Advice for repair of mast step?

[buckaroo]

Hi, all --

Wanted to run my plan for repairing my mast step by you before I start, to see if there are any obvious flaws in it.  A little background:  I bought my CP16 knowing that the mast step would have to be repaired.  It looks like water penetrated the step area under the tabernacle, rotting the glassed-in plywood block around at least one of the four screws.  Here's a photo:



My plan is thus:

1. Cut away the bad glass and gelcoat in the immediate area of the really bad screw hole. Remove as much rotted crumbly wood as possible.
2. Inject Rot Doctor in all the holes, saturating the rotted wood I couldn't get to.  Let this cure.
3. Fill the remaining gap and the screw holes with an epoxy filler, probably also from Rot Doctor.
4. (?) Here's where I'm unsure how to proceed.  Do I need to glass over the repair, and then apply new gelcoat, or it sufficient to just fair the epoxy filler and paint it after it cures?
5. Redrill holes, mount tabernacle using appropriate bedding material. (3M 5200?)

Now, additional questions:  is the filler going to have sufficient strength to hold the tabernacle screws? I have no intution about the forces this area receives (though given the length/pitch of the screws, it's hard to imagine that it's that much).  Also, I hear rumors of a large screw through the mast step and deck into the compression post.  If the rot has extended as far as this screw, is it sufficienct to leave it in place and fill around it?  And one last one: is epoxy-based filler what I want to use?

Thanks for any insight!

[Tim Gardner]

Go to www.smithandcompany.org to find the least expensive CPES & Epoxy Fill - It. I've been using and recommending CPES to restore wood for years.  I restored an old Chris Craft & used CPES not to bring rotted wood back to life , but to keep what was left,  there.

Remove the whole rotted wood on your mast step - Seal your new plywood with the CPES & Epoxy repair the whole area.  No shortcut will help your boat.  Do it right first and once.
TG

[skip1930]

Well we dragged my buddies CP-19 down to the water for launch.
Against my advice he NEVER has pulled the bolt and removed the mast from the tabernacle for all the years he has owned this boat.
We go to push the mast up and the tabernacle lets go.

In a rush, we ran over to the ships chancery for four 1/4"-20 x 2" ss screws, flat washers, lock washers, finishing washers and two large Marine-Tex epoxies and to my house for the cordless drill. Once again. Screw dia in inches x 10,000 lb divided by 4 = the safe working load for each machine screw. No matter, ss or black iron [steel]. So 625 lb /fastener. Much more then will ever be used or required by the tabernacle to steady up the base of the mast. The standing rigging does the work.

Drilled clean through the rot into the top of the doghouse cabin. Right into the same holes the screws pulled out of. That put four holes around the compression post, one of those holes into the cabin light which can't be seen when the diffuser lens in in place.

Mixed up both Marine-Tex's and slathered some into the offending area. Let it ooze clean through the drilled holes.

Coated the bottom of the tabernacle, laid that in place. Dipped the ss machine screws in Marine-Tex and twisted them into the drilled holes with the assembly of finishing washers under the screw heads and on top of the tabernacle.

From underneath put the flat washers, lock washers, and nylok nuts up there and squeezed the whole mess together. Clean-up a bit. Wait an hour. Finished stepping the mast and sailed back to the dock. That was three years ago. No problem. And this boat has weathered a few 30 knot winds and was looking for more.

After all was cured, ground off the excess screw length and replaced the nylocks with decorative acorn cap nuts. Actually it looks great.

skip.  

[buckaroo]

Thanks, y'all.  I probably won't through-bolt like you did, Skip, because I'd like to preserve the "sacrificial" characteristics of the step area in case my lubberly skills send my mast into a bridge.  But it's reassuring to know that the scews probably aren't receiving as much force as one might think.  I probably should have guessed this anyway, as the original screws are only an inch or so long and not through-bolted.

Tim, I think you're right, but I don't want to replace the whole block, as that's a bigger job than than I'm up for and I don't think I could achieve an attractive result.  I think I will modify my orignal plan, though, and use a wood plug rather than just filler, assuming there's enough bad material to warrant it (I haven't yet dug down into the hole to figure out what's there).

[buckaroo]

So, I go out to the boat intending to start the repair process, figuring I'll drill out the bad hole and remove any rotten wood.  I start:



Hmmmm. The wood is worse than I expected.  It's basically compost, and wet to the touch, so I dig with my chisel trying to find a spot where the plywood is dry.  Pretty soon this is the result, and I still haven't found dry wood:



And now I'm sick at the thought of what I've done to my boat.  But anyway, I didn't find at all what I expected.  I figured I'd find a thick wood block, glassed in with lots of layers of cloth.  Instead, it looks like a thin layer of cloth was laid down in the mold, and a brittle filler of some kind (thickened epoxy? Can some one tell me what this stuff is?  It's kinda pinkinsh/off white and fractures in a glassy kind of way) was filled to a depth of 5/16", then 1/4" (1/2" ?) plywood was placed in, and another layer of filler laid on top of that.  Here's a piece of what I found:



There actually was a sizable void between the cloth and the filler up at the front, around where the bad screw hole was.  I suspect that this manufacturing defect is what caused the problem to begin with. So what now?  

