Cracked Transom

[lumberdude]

I don't really understand why my boat is drying out so much now after sitting for 30 or 40 years in a barn. Maybe the humidity in Missouri is less than northern Iowa. I guess it's also possible that it's getting too dry in my little varnish booth.

At any rate, I have a problem. Cracks are showing up in my transom. How serious is this problem? How do I go about fixing them? They don't appear to go all the way through the transom. It just looks like the grain is seperating as it is drying out.

Should I put a humidifier in my varnish booth? What is the ideal varnishing humidity?

I reeeeeaaaaalllllyyy don't want to replace the transom.

Help!!

lumberdude

[dasboat]

DUDE...I sure hope you can post some pictures.This one should be looked at closely before trying a fix.

[lumberdude]

I will try to round up a digital cam. Maybe by tomorrow afternoon I'll have them up on the board.

[Noah]

Is the transom mahogany or cedar?

In my experiance cedar is very effected by humidity. It will shrink and split!

Also we can forget just how dry the air is in the winter. I'm guessing that your dust free booth is really really dry. I would put a big humidifier in the booth ASAP until you get some kind of finish on the boat.

If it is mahagony I'm surprized that it is doing this, but it could be caused by a laminate construction. Especially if the transom has both horizontal and verticle plys to it. IE the outside running horizontal, and an inside layer running vertically.

Either way, give your boat some moisture. Once it has a coating on it, the moisture movement will be slowed down, and it might not be as big a problem.

Noah

[backyardbuilder]

What kind of boat do you have, and what is the transom material and thickness? Are you talking about surface checking or is it spliting? Is the material sound other than the cracks?

[lumberdude]

The transom is white oak and it looks to be two pieces, I assume glued together. I'm not sure whether this split is the glue joint, or if it is the grain cracking. It's really hard to tell in oak. The grain is so course and straight, I may just be looking at a split in the grain.

This afternoon I put a humidity gauge in the booth along with a humidifier. The initial reading was less than 40% humidity, now it's up to almost 50, and in just a few hours, the water in the humidifier has gone down about 2 inches. Any ideas as to what the target humidity should be?

The boat itself is a 14' cedarstrip with a cedar deck. White oak trim, transom, and frame members. The transom is 1-1/4 thick and seems to be very sound. I'm just worried about a motor hanging on this thing if it has a crack in the middle of it.

I have been noticeing that the 1x2's I built the frame of the varnish booth have been moving around all over the place. If I would have been paying attention to that signal, I might not have had this problem. Duh.

Somewhere in my head I knew it was getting too dry in there, I just kept thinking about how long it had set and I thought all the drying it would do would already be done.

http://www.imagestation.com/picture/sraid28/pcdbb074fe4d5d75784421bc2ea4b6cf6/fe11d3bb.jpg

[This message has been edited by lumberdude (edited 01-05-2002).]

[This message has been edited by lumberdude (edited 01-05-2002).]

[PugetSound]

Looking at your picture, I'd have to agree with Noah. Remember that humidity is Relative to temperature. The same amount of moisture in the air that gives you 80% humidity at 40 degrees (F) will give a relative humidity of mabey 40% at room temperature.

Anyway, I think the important thing is the dimensions of the cracks. If they are hairline thin and going with the grain, then I would say to just seal the suckers and continue with the varnishing. Personnally I think that the majority of the damage is to the lining of your stomach. Relax, you'll make the right decision and things will work out OK.

[Dale Harvey]

Do not try to run this boat with more than about 5hp without adding a plywood layer to both front and back of transom. Ply should be at least a foot wide and extend at least to waterline outside. Glue with flexible epoxy or bed in 5200 and thru bolt. With 25hp it shoud run to the bottom both sides. A metal motormount plate on the inside would be good if you can clear it in the outboard bracket. A couple of top to bottom 1x4 cleats halfway out to the hull would also be good. Oak is a fairly easy wood to split. You don't want to do it with an outboard!

