Repairing bottom planks - dory skiff

[Thorne]

It's me again!

;- )

After removing the false ply bottom (badly rotted) from the dory and letting the solid fir planks dry, there is some softness in the center plank near the skeg in several spots.

I'm planning on using Smith & Co. CPES (http://www.smithandcompany.org/CPES/index.html) and epoxy fillers, and here's their basic instructions:

Use a wire brush to remove any soft rotted wood from the surface.

Clean with MEK to remove any old glues, paint residues, etc. (outdoors on windy days with a respirator).

Soak wood with CPES, let cure for several days. Keep dry!

Use Smith's epoxy filler and let cure.

Sand flat / fair.

Use a little CPES to coat filler.

At this stage I will then mix up the red lead bedding compound (possibly with Die-al if I can find it and/or convince someone to sell it to me un-mixed with paint). Then I'll cover the bottom planks with this bedding compound, and attach a new marine ply false/sacraficial bottom, then paint.

How does that sound? Don't think the bottom planks are so rotted as to need full replacement, as the softness is mostly just surface (where the false bottom was merrily rotting away in contact with the fir).

TIA

[ishmael]

I don't have much experience with the thin epoxies. But I will say that the apparent rot in a plank is just the surface of matters. Spores and their roots run out from the rotted part.

Without seeing it it's hard to say, but the safe thing to do would be to replace it.

[Thorne]

That is what the CPES is all about -- the bottom plank will be reasonably saturated with it from both top and bottom.

Check out the Smith & Co website and read about it, it seems to be a fairly good method of preserving wood and combating rot. These guys sell a lot of product to Scandanavia for wooden boats, and seem to know their stuff.

Yeah, to be on the safe side I should probably build a new boat -- but instead I'm restoring this one. Since dorys are built around the bottom planks, I'm less than eager to consider that much of a deconstruction process.

With judicious use of CPES, epoxy filler, red lead, Die-al, and a false bottom also saturated in CPES, I hope to bring this boat back and have her last a long time.

None of the above means I don't want advice, however!

;- )

If the bottom plank seems structurally damaged, I might replace it. But if I can treat it so no more rot happens and it is stronger than before, I'll do that thing.

After all, despite all the fun as you can have with things like: building, scraping paint, working with toxic stuff like MEK and CPES, and lifing heavy boats to turn them over -- at the end of the day (or winter) I want to be out on the water in this project boat...

[ 10-13-2005, 06:20 PM: Message edited by: Thorne ]

[ishmael]

I understand. Not seeing it it's hard to say. What you see as a bit of surface punkiness another might see as a board full of rot. Or, it might just be a bit of punkiness that the gunk will fix quite well. Soaking it with epoxy will definately slow it down. I've done it before with framing that was soft, but the owner hadn't the pockets to rebuild.

I'm chary of such fixes because I've seen how often they don't work terribly well in the long run. But it's your boat, carry on.

[Mike Vogdes]

I know CPES is the latest and greatest preservative for anything wood, but... if you have softness in several spots on the bottom planks you should think twice about using fillers to repair the plank.

How far can you sink a screwdriver into the rotted spots?

[Bob Smalser]

Smith's leaves out the part that for a lasting repair, all the soft, rotten wood has to be cut out. CPES is then valuable to treat any incipient rot in those freshly cut ends and adjacent areas of sound wood prior to epoxying in new wood.

Buy completely into their advertising hype, and your boat won't last a season before you'll be repairing it again.


Restoration of wood inside a house, such as in a bathroom, a door threshold or the inner part of a window sill... Smith's was originally developed for restoring old homes, not boats.....your porch column sinking two inches after your Jimbob quickie repair fails ain't the same thing as that plank failing 4 miles from shore in December.

[ 10-13-2005, 07:13 PM: Message edited by: Bob Smalser ]

[Thorne]

Smiths recommends using a wire brush to remove any loose rotted wood fibers, but I haven't gone to that stage yet.

Screwdriver goes in about 1/4" in the few soft spots, the rest is reasonably hard. The soft spots are about 3-4" long and maybe 1/2" - 1" wide.