Option one: Continue chiseling until I find "good" plywood, then clean up the hole, cut another piece of plywood, bed it down in whatever stuff Hutchins used to begin with. Slather that stuff over the top, too, filling it to the previous depth. Fair it, glass over it. gelcoat and/or paint. Pull out the compression post, drill up from underneath to get the hole back.  Countersink from the top until I get to the wood, screw in the compression post screw. Drill pilots for tabernacle, bed tabernacle in 5200.  Done!

Option two: Pay someone to fix the damage I've caused. Any guesses on how much this might cost?

What would you guys do?

[Tim Gardner]

OK, Buckaroo, Here's the procedure.    Stop gouging out the plywood.  Drill 1/4 in. Holes in a 2X2 inch pattern over the rest of the mast step block.

Square up the gouged out area, and cut a new piece of plywood to fit in the void.  Epoxy it in place after you do the following:
Buy some Smiths & company CPES  and mix it up using one of their syringes, inject it into the hole pattern you created.  Keep adding the CPES utill the wood will not absorb any more.  Allow  afew days for the CPES to finish it's chemical reactions.

After you epoxy the plywood in place, Mix some more epoxy and thicken it with glass micro-balloons, and fill the remaining void and holes.  Fair the resulting surface, paint & re-install the mast step.

Sounds easy doesn't it?  Takes a little time but this procedure works well, and you can do it yourself.

TG

[skip1930]

Good advice. -->"Mix some more epoxy and thicken it with glass micro-balloons ." I'd only add that the optional choice for the Glass Micro Balloons is to pick-up the one's that are filled with Helium. I use these in my R/C aeroplanes.

snicker...snicker. skip.

[crazycarl]

carefull were you use 5200.  remember it is a permanent adhesive and mainly used for hull to deck joints.  if you need to remove the mast step in the future,  you could very easily tear out the surface of the step.  i have been using 3M 4200 for some time and i'm very pleased with it.  it has the same qualities as 5200, but is semi-permanant and can be removed without damage to the boat's surface.

i had re-bedded all the deck hardware on a previous boat and 2 years later decided to paint that same deck.  i was able to remove all the hardware without any damage to the deck.

on another boat,  the previous owner had bedded new ports with 5200 just before we purchased her.  he did an inadequate job and they leaked.  i tried to remove them, and although i was very carefull, the plastic ports were destroyed, and the gelcoat around them came off.  i was sickened at the sight, but with a lot of patience and not too much time, the areas where back to original condition and new ports installed.

there are many experienced do-it-yourself-ers here that can guide you along, and the next time you run into this sort of problem you'll be able to say "been there, done that"! 

good luck with this, and let us know how it turns out,  carl

[skip1930]

crazycarl-->"i had re-bedded all the deck hardware on a previous boat and 2 years later decided to paint that same deck.  i was able to remove all the hardware without any damage to the deck. "

When I pulled the four 1/4-20 bolts and nuts from the aluminum rudder assembly on my CP-19 transom for powder coating in hammer-tone gray, I had to heat with a paint stripping gun and beat the son-o-gun off the transom with a rubber mallet.
Heat hot enough till you almost can't touch the casting. That's about 160 deg F. [About as hot as a black car in the full sun near the equator].

That casting was glued on their with factory dots of 3M-5200 in each of the four drilled holes from the factory. I don't think we needed bolts. Other than for 'point of purchase'. "Can't buy it if there is no bolts showing."

skip.

[buckaroo]

Thanks, everyone.  Tim, I'll do exactly that. So, no need to glass over the repair?  I like that.  Do you have any favorite brands for the non-CPES goop I'll be using?  I imagine I'll just use West System 105/206. 

[buckaroo]

I had a thought:  Given that the wood was originally less than half the volume of the mast step, and that the screws for the tabernacle were mostly threaded in the thickened epoxy (only the lower half of the threaded length of the 1" screws were in the wood to begin with) is there any reason I really need new wood at all?  Can I CPES the remaining plywood, and just fill the cavity with 105/206/404 mixture, or maybe alternating layers of cloth and thickened epoxy?  It occurs to me that maybe the wood was there to begin with not for structural considerations, but for simple expediency in manufacture.  An alternating pattern of cloth/epoxy, or even just pure thickened epoxy, might be an improvement in strength, and it would reduce the possibility of any further water incursion.  Opinions?

[skip1930]

Forget the glass cloth.
Epoxy fill the divot.
Screw or bolt down the tabernacle.
Clean up what squishes out.
Wait an hour. Do a little touch-up painting.
Step the mast.
Hook-up the wiring.
How much strength is necessary?
Go sailing.

skip.

[Tim Gardner]

Personally, I would replace the wood.  That's me.  It's how she was built.  No glass needed , but that's also how she was built.

The forces on the mast step are for the most part pointed at the keel.  Add a vang, lead your halyards to the cockpit, or use a spinnaker, & the forces change, so I would want the stability & the force distribution the wood block provides.

TG

[skip1930]

I wonder if a guy could pick-up the whole boat by the mast with a crane?
I bet he could.

skip.