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Keel Bolts, Bilge and plywood stiffener

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thaind
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Canada
145 Posts

Initially Posted - 02/03/2005 : 10:29:25

I purchased a 78 #729 keel version last autumn. There has been much discussion about soda/sandblasting and other methods of repairing the seperation of the fairing compound from the keel. Realizing that the damaged area was less than 5% of the keel surface, I sandblasted/ feathered/primed/filled damaged areas and epoxy sealed complete keel area with six coats of interlux epoxy sealer. It occurred to me that much of the repair was along the seam between hull and keel, and that in all likelyhood the water migration that had initialy started this problem was most likely from the bilge inside the boat, even though visual inspection showed this area to be solid. Yesterday I bit the bullet and drilled some test holes through the bilge down into the plywood stiffener. Sure enough this wood is black and damp. I continued to perforate this area, will let it dry, soak with Git-rot, or other similar epoxy, and will then attempt to seal bilge area if this is in reality possible.

In hindsight it is inconceivable that water could not have found it's way into this area within 25 years, and in my environment that means freezing and expanding every winter, causing a myriad of further paths of egress.

Derek Thain 78 TR FK "PASSAGES"

Edited by - thaind on 02/03/2005 12:48:38

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 02/03/2005 : 12:17:50

It sounds like you are in the process of contributing both knowledge and technique to the knowledge base of this group. Thank you for that. Please take pictures and continue the narrative as the project progresses.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1889 Posts

Response Posted - 02/03/2005 : 18:14:48

Good grief Derek, replace that mess!

For any epoxy to distribute stress over distance it needs a matrix of fibers to work with. The rot ate the fibers in the plywood -- they're gone. The "Git-rot" or similar approaches are intended to apply a bandaid to relatively low stress problems like a wood cored deck that's delaminating from water intrusion and subsequent freeze cycles. Temporarily eliminating the disconcerting oil-canning of deck delamination under the press of a boat shoe carrying 200 lbs. for long enough to sell a used boat is a far different application than distributing the dynamic loads from keel bolt washers supporting the weight of a ballast keel for the rest of the boat's normal life expectancy. In addition, I see no reason to assume that the penetrating epoxy is going to wick into every microscopic nook and cranny of the damaged plywood -- there are likely to be untreated pockets of rot remaining. Also consider the relative consequences of the repair failing in those two examples. In the first case the deck still feels a little squishy and maybe creaks when walked on. In the second case, the keel comes loose under the worst conditions encountered.

But, that's just my opinion.

Perhaps I'm just an alarmist.

In addition to collecting other opinions here, you might want to contact the makers of "Git-rot", or WEST, or System Three, describe exactly what you are up against, and ask them point blank if they recommend their product for that application.

-- Leon Sisson

Edited by - on

thaind
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Canada
145 Posts

Response Posted - 02/04/2005 : 10:02:51

If you are an alarmist Leon, you are probably correct to be. There is the old saying about there being "Old pilots and Bold pilots, but no Old Bold pilots". Sailing is probably the same. I appreciate your comments and have contacted Git-Rot/ and Rot-Doctor to see if they consider their products up to the task and will post their responses.

I am now wondering what would be the proceedure to replace "the mess". My keel bolts are pretty well seized but seem solid. Either Catalina or some long previous owner has heavily painted the area. Any degradation to the bolts would be found or will occur in the punky plywood area and would not likely be visible. Access to the whole of this area is quite poor.

It would seem that:
1. The top layer of glass and all wood should be removed.
2. Cavity should be epoxy sealed.
3. Hollow should now be filled with polyester roving and resin to original thickness.
4. Flood with epoxy sealer.

Do you think this would seem reasonable?

Thanks

Edited by - on

Buzz Maring
Master Marine Consultant

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USA
1762 Posts

Response Posted - 02/04/2005 : 11:13:17

Hi Derek, Leon, and others,

I'm confused. I thought the hull was solid fiberglass. What plywood are we talking about?

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 02/04/2005 : 11:52:11

Is it the wood plate between the hull and top of keel? I was not aware of any wood in the layup. It could also be a "repair" from damage long ago.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 02/04/2005 : 11:58:38

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Buzz Maring
 I'm confused. I thought the hull was solid fiberglass. What plywood are we talking about?

<hr height="1" noshade id="quote"></blockquote id="quote">

Buzz,

On fixed keeled C25's, there is a piece of plywood in the keel stub that the keel bolts come up through.

