[Rhodes22-list] Mast Crutch

[Gardner, Douglas (LNG-DAY)]

Ahhh.... standard mast.   Considerable lighter than the IMF.  I also lash
the mast to the stern rail (IMF), but I don't lay it centered on the rail.
Instead, I position it at a stanchion.  I'd still be a bit wary of mounting
a crutch directly to an OEM stern rail without additional support. I can
think of several issues:
1. In addition to the mast, you add the weight of the crutch. Still probably
not bad for a standard mast.
2. When moving the mast fore or aft into raising or trailing position, there
are additional forces on both the tubing and on the mounting points.
3. How do you keep the crutch from rotating on the rail?  I have a hard
enough time keeping my rail mount magma grill from rotating on the rail.  I
couldn't imagine how tightly you'd need to clamp a mast crutch to it so that
it doesn't rotate when you roll it into position.  Roger's design excepted,
I don't see the relative advantage of a rail mounted mast crutch.

So, I stand by my original advice.  If you have an OEM rail, I recommend
that a mast crutch be built with additional support than the rail alone can
provide.

Or, you ask Roger to make you a copy of his rail and crutch combination.



-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org]On Behalf Of Rob Lowe
Sent: Tuesday, May 11, 2004 1:58 PM
To: The Rhodes 22 mail list
Subject: Re: [Rhodes22-list] Mast Crutch


Doug,
While your advice is certainly valid, I just lay my (standard) mast on the
stern rail using a cushion between them and lashing the mast to the rail.
Might not be the best way to do it, but that's how the PO did it.  Also, I
can say from personnel experience that the stern rail can absorb the force
of the mast being dropped on it from a few feet above it.  No damage (either
time) to the mast or the rail.  The mast lowering procedures have been
modified, so hopefully I won't have to test it a third time.

Rob Lowe
S/V Getaway

----- Original Message ----- 
From: "Gardner, Douglas (LNG-DAY)" <douglas.gardner at lexisnexis.com>
To: "'The Rhodes 22 mail list'" <rhodes22-list at rhodes22.org>
Sent: Tuesday, May 11, 2004 12:35 PM
Subject: RE: [Rhodes22-list] Mast Crutch


> 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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> >
>
>
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