All the problems seem to be on the bottom surface (where it touched the false bottom), nothing really internal that I've found yet. But I'll take a harder look when I wire-brush out the soft stuff...

[Bob Smalser]

Screwdriver goes in about 1/4" in the few soft spots, the rest is reasonably hard. The soft spots are about 3-4" long and maybe 1/2" - 1" wide. The plank's less than an inch thick.

If there's any soft spot in it at all, the entire thickness is compromized. If you find one with only one or two isolated soft spots about an inch in diameter, then you can use you CPES and filler. Multiple 1"X4" strips of rot require new wood.

Remove the plank, cut the plank through on either side of the rotted section well past the soft spots, plane in scarfing bevels, and epoxy in new wood to match the plank's length...then reinstall.

You can only do one scarf like that per plank....if the soft spots and throughout the plank, replace the entire plank using the old as a pattern.

Repeat for each plank thus affected.

[ 10-13-2005, 08:35 PM: Message edited by: Bob Smalser ]

[Thorne]

Another question about the gaps between the three bottom planks.

The gaps are about 1/8" at their widest near the center of the boat, and were filled with a fairly hard putty-like substance. I've cleaned out this decayed stuff, and am ready to fill the gaps.

Bob, if I've read your posts correctly (and ya never know with us beginners), it looks like a good filler would be the Vulkem 116, since the planks should swell up quite a bit when wet.

Should I just tape the bottom side of the gaps and fill from the top?

And regarding the sacraficial / false bottom -- what quality plywood should be used? It needs to be 10' long, as I'd rather not scarf it due to fears of rot/failure on the joint.

Gardner calls for the false bottom to be made of either a full bottom of plywood or two strips of 1/2" oak. Would a boat with a repaired bottom plank be better off with a good quality ply false bottom bedded in red lead and painted, or strips of oak on just the sides of the bottom planks (which would let the bottom planks dry more completely)?

TIA

[Bob Smalser]

Originally posted by Thorne:
...the gaps between the three bottom planks.

The gaps are about 1/8" at their widest near the center of the boat, and were filled with a fairly hard putty-like substance. I've cleaned out this decayed stuff, and am ready to fill the gaps.

... false bottom -- what quality plywood should be used? It needs to be 10' long...Those gaps, I bet were caulking seams and the decayed goo in there is cotton. If so, it needs recaulking with fresh cotton after soaking in linseed to swell the wood a bit. Check and see if there are bevels in the edges of those planks.

I'd make your false bottom out of 1/2" knotty Doug Fir heartwood as shown. Cheap enuf there and easily available in 10' lengths and longer. Check out the rafter stock at a good lumberyard for resawing.

Never plywood...especially on top of solid.

http://pic3.picturetrail.com/VOL12/1104763/7309305/95249354.jpg

http://pic3.picturetrail.com/VOL12/1104763/7309305/95249350.jpg

http://pic3.picturetrail.com/VOL12/1104763/7309305/95249348.jpg

[ 10-19-2005, 01:01 AM: Message edited by: Bob Smalser ]

[Wild Wassa]

Wire brush? ... try a circular wire brush in a drill, be ruthless. View the boat as a giant tooth and you are the dentist.

If you are using Smith and Co's Fill-It, as the (compression strength) filler? ... don't let it cure for a week before attempting to sand it back, the stuff is bullet proof. I find Fill-It is best sanded/cut after about 17 hrs ... if this is the route that you take?

Warren.

[ 10-19-2005, 12:59 AM: Message edited by: Wild Wassa ]

[Bill Torok]

THORNE:
This may sound crazy but I read where 50/50 antifreeze make a excellent wood preserve and kills rot spores that are sill there. Just spray it on.
:cool:

[ 10-19-2005, 07:36 AM: Message edited by: Bill Torok ]

[Thorne]

Thanks to everyone for the replies.

Bob - no sign of fibers in the white/yellow putty-like substance in the gaps, and no modification of the edges of the planks. Looks like they just puttied in something and then put resorcinol glue on the bottom of the puttied gap before attaching the false ply bottom.

Is the Vulkem 116 a good choice to fill the gaps in the bottom planks?