Although this relates to a C27, I'd imagine that these factory instructions for repairing the wood in the keel stub would probably apply to the C25 also, but check with the factory to be sure.

[url="http://www.blumhorst.com/catalina27/images/keel_factory_drawings/keel_stub_wood_procedure_from_catalina.gif"]C27 Keel Stub Wood Removal Procedure[/url]

Edited by - on

Buzz Maring
Master Marine Consultant

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USA
1762 Posts

Response Posted - 02/04/2005 : 12:52:27

Buzz, On fixed keeled C25's, there is a piece of plywood in the keel stub that the keel bolts come up through. - Don

Thanks, Don ... now I know what we're talking about.

Hmmmmm ... I have to wonder though ... why would Catalina put plywood in the bottom of the bilge? It seems to me they would use something rot-resistant. After all, the bottom of the bilge is where water is going to pool ...

Edited by - on

thaind
Navigator

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Canada
145 Posts

Response Posted - 02/04/2005 : 14:52:47

When I look at Don's link to the Catalina 27 diagram and repair, that is exactly what I see in my bilge.

I said that I would post any responses received from epoxy suppliers so will do so.



Derek,

Based on your description, we'd recommend that you scrub the area absolutely clean (trisodium phosphate in warm water), dry it as throughly as you can with fan-driven air, and then treat the ply and the cracked bilge area with CPES (Clear Penetrating Epoxy Sealer). Our 2-pint unit would be sufficient product for this application.

We would then suggest that after the CPES has cured (a couple of days, or longer) you soak the wood and the cracked bilge area with our Layup & Laminating Resin. This is a very slow-setting, non-blushing resin that will not crack or fracture. In places where it absorbs into the wood, come back and re-apply new resin. I would think our 2-pint unit of the L&L Resin would be sufficient here (unless you want to take the third step -- see next paragraph).

Basically I think the above would do the job. However, if you want to take it one step further and add strength to the area, you can consider the possibility of laying down some fiberglass cloth with our Layup & Laminating Resin, especially on the area of the fiberglass hull where the cracking has occurred. Do not use a polyester resin. Polyesters do not bond well with epoxies, and they are not nearly as strong a resin as epoxy. If you choose to take this step, then you would probably want to order our 2-quart unit of the L&L Resin.

Feel free to come back if you have additional questions. If you wish to order you can do so via phone or our secure on-line order form. We have warehouses on both coasts so shipping time is 3 days or less to any point in the US.

Doc
--
The Rot Doctor
http://www.rotdoctor.com 

I don't intend this to be an ad but rather an answer or discussion point, so please take it as such. I too have no idea why Catalina would place a piece of ply where it is guaranteed to cause problems.

Edited by - thaind on 02/04/2005 14:53:42

Leon Sisson
Master Marine Consultant

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USA
1889 Posts

Response Posted - 02/04/2005 : 19:19:51

Derek,

[url="http://www.blumhorst.com/catalina27/images/keel_factory_drawings/keel_stub_wood_procedure_from_catalina.gif"]Don's excellent link[/url] to Dr. Judy's copy of the Catalina factory procedure for repairing this problem in a older Catalina 27 is pretty much what I imagined it looked like, and is about how I would suggest you proceed. Here are a few things I would do differently. Build up a greater thickness of fiberglass roving than the three layers they suggest using specifically WEST epoxy resin. I think I'd leave out the 1.5oz mat, as I don't consider it necessary or compatible with epoxy. Be sure to grind, sand, and clean, clean, clean before beginning to laminate. I'd suggest several turns of electrical tape for masking the portion of the threads you will need to run the nuts back onto. For the portion of the threads that will be buried in the new laminate, you might try painting on enough 3M 5200 to fill the threads. That way, after you're done, you've already protected and calked the threads against water from below while avoiding permanently bonding the keel to the hull with epoxy. Where the Catalina instructions mention "paint out the sump with white gelcoat", they are likely wanting to:

1.) Protect the keel bolts from being damaged by bilge water.

2.) Make this look a lot less like a serious repair job of unknown skill level.

3.) Restore the impecable asthetics boat bilges are known for.

As The Rot Doctor suggested (in between the heavy-handed sales pitch), it would be important to grind back and thoroughly clean the area to be bonded to. I would suggest you also contact [url="http://www.westsystem.com/"]WEST[/url]. Those people literally "wrote [url="http://www.westsystem.com/webpages/productinfo/guide/index.htm#publications"]the book[/url]" on using epoxy in boat construction and repair. I'm confident you will find their technical consultants very helpful and amazingly knowledgable.