[Don Maurer]

That looks like a concrete floor. Wet it down with a mop before you start varnishing. It will keep the concrete from absorbing the moisture out of the air and also help keep dust down. If you are using radiant heaters to heat your shop, make sure to keep them pointed away from the boat.

[lumberdude]

Dale, Can I use anything other than plywood?
Maybe something a little fancier? I almost hate to put plywood on this thing. Would a metal plate wrapped around both sides of the transom add some strength? I could have someone weld up something custom to the boat.

I'm only planning on putting maybe a 10-15 hp max.

Thanks everyone for the posts. I'll try to get some detail pictures later today.

[Smacksman1]

Why spoil a nice boat by slapping chunks of ply on the transom. We are talking 1 1/4" oak here. The bigger consideration for big hp would be keeping the oak tramsom attached to the rest of the hull.

[lumberdude]

I guess I should be asking, what size motor should I have on this? It's pretty light, so I don't think it will take much to move it. Of course, I've never had it in the water, so I have no idea how it sits.

The fasteners and strips seem solid where the transom attaches. There are already some 1x4 oak cleats from the top to the bottom, and a center brace with a bolt through the keel. It should be okay.

[lumberdude]

Heres a pic of the infamous crack. It's just big enough for my fingernail to get in there.

Let me know what everyone thinks about this.

http://www.imagestation.com/picture/sraid28/pe4e30a47c8e526cb8eac89b0af31b2d3/fe04eea7.jpg

[Ian Wright]

Originally posted by lumberdude:
http://www.imagestation.com/picture/sraid28/pe4e30a47c8e526cb8eac89b0af31b2d3/fe04eea7.jpg

Oil,,,,,,, Varnol or even Deks Oljie four or five thin soaking coats, turn the heat down, then Varnish,,,,,,
IanW.

[HizzenanHern]

I agree with Smacksman! What a beautiful little boat!

I think my attack would be to clean out the crack with a very fine knife blade, doing my best not to do any "carving" at all; then apply painter's masking tape across the crack at though to hide it; then, using a syringe, inject West System into the crack through the tape, injecting at maybe 1/8-inch intervals, then applying another layer of tape to keep the West System from running out (one trick will be a lot of care not to inject so much that very much runs down the outside of the tape). A very small amount of refinishing should finish the job and leave a virtually invisible repair.

If the transome is well attached to the rest of the boat, and the whole boat is strong and sound, I wouldn't hesitate to use 25 to 35 hp. These motors are not any heavier than the 10s and 15s being manufactured when this boat was built, and you don't have to run them wide open ALL the time. . .

[HizzenanHern]

Just took a second look at the transom picture. What's with the darker wood along the bottom? Any problems there?

[HizzenanHern]

Just took a second look at the transom picture. What's with the darker wood along the bottom? Any problems there?

[HizzenanHern]

Originally posted by HizzenanHern:
I agree with Smacksman! What a beautiful little boat!

I think my attack would be to clean out the crack with a very fine knife blade, doing my best not to do any "carving" at all; then apply painter's masking tape across the crack as though to hide it; then, using a syringe, inject West System into the crack through the tape, injecting at maybe 1/8-inch intervals, then applying another layer of tape to keep the West System from running out (one trick will be a lot of care not to inject so much that very much runs down the outside of the tape). A very small amount of refinishing should finish the job and leave a virtually invisible repair.

If the transom is well attached to the rest of the boat, and the whole boat is strong and sound, I wouldn't hesitate to use 25 to 35 hp. These motors are not any heavier than the 10s and 15s being manufactured when this boat was built, and you don't have to run them wide open ALL the time. . .

[HizzenanHern]

Originally posted by HizzenanHern:
I agree with Smacksman! What a beautiful little boat!

I think my attack would be to clean out the crack with a very fine knife blade, doing my best not to do any "carving" at all; then apply painter's masking tape across the crack as though to hide it; then, using a syringe, inject West System into the crack through the tape, injecting at maybe 1/8-inch intervals, then applying another layer of tape to keep the West System from running out (one trick will be a lot of care not to inject so much that very much runs down the outside of the tape). A very small amount of refinishing should finish the job and leave a virtually invisible repair.