Do you recommend treating the false bottom fir planks with anything, or will the Die-al and red lead bedding fix any issues with rot between it and the fir bottom planks?

And is that "stem shoe" (or whatever it's nautical name) shown in your lower picture available commercially, or do I need to fab something up? My dory has two bolt ends with nuts projecting slightly through the bottom planks at the stem end, so protecting them is a good idea.

http://www.luckhardt.com/stembolts.jpg

Wild Wassa -- yeah, bought one and used it. Just had a crown fitted, so enuf with the dental analogies, y'hear!

;- )

I am using that material from Smith, so will take your advice and hit it with the belt-sander a bit early in the cure. Already blew out the old palm-sander on this job.

Bill -- I have cats and a dog that likes sweet stuff, and so am afraid of using the anti-freeze method for fear of poisoning the little furry darlings. I'll also admit that I'm more attracted by oiling the wood than anti-freezing it if I need to swell it up.
http://www.woodenboat-ubb.com/ubb/ultim atebb.php?ubb=get_topic;f=1;t=011750 (http://www.woodenboat-ubb.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=011750)

I understand the risks of working on a wooden boat fully dry, but since this boat will be dry-sailed in a hot and dry climate, I'm guessing that it is best to work it dry and just use materials flexy enough to handle the changes.

[ 10-19-2005, 09:45 AM: Message edited by: Thorne ]

[Bob Smalser]

Hmmmmm....shoulda had caulking seams but doesn't.

Sounds like that's why they used a plywood false bottom instead of solid, relying on the goo between the planks and the plywood bedding to make it all relatively watertight. Not a good practice.

You've two choices....one is to duplicate what the original builders did, using a poly sealant both between the seams and to bed the edges of the ply false bottom. Not the best choice, but it'll work for a while.

I'd leave the bottom assembled, saw in caulking bevels with a non-carbide cirular saw blade with the teeth reground, tapering to a point, using one pass down one side of the seam. Saw depth set to cut thru 2/3rd's of the plank thickness. Then I'd probably batten the back of the seams with 1/2 X 2 strips of Doug Fir for insurance, then caulk the seams after soaking them in raw linseed fro a few weeks to swell them. I've done this before successfully.

You could also use a router to make these cuts. The idea is to get a bevel in one plank edge of every two that mate, then pound cotton in there with a caulking iron so as to tighten the bottom outwards against the garboards and bottom cleats to make it watertight. All that without pounding the cotton all the way through the plank seams....and here the batten will help.

[Invader]

New to the list so please excuse me if I am speaking out of turn.

For rot I do some stuff I am not seeing on these boards. So I am going to spit this out but I might be repeating logs I have yet to read.

I use this for small sections in solid timber or ply that are starting to go south.

First I get out the drill and find out how far it has travelled.

I drill holes every two inchs or so along the plank or around the affected area. Untill I find sound wood again.

I then soak woth acetone several times and then give the acetone a couple of days to dry off.

I use cold cure mixed and then add about 1/3 more acetone to the mix. I will use a small seringe to inject the plank and continue untill the wood will not take the mix any more.

Wait a day or two and repeat again. Then wait a day or two more and the wood will be sound again.

I find epoxy breaths well and works with wood.

For the surface bacteria ( white kinda poweder )I brush acetone on wait a bit and wipe off. Again I have yet to find a bacteria that will live through acetone.

Be carefull with this stuff and make sure its use is in a well ventilated area cloves etc.

To fill the holes or to fair in the repair I will add the poly filla dry mix to the cold cure to make up a paste or fairing compound.

I find cold cure with acetone makes a great sealer before you epoxy or paint etc.

My two scents ?

Willy
Invader No 1
39 Kishi Conversion

[Thad Van Gilder]

Um, well, I have never found epoxy quicky repairs in solid wood to last through many launchings...

As far as planks without outgauge or whatever you want to call it (room for cottom), I' have worked on a couple of dories without them. They are like garveys In that they are meant to be kept swelled shut, and they leak a lot in the spring. They is never anything in the seam though... I guess someone could have tried to caulk her up tight and the cotton turned to goop in time.

