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View Full Version : Real question re: deck beam repair



Concordia...41
11-21-2006, 05:09 PM
I've pretty much made my decision, but would like opinions while there's time to change plans if my decision is really dumb.

There are pictures of Sarah from the 60's with a wheel and binnacle, and I just assumed the plate in the center of the cockpit was a cover where that hardware was removed.

http://www.imagestation.com/picture/sraid219/pa665f0369c1d1b269a3b82a593e7a339/ebf48325.jpg

Well, during the survey we ascertained that the plate was dual purpose - to cover the old hole and have a base for a cockpit table. All well and good, except for the damage to the deck beam below.

http://www.imagestation.com/picture/sraid219/p517468053680b5a12b711ea80a340e64/ebf48395.jpg

I have no idea why James didn't replace this when the cockpit floor was out and on the shop table, but he didn't and I'm left dealing with it.

I know that the correct repair would be to remove and replace the beam but:

a. making a new beam is beyond my ability. It has a convex compund curve and removal of the whole piece intact is going to be problematic because in addition to the 20ish deck screws, either side has a formidable looking bolt, which much be hidden below the outermost trim in the first photo. As one thing leads to another, this might lead to having to replace the "reverse quarter round" that trims the outside of the cockpit floor. Also waaaaaay beyond my ability.

b. even if I chose to tackle it, it is a 2-4 day project (easily) and averaging a day and a half a week at the warehouse, a 4-day project could add a month to the job. Picking my battles has become an integral part of the process.

Now if advice is to replace it no matter what, I can hire it done. There is some work - some damage on the rudder that Paul Haley pointed out comes to mind - that I am going to bring someone in for.

Picture 2 isn't current the bolts are out and just the gaps and damage remains. All other deck beams - especially those immediately fore and aft are fine and the cross pieces that support the cockpit front and back are new.

My plan: Build a dam under and in front of the damaged area and fill from the top with CPES and epoxy.

What say you? Seriously, I'm interested in your thoughts.

Thanks!

- M

Edited to add the most recent picture I could find:

http://www.imagestation.com/picture/sraid207/p37fcac5b3117015d3648e76560d185b2/ee929d4e.jpg

Note, 4 pieces replaced on starboard, seams reefed, hole from cockpit table base filled, and most areas refastened.

Peter Malcolm Jardine
11-21-2006, 06:04 PM
I might consider sistering a small piece of oak along both sides of the beam.... as in 3/4 thick and about, judging from the picture, a foot to 18 inches long. I would cut them to size roughly, then fit them with a hand plane, then glue and clamp them to the beam. Then a dam underneath and fill the holes. Just some extra strength without making it a huge job.

Canoeyawl
11-21-2006, 06:06 PM
It appears that the bolts are slightly off center on that beam. I would chisel out the bad section and scarf in a “Dutchman” This may involve removal of some bungs and refastening from above. At the very least I would just poison it w/cuprinol and leave it to drain.
The damage may extend along the top of the deckbeam and I would not want to trap any condensation moisture by adding an epoxy patch.

Bob Smalser
11-21-2006, 06:09 PM
Both holes appear to substantially off center, leaving plenty of meat still in the beam.

Perhaps the scale is misleading, but the beam also appears larger than the task requires. If there was no deflection, I might do what you propose, but I'd add fabricated SS plates extending outboard around 8" from each bolt hole and sandwich the beam in steel held by 4 bolts.

Call your local welding/steel supply or rebar supplier servicing builders and ask who fabricates steel connectors locally. They'll recommend bolt size and spacing based on building codes, which will be more than sufficient for your purpose. Bed the plates and bolts after priming the plate area with red lead.

GregH
11-21-2006, 06:09 PM
I'll second the motion for the sister act- but would consider applying some sort of rot-stop material to the original before applying the sisters.

Ken Hutchins
11-21-2006, 06:10 PM
What PMJ said, sister in a piece.

Dan McCosh
11-21-2006, 07:30 PM
I can't see if there is reasonable clearance both sides of the bolt holes, but I would scarf in a dutchman on the beam itself, and reinforce it with either steel plates a la Smalser, or wood sisters. It looks as if there is room to do a decent scarf, even without reinforcement.

paladin
11-21-2006, 09:42 PM
and...if you're gonna sister it, you could do it in place with some precut laminates....

Jay Greer
11-21-2006, 11:32 PM
Just looking at the beam leads me to believe that, although is is suffering from iron sickiness, it is not rotten. If you can stick a ice pick or a knife into the wood and find that it is solid, you can get a way with a treatment of oxolic acid to remove the iron oxide, followed by a treament of a base such as ammonia or a soda saturation. Once thoroughly dry, acetone will remove moisture, a penetrating epoxy can be applied, followed by adding a sister frame to support the load of the weakend frame.
Good Luck,
Jay Greer

donald branscom
11-22-2006, 03:38 AM
I would just put wood dowels in the bolt holes and sister the beam on one side.

Concordia...41
11-22-2006, 05:47 AM
Thank you gentlemen. I like the idea of a sistering repair in addition to the epoxy. The rest of the beam is solid, the only damage being where the bolts were drilled through - or worked out the side.

Actually I'm looking forward to trying it. I was running everything through my mind before I got out of bed, and I think I can pull that off - whereas the subtle curve of a few degrees over about an 8' span I'd of never gotten right (or close). :o

It'll be next week before I have warehouse time again - Thanksgiving company and everything, but I'll keep you posted.

Thanks again!