If the transom is well attached to the rest of the boat, and the whole boat is strong and sound, I wouldn't hesitate to use 25 to 35 hp. These motors are not any heavier than the 10s and 15s being manufactured when this boat was built, and you don't have to run them wide open ALL the time. . .

[lumberdude]

The darker wood at the bottom is just the edge of the cedar strips you're seeing. No rot anywhere on the boat!!

[Concordia41]

Sarah's transom has some you could put a dime (or worse) in. Actually seperating between planks. Maybe I was just hearing what I wanted to hear, but when I hit the panic button and posted the question, the general opinion was that she'd swell back when [someday in this lifetime] she finally sees the water again.

You are doing an amazing job by the way http://media5.hypernet.com/~dick/ubb/smile.gif

[steve sparhawk]

Nize bote, lumberdude.

These things were not intended to be run hard. The round bilges won't let you get her too fast before getting squerrily. A ten horse will be a handful. I have a similar model of about 12 feet built in Alexandria, MN in 1940. I put an old Merc on it and noticed it had too much wetted area to get up and really go without me getting nervous. They were built for fishing.

A great little classic. Find an older 40s motor and complete the image.

Let us in on any developements.

[Dale Harvey]

I see the cleats now, and they are good. My concern would be for the force and twisting moment applied above the center brace on the old oak. A pair of nicely shaped 1/4" aluminum plates well bedded in 5200 would be fine, and would not look overly out of place on an outboard boat. If you have a wide enough sprayrail just above the turn of the bilge, these round hulls can get up an go quite well.

[Alan D. Hyde]

I like the boat lumberdude; congratulations on a good job.

The small cracks will possibly close by themselves with more humidity; I personally wouldn't put epoxy or anything else into them that would keep them from closing. If you do, and humidity DOES start to close the cracks, then you will have inserted a wedge.

I second Dale's comment on the spray rails: they can make a big difference.

Alan

P.S. Dale's also right about the aluminum plates on older boats like this; the ones we had were made of 1/8 inch "half-hard" aluminum.

[This message has been edited by Alan D. Hyde (edited 01-07-2002).]

[TerryH]

Dale's concern is very real, have had experance in this area. Remember that the twisting force that Dale talkes about is 18" above the attaching point, at light loads the force will be low and of short duration, but with a heavy load, three adults and gear the load on the transom will be much higher and longer.

My solution would be to take boat out with light load and watch transom closely, if you see any flex then take the approate action, otherwise don't change the lines/apperance of a beautiful boat.

[TerryH]

Should be 18" below attaching point.

[lumberdude]

Thanks again for all the suggestions. I'll admit I went a little googly when I bent down and saw that crack. I'd seen that spot a thousand times and I knew it wasn't there before.

I've got a humidifier going in there now, and I have a feeling once the humidity gets up there, it won't be so much of a worry.Thanks to all for easing my mind. It's amazing how attached we get to these boats!

[imported_Ola Sylwan]

The boat is clearly built to carry an outboard.
1/8" aluminum plate is not much better than tin foil for stiffening your transom. Aluminum that thin can be bent, in my hands at least, try yourself before you install anything. It will protect the beatiful woodwork from the engine clamps but then you can´t see the wood.
Don´t use 5200, you will hate yourself in the future.
Good luck and don´t worry, your transom will not fall apart.

[Alan D. Hyde]

OlaS-------

It's been many years, and I was perhaps 10 years old at the time, but I don't think the aluminum plate was much more than 1/8". It was, however, if I recall correctly, "half-hard."

Someone here will know more about that than I do, but I don't believe it could be bent with the hands.

Anyone remember the stuff I'm talking about?

Alan

[imported_Ola Sylwan]

Alan.
I will back down a little http://media5.hypernet.com/~dick/ubb/redface.gif. I tried to bend a 1/8" thick aluminum flooring plate that I have lying around. It was approx. 15" long and 12" wide with a 90 degree bend on the long edge. It did not bend, but flexed quite a lot more than than a two foot long piece of 3/4x2" ash.
If you compare this to Lumberdudes 1 1/4" oak transom you may see what I am getting at.