Good luck, and keep collecting and sifting those opinions!

-- Leon Sisson

Edited by - on

John Mason
Admiral

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USA
687 Posts

Response Posted - 02/04/2005 : 19:57:34

I read somewhere that if you wipe down the clean fiberglass with styrene, it will somehow (I'm no chemist) re-activate the resin and will allow something of a chemical bond to develop with the new resin.

Anyone know if this is true? Or if it applies only to polyester or epoxy specifically?

Edited by - on

Dan86
Navigator

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130 Posts

Response Posted - 02/04/2005 : 22:49:33

Well if that doesn't scare the heck out of a fin keeler, I do not know what would. Let me simplify the process to see if i've got it. I need to pull boat, rest with some weight on the keel, pull the nuts off the bolts, clean, clean, clean the bilge area, treat wtih git rot or an equivalent, then possibley laminate up to three or four layers of glass, then rebolt, and either gelcoat or paint? Hope that is it in a nutshell, I guess I will pull a year early so as to sleep well at night!!

Edited by - on

atgep
Master Marine Consultant

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1009 Posts

Response Posted - 02/05/2005 : 00:12:48

Is it just the fin's or do the wings have wood too.....? It would seem logical as they use a similar mount as the fin.

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 02/05/2005 : 08:16:36

Hey Guys,
A few words. First make sure that you actually have a problem. The fact that the wood is soaked and dark does not mean that its bad. Wood that is saturated with water is less strong and stiff than dry wood but will not rot and retains most of its compressive strength. If the keel bolt washers are not collapsing down into the wood by crushing the glass around them you are OK. Freezing and thawing cycles on this plate in fresh water would be the worst problem.
Second if you follow the Catalina instructions you would put in 4 layers of 1.5 oz mat and 3 layers of 24 oz. roving. That would be about 1/2 inch of solid glass and is plenty.
After building boats since the sixty's I consider Git-Rot etc. to be about as effective as piling real horse droppings over the affected part. If its bad replace it.
To find out if its bad. Take a 1 inch hole saw, set the drill so that it just sticks out, cut through the top layer of glass somewhere thats handy to get to and not too close to a bolt, take the drill out of the hole saw, cut down through the ply, stop before cutting the lower glass much, pry out the ply and examine. If wet but sound epoxy the hole closed. If crumbly prepare to remove the stuff. On something the size of this you might do 2 or 3 test holes.
The Cat instructions indicate remove the ply if its bad not glass over the existing stuff. This is because the old core will crush and the keel will come loose if the core is soft.
The ply was put in there to limit the amount of glass in the layup to keep from over heating the mold and because it does get wet and swell if water seaps in and thus closes off the leak. Since its closed off from air, stable in moisture content though wet, and free of rot spores when installed, it should last without problems mostly.
Wings are built the same as fins, From the Cat drwing I would guess anything before 1988 is the same. Dave

Edited by - Dave Laux on 02/05/2005 08:24:07

Leon Sisson
Master Marine Consultant

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USA
1889 Posts

Response Posted - 02/05/2005 : 09:46:45

Derek, listen to Dave Laux carefully. He has the very knowledge and experienced you need in this situation. He has provided your counter-alarmist input.

Also a bluntly stated opinion of Git-Rot etc. I fully agree with.

I like the core samples idea a lot.

Dave, is there 1.5 oz glass mat available that's compatible with epoxy resins? I'm under the impression that mat is held together with a chemical binder that dissolves harmlessly in polyester resin, but interferes with the ability of epoxy to adhere to the mat fibers.

-- Leon Sisson

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 02/05/2005 : 10:31:14

Leon,
There is a lot of mat that is stitched rather than glued together and works fine with epoxy. The old stuff actually worked all right it just looks wierd . For this repair if done as Cat recommends you could use polyester resin with no problem. It would be cheaper, you are going to use about a gallon of resin to do this, and you can gel coat it which you cannot do with epoxy.
BTW I do not think that the application of styrene monomer to the existing resin will do anything. Sand until its 75% plus clean surface with really coarse (36 grit) cloth back discs and laminate. Another advantage to poly resin is keeping the bolts clean will be easier.
I would also think about lifting the boat off the keel and recaulking if you did all the rest of this. Dave

Edited by - Dave Laux on 02/05/2005 19:33:23

Dave Laux
Captain

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318 Posts

Response Posted - 02/05/2005 : 10:38:19

Thanid
Where are you?
Dave

Edited by - on

thaind
Navigator

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Canada
145 Posts

Response Posted - 02/05/2005 : 12:22:27

Thanks for all comments.

