12.9 N/A 1.3 4.0 N/A SWELL 9.5 <br />05 24 8:00 am 7.9 7.9 12.1 N/A 1.3 3.6 N/A SWELL 8.7 <br />05 24 7:00 am 7.5 7.2 12.1 N/A 1.3 3.3 N/A SWELL 8.4 <br />05 24 6:00 am 8.5 8.5 12.1 N/A 1.0 3.1 N/A SWELL 9.1 <br />05 24 5:00 am 7.5 7.5 12.9 N/A 1.3 3.8 N/A SWELL 8.5 <br />05 24 4:00 am 7.2 6.9 12.9 N/A 1.3 3.7 N/A SWELL 8.2 <br />05 24 3:00 am 7.9 7.5 12.9 N/A 1.3 3.4 N/A SWELL 8.1 <br />05 24 2:00 am 8.2 7.9 12.9 N/A 1.3 3.8 N/A SWELL 8.5 <br />05 24 1:00 am 7.2 6.9 12.9 N/A 1.3 3.6 N/A SWELL 7.7 <br />05 24 12:00 am 7.9 7.5 13.8 N/A 1.6 3.8 N/A SWELL 7.7 <br />05 23 11:00 pm 7.2 6.9 13.8 N/A 2.0 3.8 N/A SWELL 7.3 <br />05 23 10:00 pm 7.5 7.2 12.9 N/A 1.6 3.8 N/A SWELL 7.1 <br /><br />Plot of wave energy versus frequency (and period)<br /><br /><br />--------------------------------------------------------------------------------<br /><br />Description of Measurements
If you are talking waves sure.........<br /><br />Swells can be thought of as a fairly regular (though not continual) wave signal existing in the midst of strong noise (i.e., normal waves and chop) Basically swells are generated from some distiance away. They are seperate from a wave. A 9ft swell over enough time is barely noticeable......but a 9ft wave will likely cause some damage. Like others have said the frequency combined with the height that is key.Originally posted by JB:<br /> When in doubt, stay ashore. 9' are more dangerous for a 24' than a 17'.