[Rhodes22-list] Wind Loads

[Bill Effros]

Ron,

I'm with Michael on this one.  I don't believe these wind load factors 
for a minute.

There's some highly respected guy I keep stumbling across who has spent 
far more than one summer actually measuring the wind loads, as opposed 
to estimating.  He says that all the standard tables are way off on the 
high side.  I'll find him again in the course of this discussion.  I'll 
let you know when I do.

But if we take the numbers provided by Fortress and others at face 
value, do you really think any of your cleats or eyes, mounted in heavy 
duty Spitzer fiberglass could withstand a sustained force in excess of 
3/4 ton?  I wouldn't want to be anywhere near a boat subjected to 
anything like that amount of force -- whether the anchors could hold or not.

I've been on board in 20 knot winds at anchor.  Everything creaks.  It's 
scary.  Don't ever want to do that again.

I've seen my boat subjected to 300 lbs of force on the bow cleat.  It 
lifts the stern right out of the water.  I wouldn't ever want to see it 
subjected to 5 times that much load.

Will get back to relative holding power as a function of shaft angle later.

Bill Effros



Ronald Lipton wrote:

> There is a table of wind loads at the fortress site:
> http://www.fortressanchors.com/safe_anchoring.html
> It looks like 1600-1700 pounds at 60 mph for a 22ft
> boat.  The page also shows the relative holding power
> as a function of angle of the shaft with respect to the
> bottom.  Parallel to the bottom is 100%, it falls to 10%
> with a 2:1 scope (looks like about 30 degrees).  This is a faster
> loss than I had thought.  The difference between 5:1 and
> 10:1 is about 30% in holding power.
>
> I never would have known this stuff if Bill hadn't incited
> the mob.
>
> Ron
> On Jan 12, 2006, at 9:05 PM, Michel Meltzer wrote:
>
>> d)I could not find the tables for windload from the last time, can
>> someone calculated look/up the load in lb for a rhode22 type of
>> sailboat, IIRC I estimated about 900lb's at the top number, but I might
>> be high.
>
>
> __________________________________________________
> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>