[Rhodes22-list] Mast Crutch

[Gardner, Douglas (LNG-DAY)]

John, 

  Just another note on Roger's response...

Given Roger's expertise and penchant for over-engineering things (especially
safety gear), his railings could probably support the weight of the boat.
Just look how his stern rail is mounted.  There are at least 4 mounting
points with 4 bolts each for 2 stanchions.  My guess is that they are
through bolted with stainless backing plates. There is additional diagonal
bracing supporting the center of the rail. My guess is that if anything in
that design fails, its going to be the transom. (I mean that as a
compliment, Roger.)

Depending on where or how you were to load the OEM stern rail with a mast
crutch, I suspect you'd either bend or crush it.  All of the other mast
crutches I've seen use either the transom, gudgeons, or both to support the
weight of a crutch.  The rail is typically used for stability, as already
indicated.

I built mine to be supported by the transom, and it is lashed to the stern
rail for additional support.  I never worry about the transom.  However, I'm
always worried about bending the rail when I roll the mast out or roll it
back in.  In the center, it has a pretty wide unsupported span.  It is
strong tube, but not strong enough to resist bending when heaviliy loaded in
shear.

So, I'd add a word of caution about mounting a mast crutch to your stern
rail, unless you've built a stern rail like Roger has!

--Doug
S/V Fretnaught



-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org]On Behalf Of Roger Pihlaja
Sent: Monday, May 10, 2004 9:51 PM
To: The Rhodes 22 mail list
Subject: Re: [Rhodes22-list] Mast Crutch


John,

The enclosed link will take you to a pretty good picture of the aft mast
crutch on Dynamic Equilibrium:

http://www.rhodes22.org/rhodes/pics/bimini_room_1.jpg

My mast crutch is homemade & is designed to be installed outside of the
stern rail with the stern rail supporting the weight.  However, a perfectly
servicible mast crutch could be designed to be mounted inside or outside the
stern rail with the weight supported on the stern rail or on the transom.
Build your mast crutch however you want!

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: <jmh123 at juno.com>
To: <rhodes22-list at rhodes22.org>
Sent: Monday, May 10, 2004 8:10 PM
Subject: [Rhodes22-list] Mast Crutch


> I'd like to build a mast crutch but am not clear on the best way to
> support the weight of the mast and crutch. A careful examination of a
> number of pics on the web site appear to show the mast crutch aft (or
> outside) the stern rail. But I have been unable to determine if the base
> of the crutch rests on the narrow deck (or combing) at the stern. Or
> perhaps the stern rail itself is bearing the weight?
>
> Can anyone shed some light on this?
>
> Thanks,
>
> John Hill
>
> s/v Clarity
>
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