I second the idea that they plywood is a bad idea. cheap doug fir, or oak, or whatever, about 1/2 inch thick is much better.

-Thad

[Thorne]

Thanks again for the prompt assistance!

Bob and Thad -

Any sort of treatment suggested for the false bottom planks made of fir (including linseed oil)? Or will the red lead and Die-al bedding fix any issues of rot between the false bottom and the real bottom? Should the false bottom planks be painted or left nekkid?

Also, if I put on the false bottom planks before caulking, won't that eliminate the need for a batten on the bottom of the gaps?

One last repeat - the metal shoe/plate/thingie in Bob's photo -- can it be purchased or should I make one, and if the latter, what material? I like the idea of extra protection for the stem edge of the false bottom.

[ 10-19-2005, 06:02 PM: Message edited by: Thorne ]

[Bob Smalser]

Originally posted by Thorne:
Any sort of treatment suggested for the false bottom planks ...

...if I put on the false bottom planks before caulking, won't that eliminate the need for a batten on the bottom of the gaps?

... the metal shoe/plate/thingie in Bob's photo -- Red lead primer followed by alkyd paint on the wear surfaces.

Caulking has to be done from the outside in before the false bottom goes on. You can try it without the battens, but one of their primary purposes is to hold the linseed in the seam so it swells sufficiently for you to bring tight with the cotton. You can't caulk unless the back of the seam is closed.....if it's open significantly, then the fix is a wedge filler glued to one plank only.

The skid plate is fabricated from either SS or silicon bronze sheets available at Alaska Copper or McMaster Carr.

[ 10-20-2005, 01:17 AM: Message edited by: Bob Smalser ]

[Thad Van Gilder]

I'd use dolphinite bedding compound between the outer bottom and the bottom planking.

and I find bottom paint doesn't stick to well to red lead . I usually put bottom paint on bare wood.

-Thad

[Thorne]

Cool!

Bob, I've ordered a drain and plug (from Jamestown) as you recommended in an earlier thread, altho it will go near the bow as the way the trailer is built means the bow is often the lowest part.
https://www.jamestowndistributors.com/woeimages/00006389.jpg

Any tips on how to bed/seal the open end of the drain? Easy enough to just seal it around the real and false bottom with polyurethane adhesive lke Vulkem 116.

As for the skidplate, the wife works for Seaport Stainless, so I suspect that the guys in the shop can fab me up something nice out of scraps.

;- )

Thad - I'll probably try your suggestion of Dolphinite and add the Die-al, as red lead bedding compound isn't available here, and I've already placed my order with Kirby's for red lead primer. The boat will be dry-sailed, so I won't use bottom paint, just regular marine enamel.

[ 10-20-2005, 02:41 PM: Message edited by: Thorne ]

[Bob Smalser]

First, adjust your trailer so it both fits the boat and allows easy launching and recovery. A heavy boat can easily sag out of shape on a poor-fitting trailer. Flatbottomed dories can have their bottoms ride on flat rollers bolted to the trailer backbone with the garboards supported by the trailer bunks. A stem roller forward stops the boat, ideally with the flat bottom dead parallel to the trailer frame. The height of the bow, then, is controlled by the tongue jack, and you can place the drain in the stern where it is easily accessed in an emergency.

Many boats have their drains in the garboard....on dories, I like them in the bottom for more thorough draining. Your choice....just put it where it isn't easily kicked.

http://pic3.picturetrail.com/VOL12/1104763/7562968/99128122.jpg

Position it so you don't drill thru a fastener. In solid wood, the hole should be sized for a slightly loose fit, the hole painted with red lead, and the hardware installed with bedding compound. In plywood, the hole should be double drilled so as to line it with epoxy.

Red lead is a toxic, fungicidal paint available from Kirby's in Mass or you can buy lead tetra-oxide powder from a chemical supply house or fireworks manufacturer and mix your own primer from 50-50 linseed-turps, enough powder for a goo orange color, and Japan Drier. Copper bottom paint available at any marine store is a second-best substitute to prime faying surfaces.

[ 10-20-2005, 04:46 PM: Message edited by: Bob Smalser ]