SailNet Community - View Single Post - Battening down for heavy weather
View Single Post
  #74  
Old 03-27-2007
chris_gee chris_gee is offline
Senior Member
 
Join Date: May 2006
Posts: 825
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 9
chris_gee is on a distinguished road
I have read all this material and the research again. A variety of methods will work for different boats and different levels of sea.
The Jordan drogue is designed to cope with a 40' breaking wave, not one that has broken but is breaking on you.
So that is extreme. The claim is that other methods will not work in that circumstance.
(The peak load is greater than the apparent load on a 35 foot boat at anchor in 60 knots without allowing for wave forces although the normal storm load is rather less. The data for anchoring suggests a 3/4 " inch storm rode is required as a minimum.)
Whether one should cater for such waves depends. However since a certain proportion of waves I think 1/100 are twice the size of others , one might consider deploying it when the waves are smaller like 20-30 ' even though only a few will break properly.
In general one would expect to encounter these conditions predominantly in certain areas on ocean passages
While they could occur elsewhere you have to consider whether a coastal cruiser with normal prudence ( ie sufficient to know about drogues and have one) would be out there on a lee shore.
True some eg Berrimilla didn't use anything and survived the southern oceans and the capes with as I recall only 5 knockdowns in about a 35'. They were highly experienced and perhaps lucky.
However with survival conditions occurring in a small but significant proportion of say NZ to Pacific Islands trips, some sea anchor or drogue system is mandatory for NZ boats. Personally in such circumstances I would not care very much if I were driven off course.
Using a drogue stops the big impact of coming to a stop virtually instantaneously from say wave speed of 23 mph when hitting a trough. The force in mass times deceleration would be substantial. Talk about hitting a brick wall. The drogue would appear to help in cutting down the time one was exposed to the accelerating force of the breaking wave and therefore the resultant velocity, as well as its braking effect.
I doubt warps would suffice though there are some accounts that they help reduce the chance of a wave breaking.
I agree that one might be aware of and use a variety of approaches. I would think though, that changing plans before things get too bad (but worse) might be quite a good idea. It may not always be so easy to swap from lying hove to through beam on to downwind if you leave it too late.
As I said our requirements are that you carry a sea anchor or a drogue. End of story else you don't go. Some of those Maritime Safety Authority cookies are more knowledgeable and experienced than I am. Of course we are talking 1000 mile ocean trips to the nearest foreign picnic spot where the weather will change within that time not daysails in a weather window.
Reply With Quote Share with Facebook