Core Repair Under Cowl Vents

[Noah]

The solar vent covering is not relative. I believe drilling straight down the cowl vent mounting screw holes won't reach far enough laterally to determine/fix any creeping core damage, as the vent pedestal is a hollow box that is several inches above the deck level. If water got into the core it has perhaps migrated. You will have to explore and excavate for damage from below sideways where the tube meets the deck crack and if it is soft laterally you will have to drill from outside, further back outside border of the vent tower pedestal or from below—or cut an inspection hole into the pedestal box and repair pedestal afterwards. Not fun.

[KWKloeber]

Re: Noah's

Ah yes, I just now was able to look at pics.  I took MB comment that they weren't on a dorade, that they were mounted directly on a flat deck. Obviously a bad ass/u/me. 

Ok, that mea culpa said, what is the construction of the riser?  Are they solid?  Hollow and "sit" on a solid deck? Other?

Mike, what dia are the rings?  Is there enuf space to get vents on there?

[Noah]

The towers for the "dorade boxes/pedestal towers" (whatever you want to call them) I believe are hollow with a 3in. or 4 in. diameter fiberglass tube inserted in the middle that penetrates/intersects through the deck into cabin headliner. Getting to what is inside the deck that is surrounding the tubes, under those hollow towers, is where I see the possible issue. His photos are pretty self explanatory. Unless I am mistaken on how the towers are constructed. 

[KWKloeber]

The towers for the "dorade boxes/pedestal towers" (whatever you want to call them) I believe are hollow with a 3in. or 4 in. diameter fiberglass tube inserted in the middle that penetrates/intersects through the deck into cabin headliner. Getting to what is inside the deck that is surrounding the tubes, under those hollow towers, is where I see the possible issue. His photos are pretty self explanatory. Unless I am mistaken on how the towers are constructed.

Thanks Noah for the come back on that (which was indeed a question not a statement or an opinion, because it ended in ?s, not with periods.)
I'm trying to picture in my mind how they are formed - the c30 mk-II has similar towers (not the mk-I and dropped on the mk-III, not sure about the II-1/2) and tho I've looked for it there's no good info about our's construction (I'd have to think they share similarities?)  AFAIK (= as far as I know) cost had always driven Frank/Gerry designs so I'm thinking the least cost way. Obviously the shell/shape is formed (upside down) in the deck mold and the guts laid up (or down as it were) and the easiest/quickest is probably how it was done (time is most costly, difference in material is nil.)  That would lead me to believe (I guess this constitutes pontificating?) that the traveler and adjacent cowl mount were "continuously" filled en masse (easy?) around a tube. Obviously that's just speculation. Our forum has a very knowledgeable guy on general construction - worked for 2-3 mfgrs (= manufacturers) but not specifically CTY (= Catalina.)  It's not really germane to mr brown's problem but thanks anyway.

Oh PS, yep the pix (= digital photographs) are telling once I viewed them - I dint realize mike posted them as they don't show on the forum text-only version (which is easier to use on my phone screen.)

[Stu Jackson]

I've got the same condition on my port vent.  Finally traced it down to, most likely (we think, Les Troyer the C36 tech editor and I), the wood around the sliding hatch. 

I'm currently praying for no rain, even though we desperately need some!!! 

Here's a very good discussion about that wood trim:

http://c34.org/bbs/index.php/topic,7191.0.html

[Noah]

Stu- Somewhat different issue I believe. I think Mike's concern was to determine how much the crack in the vent tube at deck level has damaged the core (has it migrated under the cowl tower?)—and how to fix it? But haven't heard a response from Mike, so I may be all wet here?

[Stu Jackson]

Noah, good points, I should have been more clear.  In my case, there was water dripping through those cracks in the "tube."  That's why we had to trace it down to some source.  I rebedded the cowl.  No luck.  I rebedded the traveler track.  No luck.  It's simply a process of elimination t identify what's UP THERE...

If there are only cracks and no water, it's purely cosmetic, and all I'd do is slather MarineTex on it and call it a day.  In my case, I needed to find the source of the water ingress to avoid the water's egress through those cracks.  (I should be so lucky...)

[rmbrown]

I opted to cut out the top of the tower, expose the rotten wood... hopefully all of it... by removing as much fiberglass skin as I could and still have the patch covered by the 9" vent.

I used a zip saw to follow my pencil line and I've managed to get down 1/2 to 3/4 inches... and I'm still in fiberglass!  These towers don't appear to be hollow and don't appear to entirely wood filled.  I've emailed Warren Pandy at Catalina for more intel.  I just sealed it back up this weekend and decided to sleep on it.

Here's a photo of where I'm cutting.

[KWKloeber]

Hey Mike

Here's another thought that it's likely someone will comment doesn't apply to C-34s, or isn't germane to, or is pontificating about your unfortunate tower situation 
When we check out the condition of the (sometimes just wet, sometimes rotted) wooden plank buried in the c30 keel stub, we drill down thru the bilge w/a 1/4" bit, into the wood and extract/inspect the chips (dry - wet - rotted.) You could do the same because you're already "committed" to covering/fixing the surface.

