[Rhodes22-list] Mast Mount Issue

[ROGER PIHLAJA]

Stephan,



Besides the pivoting winch & ginpole on the foredeck, are you also using Stan’s mast crutch at the stern to raise the mast as high as possible prior to the start of the lift?  Without going into the nasty mathematical details, mast raising is a vector force problem.  From the point of view of shearing force at the mast mount/cabin roof joint, the critical time is right at the beginning of the lift.  As the lift proceeds and the mast angle gets steeper, more and more of the weight of the mast is directed down into the cabin roof, where the load is taken up by the mast compression post and there is less and less shear force on the mast mount/cabin roof joint.  The more you can lift the mast up from the stern at the start of the lift, the lower will be the initial shear force on the mast mount/cabin roof joint.  Obviously, pushing near the bottom of the mast during the lift also adds to the shearing force while contributing little to the lift; but, you already knew that!



Now that you’ve already stripped out the screw holes, I would rebuild them using epoxy thickened with fumed silica.  Be sure you drill out any rotten wood, caulk, etc before you fill the holes.  To assure a good bond to the cabin roof, first paint the inside of the holes with unthickened epoxy.  Let it soak into the sides of the holes and let the epoxy kick off; but, don’t let it completely cure.  Depending on temperature, 15-25 minutes is the appropriate time to wait.  Then, fill the holes with thickened epoxy and let it completely cure, say overnight.  You want the epoxy thickened to the consistency of peanut butter.  By not letting the unthickened epoxy completely cure before adding the thickened epoxy, you will achieve a much stronger, waterproof bond with the cabin roof.  It’s also cheap insurance against any future water intrusion into that critical joint.



Hopefully this helps.  Good luck!



Roger Pihlaja

S/V Dynamic Equilibrium



Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10



________________________________
From: Rhodes22-list <rhodes22-list-bounces at rhodes22.org> on behalf of Stephen Staum <snstaum at gmail.com>
Sent: Monday, June 10, 2019 5:29:54 PM
To: The Rhodes 22 Email List
Subject: Re: [Rhodes22-list] Mast Mount Issue

Yes.  I have Stan's mast system.  I did not epoxy the mount in place, but I
did rebuild the worn screw holes with epoxy.
Pray for a safe mast raising.


*Stephen Staum*

*s/v Carol Lee 2*


On Mon, Jun 10, 2019 at 11:16 AM Lowe, Rob <rlowe at vt.edu> wrote:

> Stephen,
> You do not want to epoxy the mast step to the cabin top.  The mast step is
> designed to break loose, likes yours did.  Are you using the mast crutch
> and the mast raising system? - rob
>
> -----Original Message-----
> From: Rhodes22-list <rhodes22-list-bounces at rhodes22.org> On Behalf Of
> Stephen Staum
> Sent: Sunday, June 9, 2019 10:43 AM
> To: The Rhodes 22 Email List <rhodes22-list at rhodes22.org>
> Subject: Re: [Rhodes22-list] Mast Mount Issue
>
> Thanks Graham. I will head out to the mooring shortly - epoxy in hand.
>
> Stephen
>
> On Sun, Jun 9, 2019 at 9:04 AM Graham Stewart <gstewart8 at cogeco.ca> wrote:
>
> > Stephen:
> > I would definitely use epoxy rather than plastic wood. You really
> > don't want water to work its way into the cabin top and I would not
> > trust plastic wood even with sealant.
> >
> > I know that there has been discussion about not bolting the mast step
> > to the cabin top, for the reason you mention, but filling damaged
> > screw holes with epoxy should not be a problem.
> >
> > The fact that the screws came out so easily would make me want to
> > check the condition of the core in the area just to make sure the
> > core, if wood, is still solid.
> >
> > Graham
> >
> > -----Original Message-----
> > From: Rhodes22-list [mailto:rhodes22-list-bounces at rhodes22.org] On
> > Behalf Of Stephen Staum
> > Sent: Sunday, June 9, 2019 8:04 AM
> > To: The Rhodes 22 Email List
> > Subject: [Rhodes22-list] Mast Mount Issue
> >
> > Dear All,
> >
> > I am having a problem with my mast mount attachment to the cabin top.
> > When launching last Sunday, a well meaning friend pushed up from the
> > cockpit intending to help the winch to lift the mast but instead
> > popped the mount off the cabin top. I attempted to reseat it using
> > ribbed metal strips that grip the holes and the screws.  The screws
> > all seemed to be tight but when raising the mast yesterday the mount
> > popped off again just at the mast left the stern crutch.  Nothing
> > broke and nobody got hurt but I am back to square one.
> >
> > I remember past discussions about not using epoxy for the repair as it
> > is supposed to give rather than tear out the cabin top if anything
> > goes wrong.  I am planning to fill the holes with plastic wood, drill
> > pilot holes and rebed the mount.  I am also considering 1/2" longer
> > screws for more bearing surface.
> >
> > Any thoughts or suggestions are welcome and appreciated.  I could not
> > find the past discussions on nabble.
> >
> > Thanks,
> >
> > *Stephen Staum*
> > *s/v Carol Lee 2*
> >
> > *Needham, MA*
> >
> > --
> Stephen Staum
> Pariser Industries, Inc.
>