Tim:
The strut on my boat (42 Custom) was not mounted as securely as one would
expect (no backing plate, for instance), and a prior owner had done an
inadequate job on a previous repair. Probably the same PO that used bondo to
level the limber holes – but I digress. Worse yet, the damaged fiberglass had
allowed water to enter balsa coring, causing even more harm. I had it
professionally repaired. My guru cut out the inner skin all around the strut
area, filled it with West System and glass (no coring) both to strengthen and
to seal off the area from balsa core, repaired the outer skin damage and
faired, and remounted the strut -- this time using a backing plate. I have not
had any issues since.
One of the problems with the Martec folding prop is that it will sometimes
open half-way (one blade), which shakes the hell out of the boat. I went to a
Flex-o-Fold prop in part for this reason. As I’m sure you know, the solution
is to go to neutral, then reverse, then back into forward. The excessive
shaking when this occurs (and the occasional dock line grab) cannot be good for
the strut, so it should be solidly mounted.
On the hull flex question, the amount of deflection likely depends on where
the pads are located. I would think that there isn’t much change near the
strut. You must repair it on the hard in any event, so I suggest getting it as
close as possible to it’s present location. The idea of remounting it with the
shaft in place sounds right to me.
From: Tim Rutherford via CnC-List
Sent: Wednesday, November 28, 2018 10:15 AM
To: cnc-list
Cc: Tim Rutherford
Subject: Stus-List Prop Shaft Strut - Removal, Alignment, and Re-bedding - C&C
36-1 KCB
Prop shaft strut is weeping around the nuts inside the hull and externally the
fairing shows cracks around the perimeter of the strut base although it doesn't
feel loose. No slop in the Cutlass bearing. She's on the hard for bottom job
and driveline maintenance. I'm interested in your thoughts on how best to
proceed to remedy the strut mount leak and cracks in the fairing.
>From the few posts I have found here, it seems the struts are aligned and
>bedded onto a hard substrate and that the mounting holes were drilled with a
>close fit. That said, it seems that to remount the strut all that is required
>is to remove the fairing material and then simply remove and replace, seal,
>and re-fair.
My questions are:
1.) How best to assess whether comprehensive strut alignment check is necessary
i.e., laser, scope, yadda-yadda? I'm thinking that if the shaft slides easily
through the remounted strut and into center of the shaft log and seal, and
visually appears dead on center through all the above, than I can proceed with
the engine alignment. If not what, call a pro? I have more time than money, so
DIY work is preferred.
2.) How significant is hull flex on these boats while on the hard? I plan final
engine alignment after launch, but could loading on the yard stands cause strut
alignment to appear skewed? BTW, I'm working with an independent Yanmar
mechanic for the engine mounts and alignment.
2.) What material for fairing and sealing the strut bed? What's the method of
application?
The prop is a folding Martec two-blade RH17DX10P-3 Eliptec with 4" of clearance
to the hull; found the center pin broken on one end. It's back at Martec for
refurb. The motor mounts were DF2205-2 going back with OE Yanmar mounts. While
under way, the vibration caused the sail locker lid to sound like rubber
marbles in a blender at a frequency that was probably 2X prop speed. It seemed
like a lot of vibration but there was no change since I purchased the boat in
June '17, and after about a hundred hours of motoring. Shaft seal is a PYI PSS
that is getting a new maintenance kit, and of course, the strut a new cutlass
bearing.
Please share your thoughts if you have been through this or something similar.
All help is appreciated.
--
Tim Rutherford
C&C 36-1 KCB #244 - Chamamé
Tampa, FL
[email protected]
813 748 4888 cel/text
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_______________________________________________
Thanks everyone for supporting this list with your contributions. Each and
every one is greatly appreciated. If you want to support the list - use PayPal
to send contribution -- https://www.paypal.me/stumurray