Lumberdude, don´t mess up your beautiful boat with unnecessary repairs. Boatbuilding is not rocket science. A sprinkle of water now and then on the floor will do wonders for your cracks as Don said. Borrow a 5-10 hp outboard when you are waterborne and do some sea trials.
More power=more speed=more fun is not always true.
Good luck. Ola.

[rickprose]

lumberdude,
just to throw in my 2 cents - don't put 5200 anywhere near a wooden boat for any reason and don't muck up your transom with plywood. If this boat's been around a while, it's been run with a motor, and, obviously, the transom hasn't fallen off yet.
Also, don't worry about the small check in the oak, that's normal, it's what wood does when it gets too dry. By all means don't squirt epoxy into it, because if you do, here's what will happen - epoxy is hard and doesn't shrink or swell, wood does; when the wood swells up with increased moisture, the edges of your little crack will be crushed against the unyielding epoxy, the compression will ensure that the crack never swells as tight again. so, you'll put more epoxy in it, then the process will just keep going, swelling, crushing, bigger and bigger crack, more epoxy.
Repeat after me, "Epoxy is glue, not a universal panacea, epoxy is glue..."

[lumberdude]

Everyone is mentioning 5200, should I not use that to caulk along the keel? The keel is the next project after the varnish is done. Then fairing compound, then primer, then paint.

What do I use on the keel?

[steve sparhawk]

L-dude, don't go teasing the esoteric among us with that 5200 ploy. I know you are just trying to get a rise. http://media5.hypernet.com/~dick/ubb/smile.gif Standard seam filler - if it won't close with moisture. At least the seam filler will squish out if it gets pressure.

I used 5200 on mine and the "traditional" police showed up before I ejected the cartridge.

[rickprose]

l-dude, i repeat, don't put that nasty 5200 anywhere near your boat. period.
i rebuilt an old town runabout a few years ago, very similar in style and construction to yours, and there wasn't a bit of synthetic anything in it to keep the water out, it was all accomplished by swelling wood sealing the seams. i did use a little slick seam along the garboard seam to fill up any open spots, knowing that it would be squeezed out when it took up, since this boat had been dry for twenty years or so.
so, put down that long white tube, my friend...

[imported_Ola Sylwan]

I seem to remember that boats were built before the advent of miracle stuff like 5200 and Googe.
They were made to float, not by the application of prayer, but by the use of tallow and similar esoteric products.
If you can´t get tallow you could try margarine, it will stay in the seams until they take up.

[DragonFly]

Wanted to add my own two pence worth about the motor mount. Knowing that the transom is oak with the grain running horizontal I would be a bit worried about mounting a heavy engine on the stern.

I had a small 5hp motor on the stern of a J-24 snap a plastic block off when I cranked her up to get into the dock. Now I didn't goose her all at once, but it wasn't slow like my grandmother either. Luckily I had my hand on the motor and was able to grab the handle before it became a fish haven. Must say the Japanese motors do run great half submerged. Chewed up the stern a wee bit but it's a plastic boat, fixed easy enough.

I agree with the comments about putting some type of re-enforcement on the stern. Don't use 5200 on the stern though. That stuff is the worst to get off, pretty much impossible.

She's looking great.

[mklein]

lumberdude, ignore this if you've already thought of it or dealt with it, but those cross-grain cleats shown on the interior of the transom worry me. Make sure that however they're fastened to the transom still allows for movement. Beautiful boat, hope you're on the water with her this season. Cheers, Mike.

[lumberdude]

Okay, I'm convinced. I'll hang my two squeeze tubes of wal-mart bought 5200 up in the garage for a momento of what not to use. Now, where do I find the stuff to use? Here in missouri, there aren't alot of wood boat shops.

As for the transom, I've been humidifying my varnish booth since I first posted this thread, and either it's my imagination or that crack isn't as ominous as it first appeared. Other areas seem a bit smaller too.(maybe I've grown?) Anyway, thanks for the advice. Keep it coming!!

lumberdude