[Public-list] Replacing Wooden Spreaders

[Don Campbell]

Philip
    Brion Toss has some things to say about spreaders in his book the 
Rigger's Apprentice which you might want to check out for yourself.
     I have also built myself a rudder for another boat and wanted a 
foil there for lift. I am doing this from memory but the ratio of chord 
to depth is a fixed ratio and fairly large like 8 to 10 :1 and then 
there is the polacement of the deepest chord. For spreaders, if you want 
the full lift theory to work, this is a bit extreme as you really need 
the compression strength. I think those measurements  were in Gougeon's 
book The complete book on boat building or some title close to that. My 
copy is on permanent loan at the moment!
Don #528

Philip Sparr wrote:
> I want to thank everyone for their input.  I am especially interested in what Gord had to say; I noticed that the center of my mast tends to bow backwards when pressing hard, which has been worrying me since I noticed it.  I had tried putting a alot of tension on my foward lowers, but it didn't seem to help.  I'm definitely going to make the new spreaders with tips on centerline or aft slightly, and am interested to see what difference it will make to my rig.
>
> Philip
>
>
> ----- Original Message ----
> From: Gordon Laco <mainstay at csolve.net>
> To: Alberg 30 Public List -- open to all <public-list at lists.alberg30.org>
> Sent: Monday, April 2, 2007 6:49:23 PM
> Subject: Re: [Public-list] Replacing Wooden Spreaders
>
>
> Hi there -
>
> Mine were that way too... I flipped them over so that the tips are slightly
> aft.  The airfoil is wrong now but the spreaders work better now.
>
> Even with masts like ours you want to set things up so that when the system
> is under load the tendency is for the middle to bow forward slightly.  What
> that will do is draw depth out of the main ever so slightly...and improve
> your boat's ability to carry sail and remain under control in heavier air.
>
> The way you spreaders and mine were - combined with the lower shrouds being
> set up wrong - the mast tended to bow aft when under load.  That increased
> the draught in the mainsail, which increased the healing which increased the
> weather helm which made the boat feel out of control when being pressed.
>
> I think the common feeling is that the lower shrouds should be set up with
> more tension on the forward ones than the after ones.  That holds the stick
> in column when at rest but allows some flex when it is under great stress.
>
> So what started all that?  Oh ya, the spreaders.
>
> I fitted mine with the tips slightly aft and whether or not an engineer
> could measure the benefit... That was a small part of the many little
> adjustments I made; the aggregate of which resulted in a better sailing
> SURPRISE than the one I first sailed.
>
> Cheers - Gord
>
>
>
>
>
>
>   
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