- Margo

Andrew Craig-Bennett
11-22-2006, 07:33 AM
That looks familiar...(DAMHIKT)

Looks like half the beam is still good, but for that much corrosion to have taken place there must have been some water seeping down, so don't be too surprised if you find that you have "gutter syndrome" (three visible sides of oak deck beam OK, top and middle quite rotten).

I would do my best to get the bolts out then chisel back to clean wood and glue in a dutchman, and sister as Bob recommends.

Canoeyawl
11-22-2006, 10:47 AM
Using the scarfed Dutchman as a “sister” the beam will be dimensionally the same as original and you should not need any other parts. I would use epoxy on the scarf joint and bedding compound at the deck to beam joint with a couple or three (bronze) fasteners at the neutral axis (centerline, fore and aft). This will mostly prevent gluing the planks to the deck beam, which would be inconsistent with the original build. Gluing of traditional cross grain construction (deck to beam) is generally a bad idea.

nedL
11-22-2006, 12:38 PM
As if you don' thave enough suggestions Margo I'll toss in my .002 :D I agree that I'd sister it (using fairly small diameter through bolts - on the centerline as has been suggested - so as not to waken the beam). Personally I'd probably stop there if there is no bad wood. I would clean things up & throw on some varnish to seal the wood. This area should not be subject to routine wetting, so heroic measures to seal and encapsulate things will not gain you anything. Cosmetics isn't really an issue here, and I think anything else is pretty much for cosmetics sake. I wouldn't want to remove any more material from the beam which would only weaken it further (unless a long dutchman, basically a long scarfed in section were fitted in place - I think this is overkill). Personally I don't think I'd even fill the holes with any kind of epoxy mix. It won't add strength & will tend to cover up possible signs of early decay in the future which could otherwise have been caught. Good luck and have fun. :)

JimConlin
11-23-2006, 11:27 AM
The beam was originally oversized to support a point load that's no longer there, so it could still be OK if its strength is somewhat compromised by the errant bolts. If the beam is not significantly softened at the top and the structure doesn't feel soft, I'd not feel the need for a structural repair. See Smalser's counsel re chemotherepy above.

From the top side, the four smaller holes can be treated with teak bungs. If one falls on a seam, use your fine Fein saw or a router to burrow a groove. The larger hole can be treated with a glued-in dutchman or, if you're not up to that whittling, any one of us could make you a tapered teak bung of the dimensions of your choosing. An alternative would be a small bronze deckplate. If someone asks, tell 'em it's the fill for the rum tank.

Concordia...41
12-14-2006, 07:41 PM
OK gentlemen I'm done. Actually, I was done a week or so ago, but hadn't had time to update the thread.

Primary motivation now is to say thanks and let you know that I used the advice given here and that it came out wonderfully (to me).

Essentially I followed PMJ's suggestion (and GregH, Ken Hutchins, donald brascom and nedL votes for sistering), and sistered a 3/4" piece, built a dam underneath and filled the holes. I followed Bob Smalser's instruction to measure 8" out from the damage (14" width including discolored areas) so the piece came out at 30" x 2 1/2" x 3/4". As some of you have caught on, I have someone that is helping me and he actually cut the piece and scribed the curve, but I now know how to do it and I ended up doing a second beam repair (more below).

Following GregH's and Jay Greer's points (and my own personal policy), I CPES'd all surfaces - including filling from the top to hopefully address the "gutter syndrome" mentioned by ACB.

I also doweled the holes per donald branscom (I'd planned to do that anyway, just forgot to mention it in the first post).

The holes in the deck are filled from above (James had already made a plug for the large hole) and - as Jim Conlin suggested - if anyone asks, I'll tell them it's the old fill for the rum tank :D

The problem:

http://www.imagestation.com/picture/sraid220/p9e3b92c26efdeb48238944dfc573ff85/eb9e83d6.jpg

The solution:

http://www.imagestation.com/picture/sraid220/p2489bb3075ab6880de57ab478a9d5c69/eb9e8124.jpg

And yes, even though it won't show (once the engine is in, the area is virtually inaccessible) I cleaned it up some with the sander and knocked off the epoxy drips. And yes, there's two screw holes there on the left. My first attempt wanted to occupy the same piece of real estate as a deck screw so filled hole and went a bit farther out.

There was also a repair done by James where a beam had been actually cut out for the engine controls. I was startled to say the least when I saw this :eek:. (note picture is reversed)

http://www.imagestation.com/picture/sraid220/p04f7cc410636a4bbd61fa21c1e5c2fa5/eb9e7618.jpg

Using the information from this thread, the remainder of the 3/4" board, and my new-found curve scribing skills, I knocked out the three bolts James had through the piece and sistered that beam also. I'm telling you folks, I'm on a roll... ;)

http://www.imagestation.com/picture/sraid220/p897d6b0b3ecba068d1a66721045fe26d/eb9e80e4.jpg

Anyway, I still plan to bring the bolts back through the second sister (should I bolt the first one in addition to the screws and epoxy?) but that's it for project #858b of 15,000...

(YES I know I have some major issues visible here. The plan is to finish the cockpit floor and bridge deck this month and then spend January and February back under the cockpit :()

Thanks all. You're the best!

- Margo & Sarah

Peter Malcolm Jardine
12-14-2006, 10:06 PM
The deck beams on that boat could support a small train.

Bob Cleek
12-15-2006, 12:15 PM
Well done! One of the benefits of working on a "gold plater" is that they are overbuilt. There lots of strength there. Not to worry!

nedL
12-15-2006, 12:23 PM
Great job Margo! That will last longer than any of us could ever need. The best part is now you are one step closer to the water again! :)

(I think I'd say you could call it good on that first one & not worry about adding the bolts.)