Dave, I am in Prescott, Ontario along the Saint Lawrence in Canada, but my boat is in my classroom in Kemptville Ontario ( glad that my Director doesn't read this forum). I totaly agree with your approach and am there now looking at things. First step however in process should read:

"Take saw and cut 12X72" hole in cabin sole, otherwise following steps are not possible."

An other option might be to simply dump a gallon of antifreeze into the bilge each autumn, but I do believe in solving problems once.

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 02/05/2005 : 18:22:33

Derek,
We are usually on Lake Huron from early July thru late August. Would enjoy seeing you for the Trailer Sailor Cruise which if memory works starts July 16 in Spanish.
Actually you might want to cut the whole sole out. I did on our wing keel boat and have a much more civilized cabin with head room almost every where and a level sole with no humps or bumps. It all goes in at about the level of the area in front of the stove.
Are you sure that the keel bolts are crushing the inner glass layer?
What sort of class is this? Dave.

Edited by - on

thaind
Navigator

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Canada
145 Posts

Response Posted - 02/05/2005 : 22:36:51

I teach a course at the Secondary level called Design Technology where we deal with designing, fabricating, and testing solutions to various problems. It is a kind of amalgamation of most Broadbased Technologies, and I therefore have almost every type of wood/composite/metal equipment available except CNC.

I perforated much of the ply area with 1/8" holes to see what I was dealing with. All of it was moist although only one area about the size of a postcard (and strangely the most accessable) has been found to be black. Most of the washers beneath the bolts are sunken flush with the fiberglass, and most of the top glass has hair cracking. I will see what I can do to post photos.

It is beginning to sound like a lot of work and I hate to do anything that isn't an improvement, but the idea of solving this problem and ending up with a Teak and Holly sole does have merit...

Edited by - thaind on 02/06/2005 11:44:55

Dave Laux
Captain

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318 Posts

Response Posted - 02/06/2005 : 07:40:42

Thats what we have. Teak and holly with a 9 by 70 lift out panel for bilge access. Level with a gentle curve up to the head sole. Its about 3 inches lower in front of the port seat and more than that in the aft starboard corner. Dave

Edited by - on

thaind
Navigator

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Canada
145 Posts

Response Posted - 02/06/2005 : 11:49:53

I have posted the following as I felt obliged to.

Received on:2/4/2005 @:10:29:00 PM
referring_form: tech support request

I have a 1978 Catalina 25. These boats feature an 1800 lb keel bolted with eight bolts (1,2,2,2,1) to the fiberglass hull. At the bolt through location there is a plywood stiffener glassed on each side, the inside of the hull being the bilge. The nuts are seized on the bolts but seem solid. Inevitably water has seeped from the bilge
into this sandwiched ply area,has frozen in the winter causing a myriad of cracks in the bilge, and the plywood is now black and damp. I have perforated the area with holes to promote drying. I assume that the plywood is in reality more of a thickener than a stiffener.

I could either dry the area as well as possible, soak with thin epoxy to stabilize and seal all with epoxy, or, remove all plywood leaving bolts proud, and reinforce complete area with epoxy and mat until original thickness is restored.

My question is whether you consider any epoxy suitable for the repair
following the first route, or if the more arduous second strategy (or
another which you may have}is in order.

Your first approach should work. Use the 105 Resin and 206 Slow
Hardener. After saturating all the holes and wetting the dry and
50-grit sanded surface with the clear epoxy, thicken with #403
Microfiber to fill all gaps. You could cover with several layers of
glass if you can; that would'nt hurt the situation.
Gougeon Brothers, Inc.
100 Patterson Ave., PO Box 908
Bay City, MI 48707-0908 U.S.A.
tel: 866-937-8797
tel: 989-684-7286
fax: 989-684-1287
URL: www.gougeon.com or www.westsystem.com

I appreciate all assistance that this forum has given me, and don't realy know what I'll do untill I drill the core as suggested tommorrow.

Thanks again

Edited by - thaind on 02/07/2005 20:25:00

Dave Laux
Captain

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318 Posts

Response Posted - 02/08/2005 : 07:15:40

If the ply is rotten and collapsing this does nothing to fix the problem. If the ply is sound it seals out the air required for it to get rotten and will atleast slow down the decay proccess. Dave

Edited by - on

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