IIWMT (if it were my tower) I'd start with the screw holes, progressing in a pattern depending on what you find each time. You might find the lay up is competent in all but a few spots that could be treated by using infusing penetrating resin.  At least you might define ahead of time what spot(s) need to be gouged-out if it's more widespread.  Of course, it would also define whether the box is vacant below some depth or fully occupied.

Is what you've found so far matching with this approach?

If that approach makes sense, lastly depending of course on the findings/extent, I'd drill a series of holes outside the tube circumference and inject penetrating resin to make sure that crack leakage is fixed. Could be in conjunction with Dremeling out the crack(s) and injecting resin from inside the tube (attacking the attack from two directions as it were.) 

IIWMT (no need to repeat) I'd drill it incrementally — based on "chip feedback" drilling to the core level incrementally to determine both the extent and depth (if any) of the rot layer.  You may find (makes sense) that it's all laying down at the "deck level."

How tall is the tower (realizing of course, that I'm opening the door for continuing personal attacks because I should have bought a 34 so I don't need to clog up the forum with such silly questions about it's construction.)  Can you reach to the crack level with a jobber bit or would you need an electrician's bit?  Whatever length, I'd mark it with BRIGHT tape so you reach to the core level and hopefully not thru the headliner. )

Gee I wonder what the negative feedback will be this time?

[rmbrown]

In hindsight, it being 2020, or even better, I wish I'd just drilled through the screw holes to see what I have... but I'm pretty sure (not) that what I'll find is a small ring of plywood glassed into the tower that's likely  got some rot but could be sufficient repaired by just overdrilling and filling with epoxy, and then way more significant core damage at deck level. 

I'd guess the tower is 3" tall, from hull liner to deck plate mounting surface and I'd further guess that about 2" of that is tower and 1" is deck.

If have my thoughts on what the inside of the tower looks like but I'm really hoping that Warren @ Catalina will educate me before I proceed. :)

[KWKloeber]

Mike I agree with, close to 100% of your assessment. It may be polyester resin/ply or resin/matting but doesn't really matter since both are hydrophilic. Structurally I doubt (99.9%) there's any issues but I know you want it repaired. I would be surprised if the rot is very extensive - the crack just caused by our (infrequent) freeze cycles over here.  I think it's just needing to arrest any more intrusion and infusing what's easy and sleep better.
You might also try GD directly. ( Gerard@ )

I believe there's many construction "shop drawings" that are not in the (30 or 34) documentation (I've seen a few.)  Sure wish we could get hands on a complete set, but maybe they also were lost in the flood.

[rmbrown]

I'll give warren a day or so and then call. :)

[rmbrown]

Warren's reply...

***********

Hi Mike,
Below the teak ring, the "raised tower" should be all fiberglass and FRP related products, so the wood deck core typically won't be found or start until you are about 3/8" to ½" below the surface of the surrounding walk deck.
WP

***********

It looks like all I did from the top was make a mess... I'll either have to cut all the way down, which would be crazy, cut up from the bottom, or tackle it from inside the tube.   Time to sleep on it.

[Noah]

Mike-Very sorry if I steered you wrong on the towers being hollow. I said I wasn't sure, but probably little comfort. However if Warren is correct, then Stu's comments were important, as perhaps the cracking at the deck inside the tubes was not from your dorade vent cowl at all—as the screws securing those to the tower  went into solid glass—not exposed core. Thus your leak, if you have one, is coming from elsewhere, and showing up in the tube/deck joint. I would just dig from the side in the cracks and see how far you get. And/or drill a few small holes and see what come out in the shavings.

[rmbrown]

Noah... rest easy my friend... no placing blame here.  I cut into that tower primarily because the screws that hold the deck plates and teak trim rings down only go 1/2" into that deck tower and, since two of them spun out, I assumed that "wood" was rotten!

Also, while I can definitely see the possibility of the water getting to the core some other way, I'm hopeful that's not the case because while on a 2+ week trip, we had a lot of rain and both cowls had water dripping from the core... bad enough that I had dishpans under them.  I removed both cowls and screwed in the deck plates and wet them with a hose... the dripping, from the core split, was immediate.  I pulled up the trim rings and deck plates with the intention of rebedding them with butyl tape.  I got one rebedded but only two screws would hold and, since there was a storm coming, I just taped a piece of plastic over the screw holes and deck plate 3.75" opening.  Two days of rain and no drip.  Sprayed it with a hose and no drip.  Not one single drop from either cowl vent, then or since.  Question then is how is the water getting from the upper screw holes to the core... I think me and a 1/2" bit are going to answer that question from the top.  Unless, of course, I change my mind before I get back to the boat saturday.