Re: Man Overboard

Mac Davis (cgula@innet.com)
Mon, 12 Apr 1999 11:49:42 -0400

- - - - - - - - - - - - - - - - - - - - - - - - - - -
West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
- - - - - - - - - - - - - - - - - - - - - - - - - - -
Greetings, all:
Having on a previous boat rigged a 4:1 tackle to allow me (then 175 pounds)
to hoist myself up mast, the factor of friction in the blocks cannot be
overlooked. I'm afraid that Eric will find something in the neighborhood of
115# pull required to lift 225 # on a 4:1 purchase. Going to 6:1 with
triple blocks will require some 40 + feet of line for 6 foot lift. Might be
better to use two 3:1 tackles cascaded. Something like this:
With person in water (PIW) secured to boat and slack removed, rig 3:1 vang
from boom end to PIW and take up slack. Secure second 3:1 tackle at
convenient place and use it to pull on vang free end. When blocks on
second tackle meet, (can't pull any more), tie off PIW with safety line,
spread blocks apart and repeat. This will give 9:1 advantage and shoud be
within strength range of most Potterers of either gender.

Hope this helps,
Mac Davis, Kelpie, WWP19#804, Aripeka, Fl

-----Original Message-----
From: Eric Pederson <eric@winternet.com>
To: wwpotter <wwpotter@tscnet.com>
Date: Monday, April 12, 1999 10:52 AM
Subject: Re: Man Overboard

>- - - - - - - - - - - - - - - - - - - - - - - - - - -
> West Wight Potter Website at URL
> http://www.lesbois.com/wwpotter/
>- - - - - - - - - - - - - - - - - - - - - - - - - - -
>It has been rumored that JBlumhorst@aol.com said:
>>
>> This procedure might even damage a P119; I don't know if the P19
gooseneck is
>> strong enough to survive long enough to get the MOB on board. The boom
is, I
>> think even if it does bend a little, but maybe not the gooseneck
>
>Hmmm... I'm considering beefing up my topping lift to 1/4" specifically to
>support MOB recovery using the boom. I hadn't considered the sheer force
>on the gooseneck, but, with the lifting tackle attached near the end of
>the boom (maybe right at the topping lift attachment), and the boat heeling
>with the weight of the MOB, I'd think the vast majority of the force would
>be straight down. That downward force would be taken by the topping lift,
>not the gooseneck. I'm very curious about your experiment with the spare
>boom.
>
>> I was talking to a girlfriend of mine with thirty years cruising
experience
>> yesterday. She has a 4:1 block and tackle on a heavy-duty velcro strap
that
>> she keeps in the cockpit. (It's like the one sailmakers give you for the
>> clew of a loosefooted mainsail; you could hoist a grand piano with it)
>
>Correct me if I'm wrong, but lifting my 225 lb self with a 4:1 arrangement
>would require 56.25 lbs of force, right? We experimented this weekend with
>the mast raising tackl, which gives 3:1. I secured one end to an overhead
>tree branch and the other end to me. My wife tried to hoist me off the
>ground, and had a difficult time of it. The 3:1 purchase would have needed
>75 pounds of force. I'm going to rig a 4:1 to see if it seems good enough
>for her, but I think 5:1 might be the way to go.
>
>Of course, the triple block with cam cleat needed for one end of the 5:1
>system is not cheap. If 4:1 works well, I'm may just get one of those
>Garhauer vang kits for the purpose.
>
>--
>Eric L. Pederson
>P-19 #970, Necessity
>Bloomington, MN